Daikin VRV systems in hot humid climates

[NB34]

Hello I am trying to gain an understanding of the Daikin VRV equipment because it is starting to become a player in the Southeastern United States market, and in particular the Florida market. After reviewing the marketing and engineering documentation and going through the Daikin marketing presenatation I have a couple questions for someone who has acutally had experience with this equipment.
For cooling applications:
1) Do the indoor units have variable capacity? For a 1 ton indoor unit, does it have the ability to operate at a capacity less than 1 ton if the load in the room does not warrant 1 ton of cooling?
2) Is it true statment to say the evaporator fan for each indoor unit is constant volume and does not automatically change speeds with the electronic expansion valve while in the cooling mode?
3) If the answer for question one and two is yes, isn't there a large possiblity that the CADP will be greater than the entering air dew point (assuming the entering air conditions are equal to the room conditions)?

If this is the case I do not think these are a viable solution for hot-humid climates, especially if the indoor units are oversized.

[nike123]

They are effectively control humidity with integrated dry function!

[mchild]

Hello I am trying to gain an understanding of the Daikin VRV equipment because it is starting to become a player in the Southeastern United States market, and in particular the Florida market. After reviewing the marketing and engineering documentation and going through the Daikin marketing presenatation I have a couple questions for someone who has acutally had experience with this equipment.
For cooling applications:
1) Do the indoor units have variable capacity? For a 1 ton indoor unit, does it have the ability to operate at a capacity less than 1 ton if the load in the room does not warrant 1 ton of cooling?
2) Is it true statment to say the evaporator fan for each indoor unit is constant volume and does not automatically change speeds with the electronic expansion valve while in the cooling mode?
3) If the answer for question one and two is yes, isn't there a large possiblity that the CADP will be greater than the entering air dew point (assuming the entering air conditions are equal to the room conditions)?

If this is the case I do not think these are a viable solution for hot-humid climates, especially if the indoor units are oversized.


I just had a Daikin VRV-S installed in my home. Haven't been through a summer yet, but I had similar concerns as you as I am located in the mid-Atlantic states. While not as humid as Florida it is an issue.

The indoor units are variable in capacity in both heating and cooling. I have been told by a Daikin engineer that they will function all the way down to 10% of the nominal rated capacity. So, for your 1 ton unit that would be as low as 1,200 BTUs.

I have also been told by the pros on this site and by Daikin that they do a superior job with dehumidification and that I will probably never put the system into Dry mode. This is because of the ability to drop to such low capacity and provide very long run times.

The ducted air handlers have two fan speeds in which they typically operate when heating and cooling. There is one additonal speed which is considered the lowest and is used primarily in Dry mode and the constant speed when in heat mode and there is no call for heat.

[NB34]

In response to nike123, while in dry mode you do not have the ability to change the temperature setting.

[mchild]

In response to nike123, while in dry mode you do not have the ability to change the temperature setting.


Not trying to step on nike123's toes here, but no, the temp setting is ignored when in Dry mode. The system puts the indoor units on the LL fan setting and cycles the compressor on and off on about a 6 minute cycle.

So if you need cooling while it is in dry mode you will have to reselect the cooling or auto mode to take it out of dry and back to maintaining the set point temp.

Also, there is no target humidity level that can be designated.

One thing to keep in mind is these systems are used around the world and have been for years. I have been told by so many pros from all parts of the world that work with these systems I will not need to use the dry mode.

The typical U.S. system has had a single capacity compressor which meant that other than at the outside design conditions the unit was over sized. Add to that the propensity of US contractors to over size on top of that and the thing was way over sized for the load. Thus, it would cycle on and off and many of the on cycles were for only a few minutes. Not much dehumidification can happen like that.

Only in the last few years have two stage compressors been widely available. While they sounded good the lower stage was normally about 75% of the full capacity so they did not do much to really help with the issue. Add to that a mechanical expansion valve to control the refrigerant flow which has a much narrower range of operation than the 500 step electronic expansion valves on the Daikin system.

The Daikin system will most likely run in a low fan setting most of the time and precisely control the refrigerant flow with the electronic expansion valve. the run times will be almost constant with some cooling occurring almost all the time which will be constant dehumidification.

We saw over night temps last night in the mid 20's. Other than a few minutes here and there my four indoor units ran in low fan almost constantly and the outdoor unit almost the entire night. This provided for a very even heat throughout the home with the heat being provided matching fairly close to the heat being lost by the home. The same will be the case in the summer and thus there will be constant dehumidification. Because of that I am anticipating being able to bump my set point temp a bit higher and reduce my energy consumption.

[Thermatech]

In the Uk we never need to use the dry function.
But the big VRF manufacturers in Japan like Daikin Mitsubishi Electric & Hitachi have been selling the product here since early 1990's. We started installing VRV's & VRF's in 1991.
Young enginners have never known a world without VRV / VRF systems.
The systems were already tried & tested in the home market in Japan for a number of years before starting to export to Europe.
The product has evolved & improved & evolved & improved thoughout that period.

This is the point,,,,,,, in Japan they have very high humidity so they need good humidity control from all a/c products as standard.

I really dont think you need to worry about the suitabilty of the VRV system for high humidity conditions.

[Gary]

What controls the compressor speed?

[nike123]

What controls the compressor speed?

Check this PDF file!

http://www.mediafire.com/?ujuy4zhytow

(http://www.mediafire.com/?ujuy4zhytow)

[nike123]

Ignore! ......

[mchild]

What controls the compressor speed?


The compressor is inverter driven. The incoming AC current is converted to DC three phase current which allows the compressor motor to run at different frequencies. For the VRV-S system currently available in the U.S. there are about 17 speeds ranging from 52Hz to 177Hz.

In order to know what speed the compressor needs to run, the outdoor unit communicates with each indoor unit and determines the amount of refrigerant flowing through the electronic expansion valves and indoor coils.

It is a fully communicating system.

[Gary]

The compressor is inverter driven. The incoming AC current is converted to DC three phase current which allows the compressor motor to run at different frequencies. For the VRV-S system currently available in the U.S. there are about 17 speeds ranging from 52Hz to 177Hz.

In order to know what speed the compressor needs to run, the outdoor unit communicates with each indoor unit and determines the amount of refrigerant flowing through the electronic expansion valves and indoor coils.

It is a fully communicating system.

It must be sensing something somewhere and maintaining the setpoint temperature or pressure of something somewhere.

[Gary]

Check this PDF file!

http://www.mediafire.com/?ujuy4zhytow

(http://www.mediafire.com/?ujuy4zhytow)

Thanks, nike

Apparently, the compressor speed maintains the evaporating temp between 37.5F/3.5C and 48F/14.5C?

The thermostat must then be controlling the fan speed?... or is it strictly on/off?

[frank]

It must be sensing something somewhere and maintaining the setpoint temperature or pressure of something somewhere.

The early G series and H series used to control compressor speed via a suction pressure transducer.

The latest M series over here communicates electronically with each indoor unit and calculates the required compressor speed based on the indoor fan coil conditions

[Gary]

The early G series and H series used to control compressor speed via a suction pressure transducer.

The latest M series over here communicates electronically with each indoor unit and calculates the required compressor speed based on the indoor fan coil conditions

What fan coil condition is it based on?

[frank]

Various conditions.

EEV opening, Suction temp (return air), Set point/Actual point temps, pipe temps, calculated superheat, etc.

It also looks at the outdoor and ambient conditions.

For instance, if it 'sees' that all the connected units have the eev's only 20% open, then it is programmed to know that the compressor only ramps up to a certain level, as only a proportion of the refrigerant charge is in circulation.

The electronics are VERY complex

[Thermatech]

Each indoor unit is aiming for a target SH in cooling or a target SC in heating.
Each indoor unit adjusts the indoor unit expasion valve to meet the target.
The electronic expansion valve has a range of 2000 settings from fully open to fully shut.
The expansion valve needle moves less than 2mm fully open to fully shut.
So when the indoor circuit board requests the valve to open one more pulse it moves the expansion valve needle about 1000 th of one mm.

Its called Veriable Refrigerant Volume on Daikin systems.

VRV systems are like a network of computers.
Each indoor sings its little song into the network system & the outdoor unit communicates with all the indoor units.
The fine detail of the control stratagy programmed into the circuit board control chips is trade secret.
But the service manuals give the basics which is enough to uderstand how the system works & trouble shoot problems.

[nike123]

Thanks, nike

Apparently, the compressor speed maintains the evaporating temp between 37.5F/3.5C and 48F/14.5C?

The thermostat must then be controlling the fan speed?... or is it strictly on/off?

There is no clasical thermostat. It is more complicated than that:
http://www.mediafire.com/?gydty1fdmly

That is not for Daikin but you got idea!

[NB34]

So each indoor unit is controlled to maintain a constant superheat with an evap. temp between 38 and 48 degrees. I am confident these conditions will dehumdify as long as the indoor unit is in operation. This control is no different than a DX split system with a TXV. How does Daikin claim they can maintain tighter temperature control with their system compared to a typical split system?

From my reading the indoor fan is always in constant operation (even with the expansion valve closed) at a fan setpoint selected by the occupants. The indoor fan speed is not controlled. I do not like this control because all of the water located on the coil in the drain pan will reevaporate once the expansion valve closes. This also means that mixing outside air and return air could be problomatic, unless a damper somehow is interlocked with the EEV closed position to close the outside air duct when the coil is not active.

Also, I live is Southwestern Florida and there are not may installed units here so a lot of the contractors are not fimilar with the equipment. What is a typical learning curve for being able to understand the equipment enough to be able to service it?

Another problem that I see arising is shutting down a large portion of a building to trouble shoot a leak or change one fan coil. Has this been a problem for anyone? Also has anyone placed service valves on each indoor coil to isolate the indoor unit from the loop without shuting the system down? Is this a possibility?

[Thermatech]

A typical split system in Japan historically had fixed speed compressor & capillary.
VRV / VRF pioneered inverter drive compressor speed control & now this has also become standard on small split systems.
The old type fixed speed compressor system will switch the off every time it gets to set point.
With VRV the indoor unit will tend to match the heat load & does not switch off at set point so often.
Mitsubishi Electric City Multi VRF take this one step further as each indoor unit is programmed for 'energy save mode'
At 2 deg C from set point the indoor unit considers that the room air is approching set point & sets a new target SH, which in turn results in the electronic expansion valve ramping down to reduce refrigerant volume.
When the retern air gets to 1 degC from set point the indoor unit now considers the room air temperature is at the comfort zone & now sets another target SH which results in the electronic expansion valve remping down to minimum opening setting.
In part load conditions this meens that the indoor unit spends most of the time in energy save mode & almost never actually stops cooling.

This type of control stratagy makes the system very energy efficient but also keeps very stable room temperature & prevents cold draft problems.

The VRV / VRF concept is based on energy eficiency because in Japan electricity has always been very expensive.
So they are very focused on energy saving.
Consultants & endusers in the UK prefer VRV / VRF due to the substantial energy savings compaired to other types of a/c systems & over the last two decades the growth of VRV / VRF sales has been at the expense of chillers & central ducted VAV type systems.

In UK the VRV / VRF manufacturers do alot of service engineer training courses & provide extensive service manuals. They also have technical help desk for technical questions.
Some manufacturers provide extensive system data available at the outdoor unit circuit board to assist with commissioning & trouble shooting.
For the most experianced a/c engineers they also have service checker / maintenance tool program which can be used with lap top computer to monitor all system data for advanced heath check & trouble shooting.

This does make service & maintenance a bit more expensive as the systems are more technically advanced but consultants & endusers are sold on the energy savings concept which far out weigh any increased cost for service & maintenance.

[mchild]

So each indoor unit is controlled to maintain a constant superheat with an evap. temp between 38 and 48 degrees. I am confident these conditions will dehumdify as long as the indoor unit is in operation. This control is no different than a DX split system with a TXV. How does Daikin claim they can maintain tighter temperature control with their system compared to a typical split system?

From my reading the indoor fan is always in constant operation (even with the expansion valve closed) at a fan setpoint selected by the occupants. The indoor fan speed is not controlled. I do not like this control because all of the water located on the coil in the drain pan will reevaporate once the expansion valve closes. This also means that mixing outside air and return air could be problomatic, unless a damper somehow is interlocked with the EEV closed position to close the outside air duct when the coil is not active.

Also, I live is Southwestern Florida and there are not may installed units here so a lot of the contractors are not fimilar with the equipment. What is a typical learning curve for being able to understand the equipment enough to be able to service it?

Another problem that I see arising is shutting down a large portion of a building to trouble shoot a leak or change one fan coil. Has this been a problem for anyone? Also has anyone placed service valves on each indoor coil to isolate the indoor unit from the loop without shuting the system down? Is this a possibility?


It is my understanding that when the system is in cool mode the indoor fan does stop when the EEV is closed to keep the re-evaporation from occurring. I have not been able to confirm this since my system was just installed and it is cold currently. The low fan speed in heat is real low. During operation (when EEV is open) the fan speed is dertermined by the system and will change as needed to meet the load. Rarely have I heard any of the indoor units in high speed.

The reason I changed from installing a Sanyo system to Daikin is the level of support provided by Daikin U.S.
They will not allow the local distributor to sell to a contractor that has not had the VRV training. They will work with the contractor to design the system and deal with issues. They are available with tech support and when the system is ready for commissioning (long check list must be completed and submitted) they will be on site if it is desired. They do a good job of hand holding.

I even made contact with their corporate offices in Texas and spend a lot of time with an engineer that help me with many issues. The fact that I wasn't the contractor did not matter - they support their product. And all of this was before the sale. When we were in the installation process we had not received a capacity plug to downsize the 12K Btu uint. We were told by the distributor that the plug was not available and it had to come from Japan. I called Texas and they had one in hand by the end of the day asking me where I wanted it sent. They support their product.

On the U.S web site they list all controcators in your area that are trained on their systems. Contact Daikin and find out which one has done the most installs. These systems, while different from the convential US sytem, are not hard to install. When the system is commissioned it goes through about a 25 minute process of determining the wiring is correct, the refrigerant charge is correct, each indoor unit is functioning correct, the outdoor unit is functioning correctly, and so on. If anything is not correct it will not complete the commissioning process and requires the problem to be fixed.

Afterwards it burns the data into its eprom and uses it to monitor system performance going forward. If there is a problem it will send a fault code and most likely shut itself down.

Unlike the typical US system that can and do often self destruct, it will not run when there is a problem. But many will report, if it is done right, there will be few problems for decades. Daikin says this is a 25 year system.

[Gary]

From a trouble shooting standpoint, the variable compressor speed would alter the dT's, TD's and approaches at part load, making it more difficult to confirm proper airflows and/or oil logging.

The variable superheat would make it more difficult to confirm proper refrigerant charge as well as refrigerant flows at part load.

On the other hand, presumably when a service tech is called out the structure is warm and the system is working at full load... hmmmm... interesting.

[Thermatech]

Air flow not an issue as most indoor units are floor mount, high wall mount, ceiling cassetts. Only ducted units might have air flow problems & most have a selection of static pressure settings to fine tune.
Oil seperators on outdoor unit.
Most systems do not need any oil traps on suction pipes due to refrigerant at high velocity.
Some systems also carry out regular oil return mode.
Estimate of undercharge is becoming slightly more difficult with R410a but so long as you know what to look for estimate of undercharge/ overcharge is straight forward.
For most systems the service manuals give detailed information on this issue.
As for most modern charge critical split systems refrigerant recovery, find & fix leak, pressure test, evacuate & weigh in correct charge is the normal procedure.

In the early 1980's I worked for a Carrier distributor but the days of straightforward 38 condensing units & air handers have long since gone in the UK.
We were swamped with good quality split systems from Japan & for many years they have dominated the market for small to medium projects.

[NB34]

A typical split system in Japan historically had fixed speed compressor & capillary.
VRV / VRF pioneered inverter drive compressor speed control & now this has also become standard on small split systems.
The old type fixed speed compressor system will switch the off every time it gets to set point.
With VRV the indoor unit will tend to match the heat load & does not switch off at set point so often.
Mitsubishi Electric City Multi VRF take this one step further as each indoor unit is programmed for 'energy save mode'
At 2 deg C from set point the indoor unit considers that the room air is approching set point & sets a new target SH, which in turn results in the electronic expansion valve ramping down to reduce refrigerant volume.
When the retern air gets to 1 degC from set point the indoor unit now considers the room air temperature is at the comfort zone & now sets another target SH which results in the electronic expansion valve remping down to minimum opening setting.
In part load conditions this meens that the indoor unit spends most of the time in energy save mode & almost never actually stops cooling.


For the mitsubishi system, does the fan speed ramp down when the targeted super heat is adjusted?

If not the energy savings mode is BAD for a humid climate because coil apparatus dew point has a large potential to climb above the entering air temperature. At this point the coil is only doing sensible cooling. This potential will rise as the difference between the acutal load and the capcity of the system increases.

Thermatech, does the Daikin VRV III system ever change the targeted superheat, like the mitsubishi city multi system?

[Thermatech]

Mitsubishi City Multi use standard energy save mode for cooling & heating mode. It can be disabled at the indoor circuit board.
Cooling fan speed stays at remote control set fan speed high med low as set by user.

For high humidity situations user can select dry mode at remote controller.
In this case indoor unit runs fan speed at low & intermittently turns off fan.
This is a dedicated dry / dehumidification mode. The on / off cycle of the indoor fan control stratagy is quite complicated & depends on the return air room temperature.

The enduser has option to use normal cooling mode during moderate humidity conditions or use dry mode which is dedicted dehumidify mode.

In the UK we never need the dry mode so we tell endusers not to use it.

Daikin VRV has a target superheat compensation control stratagy which changes the target SH depending on temp difference between return air & set temp in cooling & heating modes but I dont know the exact details of the control stratagy.
But Daikin also have dedicated dry mode which runs fan at low speed & intermitently turns off the fan for dehumidicatation / cooling.

Dont forget in Japan they get very humid weather conditions.
VRV / VRF was being developed 20 years ago & a number one requirment for the home market is a system which can provide comfort conditions even in high humidity ambient.

[Gary]

The on / off cycle of the indoor fan control stratagy is quite complicated...

You seem to consider this a plus. I would call it a major drawback.

[Abby Normal]

I just wish they sensed temperature remotely and did not have to run the indoor blowers all the time

[mchild]

I just wish they sensed temperature remotely and did not have to run the indoor blowers all the time

I have four indoor ducted units and I added remote sensors for each zone so i don't need the blowers running but can't get them to go off.

[multisync]

You seem to consider this a plus. I would call it a major drawback.




Check your watch -it's 2008 already

Multisync
London

[Abby Normal]

Check your watch -it's 2008 already

Multisync
London


It took them until 1998 to finally document and prove that constant fan elevated humiidity, it is still an inherent flaw 10 years later

[Abby Normal]

I just had a Daikin VRV-S installed in my home. Haven't been through a summer yet, but I had similar concerns as you as I am located in the mid-Atlantic states. While not as humid as Florida it is an issue.

The indoor units are variable in capacity in both heating and cooling. I have been told by a Daikin engineer that they will function all the way down to 10% of the nominal rated capacity. So, for your 1 ton unit that would be as low as 1,200 BTUs.

I have also been told by the pros on this site and by Daikin that they do a superior job with dehumidification and that I will probably never put the system into Dry mode. This is because of the ability to drop to such low capacity and provide very long run times.

The ducted air handlers have two fan speeds in which they typically operate when heating and cooling. There is one additonal speed which is considered the lowest and is used primarily in Dry mode and the constant speed when in heat mode and there is no call for heat.
I could see the condenser's capacity turned down low, perhaps even to the 10% claimed.

But the condenser is hooked up to mulitple fan coil units, not a single unit the same capacity as the condenser. They have the single zone inverters, no way they turn down to 10% as a guess I woulds say 40 to 50%.

So with the multizone system, you may only have one zone still calling, its not like you will have that one zone down to 10%.

[multisync]

I have four indoor ducted units and I added remote sensors for each zone so i don't need the blowers running but can't get them to go off.

I wonder if the Itouch would have been a better option for your set up rather than a std remote?

Multisync
London

[mchild]

I wonder if the Itouch would have been a better option for your set up rather than a std remote?

Multisync
London


Please share with me your thoughts on this. I am considering a different controller as I now understand that I can not set different temps for the zones using the standard controller.

I thought the DCS302 would accomplish what I would like to do and now you suggest also the iTouch. Unfortunately, as these systems are still fairly rare here in the U.S. I have limited resources to draw on here to help with these issues. My installing contractor has been through the Daikin training and did a good job on the basic installation, but he does not know the product line and what options are available. I am not complaining as I knew this was the case. The group here on R/E has been most helpful so I figured I could get some direction here if needed - as now it is.

Thank you.

[Gary]

Check your watch -it's 2008 already

Multisync
London

There is nothing so complex that it can't be explained in a way that everyone understands it, and once understood it is not complicated anymore... and is no longer a drawback.

Saying "It's complicated" doesn't help, regardless of what year it is.

If the service tech doesn't understand it, or more importantly doesn't know how to troubleshoot and repair it, then it is an inferior product whose days are numbered.

[Thermatech]

There are a number of options

1/ install a standard remote controller for each indoor unit which will allow a different set temp & fan speed for each indoor unit.
The heat / cool change over can be set at a master remote controller. This option needs to be activated with a setting at the outdoor unit & then select the remote control you want to use as the master.
Or using the ABC terminals at the outdoor unit for remote heat / cool switch or thermostat auto change over control. You can make up your own heat / cool changeover setup using the ABC terminals at the outdoor unit.

2/ Use a central control Itouch intelegent controller which has lots of additional features but is very expensive.

I also suspect that there is a field setting which can be made for fan off when thermostat at set point but it might only be for heating mode.
Its not listed in the service manual which I have for VRV2 & I have never used it but I seem to recall an engineer telling me he had used it to prevent overheating in a very small office.

If you look back I think there was a post on this site about secret Daikin field setting codes.

[mchild]

There are a number of options

1/ install a standard remote controller for each indoor unit which will allow a different set temp & fan speed for each indoor unit.
The heat / cool change over can be set at a master remote controller. This option needs to be activated with a setting at the outdoor unit & then select the remote control you want to use as the master.
Or using the ABC terminals at the outdoor unit for remote heat / cool switch or thermostat auto change over control. You can make up your own heat / cool changeover setup using the ABC terminals at the outdoor unit.

2/ Use a central control Itouch intelegent controller which has lots of additional features but is very expensive.

I also suspect that there is a field setting which can be made for fan off when thermostat at set point but it might only be for heating mode.
Its not listed in the service manual which I have for VRV2 & I have never used it but I seem to recall an engineer telling me he had used it to prevent overheating in a very small office.

If you look back I think there was a post on this site about secret Daikin field setting codes.


Can't the DCS302 also be used for a central controller and accomplish all this with less cost than the iTouch?

I thought the standard operation of the VRV-S was for LL fan when temp is reach in heat and fan off when reached in cooling. No?

Thank you.

[mchild]

If you look back I think there was a post on this site about secret Daikin field setting codes.


Found the discussion you reference here. Some talk of secret codes such as 50 and 60 but nothing confirmed as to using them. Oh well.

[multisync]

http://www.daikin.com.sg/manual/VRV_iTouch.pdf

Yes it is expensive compared to a std controller

Multisync
London

[Thermatech]

If you have the old style DCS302CA51 central controller you can control all individual indoor units with seperate set temp& fan speed.
It can be used to control up to 64 groups of one unit or more.
The install contractor should have set a permanant address into each indoor unit using a standard remote controller temporarily attached to each indoor unit to do this.
Then the centralized controller can communicate with each individual indoor unit.
So if you have the centralised controller & the contractor has set it up correctly you should have individual control of each indoor unit.
On the controller you can scroll through the units 1-00 , 1-01 , 1-02 , 1-03. Select the unit & then make any changes to temp & fan speed.

The other old style controller is DCS301B51 unified on / off controller.
With this you can only switch on & off 16 groups of indoor units.

The all singing all dancing controller is the I touch intelegent controller which has lots more fuctions.

Someone might be able to help with your fan off question.
In UK all the Daikin VRV indoor units I can remember commissioning & trouble shooting run continually at set fan speed when in cooling mode.
But with remote sensors fitted in the room at occupant level I can uderstand that you might consider fan off at set temp satisfied to a better option.
I dont know if this is an available option on the Daikin VRV indoor units. I have never seen it as an option.

[mchild]

http://www.daikin.com.sg/manual/VRV_iTouch.pdf

Yes it is expensive compared to a std controller

Multisync
London


Thank you. I will review it.

[mchild]

If you have the old style DCS302CA51 central controller you can control all individual indoor units with seperate set temp& fan speed.
It can be used to control up to 64 groups of one unit or more.
The install contractor should have set a permanant address into each indoor unit using a standard remote controller temporarily attached to each indoor unit to do this.
Then the centralized controller can communicate with each individual indoor unit.
So if you have the centralised controller & the contractor has set it up correctly you should have individual control of each indoor unit.
On the controller you can scroll through the units 1-00 , 1-01 , 1-02 , 1-03. Select the unit & then make any changes to temp & fan speed.

The other old style controller is DCS301B51 unified on / off controller.
With this you can only switch on & off 16 groups of indoor units.

The all singing all dancing controller is the I touch intelegent controller which has lots more fuctions.

Someone might be able to help with your fan off question.
In UK all the Daikin VRV indoor units I can remember commissioning & trouble shooting run continually at set fan speed when in cooling mode.
But with remote sensors fitted in the room at occupant level I can uderstand that you might consider fan off at set temp satisfied to a better option.
I dont know if this is an available option on the Daikin VRV indoor units. I have never seen it as an option.


Yes, we have the DCS302C71 available here as well as the more simple DCS301.

If using the 302, can that stand alone as the system controller or is a remote necessary also? I don't think I need the all singing all dancing iTouch unit.

Contractor did not set permanent address on each indoor unit. What code is used to do that? I see that addresses can be changed using the Service Code 45. Is that how you set the permanent address? Can that be done with the daisy chain wiring on P1/P2 that I have now or does a remote have to be connected temporarily to the indoor to do that?

This is insightful information. Many thanks.

[nike123]

There is nothing so complex that it can't be explained in a way that everyone understands it, and once understood it is not complicated anymore... and is no longer a drawback.

Saying "It's complicated" doesn't help, regardless of what year it is.



If the service tech doesn't understand it, or more importantly doesn't know how to troubleshoot and repair it, then it is an inferior product whose days are numbered.


I happened to agree with you here!

[multisync]

Quote:
Originally Posted by Gary http://www.refrigeration-engineer.com/forums/images/VA_RE/buttons/viewpost.gif (http://www.refrigeration-engineer.com/forums/showthread.php?p=126629#post126629)
There is nothing so complex that it can't be explained in a way that everyone understands it, and once understood it is not complicated anymore... and is no longer a drawback.

Saying "It's complicated" doesn't help, regardless of what year it is.


Quote:
If the service tech doesn't understand it, or more importantly doesn't know how to troubleshoot and repair it, then it is an inferior product whose days are numbered.



I happened to agree with you here!

Complete nonsense of course. Not every tech is not capable of understanding every system. By your argument these systems should be 'numbered' err sorry to disappoint but VRV has been around since the early '80's and is growing at a rapid rate..

Inverter + technology via the Japanese will destroy the American std AC market as easily as they did their auto one..

Wake up and smell the coffee..

Multisync
london

[nike123]

Complete nonsense of course. Not every tech is not capable of understanding every system. By your argument these systems should be 'numbered' err sorry to disappoint but VRV has been around since the early '80's and is growing at a rapid rate..

What you are referring here as "nonsense"? I don't follow you here! Where did you find my "argument" about "numbered"? Please, quote!


Inverter + technology via the Japanese will destroy the American std AC market as easily as they did their auto one..

That doesn't necessary mean that these products are superior to others. That only means that they are temporary ready for market and that customers are willing to buy them. Good comparison is VHS-video and BETA-video. Beta is much more better but market is at that time more ready for VHS.

[Gary]

I don't doubt that mini-splits will eventually proliferate in the USA... but not until our service techs understand them. Saying "It's complicated" instead of explaining how it works isn't going to get it.

[Brian_UK]

Sadly Gary that is the way it is outside the US.

The idea of a Techie visiting site with a technical manual in his hand is alien to us. The customer tends to think that if you have to look in a book then you don't know what you are doing.

I had some training some years ago from Robur and was impressed with the knowledge that they shared around. Also the fact that you could go to a non, or semi, working unit with the manual in your hand and the correct tools and trouble shoot the system.

With the electronics now you are dependent on the poorly worded manual, if you have one on site, and the fault codes given by the machine. Unfortunately the codes can cover a range of faults going from a duff sensor to a dead PCB. The fact that they include faulty PCBs indicates to me that the build quality could be a bit suspect on some machines.

[/rant]

[Abby Normal]

Quote:
Originally Posted by Gary http://www.refrigeration-engineer.com/forums/images/VA_RE/buttons/viewpost.gif (http://www.refrigeration-engineer.com/forums/showthread.php?p=126629#post126629)
There is nothing so complex that it can't be explained in a way that everyone understands it, and once understood it is not complicated anymore... and is no longer a drawback.

Saying "It's complicated" doesn't help, regardless of what year it is.


Quote:
If the service tech doesn't understand it, or more importantly doesn't know how to troubleshoot and repair it, then it is an inferior product whose days are numbered.




Complete nonsense of course. Not every tech is not capable of understanding every system. By your argument these systems should be 'numbered' err sorry to disappoint but VRV has been around since the early '80's and is growing at a rapid rate..

Inverter + technology via the Japanese will destroy the American std AC market as easily as they did their auto one..

Wake up and smell the coffee..

Multisync
london
daikin was all over the caribbean back in the 80s, then they up and left. Now they want to come back again

I am using the relabelled McQuay version on a project here. They have their niche, they just need to make them so the indoor fan coils do not have to run all the time

[Thermatech]

The fact is that on this thread we are talking to an enduser in the USA who is not an airconditioning engineer but who has opted to try a high tech system from Japan although the local air conditioning contractor know little about the complexities of the technology.

Most days I spend on site visits & carefully explain the complicated aspects of complex airconditioning systems to younger engineers.

But in this case we are not talking to a refrigeration or airconditioning engineer. We are trying to help an end user who has limited airconditioning experiance.

If any airconditioning engineer looking at this site & reading this thread wants to understand the VRV technology & control stratagy he or she can go to any one of a number of Manufacturer web sites & down load the service manuals & do the research to find out for them self how the system works.

[Thermatech]

I would like to learn about the chalange of high humidity air conditioning even though it is never an issue for me in the UK.
Therfore I have started a new thread requesting engineers to provide technical details about sytems which can cope with this application.
I am looking forward to recieving some intelegent replies.

[back2space]

When you are referring to American STD Air Con Market are you referring to the window rattlers that you see all over the place in America?

Or have i misunderstood?

[NB34]

The fact is that on this thread we are talking to an enduser in the USA who is not an airconditioning engineer but who has opted to try a high tech system from Japan although the local air conditioning contractor know little about the complexities of the technology.

That is contrary to the fact. I am an hvac engineer in florida and I wanted to get an understanding of how other people viewed these types of systems and if they have ever encountered problems when they were placed in a high humidity environment. My questions about the fan coil leaving air conditions still have not been answered.

[multisync]

When you are referring to American STD Air Con Market are you referring to the window rattlers that you see all over the place in America?

Or have i misunderstood?

Nope Rheem etc type wind and tin. "Union made" stickers are a clue to their quality control..

Multisync
London

[Thermatech]

NB34

appologies but the thread was side tracked trying to answer questions by Mchild.

I am also trying to uderstand the chalange of high humidity aplications & so have started another thread.

The posters so far are well known on these boards.

The Mitsubishi Electric VRF systems for example use control statagy to maintain suction pressure & evaporating temperature at indoor units which maintain the ADP & provide continual dehumidification in cooling mode. Therfore constant dehumidification even when the indoor unit reduces capacity.

The exception is when the indoor unit enters the power save mode at 2 deg C above setpoint. The indoor unit then sets a new higher target SH & the LEV valves ramps down to reduce refrigerant flow. The dehumidification at this point might be slightly reduced depending on the air on coil conditions.

Some engineers with a biased opinion & different agenda are critical.
However I have spent the last 16 years specialising in VRF commissioning & trouble shooting & I am confident that the system will perform well in higher humidity conditions than we see in the UK.
I have spent most of the last 12 years carrying out commissioning & trouble shooting site visitson VRF products & spend most days monitoring the system operation with a lap top computer.

I would suspect that critical comments come from engineers who dont have a high level of understanding about how VRF systems operate.

The small size of the indoor unit coil, low air volume & Sensible Heat Ratio all conspire to make dehumidification unavoidable even when the refrigerant flow is reduced.

As already stated in Japan high humidity is also an issue which the manufacturers have to overcome to provide comfort cooling to the staisfaction of local customers.

I wonder how many who comment here have been to Japan to see for themselves.

[Gary]

I would suspect that critical comments come from engineers who dont have a high level of understanding about how VRF systems operate.


And rightly so, Why would you expect end users to purchase expensive equipment that is not widely understood? This places them at the mercy of those chosen few who know the secret handshake.

[Abby Normal]

I wonder how many who comment here have been to Japan to see for themselves.
lol I wonder how many who comment have dealt with tropical humidity

[frank]

Why would you expect end users to purchase expensive equipment that is not widely understood?

This could also relate to computers or even motor vehicles et al

[Ross]

NB34

I am a tech in Australia previously worked for Daikin, commissioned many Daikin VRV including up in Darwin (northern Australia) where temp are typically 35degC & 80-90% humidity in summer. Some of these systems the indoor unit also introduce outside air and the systems work perfectly fine in these conditions...Go for it, you won't be disappointed!

[SUBCONTRACTOR]

That is contrary to the fact. I am an hvac engineer in florida and I wanted to get an understanding of how other people viewed these types of systems and if they have ever encountered problems when they were placed in a high humidity environment. My questions about the fan coil leaving air conditions still have not been answered.

Dude,the prblem with these system is not the high humidity,they work absolutely fine but when the humidity is very very low then you gonna have frozen coils....
The other problems that you can expect somtimes is the complicated electronics and availability of replacement pcb.

[NB34]

Thank you to everyone for your responses. I have a couple other questions in regards to the VRV III systems.

1) What is the typical condensing unit downtime for changing a leaky evap coil? (I ask because I am trying to figure out the best combination of indoor units to place on a single piping system. I want to minimize the time the other indoor units would be offline in order to fix the troubled unit)
2) Can the indoor units be isolated from the piping system by service valves so that an evap coil could be replaced without shutting down the entire system? Has anyone ever done this?

These question all stem for the use of Daikin in hotel room applications. I do not want one unit going down and in order to fix the one room 10 other rooms will have to go down for an extended period of time.

[Abby Normal]

or ask your self what kind of job some hack in south florida will do piping it up in the first place

there is a few systems installed down here, i am a good 400 miles south of you, I am keeping an eye on how it performs. I just wish they would shut the damn blowers off when they were modulated down all the way

[Thermatech]

Some contractors have fitted service valves & schreader access for gauges for indoor units. Although often this is for the option of installing extra units at a later date.

In the UK hotels use the VRV / VRF as the only heating / cooling in the bedrooms.
The really big hotels, like over 400 rooms have a maintenance engineer on site for general maintenance & 24/7 emergency cover from specialist a/c contractor.
The hotel will keep a stock of spare parts on site.
So most any problem can be resolved within a few hrs.

The smaller hotels have specialist contractor on call but dont keep any stock of spare parts so they have to wait for next day delivery if parts are required & they pay for the contractor to attend site twice.

Most hotel managers prefer the VRV / VRF systems because if there is any problem it will only affect a small number of rooms & the hotel can often work arround this.
With a chiller if there is a problem every room in the hotel is affected.
In hotter climates perhaps hotels opt for the installation of a standby chiller ?

[NB34]

I agree with you Abby, I am very leary of specifying this equipment because of that reason. The contractors have a tough time installing and trouble shooting a split dx system. I am more worried about how the system is going to get fixed than installed.

[NB34]

Typically there would be two or three chillers.

[Thermatech]

There will always be split bashers
&
there will always be chiller technicians

In between there is the VRV / VRF technician

Installation & service engineers with half a brain tend to move on from split systems into VRV / VRF systems.

15 years ago hardly any a/c engineers knew anything about VRV / VRF systems here in the UK but for quite a few years now almost every service job advert states VRV / VRF experiance required.
Thats because our market has been swamped with this kit so every a/c contractor in the country needs to be able to install & maintain VRV / VRF equipment.
It is the every day bread & butter work for most a/c contractors.

When a manufacturer starts selling this type of equipment into a new market they have to provide extensive technical support for commissioning & trouble shooting to assist the a/c contractors. Also provide extensive technical training for the installation, commissioning & service engineers.

It takes a year or two but contractors get to know the equipment & become confident with it the same as they would with any new type of chiller.
If there is any unusual problem they can alway call on the manufacturer to assist to solve the problem.

Generally I tend to find that most a/c engineers will make an effort to learn about new technology.
This week I was working for a day with a 70 year old a/c service engineer & he spent the whole day bending my ear with questions because he really wanted to understand how it works & because he knew his stuff he was asking very intellegent questions.

So your never to old to learn about new technology.;)

[Gary]

So your never to old to learn about new technology.;)

Obviously, we are not going to learn from you.

[Gary]

This week I was working for a day with a 70 year old a/c service engineer & he spent the whole day bending my ear with questions because he really wanted to understand how it works & because he knew his stuff he was asking very intellegent questions.



Did you actually answer his questions?... or did you just say "It's complicated"?... tell him to go to Japan?... and then call him a "split basher"?

[puddleboy3]

Did you actually answer his questions?... or did you just say "It's complicated"?... tell him to go to Japan?... and then call him a "split basher"?

timeout guys!!!!!! go to your corners

[Abby Normal]

I agree with you Abby, I am very leary of specifying this equipment because of that reason. The contractors have a tough time installing and trouble shooting a split dx system. I am more worried about how the system is going to get fixed than installed.

I have been stalling a job here its going to go with the mcquay version of the daikin vrv,its a larger estate home about 15,000 square feet

I am sticking to my guns, and I have a couple heat pipe BKP series in doing the big granidoise open areas of the central cores on each floor, they will work like AC most of the time, blow some warm dry air in an extreme worst case scenario of zero solar gain, 80F dry bulb and 80F dew point, and owner setting stats at 80F to save energy when not in various areas of the home. The BKPs draw in fresh air whenever they run the compressors. It is imperative here to have spaces pressurized.

But instead of going with a small chiller or multiple split DX systems the vrv is being considered as a way of dealing with the structure and the aesthetically pleasing high ceilings that leave no room for duct work.

So anyways, I am running the load like a commercial VAV system, and sizing the condensing units for whatever the building peaks at, then sizing all the mickey mouse fan coils and cassettes for what ever the zones peaks at.

I predict in my worst case scenario that can linger for days on end, it will be the dehumidifers that save the day as opposed to a system that has to function by running a fan all the time.

This thread is interesting as you see the fear of something new, resistance to change. Then on the other end of the scale you see the salesman mentality where rather than explain something you get into techno-babble.

To me if you cannot explain a concept in the terms relative to your audiences frame of reference, it is because you do not fully understand what you are talking about.

Salesmen when challenged by a question, try to make it sound more and more complicated to shame the person posing questions into feeling too stupid to persue the question anymore, when the fact is the salesman does not really have the answer to the querstion in the first place.

Whenever I start hearing 'flux capacitors' or needing 'X15 modulators' it is a red flag.

[mchild]

. . . opposed to a system that has to function by running a fan all the time.




Does the discussion here: http://www.refrigeration-engineer.com/forums/showthread.php?t=16250 resolve this issue?

[Abby Normal]

maybe when obi wan replies it will be resolved

[2498]

In each IDU there are 3 sensors, 2 for inlet and outlet of refrigerant system and 1 for return air temperature, to modulate the refrigerant flow rate to suit the required load which getting from return air sensor and desired temperature. Integration of the flow rate required from the whole IDUs in the same refrigeration circuit this will lead to call the required flow rate from CDU. Currently both refrigerant and air flow rate are able to vary in order to match to flictuated load precisely.

Piping design and charging volume are very critical. Follwing manufacturers guideline is strictly request.

[NB34]

Abby
Our firm also designs a lot of estate homes of that magnitude in the Naples florida area and have been looking at Daikin as a possible solution to the zoning problem within large estate homes. The owners of these homes want control of each space within their house and with the vrv system and there smaller sizes this is possible. This is hard to accomplish with dx systems because they do not come smaller than 1.5 ton. I just want to become more fimiliar with the product before we venture out and specify the product. A good knowledgable service tech in our area is hard to come by, so our motto is the simplier the better (to an extent). I have had conversations with the Daikin's engineers in the states and they indicate that the fan cannot be turned off (while in cooling mode)during the thermostat off condition. The other thread seems to indicate that the fan can be turned off during the cooling mode with programming. I agree with your approach of using a seperate type of system to handle the latent load and use the VRV systems to handle the sensible portion. I would not count on them for dehumidification, especially with constant fans.

Our ideal design for these large estate homes is with constant volume, face & bypass, multizone, chilled water air handlers located in a mechanical room under the house. This type of system will provide dehumidification at times while the building is in the cooling mode. The outside air is injected between the face & bypass damper and cooling coil assuring that the outside air will always be conditioned.
Combine this with an extended plenum ductwork design and use the millwork (carpenters are better at finish work then a/c contractors, plus there are no visible diffusers or grilles in the house) as your diffusers and you have the ultimate air conditioning system for florida!

[Abby Normal]

Well we get more humid than Naples, but what our worse case is here is a lingering unorganized system where it is about 80F and 80 dewpoint.

Most of these homes have the unshaded mulit-million dollar view of the Caribbean so more cooling than typical to handle that sun. They also tend to get spacious internal zones as well.

So with sky high humidity, temp not warmer than 80 and no sunshine, nothing tells the AC sized for the sun to run and the places can load up with humidity. When it is cloudy and a system is going by there is wind. Wind increases infiltration- especially in from the attic.

So in these spacious cores I like to use Heat pipes BKP systems with a remote condenser. They will blow cool air like an AC unit or, if the humidity gets high and the space is cool, they will use the hot gas to reheat the supply air like a traditional dehu.

We build primarily with block down here and that can make for a tight wall. But if you take it the step of sealing an attic, you will have an extremely tight home and no humidity problems.

I easily hold 40% RH in my own home, single speed, 13 SEER unit, PSC blower (actually running 520 CFM per ton).

When you take infiltration out of the equation you get better performance than all the variable speed, multi-stage systems, with "Comfort R" ramping, or "Dry Modes" without even trying.

[mchild]

Abby
Our firm also designs a lot of estate homes of that magnitude in the Naples florida area and have been looking at Daikin as a possible solution to the zoning problem within large estate homes. The owners of these homes want control of each space within their house and with the vrv system and there smaller sizes this is possible. This is hard to accomplish with dx systems because they do not come smaller than 1.5 ton. I just want to become more fimiliar with the product before we venture out and specify the product. A good knowledgable service tech in our area is hard to come by, so our motto is the simplier the better (to an extent). I have had conversations with the Daikin's engineers in the states and they indicate that the fan cannot be turned off (while in cooling mode)during the thermostat off condition. The other thread seems to indicate that the fan can be turned off during the cooling mode with programming. I agree with your approach of using a seperate type of system to handle the latent load and use the VRV systems to handle the sensible portion. I would not count on them for dehumidification, especially with constant fans.

Our ideal design for these large estate homes is with constant volume, face & bypass, multizone, chilled water air handlers located in a mechanical room under the house. This type of system will provide dehumidification at times while the building is in the cooling mode. The outside air is injected between the face & bypass damper and cooling coil assuring that the outside air will always be conditioned.
Combine this with an extended plenum ductwork design and use the millwork (carpenters are better at finish work then a/c contractors, plus there are no visible diffusers or grilles in the house) as your diffusers and you have the ultimate air conditioning system for florida!


NB34 and Abby Normal,

In an earlier post in this thread I asked Abby if a discussion in another thread answered the question to his satisfaction about being able to have the indoor units cycle the fan off when the call for cooling had been satisfied.

In that other thread I had been provided information in a PM that described how to program the air handlers to cycle off the fan when the call for cooling had been satisfied.

Since then it has been rather cold here so I had not switched the system to cooling in order to test it. Today I was finally able to test it and I can report that the fan can, in fact, be programed to turn off when the calling for cooling is satisfied. Thus, the fan can be off in both cooling and heating.

I understand that when the new VRVIII-S systems are available in the U.S. this feature will be one of the new field code available for general programing. With the current VRVII-S system you have to go deeper into the programing to accomplish this.

I hope this helps both of you in your understanding of Daikins VRV systems.

[NB34]

NB34 and Abby Normal,

In an earlier post in this thread I asked Abby if a discussion in another thread answered the question to his satisfaction about being able to have the indoor units cycle the fan off when the call for cooling had been satisfied.

In that other thread I had been provided information in a PM that described how to program the air handlers to cycle off the fan when the call for cooling had been satisfied.

Since then it has been rather cold here so I had not switched the system to cooling in order to test it. Today I was finally able to test it and I can report that the fan can, in fact, be programed to turn off when the calling for cooling is satisfied. Thus, the fan can be off in both cooling and heating.

I understand that when the new VRVIII-S systems are available in the U.S. this feature will be one of the new field code available for general programing. With the current VRVII-S system you have to go deeper into the programing to accomplish this.

I hope this helps both of you in your understanding of Daikins VRV systems.

Does this also pertain to the 3 and 4 ton VRV-S systems? Also could you send me a link to where this programming is explained. With no airflow, the return air sensor can no longer control the fan coil unit, so does a remote sensor have to be located in the zone to control the fan coil?

[NB34]

NB34

appologies but the thread was side tracked trying to answer questions by Mchild.

I am also trying to uderstand the chalange of high humidity aplications & so have started another thread.

The posters so far are well known on these boards.

The Mitsubishi Electric VRF systems for example use control statagy to maintain suction pressure & evaporating temperature at indoor units which maintain the ADP & provide continual dehumidification in cooling mode. Therfore constant dehumidification even when the indoor unit reduces capacity.

The exception is when the indoor unit enters the power save mode at 2 deg C above setpoint. The indoor unit then sets a new higher target SH & the LEV valves ramps down to reduce refrigerant flow. The dehumidification at this point might be slightly reduced depending on the air on coil conditions.

Some engineers with a biased opinion & different agenda are critical.
However I have spent the last 16 years specialising in VRF commissioning & trouble shooting & I am confident that the system will perform well in higher humidity conditions than we see in the UK.
I have spent most of the last 12 years carrying out commissioning & trouble shooting site visitson VRF products & spend most days monitoring the system operation with a lap top computer.

I would suspect that critical comments come from engineers who dont have a high level of understanding about how VRF systems operate.

The small size of the indoor unit coil, low air volume & Sensible Heat Ratio all conspire to make dehumidification unavoidable even when the refrigerant flow is reduced.

As already stated in Japan high humidity is also an issue which the manufacturers have to overcome to provide comfort cooling to the staisfaction of local customers.

I wonder how many who comment here have been to Japan to see for themselves.

Is there any reason for not reducing the fan speed AND refrigerant flow as the system approaches the setpoint. I think this would be the ideal control strategy.

[mchild]

Does this also pertain to the 3 and 4 ton VRV-S systems? Also could you send me a link to where this programming is explained. With no airflow, the return air sensor can no longer control the fan coil unit, so does a remote sensor have to be located in the zone to control the fan coil?

NB34,

Yes, it does pertain the the S models - I have the 4 ton unit. I also have remote sensors in each zone to more accurately monitor temps. With ducted units I think this is the best way to go.

I have sent you a PM.

[Abby Normal]

thanks for the update on auto fan capability mchild

[clubchamp5]

i wish i had the problem of living in florida with all that lovely weather although i have been there on holiday 5 times now, i am daikin trained up to vrv3 on install and commissioning but i much prefer mitsubishi city multi vrf by far the best all round systems i have just commissioned 16 outdoor vrfs serving 148 ducted/ cassettes/ wall mounts over 8 floors in an office block in Glasgow Scotland U.K. and the weather at this time of year is wet, then minus 8 hail, sleet and snow so humidiyt is never a problem