Daikin VRV vs. Mitsubishi Multi City

Hi all:

My name is Gabriel and I'm glad to find this forum. I'm a project manager for a consulting engineering firm in Los Angeles. I specialize in large upscale homes, some as large as 80,000 sf and lately I have started specifying Daikin VRV systems and have attended the classes, but on some of my larger jobs, the contractors want to subsitute the Daikin for the Mitsubishi City Multi units.

Both systems are close, but Mitsubishi claims less installation costs because their copper fittings for the refrigerant pipes are threaded not brazed.

I have to write a big letter tomorrow explain the difference between the two systems. Any one in here ever study these two systems?

if the fittings are threaded, the reason for brazing copper pipe is to reduce the amounts of possible leaks within the refrigerant circuit.
If you have a system with 50 fan coils you will have at least possibly 150 - 200 connections.
I would be more confident with a braze..
When you are installing a VRV or VRF system the more threaded connections, the more possibilities of refrigerant leaks.

Make sure that you use oxygen free nitrogen when you are brazing to ensure you do not contaminate the pipework.

Thanks Brunstar. The copper piping of the Daikin system has to hold 550 psi for 24 hours before you can put in R410A refrigerant and I also feel more comfortable with the brazed fittings.

The Daikin VRV III system uses a branch selector box to regulate the refrigerant to each fancoil, but the Mitsubishi has a manifold system in which multiple fancoils tie into a single manifold and I have a feeling if that manifold goes down, so does every fancoil thats connected to it.

Oppps the Mitsubishi system is City Multi, not Multi City.

if you want a central position for the boxes Daikin also do a 6 way box that can be installed in a central location depending on what is required on site.

The mitsi kit is much faster, easier and cheaper to install I find. Less pipe work, fewer BS boxes.

Eggs

I can uderstand that you think the two systems are close & if you are talking 2 pipe heat pump then the two are sort of similar.

But if you are looking at VRV 3 pipe heat recovery / City Multi R2 heat recovery then you are looking at completely different systems.

On the Diakin for every BS box there has to be 3 refnet joints with 9 brazed tube joints at the refnets & a further 5 tube joints at the BS box & two at the indoor units. Very time consuming & uses lots of OFN for purging welding gas & brazing rods. Total 16 tube joints for each BS box & indoor unit connection.

City Multi has only 2 tubes from outdoor unit to central BC distibution box & then only 2 tubes typically S= 1/2 & L= 1/4 from the BC to each indoor unit.
Very quick & easy to install & much less materials than any 3 pipe VRV/VRF system.
Only 4 tube joints for each indoor unit 2 at the BC box & two at the indoor unit.

If you want the most user frendly central controller then you have to Mitsubishi AG150 as the Daikin I Touch central controller is even very difficult for experianced ac commissioning engineers let alone the end user.

Then you could start considering some operational issues like if you acidently switch off the 240v 1ph power to any indoor unit on a Diakin system it has to shut the complete system down to protect itself as it has no backup way of closing the EEV at the indoor unit to prevent refrigerant bypass.
With City Multi the indoor unit has emergency backup way of closing down the EEV by using the 30v Mnet control. So you can at any time cut 1ph power to any indoor unit & it will be able to close the EEV to prevent refrigerant bypass & the rest of the system can carry on operating without any danger of damage.

At the end of the day
Consultants tend to like City Multi due to the really good energy efficiency & heat recovery.
Installation engineers tend to like to install City Multi because it saves at lot of time & is easierto install.
Service engineers tend to like City Multi because they can get all live & recorded operating data from the outdoor unit without any need for a laptop computer service checker which really helps to quickly identify problems.
Undusers tend to be ignorant & could not tell the difference between any ac system.

I have always found that all manufacturers will highlight advantages & benifits of there units but try to hide the problems & disadvantages.
So the best way to find out is by personal experiance.
But consultants dont really ever get that hands on experiance because they never install the units with there own hands & never have to trouble shoot any operational probem because the commissioning engineer & service engineer do that.
If consultants did spend time getting hands on experiance then the ac market place would I suspect look very different.

Although Thermatechs comments are very comprehensive they do come across a bit biased as he has failed to mention any of the points that VRV has over Mitsi City Multi R2. So I thought I would try to even things up a bit :D.

• Unlike Mitsi the Daikin VRV passes discharge gas directly to indoor coils when in heating mode, this results in much higher coil temperatures, faster pre heat and much quicker warm up of rooms.

• Daikin VRV3 also gives continual heating during a defrost cycle, when compared to Mitsi the capacity drop is significantly less during defrost.

• The VRV is a true heat recovery system using liquid refrigerant from indoors operating in heating mode to supply indoors operating in cooling. This allows the transfer of heat from a warm area to a cold area (unlike Mitsi).

• VRV3 can also be set for technical cooling making the system suitable for computer room application (unlike Mitsi)

• This is part of the reasons why the Daikin VRV3 has won 2 HVAC product award.

• The VRV outdoor unit automatically addresses with indoors and BS boxes, on the Mitsi system you have to manually address every indoor, remote controller and BC box by adjusting PCB rotary switches.

• Screened cable must also be used and the screen bonded with Mitsi systems, Daikin use a standard 0.75 YY cable.

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On the Diakin for every BS box there has to be 3 refnet joints with 9 brazed tube joints at the refnets & a further 5 tube joints at the BS box & two at the indoor units. Very time consuming & uses lots of OFN for purging welding gas & brazing rods. Total 16 tube joints for each BS box & indoor unit connection.
City Multi has only 2 tubes from outdoor unit to central BC distibution box & then only 2 tubes typically S= 1/2 & L= 1/4 from the BC to each indoor unit.
Very quick & easy to install & much less materials than any 3 pipe VRV/VRF system.
Only 4 tube joints for each indoor unit 2 at the BC box & two at the indoor unit.

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Daikin also offer a multi BS box allowing a similar configuration (up to 6 boxes) or single BS boxes which makes the system more versatile, the Mitsi BC box is huge and requires service access which can be problem on some installations. I don’t think there is much difference in labour hours when you combine total installation and commissioning time.

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If you want the most user frendly central controller then you have to Mitsubishi AG150 as the Daikin I Touch central controller is even very difficult for experianced ac commissioning engineers let alone the end user.

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I think the Daikin I controllers are fairly simple after attending the training course

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Then you could start considering some operational issues like if you acidently switch off the 240v 1ph power to any indoor unit on a Diakin system it has to shut the complete system down to protect itself as it has no backup way of closing the EEV at the indoor unit to prevent refrigerant bypass.
With City Multi the indoor unit has emergency backup way of closing down the EEV by using the 30v Mnet control. So you can at any time cut 1ph power to any indoor unit & it will be able to close the EEV to prevent refrigerant bypass & the rest of the system can carry on operating without any danger of damage.

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Daikin also offer this as an option but don’t really see the point as the error would highlight the fact that an indoor has been switched off accidentally.

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Consultants tend to like City Multi due to the really good energy efficiency & heat recovery.
Installation engineers tend to like to install City Multi because it saves at lot of time & is easierto install.

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Depends on the consultant and which engineer you speak to. The energy efficency is no better than Daikin.

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Service engineers tend to like City Multi because they can get all live & recorded operating data from the outdoor unit without any need for a laptop computer service checker which really helps to quickly identify problems.

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Personally I don’t see this as a bad thing as it helps ensure the engineer working on the system has been properly trained.

VRV111
I was wondering how you came to the following conclusions.
Hope you have not been believing those sales people.:D

Issue 1
Unlike Mitsi the Daikin VRV passes discharge gas directly to indoor coils when in heating mode, this results in much higher coil temperatures, faster pre heat and much quicker warm up of rooms.

Heating only mode operation
On Daikin 3 pipe the hot gas goes down the hot gas tube from the outdoor unit to all the BS boxes & from the BS box on to each indoor unit. So the hot gas is pumped direct to each indoor unit.

On City Multi the outdoor unit pumps hot gas down the high pressure tube directly to the BC box & from the BC box directly to each indoor unit. So the system pumps hot gas directly to each indoor unit.

Issue 2
The VRV is a true heat recovery system using liquid refrigerant from indoors operating in heating mode to supply indoors operating in cooling. This allows the transfer of heat from a warm area to a cold area (unlike Mitsi).

Heat recovery mode operation
Daikin system pumps hot gas to the indoor units calling for heat & the warm liquid exits the indoor unit & return to the BS box. After subcooling at the BS box liquid is dumped back into the common liquid line & is then available for any indoor unit calling for cooling & after cooling the suction vapor return to the outdoor unit compressor on the suction tube thus making the complete circuit & full heat recovery from the units heating & the units cooling.

City Multi system pumps hot gas to the BC box & then on to any indoor units calling for heating. The warm liquid forom the heating units returns to the BC box & through a subcooler. The liquid is then available for any indoor unit calling for cooling. After passing through the cooling indoor units the suction vapor returns to the outdoor unit on the suction line completing the circuit & thus direct heat recovery from indoor units cooling to indoor units heating.

Both Daikin VRV 3 pipe & Mitsubishi R2 VRF are full heat recovery systems & can cope with any number of indoor units being in cooling & heating mode at the same time.
The main difference is that City Multi can do this with only 2 pipes instead of 3 pipes for the daikin VRV system.

If you go on the Mitsubishi City Multi training they will show you the referigerant flow diagrams which show the refrigerant flow in all heating / cooling % combinations.

You would then see that the City Multi system provides full heating & cooling at the same time even if most indoor units are cooling & only 1 heating or if most indoor units are heating & only 1 cooling complete with full heat recovery between the indoor units cooling & indoor units heating.

i like braze over threaded connection ...

In truth, there is little difference between the 2, apart from one is 2 pipe and the other 3. They are both full hest recovery and similar in efficiency. I guess it comes down to personal choice. The mitsubishi seems more restrictive to me, 1 huge box makes it less flexible. Daikins smaller bsvq boxes mean they can be put in almost anywhere, so is more flexible.

Id go City Multi. Mitsubishi are ALOT more reliable than Daikin systems, In my time as an engineer ive changed 1 Mitsubishi compressor. Ive lost count of the amount of Daikin compressors ive changed.

The city multi kit is by FAR the most reliable of the two.

IF a city multi R2 does fail it is much harder to fault find than the VRV (unless you really know how it works) but in 12 years ive yet to see a well installed R2 fail seriously (the odd PMV valve and maybe the odd solenoid) but Daikins reliability on inverter stuff is pants - Fan motors let in water, short the PCB and blow main boards, the inverter heat sinks arent sealed properly so they let water in to short the inverter, Power supply leads to the main boards from the filters are poor and cause poor neutral faults which in turn blow the **** out of everything... you get the idea. All common faults on VRV 1,2 and 3

Also dont be too concerned about the one point of failure with the BC box, if any BC box goes on the daikin you loose the comms anyway - instant U4 fault system shuts down (although you can then loop it out to get it going in the meantime i suppose)

But consultants dont really ever get that hands on experiance because they never install the units with there own hands & never have to trouble shoot any operational probem because the commissioning engineer & service engineer do that.

what's the point in having a consultant? just go ask the engineer.

can someone please explain to me how i can get paid to inform people on topics i know nothing about......

"Consultants tend to like City Multi due to the really good energy efficiency & heat recovery."

In the UK this has become a critical issue following the introduction of new Building Regulations in October. The system with the highest CoP's and seasonal efficiencies will always get named and specified on projects.

I would point out that consultants need a wide knowledge base to design buidlings and should seek specialist knowledge from commissioning and service engineers....maybe sometimes by visiting forums like this....when they need to.

Not having a go...just making a point.

One thing to consider here is this!
There is legislation in Japan,I believe it is called the technology agreement,
Which basically means that 3 years after a new product has entered the market all the technology used in the product has to be made freely available to all in the technology sector.
So considering Mitsubishi are the only one's using the 2 pipe simultaneous system and none of their competitors have followed suit although having free access to all the design specs it sort of tells it's own story.
Both systems have pros and cons and each individual will have their favourite.
Both systems perform well if got right from the get go,but regardless of what Mitsu say the R2 struggles in low ambient conditions,you may install it in half the time ,but that's no use when you're freezing your nuts of in winter:p

Just a few tidbits from my experience:
1. Mitsi R2 TJMU model gets great heating performance at low temps.
2. they are the only one that can really guarantee low ambient cooling
3. The "continuous heat through defrost" that Daikin offers also results in continuous loss of capacity up to 70%! Read there own literature...you get heat but not enough to heat a coil. Personally, I'd rather let it shut the fan off for defrost and get ot done FAST!
4. BS vs BC- BS need electrical and access and so do BC. One box means longer lines, but 2 in stead of 3, means WAY fewer connections: what is your labor rate? Yes, you can use one daikin Bs for multiple units but they cannot get heating OR cooling once they leave the box. This limits the zones.
5. i get better response from Mitsi tech than daikin...guess its the local guy

Daikin VRV can also do low ambient cooling with activation of the "Technical Cooling Function", there is also a setting now to allow the cooling of comms rooms without freeze up occuring due to the conditions of these rooms. The Altherma can also be connected to the VRV system (3 Pipe), so can do sanitary water within offices as well as heating or cooling the office areas. Can Mitsi.......I dont think so, correct me if im wrong.

Daikin has much better options, I hear from a guy I know who works at Daikin, that a wireless wall sensor will also be available this year, and if you have an I Controller, will be able to activate the "Leak Check Function" remotely by web access. I install, service and maintain sites where Daikin and Mitsubishi are installed, for me Daikin is much better and easier to work on, but I guess its personal choice

Mitsubishi City Multi heat pump boilers have been arround for a few years now.
Connect heat pump boiler to City Multi system the same as any other indoor unit for domestic hot water or central heating under floor heating ect.
Been commissioing these for at least the last 2 years.
Standard or high temp R134a cascade versions.
Have commissioned lots of these & found they have impressive performance.
Unlimited pottential as every commercial building that needs air conditioning also needs hot water if only for the toilets.
Therefore all major manufactures are looking to providing this option for VRF type systems.

Technical cooling is a bit of a sales ploy.
It only prevents coil frost prevention. The indoor units still have poor SHR & therefore low sensible cooling performance so not really ideal for comms room applications but good if you want to combine with Altherma for free hot water.
Mitsubishi have been providing for about 6 years dedicated high sensible down flow commuter room units connected to City Multi outdoor units which is proper engineered solution which provides energy efficent cooling to computer rooms.
Have commissioned quite a few of these & again very impressive performance.

Daikin VRV3 50/50 defost is interesting & the leak detection function will be usefull for Fgas leak check but the sales engineer may not tell you all about the extra time at commissioing to carry out the auto charge & learning fuctions which the system must carry out to make the leak detection function available.
Daikin Replace VRV systems for reusing R22 pipes are very good allowing endusers to upgrade to latest VRV systems with minimum disruption.
Have been commissioning these & found to have impressive performance.

Daikin & Mitsubishi both continue to inovate & develop some of the best VRV / VRF equipment but please be carefull to check what sales people tell you because its in their interest to down play the opposition & talk up their equipment to get the sale.

Oh Well looks like we have Mitsi fans and daikin fans, But what you are not telling every body that the mitsi when especally running on slow speed ( the Inverter Compressor) the change over compensation valve on the indoor unit is an unberable noise like the unit is coming apart with the massive noise and vibrations, and the solution for this that mitsi people will guide you to arrange a couple of dip switches on the outdoor main board not to let the inverter compressor to run below 60% of its capacity and Daikin the noise that the bc boxes does it is like having a steam train hovering around your unit and boxes. So all units have got their ups and downs, so In My opinion go for the cheapest and don't forget their are more brands than mitsi and daikin which are still as good and even better.