|
Posted by Pat on March 29, 2008, 2:44 am
> Bill wrote:
> > As you may know, an electric water heater can be 30% of your electric
> > bill...
>
> > Well I got to thinking... I have this nice woodstove which puts out a lot of
> > heat and it is always 80 to 100 degrees (F) next to the woodstove.
>
> > Is there some way I can use this heat to "pre-heat" the water going into my
> > hot water heater????
>
> > Well I came up with an idea and tried it out. It works!
>
> > I got a used 50 gallon water heater at a recycling center. Then removed the
> > sheet metal cover and removed the insulation. So now I had just a bare metal
> > 50 gallon tank. I painted it black as in theory black absorbs heat better.
>
> Just a side note on the old no free lunch. The heat that is preheating
> your water would have been heating your home instead. That's OK, if your
> wood energy is cheaper than your electric. If you want to scavenge more
> heat there's a number of methods.
>
> http://zenstoves.net/Wood.htmhas some different ideas. Otherwise some
> coils on the back of the stove and a pressure relief valve. Of course,
> copper is expensive these days.
>
> Jeff
>
>
>
> > Then I placed this tank next to my woodstove. Then disconnected the cold
> > water going to my hot water heater and ran that to the bottom (drain)
> > connection on the tank by the woodstove. Then ran a pipe going out the top
> > of the tank by the woodstove to the cold water inlet of my electric hot
> > water heater. (Cold into the bottom, warm out the top.)
>
> > Note: My electric water heater is located on the other side of the wall next
> > to my woodstove.
>
> > After just a few hours, the water coming out of the top of the tank by the
> > wood stove was about 70 degrees. (The water from the city going into the
> > tank is 40 degrees F.) At this point the bottom of the tank felt cold and
> > the top was not cold.
>
> > The next morning, the entire tank was slightly warm.
>
> > Anyway I am now "pre-heating" the water going to my hot water heater. So
> > instead of my water heater having to heat up 40 degree water, it will only
> > need to heat up water which will be from 70-80 degrees. Perhaps warmer if I
> > have the woodstove going full blast and have not used any hot water for a
> > while. So should save some $$ on my electric bill.
>
> > Building code note: Now that I see this idea works, I'm going to install the
> > tank next to my woodstove to "code"* like a water heater tank would be. That
> > is drip pan, T&P valve, and strapped to wall for earthquakes. *I don't
> > suppose code covers anything like this? I also installed a valve and pipe to
> > outside for draining the tank.
>
> > Temperature and "steam" note: The temperature next to my woodstove never
> > gets above 115 degrees F. and water boils at 212 degrees. So no possibility
> > of steam being created.
Two things. Yes, the heat "lost" by the tank is gained by the room.
So you are saving something but not as much as you imaging.
Second, most of your heat isn't from heating cool water, it's from
holding it at temp when no one is using it. You still haven't
addessed that issue.
Good luck with it.
| 
Yahoo! 
Google 
Windows Live 
del.icio.us 
digg 
Netscape 
XML Sitemap