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  1. #1
    Join Date
    May 2008
    Location
    Baltimore, MD
    Posts
    76

    Default Thoughts about solar water heating

    I considered hijacking the recent related thread because it is relevant to a project I've been considering. But I thought a new thread might be better in case others search on this later. This could go in the plumbing and/or "Green" board but I know you folks here seem to know what you are talking about. And a big part of my question is electrical.

    Background info:
    My baseboard heat and my hot water are both supplied from a relatively new oil fired boiler. There is no LP gas in the house and no natural gas utility available in the area. I'm not opposed to adding LP gas but have no immediate plans to.

    Project Idea:
    If I can stay employed I'd like to take advantage of some of the tax breaks for using alternative energy. My idea is to augment my electric supply with roof mounted solar panels (or PV shingles) and use some combination of solar water heating and electric powered tankless water heating in place of my boiler. In short I don't want to go off-grid but I'd like to reduce my dependance on it as much as possible.

    So let's just pretend money isn't the most important issue (I'm gonna buy the winning ticket any day now!!)
    I know that some solar water heaters as well as some electric tankless heaters can fall a little short from supplying the heat and volume we're used to. But I believe that some of these devices can be chained together to pre-heat water and that storage tanks for this heated water are getting better.

    Questions:
    So generally, I'm looking for your thoughts on designing a system using the best combination of these technologies in the most energy efficient way possible. (And yes cost IS actually a consideration but first I want to focus on designing the IDEAL system and then scale down as necessary).
    1. Can either of these (solar or tankless) be used to heat the recirculated water in my baseboard heating system?
    2. Since a tankless heater RAISES the current temp by so many degrees... would it make sense to use a solar heater and storage tank in line prior to a tankless heater to get an acceptable supply of really hot water... like for a nice hot shower?
    3. Does it make sense to chain multiple electric tankless heaters together to get an acceptable temperature rise?
    4. Would the electric tankless heater(s) seriously increase the number of solar panels needed to compensate for it?
    5. Can/should the oil burning boiler be kept in the line with cut-over valves as a backup system?
    6. If this is workable, does it make more or less sense to add batteries into the mix?
    7. Is this a potentially good idea... or would it take 100 years to break even?


    Thanks!

  2. #2
    Join Date
    Jun 2007
    Location
    Fayette County, Ohio
    Posts
    5,557

    Default Re: Thoughts about solar water heating

    1.Can either of these (solar or tankless) be used to heat the recirculated water in my baseboard heating system?
    Absolutely as long as you can supply sufficient temperature and volume for your system.
    2.Since a tankless heater RAISES the current temp by so many degrees... would it make sense to use a solar heater and storage tank in line prior to a tankless heater to get an acceptable supply of really hot water... like for a nice hot shower?
    Again yes.
    3.Does it make sense to chain multiple electric tankless heaters together to get an acceptable temperature rise?
    This has commonly be done. The drawback is the cost of equipment and power.
    4.Would the electric tankless heater(s) seriously increase the number of solar panels needed to compensate for it?
    This is a big yes. As a post on one of the other threads indicated the tankless heater they were looking at required 28,800 watts.
    5.Can/should the oil burning boiler be kept in the line with cut-over valves as a backup system?
    Again yes, the sun light like most things in nature is unpredictable unless you have a massive storage system.
    6.Is this a potentially good idea... or would it take 100 years to break even?
    That will depend on how it is done and how good your imagination is. A substantial savings can be realized with a small investment.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

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