Modified wood stove to heat water

[VW Splitter]

So I mentioned this system in another thread and Zogger said I should post some pics and more info on it, so here it is.
I have a Englander wood stove that I modified to heat my domestic hot water. Started by building a 1 1/2" thick chamber on the left side. The stove is about 2' tall by 2'deep. So the chamber is about 2'x2' 1 1/2". Inside the chamber is a 60' coil of 1/2" copper tubing with the ends stubbed out the bottom. The tubing is piped into the crawl space and into a 50 gal low boy water heater that I use as a storage tank. The 50 gal low boy could be turned on with the flip of a breaker if it was ever needed but I use it just for a storage tank. There is a thermostat on the wall behind the stove that turns on a circulating pump that circulates the water thru the copper coil and thru the tank. It draws the water from the bottom of the tank, where the coolest water is , and dumps it into the top. When we use hot water it draws it off the top of the storage tank, where the hottest water is and runs it thru a BIG whole house Electric instant hot water heater that is set on 130 degrees. So we always get 130 degree hot water no matter what the temp is in the storage tank. Even in the summer with no fire in the stove and no preheated water. The instant hot pulls 80 amps when drawing cold water thru it and around 20 amps with 90 degree water going thru it. With just me and the wife at home now, the water in the storage tank will stay between 95 and 130 degrees, depending on when the last shower was taken and how hot the stove is running. The hottest I have ever had it was 169 degrees, must have been going dirty without a shower. If the water coming out of the bottom of the storage tank is above 110 degrees, we can turn off the BIG instant hot and just use the hot water that the stove is making. I have a small control panel mounted on the floor near the stove where I can flip a switch and turn the instant hot off or on, also has 2 temp gauges to monitor the temp of the water going in and coming out of the stove, and a pressure gauge to monitor water pressure. Thats about it. It works like a charm. I enjoy beating the power co out of the money.

 

[stihly dan]

Thats nice. Have any pics of the coil.

 

[brenndatomu]

NICE!
I would like to try this myself. All my stuff is in the basement, I was thinking I can probably get it to work with thermo siphon, but, just in case...whatcha using for a water pump? Does it only run when the water is hot?

 

[VW Splitter]

Thats nice. Have any pics of the coil.

No didnt take any picts of the build. It was about 5 years ago, before I got on AS. I know better now. Got to have pictures.

 

[VW Splitter]

NICE!
I would like to try this myself. All my stuff is in the basement, I was thinking I can probably get it to work with thermo siphon, but, just in case...whatcha using for a water pump? Does it only run when the water is hot?

The pump was the smallest, slowest one I could find. Came out of a Grainger catalog. There is a thermostat on the wall behind the stove so it actually runs when the room is hot, but that would be when the stove is burning. If I have a fire going there is a 98% chance that the room is hot enough to make it kick on.

 

[VW Splitter]

Here is a diagram of what is going on.

 

[zogger]

Thanks! Cool build.

 

[macattack_ga]

Nice work.

Any chance of the water getting too hot and boiling?
What if you loose power / no pump?

if/when I get a stove in the basement, I'd like to fab up a similar setup.

 

[VW Splitter]

Nice work.

Any chance of the water getting too hot and boiling?
What if you loose power / no pump?

if/when I get a stove in the basement, I'd like to fab up a similar setup.

I was really worried about that when I was putting it all together. I had no idea how hot it was going to get. Thought I might be building a bomb. Made sure it had a pop off valve just in case. I have never lost power. I have had it get pretty hot a few times, when I first build a fire and the stove is getting hot but the thermostat hadn't kicked the pump on yet. You can here the water gurgeling in the pipes, but no problems with it. How hot the water gets will depend on how hot the stove is, how often, and how much hot water you use. When my 2 kids were living at home, it would very rarely get up to 120 degrees. It sees that most every day now and more with just me and the wife at home.
If I lived in a colder climate and burned a hotter fire I would make hotter water. I enjoy watching the temp gauges to see how hot it is. I have always thought if it got any where near 200 degrees I would just run some hot water down the drain and cool it off. That hasen't been a issue yet. Hottest I have seen it as 169 degrees.

 

[Jredsjeep]

i really like this setup and have to admitt it has me thinking on how to do this myself. so in side the box on your woodstove i have a couple of questions. is your box welded on the side of the stove? is there anything inside the box to assist in heat transfer or is it just an airgap with the copper coil? how did you bend up the coil? i have heard you can get better bend filling the pipes with sand so they dont crush but have to admitt i have not had much luck doing this sort of thing myself.

 

[MotorSeven]

VW very nice job on you system build. I went with a instant propane hot water heater since I am at the end of a 330' duplex line & electric was out of the question. I like my system but it does suck the gas, so first thing this spring will be to build a solar hot water heater which is similar to your system. I thought about building a tank behind the stove but it is on the opposite corner of the house from the water pipes & WH so at least for now I will focus on solar.

 

[VW Splitter]

VW very nice job on you system build. I went with a instant propane hot water heater since I am at the end of a 330' duplex line & electric was out of the question. I like my system but it does suck the gas, so first thing this spring will be to build a solar hot water heater which is similar to your system. I thought about building a tank behind the stove but it is on the opposite corner of the house from the water pipes & WH so at least for now I will focus on solar.

I have thought about hooking mine up to solor also. I have the storage tank, pump, and most of the pipeing. I would just need the solar collector and a little pipeing and a few cutoff valves to make it happen, but solar collectors are expensive. Anyone know where a fellow can get a cheep solar collector?

 

[VW Splitter]

i really like this setup and have to admitt it has me thinking on how to do this myself. so in side the box on your woodstove i have a couple of questions. is your box welded on the side of the stove? is there anything inside the box to assist in heat transfer or is it just an airgap with the copper coil? how did you bend up the coil? i have heard you can get better bend filling the pipes with sand so they dont crush but have to admitt i have not had much luck doing this sort of thing myself.

The 1 1/2 wide chamber is not welded to the stove. It is screwed on with 6 screws. Did that so I could get back in there if needed. There is nothing inside to assest with heat transfer, just the copper pipe inside. The copper pipe I used came in a roll from Lowe's. It is made for bending and shaping. I didn't do a lot of bending on it. It came in a coil that was about the size of the chamber I was putting it in. Wasn't much more than just straighting out the 2 ends to stub down with. It was easy to bend without crimping. Just be sure and get the pipe that comes in the coil.

 

[Jredsjeep]

thanks, that sounds much simplier now!

 

[Deereman76]

Here is a site I frequent that has many stories about DIY Solar water heaters, some could easily be incorporated into your system....

Solar Water Heating Projects and Plans

 

[MotorSeven]

V-dub...build your own. A pt wood frame, 50' of PEX pipe, some black paint and either clear corrugated plastic roofing/plexi/glass to cover it all. Think about it...how hot is that water when it come out of a lousy garden hose that was left laying on the ground in August? A box will just collect and trap way more heat. Winter presents a different challenge...you will either have to have a closed system that uses Propelene Glycol(won't freeze) or you will need a drain back system so all water drains out when the sun is not shining. I think I am going to go closed loop....less worry's.