air source heat pump, split system, supply water for slab heat/cool

I'm wondering if anyone can offer some advice on the best approach to get hot water for slab heating (say, 25C) in winter, and chilled water for dehumidication and slight slab chilling in the summer from an air source heat pump. The project is a small (10,000 sq.ft.) commercial building. We'd be best to size off of chilling capacity of 25 tons, which will require some supplemental heat (likely oil-fired boiler) as heating exceeds cooling in our climate. Anyway my problem is that the project's HVAC engineer has experience only with air source heat pumps that connect to air handling units and is a loss as to what to connect to generate heated/cooled water. I'd appreciate any direction.
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You really need to re-think the idea of chilling the slab in summer.... think "dew point"
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Steve,
With proper dehumidification it is easily done. I wouldn't do it up my way, or down in your neck of the woods with out dehumidifacation, but in really dry climates it is really starting to come into vogue.
This guy needs a HVAC com, or engineer versed in GEO.
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Condensation in slab is a major concern, and the dehumidification system may not compensate.
And I do agree with Bob, there are plenty of geo companies out there willing to do the engineering for you (but they are selling their product). The Litmus test comes down to climate, energy management and how much your IAQ is going to suffer. You would need heat recovery or fresh air intake.
Maybe because I live in a rain forest...just wouldn't do it..no way. Use a HP??? Boy, I do have some other ideas I have been thinking up. Would anyone like to start a thread on "theory"???
Where I am now: Need ductwork, heatpump and ERV to serve IAQ requiriements and local codes on mild load days (assuming best case Manual J scenerio). Boiler for supplemental heat in slab, using a hi effic condensing boiler, Because slab heat runs at lower temps without mixing valves or bypass pump. You can cool slab with heat pump in dry climate but ...I just am not too sure if willing to loose my IAQ, have wet carpet, have slip and falls on tile or concrete...Obviously, I do not know what purpose this space is to be used as or where?
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There are a large number of water heating HP's, most are marketed as pool heaters. Google should find a bunch... I'm not sure you'll find an Air to water heatpump that chills water... but if you do, let me know. Take care with water treatment chemicals & how the heat pump performs, although if they're built for chlorinated pool water, they'll probably handle anything your system will use. Have your engineer plot the wet bulb temps on a Psych Chart before you cool your slab. Unless your in the dessert or high in the mountains you'll have a wet floor... I believe Dew Point was mentioned earlier.
goodluck geothermaljones st.paul,mn

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