Solar Hot Water for Home Heating

Solar Domestic Hot Water and Solar hot water heating for homes and pools
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Joined: Wed Nov 06, 2013 12:49 pm

Solar Hot Water for Home Heating

Postby Pennywire » Fri Oct 17, 2014 10:27 am

Hi everyone.

I heard on the radio something about Solar Hot Water and I started thinking. I know a few places that used hot water radiators for heat, and I wondered if solar hot water was consistent enough to be used as a heat source in a home? How big would these systems be? Is it feasible?

Posts: 52
Joined: Tue Dec 03, 2013 11:12 am

Re: Solar Hot Water for Home Heating

Postby X-Hunter » Mon Oct 20, 2014 1:45 pm

There's alot of engineering involved in giving you an accurate answer, because the size of the space to be heated, insulation values, and amount of heat required all vary for each site. There are some online calculators you can use to get a rough idea of what your heating values are, but ultimately you're looking for a BTU count, ie. how many BTU is needed to heat your area. I personally just use a calculator version found here:

Once you have a rough idea of how many BTUs are required, you can estimate your system tube size with a general calculation, estimating each tube at ~200 BTU. So for an average of 30,000 BTU, you would need 150 tubes. (30,000 / 200 = 150). It's similar to the calculation used to figure out how many tubes your system needs to be to heat hot water for domestic use.

There is one rather sizable flaw in this, and that is summertime heating.

You need somewhere to dump the excess heat from a solar heating array for winter heating, as its going to produce nearly triple the necessary heat. This makes for a fantasic reason to own a swimming pool, as a heating array can add several degrees to your pool and extend the swimming season considerably. Another option is to have something to shade large portions of the array with to limit the amount of heat being generated. The most extreme step would be to remove the glycol from your solar heating system entirely, however if you're using it for hot water as well this is not an option, nor is it recommended.

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