VRV issue

[needsomehelp]

Hi am new to your forum so i hope i will not offend anyone.

We have a Daikin VRV system in one of of our offices - 6 units connected to an outside condenser. The problem being exhibited is that it doesn't control accurately to the set temperature.

During the very recent cold weather with external ambients of around zero we have some rooms set to 29 and yet the temperature swings between 24 down to 16 and back again. There is a logic in that the speed changes up and down according to demand . It seems that when it comes out of its heating cycle ie approaching set point the speed goes down and heat output lowers , heat stops and then the room temperature really drops until way below the set point and then heating restarts . In the meantime the users are experiencing drafts etc. The problem is worse in some rooms then others . We have had Daikin along but they say they can find nothing wrong. This is very puzzling as we are now having to resort to electric heaters in the room to get round the heating problem. Any ideas please.

[DTLarca]

Hi am new to your forum so i hope i will not offend anyone.

We have a Daikin VRV system in one of of our offices - 6 units connected to an outside condenser. The problem being exhibited is that it doesn't control accurately to the set temperature.

During the very recent cold weather with external ambients of around zero we have some rooms set to 29 and yet the temperature swings between 24 down to 16 and back again. There is a logic in that the speed changes up and down according to demand . It seems that when it comes out of its heating cycle ie approaching set point the speed goes down and heat output lowers , heat stops and then the room temperature really drops until way below the set point and then heating restarts . In the meantime the users are experiencing drafts etc. The problem is worse in some rooms then others . We have had Daikin along but they say they can find nothing wrong. This is very puzzling as we are now having to resort to electric heaters in the room to get round the heating problem. Any ideas please.

I of course do empathize regarding the frustrations associated with having to use electric heaters.

But as a point in general, not so much in reply to you, but sort of "while we are on the topic" - I am receiving the odd call during the week about heat pump ac problems which we are being requested to attend. I do not understand the customers complaining that they even now have to use electric heaters. Because the primary source of energy in the UK is electric power. Thus the primary source of heating is electric element heating.

Yes, there are buildings, commercial, that do not have enough electric power available to provide all the heating needs of the building using electric element resistance heating but then they would be treated as a special case for emergency back-ups in the design and after sales service when switching to full VRV from full gas/oil boiler - if they were willing to take the risk.

Every office and home that uses heat pump heating should have available as back-up adequate electric resistance element heaters. The only reason why they will also have heat pumps is to save energy - not because heat pumps are the only primary source of heat available. Argos sells 3kW electrical heaters for a tenner.

[stufus]

Hey needsomehelp
Just a few things you could check off the bat
1-is the temp in each room read by thermistor in the controller , if so is it being influenced directly by the air flow from the grilles
2-do you have a fresh air make up system such as an air handler with heater battery , electric or lphw and if so is it working
3- does each unit have a fresh air leg or is the ceiling acting as a plenum
4- the issuse with the fan ramping is there to actually reduce drafts when the unit reaches temp and closes tev temp in coil
drops so fan backs off to avoid throwing cool air about the
place , well thats the idea

best of luck

[james10]

The VRV will not function below 0C see daikin extra net for manuals

[frank]

Poor heating and constant defrosts on VRV, or any reverse cycle A/C unit is an indication of a possible refrigerant undercharge, which could be the result of a system leak.

I would recommend that you call out a tech who is familiar with your type of equipment who can then do a proper diagnosis as well as check that the controllers are set up correctly.
VRV/VRF are quite complex systems and any number of small faults can lead to poor performance

[croc1774]

He quotes Daikin have been on site Frank!!:D
29c is a very high set temp on controllers:eek:
21c is more appropiate i would of thought on all controllers and all on heating mode.
Not sure on the defrost times but in cold temps it will happen more often.

http://www.refrigeration-engineer.com/forums/image.php?u=34753&dateline=1263512719 (http://www.refrigeration-engineer.com/forums/member.php?u=34753) VRVIII (http://www.refrigeration-engineer.com/forums/member.php?u=34753) Will hopefully be able to give you some pointers.

[Gary]

Care should be taken in the placement of electric heaters. I have seen such heaters pointed towards the thermostat, causing the system to stop heating.

[wozza]

The VRV will not function below 0C see daikin extra net for manuals

Where did you get this info? Because that is aload of rubbish.

Coolng only maybe down to -5°C
heat recovery is designed down to -20°C. If they only worked down to -5° daikin would never sell any.

[needsomehelp]

thanks the 29 was set in to try and get some semblance of comfortable temperture in the room agree 21 would be normal . One of your colleagues has suggested ther may be a refrigrtaent leake that would cause the swings is this plausable - would it not be detected as a fault on the system ?

[VRVIII]

Hi am new to your forum so i hope i will not offend anyone.

We have a Daikin VRV system in one of of our offices - 6 units connected to an outside condenser. The problem being exhibited is that it doesn't control accurately to the set temperature.

During the very recent cold weather with external ambients of around zero we have some rooms set to 29 and yet the temperature swings between 24 down to 16 and back again. There is a logic in that the speed changes up and down according to demand . It seems that when it comes out of its heating cycle ie approaching set point the speed goes down and heat output lowers , heat stops and then the room temperature really drops until way below the set point and then heating restarts . In the meantime the users are experiencing drafts etc. The problem is worse in some rooms then others . We have had Daikin along but they say they can find nothing wrong. This is very puzzling as we are now having to resort to electric heaters in the room to get round the heating problem. Any ideas please.

Is this system a Daikin VRV3, VRV2 or VRV K series? Heat pump or heat recovery (full model number)

What is the model number of the problem indoor units?

Does the system have a centralised control device connected? (I Controller etc)

Where are you viewing/measuring these large fluctuations in temperatures? (controller 41 codes / I controller / hand held thermometer)

Where the electric heatear installed when measuring temperatures?

Do you know what the maximum indoor gas temperatures are (code 41 sensor 03) when all indoors are heating thermo on?

Is there any form of fresh air supplied into the rooms or ceiling voids?

How long did the Daikin engineer spend on site? Was a service checker connected and the system fully checked and monitored?

If you have an I Touch controller or I manager check and verify the heating optimization function has not been enabled.

Check if the problem indoors have been programmed with field setting 12-3-03 this will switch off the indoor fan when thermo off in heating mode allowing the return air senor to be influenced by the residual heat from heat exchanger.



The VRV will not function below 0C see daikin extra net for manuals


The minimum operation range specified for VRV3 is down to -20 CWB in heating mode and down to – 5 CDB for cooling mode.

[gammon]

The minimum operation range specified for VRV3 is down to -20 CWB in heating mode and down to – 5 CDB for cooling mode.[/quote]


Hi VRV III

Im wondering where this information is in the manual and how do they compare to VRV II and G series heat recovery?
Also how is the system efficiency affected when operating in low ambient conditions, taking into consideration pipe runs, max capacity index, high indoor demand etc
Im just curious as i have the odd site with other problems like piss poor building insulation and no wet system as back up.

Thanks

Gammon

[r.bartlett]

thanks the 29 was set in to try and get some semblance of comfortable temperture in the room agree 21 would be normal . One of your colleagues has suggested ther may be a refrigrtaent leake that would cause the swings is this plausable - would it not be detected as a fault on the system ?


In persistant cold spells around zero it would be better to leave the system running 24/7. just lowering the stats to 18 when you leave. I suspect the system is undersized for the heating requirement

Our two split HP's have been on continuously for weeks now!

[needsomehelp]

Hello VRV will get back to you with the system details but to answer some of your and others questions the 29 has been put in to try and get a reasonable temperaure in the space and we would not normally try and run it at this - however if it is set to 22 then the internals were ending up around 11 - 12 . Yes there is a VAM unit but we have turned this off just in case there is too much fresh air but again cannot understand how this would create the wide swings of temperaure. There is no i controller and the elec heaters are a long waya a way from the measurement point - interesting the in the high speed mode when the unit is in heat mode the supply temeparure is way up in the high 30 .s just seems to be going off to early it seems and then the room temperaiure comes crashing down becuase the heat just seems to go off - could this be related to a faulty pipe box - do you think. How would one get the charge checked - does this involve taking out the refrigerant to weigh it ? . thanks

[r.bartlett]

Hello VRV will get back to you with the system details but to answer some of your and others questions the 29 has been put in to try and get a reasonable temperaure in the space and we would not normally try and run it at this - however if it is set to 22 then the internals were ending up around 11 - 12 . Yes there is a VAM unit but we have turned this off just in case there is too much fresh air but again cannot understand how this would create the wide swings of temperaure. There is no i controller and the elec heaters are a long waya a way from the measurement point - interesting the in the high speed mode when the unit is in heat mode the supply temeparure is way up in the high 30 .s just seems to be going off to early it seems and then the room temperaiure comes crashing down becuase the heat just seems to go off - could this be related to a faulty pipe box - do you think. How would one get the charge checked - does this involve taking out the refrigerant to weigh it ? . thanks

It seems like it's getting a false reading from the return air. Are they ducted units ?

[DTLarca]

interesting the in the high speed mode when the unit is in heat mode the supply temeparure is way up in the high 30 .s just seems to be going off to early it seems and then the room temperaiure comes crashing down becuase the heat just seems to go off.

Also, are the units controlling off the return air sensor or the wall controllers sensor. The guys have mentioned controller service codes to check this.

At high speed the hot buoyant air is better thrown to the ground for better mixing with the cold room air which gives a colder return air which causes the outdoor unit to ramp up in capacity. At low speed the buoyant air hovers up under the ceiling and unit giving the unit the impression the that room air is satisfactory and so the outdoor ramps down.

There should also be a high ceiling service code to adjust to help compensate for this effect.

[james10]

Is this system a Daikin VRV3, VRV2 or VRV K series? Heat pump or heat recovery (full model number)

What is the model number of the problem indoor units?

Does the system have a centralised control device connected? (I Controller etc)

Where are you viewing/measuring these large fluctuations in temperatures? (controller 41 codes / I controller / hand held thermometer)

Where the electric heatear installed when measuring temperatures?

Do you know what the maximum indoor gas temperatures are (code 41 sensor 03) when all indoors are heating thermo on?

Is there any form of fresh air supplied into the rooms or ceiling voids?

How long did the Daikin engineer spend on site? Was a service checker connected and the system fully checked and monitored?

If you have an I Touch controller or I manager check and verify the heating optimization function has not been enabled.

Check if the problem indoors have been programmed with field setting 12-3-03 this will switch off the indoor fan when thermo off in heating mode allowing the return air senor to be influenced by the residual heat from heat exchanger.





The minimum operation range specified for VRV3 is down to -20 CWB in heating mode and down to – 5 CDB for cooling mode.
I stand corrected i attended a Daikin VRVIII course and the insrtuctor told us that they would not operate below 0 and the first thing to do was check if the outdoor unit was running if not try warming the ambient air sensor and if the unit started then the low ambient temp was the reason why.

[james10]

Where did you get this info? Because that is aload of rubbish.

Coolng only maybe down to -5°C
heat recovery is designed down to -20°C. If they only worked down to -5° daikin would never sell any.
Wozza, we speak and reply to one another on this forum with respect and to suggest someones comments are "rubbish". Is sheer ignorance to the purpose of this site you should think twice on how you phrase your replies as one day you might find yourself in need of help and the person you have pissed off is the person who can help.
Regards James

[jimmy wilkes]

im wondering if ur office was open plan at some stage?and has since been partioned?have u ducted fan coils?done alot of call outs with similar problems and its usually undersized system,no room remote stats and installations which now dont suit the tennants requirements and the landlord has now gone deaf?!"i said the office space was air conditioned,never said it was any good"!!!

[VRVIII]

Wozza, we speak and reply to one another on this forum with respect and to suggest someones comments are "rubbish". Is sheer ignorance to the purpose of this site you should think twice on how you phrase your replies as one day you might find yourself in need of help and the person you have pissed off is the person who can help.
Regards James

Hi James,

I suspect wozza's been having a bad day :confused: He's usually a nice down to earth chap :)

[VRVIII]

Hi VRV III

Im wondering where this information is in the manual and how do they compare to VRV II and G series heat recovery?
Also how is the system efficiency affected when operating in low ambient conditions, taking into consideration pipe runs, max capacity index, high indoor demand etc
Im just curious as i have the odd site with other problems like piss poor building insulation and no wet system as back up.

Thanks

Gammon.


Hi Gammon,

Most of the information your after can be found in the Daikin VRV technical data books or service manual, these can both be downloaded from Daikin extranet.

The data books contain various capacity tables indicating the total capacity of a system under various conditions. i.e. ambient temps, room temps & connection ratios.
They also include indoor unit capacity correction factor for pipe run lengths these are normally indicated as a graph.

There should be no need for a wet system back up providing the system has designed, installed and commissioned correctly.

I would suggest you try to attend a Daikin VRV training course as you would probably find them helpful.

[back2space]

The room sensor seems to be getting warm too quickly and then taking too long to cool back down so its either in the wrong place or is being affected by something warm... this seems to be demonstrated as when you raise the set point it heats to 16C.

Have you checked where the return air sensors are, if they are on the back of the indoor unit it might be worth while poking them through a ceiling tile or through a return air vent in the ceiling.

If the fans are cycling off on the indoor units then this could be why it is a while before the units come back on as you are getting good air offs when all are operating.

[AbsoluteWDJ]

Hi am new to your forum so i hope i will not offend anyone.

We have a Daikin VRV system in one of of our offices - 6 units connected to an outside condenser. The problem being exhibited is that it doesn't control accurately to the set temperature.

During the very recent cold weather with external ambients of around zero we have some rooms set to 29 and yet the temperature swings between 24 down to 16 and back again. There is a logic in that the speed changes up and down according to demand . It seems that when it comes out of its heating cycle ie approaching set point the speed goes down and heat output lowers , heat stops and then the room temperature really drops until way below the set point and then heating restarts . In the meantime the users are experiencing drafts etc. The problem is worse in some rooms then others . We have had Daikin along but they say they can find nothing wrong. This is very puzzling as we are now having to resort to electric heaters in the room to get round the heating problem. Any ideas please.

Hi, just a few simple questions to get a better idea

1. What height are your indoor units installed?
2. Do you have the mode set for auto?
3. Have you experienced this situation before or is this a new installation?

[brunstar]

I have a feeling that you may require some remote sensors on your fan coils possibly.
But a few more checks will be required.
Yes Wozza is a nice guy, i very much doubt that on the training course you were told that the systems would not work below 0 degrees outside, i think that you may have got confused with the automatic refrigerant charging function.

[andyac]

i always check the standing pressure vs temperture relationship before reclaiming a whole system. daikin often use contractors some are good at commissioning and others at fault. diagnostics. did they use a service checker or go to option 41 on a controller which is realtime and the checker i think is every 15 secs. i would say undersized and/or refrigerant leak

[Mabe]

I hope you use the KRCS thermistors and make setting 20-202 otherwise temprature measurements are difficult.
The simply thing if you don't have a service checker, put 50% of the indoors in heating mode and check the temperatures in setting 41 if coil temperatures getting higher and better, you could have low refrigerant in they system.