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Best way to handle two temp system

Tim_9 Member Posts: 24
So after everyone's input here my HTP UFT-80 is on its way. For reference, I did a full Manual J via Loop Cad with a heat loss of 32K(2,500 sq/ft house in SF bay area). Slab on grade first floor with a required water temp of 81.9F, dt 10F @3.69gpm. Quick track second floor(or similar, upstairs remodel to be done next year), required water temp of 96.9F, dt [email protected].

First question, do I even need a two temp system? If I run the system on design day at roughly 90F, both of my required temps will be within 10 degrees of the actual output. This seems to be generally accepted on the wall. So...,run it at 90F and call it good?

Second question, if I do decide to go with a two temp system what is the best way to go about it. I of course would like to hit my numbers right on the nose along with the ability to run individual outdoor resets on each temp. It seems the easiest way would be to have the HTP control the upstairs temp and reset, with a taco i-series 3 way valve controlling the first floor(temp&reset). Anything wrong with this strategy, better options?

Last question, do you even think individual resets would even be that much of an advantage? With the different first/second floor panels designs (quick track 1000sq/ft@20 Btu/hr vs. slab on grade 1,500sq/ft@14 Btu/hr) Thanks in advance...


  • hot_rod
    hot_rod Member Posts: 21,868
    Sometimes you can adjust tube spacing to get the required supply temperatures more in alignment. I think you are close enough to go with one temperature, there is no hard and fast rule, some "rules of thumb" for adding a second temperature. I have heard 10% within one another is close enough.

    Remember furniture and throw rugs decrease floor output (heat flux) some fine tuning can be done with their placement :)
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Tim_9
    Tim_9 Member Posts: 24
    I appreciate the advice hot rod, I will be sure to throw in some Caleffi parts in the system:) A direct piped single temp system running off a alpha 2 sure would be a lot simpler. The very definition of KISS...
    EBEBRATT-Ed Member Posts: 15,335
    One temp. You could always add a 3 way valve for the lower temp zone if need be but I think your fine as is
  • Tim_9
    Tim_9 Member Posts: 24
    True...adding a 3 way after the fact would not be that big of a deal. I'll plumb the single temp system with that in mind, so adding it later would be as painless as possible. Thanks...