Wood burner for hot water only?

[Kenster]

We have an all electric house close to 4000 square feet. We have two large heat pumps that cover the main part of the house and a separate unit that heats our sun room, which we use as a den/TV room and for most meals. We heat almost exclusively with a VC Vigilant that does a very nice job in the main part of the house and occasionally turn on the small unit in the sun room.
Having two 40 gallon electric water heaters is a killer, especially in the coldest part of the winter when the replacement water coming in is very cold. One of the water heaters is on the side of the house where the two bathrooms are located. The other water heater is on the other side of the house and feeds only the kitchen and laundry room.
We are on balanced billing with our electric rural coop. Our bill year round runs about $200 a month with very heavy use for air conditioning from mid April through late September early October. In the winter time, the biggest expense by far is the two water heaters.

I'm curious if it would be worthwhile and make economic sense to have a wood burning boiler to supplement the water heater that feeds the two bathrooms. I wouldn't think it would need to be very large with this limited application. There are only two of us living here except for a rare weekend/holiday when we might have company.
I wouldn't have a clue as to how to hook up such an operation.

I have a virtually unlimited supply of oak available to me for firewood so fueling a boiler would be no problem. I'd never have to buy fuel for it.
Do wood burners have to be fed constantly, like twice a day? How often do you need to clean out the ashes?

So, I guess the main questions are: 1) does have a wood burner make any sense at all just to supplement hot water in the house.
2) Economic sense? What would the payback period be? (How many years of savings would it take for the boiler to pay for itself?)
3) Can any good plumber install this or does it take a specialist?

Thanks!

 

[rkusek]

Look at your bill. Is the electric kW useage the same during the winter months or less than the summer months? Heating hot water with wood makes sense in places like Wisconsin or even Nebraska where I live, but I doubt you could justify it near Houston. A gasser with storage would cost close to $15k but give you free hot water year around. 1 load of wood every 7-10 days would probably cover the hot water needs during the 9 months or so that you don't need heat. An OWB would need to be hot all the time, ie. smoke and smolder and still cost $8-10k with UG line and heat exchangers in your air handlers. Some wood furnaces have a hot water coil but then it would only help your hot water situation when it was burning (ie. winter months). This may be the cheapest option, maybe $2500-4k installed but I think you would only be saving maybe $300-400 year tops on heating hot water for that 3 months since you already have a wood stove that gets the rest of the job done.

 

[flyingcow]

Agree with above post. How about a tankless water heater?

 

[Morgan]

I would be thinking solar panels more than a wood boiler if I were you...

 

[Kenster]

I wish I could go tankless but the way our house is built, there's no way to run new wiring from the breaker box downstairs to the upstairs water heater. Upstairs is open loft.
No walls in which to run wiring so we'd have to pull up floors to add the new wiring tankless would require. One thought, though, is to add a 110v mini tankless that would basically preheat water going into the tank via the cold water inlet.

Other than that, I guess the recapture rate turns this project into a no win situation. I'm all for being Green but it has to make some sort of economic sense, too.

 

[Hunderliggur]

I second the solar recommendation - year round assistance, good reliability, manageable costs. You can do a tankless in the basement. You will need about 80 amps of electric service to run an electric tankless. Better than storing hot water though. Solar preheat and tankless is the ultimate, but I bet in Texas the solar with an in-tank electric backup would work fine. Don't give up with running the extra wiring. A GOOD creative electrician may know some things that you don't. I bet you could run solar from the roof though ;-)

 

[maple1]

Have you considered a heat pump water heater? Like the Geyser? I am seriously thinking about incorporating one into my (hopefully) next year system overhaul. Sounds like you have space heating covered - if so, I am thinking the additional load on that from something like a Geyser would be minimal. From the reading I've done on them, it seems people are doing their DHW for $20/month. If that's right, it seems way ahead of even a solar array when trying to think of capitol costs & ROI. Factor in the side benefit of dehumidification & air cooling for summer months, and it's pretty compelling.