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water cooling

Is the water side that you are using a "Unico" product or is it by other?


  • J Matthers_2
    J Matthers_2 Member Posts: 140
    Water Cooling

    For AC I have a water to water Geo copled with a Unico air handler.

    I have two questions. What is the "normal" water temp supplied to hydro coils for cooling? and What should I expect as a delta T across the coil?

    With space I have added to the conditioned area, I am just over the design envelop for the Geo unit (5 ton/heat gain 57,000), and the air handlers one 1.5 ton and one 3 ton. For the most part the house cools fine but summers like this where every day is a degree day plus it works hard to get to 78*. RH is great at 45%.

    I just want to make sure the system is performing to specs.

  • J Matthers_2
    J Matthers_2 Member Posts: 140

    Yes, Unico air handler with the Chilled water coil.
  • Eugene Silberstein
    Eugene Silberstein Member Posts: 1,380
    Typical Water temps

    Typical water temps for Chilled water systems are 45 degree supply water to the coil and 55 degree return water, giving a 10 degree split across the coil.

    These numbers are typical for chilled water systems and I would recommend giving Unico a shout to get their design numbers.

    One quick question (ok, two...or three). Where are you located and what type of well system are you utilizing? Are you using a pressure tank with the system to reduce pump running time?
  • J Matthers_2
    J Matthers_2 Member Posts: 140

    I am in eastern Long Island. The well is a regular well (about 60' deep with good water) with a pressure tank. Pump and dump design. I'm on all sand and gravel so I have great drainage and am dumping into a large drywell. The heat pump cools or heats a 40 gal buffer tank and the coils are supplied from there. on a 90
    8 design day, the coldest the system can get the buffer is 48*. By the time the water gets to the coil it has gained a degree or two. The delta across the coil is about 10* and my return water is 60 to 63*. Although the airhandler is slightly undersized, the Unico system removes so much latent heat 78* is very comfortable in the house. But, at anything above 85* the system runs 24 hours a day. I have thought about putting in a diverter valve to send water directly from the geo to the coils at 30* to perhaps increase performance. This would increase my return water as well and perhaps allow the buffer to reach a set point of 42* with a lower return and supply directly from the geo. But...

    The house is a SIP built house with a fair amount of glass. I have found that I still have to cool the house on 65* nights because it gains so much radiant heat via the glass on sunny days. The envelope holds heat very well. heating is via Warmboard and radiant throughout.
  • don_156
    don_156 Member Posts: 87

    I would go out on a limb and say its properly undersize,
    however that might not be a bad thing in a sip home.

    Maybe some window tinting or awning may help.
  • J Matthers_2
    J Matthers_2 Member Posts: 140

    It is undersized since I added cooling to a third floor and garage loft, the heat loss/gain shows that(although the calcs were done as is the house was conventional construction)...but that is ok, as I say, 78* and 45%RH in the house on a degree day is comfortable. I am looking to make sure it is running at opimum performance.

    Your right, eliminating some of the solar gain may be the key, however awnings don't suit the architecture and tinting would cost as much as adding more tonage, lots of twelve over twelve divided light.
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