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  1. #14
    Join Date
    Mar 2008
    Posts
    11
    We are at the framing stages of a custom home in North Texas and are looking at the options for a/c and heat as we are trying to get US Green Building Council LEED's certification and efficiency is a consideration. Total cooling capacity needs is between 10-12 tons.

    We are considering the 4 ton residential variable refrigerant units from Daiken or Mitsubishi. The Mitsu is the S Series. The Daiken compressors are RXYMQ48MVJU. On the domestic front, we considered the Carrier hybrid system with 21 seer compressors.

    Here are the questions we are trying to get answers to before finalizing the decision:

    1. What are the differences in efficiency between the systems?
    2. What is the availability of parts look like between the two foreign companies?
    3. How well do they produce heat when there is an extreme change in ambient temperature and how cold is the a/c? Dallas ambient temperature can drop from 70-30 in one winter day and can go from 60 to 100 plus in the summer.
    4. Any other differences that we should consider?
    5. Any experience integrating the systems with whole house automation?
    Thanks.

  2. #15
    Join Date
    Jul 2007
    Location
    Haslet, TX
    Posts
    11
    I do not know enough about Mitsu, really like the Daiken and have installed 5-4 ton like you noted with 17 different air handlers on one house. Parts availability seems ok. You really should consider the proper insulation and windows to maximize your hvac equip and lower required tonnage. I'm in N. Ft Worth if you have any more questions please check my public profile for contact info. Good Luck!

  3. #16
    Join Date
    Mar 2008
    Location
    Australia
    Posts
    4

    Mitsubishi

    It would be a point to note that there are actually 2 Mitsubishi companies. Mitsubishi Electric (MELCO) and Mitsubishi Heavy Industries (MHI). MHI has a very impresive range of heat pump and heat recovery systems for both residential and commercial applications. They would be worth checking out to compare with Daikin. I think you'd be pleasantly surprised with their new KX6 systems.

  4. #17

    mitsubishi

    with daikin you have to twin outdoor units to meet the tonage you require. Mitsubishi offers many different tonages. daikin requires a BS box per fan coil which means you have to mount and power each BS box. mitsy offers a BC which comes in many different port sizes. so if you have 13 fan coil you only need one BC. which means one power supply.

    daikin is a 3-pipe system, mitsy 2-pipe. that means more piping for the job. and that cost is rising.

    we used to sell daikin and now sell city multi. sold over 200 systems. def the way to go. city multi been in the us for a long time and has a great support staff.

  5. #18
    from a contractors point of view daikin is far superior. while csipgh is correct that daikin does require a box per fan coil, this isn't a bad thing. daikin boxes are smaller and a lot lighter making them easier to handle during installation. i only need one guy to do it. they weigh like 20 pounds. the other weigh over a hundred. also the cost to replace them we have found is much cheaper than the city multi boxes. so yea, you need one box for 13 units. but if the thing breaks the customer is not going to be happy with the expense. (currently dealing with that)

    power is simple. you have to wire either manufacturer's indoor units anyway. the box is usually close to the indoor unit so just come right off of that. thats a lot easier than having to pipe a condensate line to the city multi box.

    common sense would say 3 pipe would use more than 2 pipe, but its just not so. you can use daikin y connectors (refnets i believe?) to branch off the main run without having to go all the way back to a centrallized box. this basically means one pipe run through the whole system as compared to one pipe run per indoor unit. thats a BIG difference when you start adding up your units inside.

    milton01 - haven't had any problems thus far with part availability.

    def agree with Installed-m-all.

  6. #19
    Join Date
    Feb 2008
    Posts
    4
    Does anyone have any insight on what kind of discharge air temperature I can expect when heating at low ambient temperature from Daikin or Mitsubishi? Around 0 degrees F? I've been told City Multi comes pre-wired for auxilary heat source because of its inability to heat at near zero temperatures. Any input?

  7. #20
    Installed-m-all do you have an email. have a few questions

  8. #21
    Join Date
    Jun 2008
    Location
    LONDON
    Posts
    57

    D or M

    Both brands are top, the question is which one to use.Depends on the application .Mitsi runs two pipe to the bc box and then up to 40 meter away the indoo unit.

    Daikin : using three pipe (heat recovery) but the overall piping in the system can reach 1 kilometer.

    Guys we are specialist in installation and troubleshooting these two brands

    if you need some info i shall dig up my library to find it.

  9. #22
    Join Date
    Jul 2004
    Location
    Red Lion, PA
    Posts
    62

    lets be clear

    Mitsu cant touch the heating capacity of Daikin especially in low temps. The a/c will run lower than the posted lockout temps also. Daikin is also the originator not the imitator. They are #2 in the world in hvac and if they gain 7% of the residential market they will surpass Carrier who is #1.

    Mitu guys will tell you there box is better and less piping is req but it depends on the location. and yes no condensate line from daikins b.s boxes

  10. #23
    Join Date
    Mar 2003
    Posts
    7,314
    as far as these units are concerned, they dont rate them at zero degrees, but any f the ones we have installed work well at those temps. as far as reliability, i have been selling them for over five years, and guess how many parts ive needed? nope, zero, havent needed any yet. none! bad for our service guys though. i am a huge fan ofthese daikin systems, and have used them for hospital server rooms, office buildings etc. no worries if installed right. for leed purposes, check out their new altherma unit which can also produce hot water!!! imagine using your ac to make your domestic water. gotta be leed points there.

  11. #24
    Join Date
    Jul 2004
    Location
    Red Lion, PA
    Posts
    62

    i know

    I am one of their biggest cheerleaders. We have 4 guys that we sent to cali for factory training and most problems we run into were ther contractors install mistakes. have had maybe to oder two parts. these are the future and with what Daikin has coming in the future look out

  12. #25
    Join Date
    Jun 2010
    Location
    prince albert
    Posts
    4
    im working on a pu24ek mr slim unit suction is 20psig and head pressure is 190psig did not do the piping plumber did and system is about 5 years old im thinking restricted liquid line or metering device and not sure if proper evac was ever done

  13. #26
    Join Date
    Mar 2003
    Posts
    7,314
    two words...offset flare

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