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  1. #1
    Join Date
    Jul 2002
    Location
    Centerville, Iowa
    Posts
    400
    I wasn't sure if I should have put this in refrigeration or here but does someone know if any company makes a small chilled water air conditioning system with indoor units that resemble those used with a mini-split

  2. #2
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,376
    http://www.multiaqua.com has what you're looking for.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  3. #3
    Join Date
    Sep 2004
    Posts
    3,157
    So how does this work ? does it circulate chilled water to a coil in each room?

  4. #4
    Join Date
    Jul 2002
    Location
    Centerville, Iowa
    Posts
    400

    Smile

    Thank you shophound that is exactly what I am looking for.
    Yes ct2 it does circulate chilled water to individual coils in each room.

  5. #5
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,376
    Originally posted by ct2
    So how does this work ? does it circulate chilled water to a coil in each room?
    Daniel answered affirmative so I will add that apparently a Multiaqua system can be set up to heat as well, utilizing the chiller as a heat pump to heat the water in the loop rather than chill it.

    I'd be curious to see one of these in operation, as I'm more familiar with commercial chiller systems where the chiller is online all of the time and unloads as capacity decreases. On a residential air cooled system I'd imagine the chiller would cycle to maintain the setpoint of the chilled water loop.
    I'd also be curious if a system like this has chilled water bypass if all the zones aren't calling for cooling but the chiller wants to run to maintain setpoint. If the thing just shut off when there was no cooling calls from any of the air handlers and didn't cycle, the water would warm up eventually and there'd be a lag effect once a call for cooling came in.

    Always curious...
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  6. #6
    Join Date
    Mar 2003
    Posts
    7,326
    i do some residential chillers for high end users. the system is set up to maintain temp when there is a call for cooling. these systems generally have variable speed air handlers and electric reheat for humidity control. there is usually only one chilled water coil instead of a dx coil. the newer systems can have multiple fan coils attached to one small chiller which is a better overall solution.

  7. #7
    Join Date
    May 2005
    Posts
    39
    I enjoy working on chillers, but for residential, this sounds like it's on the verge of being a solution looking for a problem. Is it that effective? If it was commercial, my first question would be "Is it over 100 tons?" Occasionally, I have engineered for problems that don't exist. Does it work in real life?

    Regards,
    Rotorbar

  8. #8
    Join Date
    Jul 2002
    Location
    Centerville, Iowa
    Posts
    400
    I think the 20 gallon storage tank is too small. I would go for at least 100 gallons to avoid short compressor run times.
    Just do the math 100 gallons X approx. 10 pounds per gallon = 1000 pounds of water. 1 BTU is defined as the amount of heat energy needed to raise/lower the temp of 1 pound of water 1 degree fahrenheit. So to cool 1000 lbs of water 10 degrees (the temp swing of the chiller) it would require 10000 BTU. Assuming the chiller is the 3 ton (36000 btu/hour) the minimum compressor run time just to cool the tank each time would be 17 minutes. Add in the capacity of the piping and it would be over 20 minutes. That should be long enough of a run time at no cooling load to allow the refrigeration curcuit to stabilize and to prevent compressor damage.
    Somebody double check my math.

  9. #9
    Join Date
    May 2001
    Location
    Bennington, Vermont U.S.A.
    Posts
    13,864
    For a long time I had a concept like this figured out in my head for climates like we have in the Northeast. My biggest hang up was finding the selections of indoor coils like this Multi-Agua has. After looking at their web site I am now saying, "Hmmmmmmmmm......"

    A little Munchkin boiler and some glycol and we could be in business. I have a call into the factory. On the website they mentioned insulated tubing but they didn't show any.

  10. #10
    Join Date
    May 2001
    Location
    Bennington, Vermont U.S.A.
    Posts
    13,864
    Originally posted by danielthechskid
    I think the 20 gallon storage tank is too small.
    Up north here I would put the storage tank in the basement. Run all the tubing in the basement as well. Like I said the only thing that I had a problem with is finding the affordable room units and the tubing. Again, "Hmmmmmm... the old man is thinking."

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