Daikin VRV vs. Mitsubishi Multi City

[VRVIII]

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 .

• 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.

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.

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.

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.

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

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.

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.

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.

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

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.

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