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Posted

Research that more, I can't imagine hot water and house heating are anywhere close to each other. From what I understand, you need ALOT of panels to heat the house and you will need backup heat or a huge storage capacity. The recovery rate is just too low.

From the little research I have done the hot water systems pay for themselves in 3-5 years depending on your current energy source. Switching from propane has the fastest payback. Whole house heat would be a much longer payback due to the size of the system. If you are in a sunny area, I would go photovoltaic and heat pump.Check with your utility company. Where I am, they rebate half the cost of the system then there are federal tax credits plus they deduct any excess energy produced from your bill. There are people here who have an $8 electric bill.

I'm sure there are others on here with much more knowledge on these systems than I have.

As far a propane use, I completely shut the propane water heater down unless it is cloudy all day or we have house guests. You do need some sort of backup for those times.

There are better hot water systems that use vacuum tube heat exchangers on the roof but they are costly.The flat panels are pretty tried and true but do take up some space.

Posted

Thanks,

The payback on PV just isn't there yet (except maybe to power a heat dump), Western NY is too cold for an air source heat pump and my heat is all hydronic.

My entire house is natural gas, so to isolate my DHW I averaged my bills for June thru August to account for estimated usage and to rule out the use of other gas appliances, we line dry laundry and use the grill a lot in summer. I then converted CCF's into therms by multiplying by 1.024 and then by 12 to get my annual DHW consumption, and it is exactly half my total usage. I think my math is pretty good, but I don't like the outcome. What is a normal DHW BTU load?

I have space constraints that limit me to a 40 gallon short tank, which meant a less efficient heater 8 years ago when I put it in. An 80 gallon electric might fit, but then I'd have the same crappy recovery rate and a more expensive fuel source, but it would be a good choice for a simple solar system with a dip tube heat exchanger.

Tom

  • 2 years later...

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