Any ideas for supplementing DHW in lieu of boiler?

I installed an electric hot water heater for the summer and off season. I am also trying to heat my water in the electric hot water tank by thermosiphon from from my oil boiler which is heated in a series with the wood boiler. If it works maybe if I have a fire on in the evenings for a bit of heat it will heat the tank up so I have 50 gallons reserve when my fire goes out.

I use an indirect tank for DHW. It's set up as a zone and can be heated from the wood boiler, oil boiler, or storage. When I heat it from wood, I run it up to 160 degrees. Combined with a preheat loop in my storage, that allows the 40 gallon indirect to last for three days (family of 3-4).

In another month, I'll fill the solar panels and heat it that way.

My solar has been working well, heating my 80 gals to 150 top and 125 bottom. 3 sunless and boilerless days would be a stretch though, which isn't likely in March or April. My final backup is an electric coil that heats just the top 15" of the tank, to about 115.

Where can I learn about solar DHW? What will it cost to install if I do it all myself?

I'll be shutting down my outdoor boiler soon, and I hate hearing the propane fire up on my water heater....

There are many sites with solar DHW info. Most aren't nearly as useful as this site, as they are peddling something.

See nofossils homepage for a lot of info, and some creative ideas. Or check your area for a local solar store. They can help you get tax credits that might help you justify a new 2 coil indirect tank, or some other goodie, even if you install it.

The key advantage we boiler owners have is that we don't care at all about solar DHW in the winter. So, we can change angles, install fewer panels, or put them at some angle other than exactly true South. Or, we can even drain them, as Nofossil does, and skip the glycol issues.

I bought my solar off Craigslist, and probably have 1500. in it, including the new 80 gal tank.

Cool, thanks! Just spitballing for now...

depends on how much hot water you need, or want. The typical formula is 20 gallons per person per day. That may be high if you are conservative.. But with teen agers in the house all bets are off.

solar pre-heat with an instantaneous is a popular way. you need to define you needs or loads. instant HW heaters are not good with multiple large loads calling at once. if you can schedule your DHW demand they work well.

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I seem to remember someone suggesting installing a water tank in the attic to preheat/heat water. Seems like a very simple thing to do. An attic is usually pretty hot in the summer.
Obviously it would only work in the summer months. Any reason not to?

Water at 8 lbs. per gallon is a lot of concentrated weight on joists that may not be sized for that kind of weight. Also, a leaking tank can cause a lot of damage quickly. I'd avoid it.

not to mention dealing with freezing/draining in the winter. my attic is hot in the sumer and cold! in the winter. However in a slightly related comment, since I installed white steel roofing on my garage(small barn) roof it barely gets warmer than the air all sumer long, it used to be an oven.

You may want to check out - www.jc-solarhomes.com and www.builditsolar.com, Lots of good information on solar water heatig on both sites.

A bare pre-heat tank in a warm attic would sweat quite a bit.

There use to be a product called solar attic or something like that. Basically a hydronic unit heater with a drip pan below. it would blow warm air out of the attic and pre-heat you domestic water with that warm air, via the coil. Clever and effective, dual purpose. Plenty easy for a DIYer to build.

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