solar home heating with AC
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  1. #1
    Join Date
    Sep 2003
    Location
    Portland.OR
    Posts
    313

    solar home heating with AC

    Anyone ever try solar hot water through an airhandler coil then have an AC coil too?

    Or would 2 coil resistance kill the airflow? Seems like it.


    This would be for a home in TX, what are the electric rate and Nat Gas
    costs there?

    Thanks in advance for your responses.

  2. #2
    Join Date
    Jan 2009
    Location
    Indiana
    Posts
    3,228
    i service several office buildings with air handlers that do this, except the hot water is made threw a boiler. U may be looking at a commercial grade coil air handler.

  3. #3
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,410
    We have installed air handler/HP units and left a space in return for customer's hot water coil for outdoor wood furnace. Only problems we encountered was the wood furnace installer screwed up the low voltage wiring and burnt up our low voltage transformer. Are you installing the solar system? If you are, then should not be a problem especially if you oversize the blower right off the start.

  4. #4
    Join Date
    Feb 2010
    Posts
    58
    With right sized ductwork I'd think this would be good application for variable speed blower.

  5. #5
    Join Date
    Mar 2003
    Posts
    7,321
    there are units already designed for use with hydronic coils. many manufacturers make them. biggest issue is what to do when solar is not available.

  6. #6
    Join Date
    Jun 2007
    Location
    Round Rock
    Posts
    3,509
    It's already a product, been out several years. Goodman makes one we've installed several times. Although a hot water heater has been used to heat the coil in the jobs we've done.
    I like DIY'ers. They pay better to fix.

  7. #7
    Join Date
    Sep 2002
    Location
    I don't know
    Posts
    2,903
    You'll need a second source of heat - natural gas if available or propane.

    Make sure that the air handler has an ECM blower if the house is going to be off the grid.
    General public's attitude towards our energy predicament: "I reject the reality of finite resource depletion and substitute it with my own; energy is infinite, we just need an alternative storage medium to run the cars on. The economy can grow indefinitely - we just need to "green" everything! Technology is energy! Peak what?"

  8. #8
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,829
    We've done it with a geo system. It works up to a point but in our area the 2,000 gallon solar tank gets pulled down pretty fast. You have to be careful about the Btu load and not depend on the solar for extended times when the sun isn't out and it's low in the sky, such as January and February. Having said all of that, the main problem we ran into was controls. Seems nobody builds a control/t-stat that will handle both the air handler blower and cycle the pump for the solar as primary and the heat pump as secondary. We got into some special control applications there. The other two issues were that the HP was to be used for cooling in the summer (2-stage) so we had to be able to run the system without the solar at all above 65F. Also, we had to be careful to turn off the solar when the tank temperature dropped or we'd be using the geo HP to heat the solar coil, which is neither efficient nor what is intended. The static is only a little higher but that is primarily due to the limited space we had to squeeze in both the air handler and the solar coil.

    We came onto the job late, after the solar installer was already at work when they realized they couldn't heat the house all winter with the solar. So in the future, my geo jobs will have PV solar rather than water solar. That way we can offset the electrical component cost of running the geo system and the net is a zero cost of operation heating/cooling system.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  9. #9
    Join Date
    Oct 2006
    Location
    Northwest NC
    Posts
    70

    solar heat

    Skippedover is right in the point that a forced air system will zap the heat quickly from a solar storage tank. In most cases, the storage will only last for 2-3 hours in cold weather. If you want to heat with solar, the best way that I have seen is radiant floor heat. The temp settings for most floors is so low (85-100 degree range) that the cushion of heat in the storage tank is pulled down slowly. Even at that, you should still have some secondary way to heat the solar storage tank in the event of several cloudy days or unusually cold weather.
    I have never been lost, but I will admit to being confused for several weeks.-Daniel Boone-

    Just because a person wanders does not mean he is lost.

  10. #10
    Join Date
    Jun 2010
    Location
    Philadelphia PA
    Posts
    2,190
    Just a matter of having enough ESP for an existing duct system with the added coil, or having sized the duct with the available ESP with a new duct system.

    Doesn't seem more complicated than that, or did I missed something?
    You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!

  11. #11
    Join Date
    Oct 2010
    Location
    SW Michigan, near Battle Creek
    Posts
    921
    I work on a old hydro heat that has a ground water cooling coil, a heating condencer coil, and a outdoor boiler heating coil. System works fine.

  12. #12
    Join Date
    Oct 2010
    Location
    SW Michigan, near Battle Creek
    Posts
    921
    things can get screwed up to. I was on my third warranty call on a water heater and suddenly noticed that I had plumbed it backward.

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