solar addition

bobde

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

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!

jumper

It may be dumb. Or brilliant. Need to consider more details than you have provided.

bobde

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

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

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

$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

How can this fit into the equation ?http://www.sundrumsolar.com/