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solar addition

bobde Member Posts: 4
I have a Polaris propane whole house on demand water heater heating my in floor radiant system in my garage that works good. I am thinking about solar electric and was thinking about an electric whole house water heater to put inline before the propane whole house heater. Am what I am thinking workable or is it dumb


  • hot_rod
    hot_rod Member Posts: 19,846
    Sure, anything to pre-heat the water before the Polaris will save energy $$

    Are you considering PV to thermal like the Sun Bandit systems? With PV dropping below a buck a watt, those systems start to make good sense. Predictions are PV may drop to .35- .40 a watt within a few years!
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • jumper
    jumper Member Posts: 2,120
    It may be dumb. Or brilliant. Need to consider more details than you have provided.
  • bobde
    bobde Member Posts: 4
    1200 sq. ft garage with radiant heat. want to use solar to heat using on demand electric water heater and solar providing the electric- dont know if electric heater can last without burning out - will use the propane as a backup --any thoughts??
  • SWEI
    SWEI Member Posts: 7,356
    What are your costs for LPG and electricity? Not the number quoted at the top or middle of the bill, but the total dollar amount (including taxes, fees, etc.) divided by the kWH or gallons used during the period.
  • bobde
    bobde Member Posts: 4
    last winter propane cost me 1.79 per gallon and I used 600 gals for a total of $1074. Electric I use roughly 6oo kwh which costs 74.54 a month for a total per year of 900 per year
  • SWEI
    SWEI Member Posts: 7,356
    $37.17 per million BTUs for electricity, about average.
    Your LPG price is quite good:
    $23.90 per million for an 82% boiler
    $20.63 per million for a 95% boiler

    Heat loss calculation will almost certainly come out smaller than any LPG boiler you can buy. If you are only using this as a backup, I would seriously consider a small electric boiler. Installed cost should be about half that of a conventional LPG boiler and perhaps a third of what a good mod/con will.
  • Rich_49
    Rich_49 Member Posts: 2,738
    How can this fit into the equation ?http://www.sundrumsolar.com/
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833