Plumbing Water Heater Into Solar Loop

Discussion in 'Solar and Geothermal Water Heating Forum' started by Highbeams, Sep 24, 2016.

  1. Highbeams

    Highbeams New Member

    Joined:
    Sep 24, 2016
    Location:
    California
    Hi, all-

    I have a solar DHW system that feeds my electric(!) water heater.

    It works great and in the Summertime the electric water heater stays turned off.

    The only problem is when no one has been home and you have to run the hot water for a bit to get the solar heated water to heat up the cold water in the electric tank before you can shower.

    I've been thinking about plumbing the electric water heater into the solar heater loop but looking at the electric water heater, I don't see a fitting to go back to the storage tank.

    I can see how I could modify the plumbing so the solar storage tank will either continue feeding into the electric water heater OR directly into the house, with valves to select one or the other, but then I would be running back and forth every day, futzing with the valves, depending on the weather.

    Is there a clever way to do this that the amateur in me cannot see?

    I do have a hot water return loop that is plumbed into the drain spigot on the bottom of my electric water heater.

    Could I use that?

    And....do I need to upload a diagram?

    I can describe, the setup: Radco drainback tank system that heats the water and feeds two Richmond S80TC-1 tanks plumbed in series. The output of one of those tanks feeds a GE residential water heater, which feeds the house and is plumbed with a hot water circulation loop.

    Hope that makes sense.

    Anyway, is there a fairly easy way to do this?

    Best,

    Chris
     
  2. Dana

    Dana In the trades

    Joined:
    Jan 14, 2009
    Location:
    01609
    Describe in more detail what is meant by "...when no one has been home and you have to run the hot water for a bit to get the solar heated water to heat up the cold water in the electric tank before you can shower"

    An electric tank heater should be heating the hot water whether or not it is getting it's being fed by pre-heated solar hot water or cold water. If it isn't delivering hot water after sitting idle for some period, it could be stratifying, or may not be functioning properly. But if you can describe the symptoms better it may be possible to figure out what is going on.
     
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  4. Highbeams

    Highbeams New Member

    Joined:
    Sep 24, 2016
    Location:
    California
    I turn the electric water heater off at the breaker to save money in the summertime.

    I can generate plenty of hot water using my solar panels. The problem is that hot water has to travel through the cold water of the electric water heater before it gets to the house.

    So I'd like to be able to heat the water in the electric water heater using my solar array, but I'm not sure how to plumb the electric water heater into the solar loop.
     
  5. Dana

    Dana In the trades

    Joined:
    Jan 14, 2009
    Location:
    01609
    Can you post a picture of the near-tank plumbing, and share more product info on the solar (particularly it's pumps & controls.)
     
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  6. ameli0rate

    ameli0rate New Member

    Joined:
    Oct 3, 2018
    Location:
    San Antonio, TX
    Just thinking out loud, could you have a small solar powered pump to circulate the hot water through the storage tank/electric heater? When you get home, hit the switch/timer and it runs for 10 minutes and circulates the water (or if it's purely solar and circulates all the time?
     
  7. Master Plumber Mark

    Master Plumber Mark Sensitivity trainer and plumber of mens souls

    Joined:
    Feb 6, 2005
    Occupation:
    Sensitivity trainer.. and plumber of mens souls
    Location:
    indianapolis indiana - land of the free, home of
    you have to be sure that all the water being circulated is POTABLE water.... if the water in the loop is separate from
    your drinking water then you could be getting yourself into a contanimation issue....

    I have dealt with this before with someone wanting to mix the boiler water with his hot water system and
    we could not mingle the waters...

    their had to be a heat exchanger involved--
    if you have one then its probably not a good idea
     
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  8. Onokai

    Onokai Member

    Joined:
    Apr 19, 2012
    Location:
    Arcata,Ca
    You could use the drain valve to make the loop back to solar tank. I use that drain valve for a grundfus smart pump so I have instant hot water at all taps but it requires a return from furthest faucet . You could do the same with a small smart pump to move the water a few times per day to keep the water heater water hot from solar tank with the electric heater turned off.
     
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  9. fitter30

    fitter30 Well-Known Member

    Joined:
    Feb 2, 2020
    Occupation:
    Retired service tech
    Location:
    Peace valley missouri
    What temp does the two solar tanks normally run? At that temp do the solar tanks keep up? What temp is the electric heater set on? In winter does the solar array shut down and the cold water stills flows thru two solar tanks?
     
    Last edited: May 20, 2021
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