old stove water heater

[jjmelt]

I want to take an old stove I have and wrap the outside in 1/2" copper coils to make hot water. If it works I will add storage. I plan on using 4 loops of 50' each and directly place them on the boiler and pour plaster of paris type material around the tubing to help with heat transfer. This stove would be dedicated to hot water. Kinda down and dirty design but $$ wont allow much else.
Thoughts??

 

[jebatty]

Burst pipe, scalding water, pressure build-up, .... For about $30 you can super-insulate an electric hw heater, add effective heat traps, and insulate your hw pipes, and unless hot water hogs reside, get the all the hot water you need for about $10/mo. I know, 'cause we did it.

 

[stee6043]

In addition to the safety issues with these types of setups you may want to consider the amount of water you can really heat. 200' of 1/2" tubing only holds roughly 2 gallons of water. How long before you have cold water moving through your loops so fast that it's not really being heated anymore? Two gallons won't last long even if you mix it down to a useable temperature.

Also...I don't think plaster of paris would last very long in this type of setting. But if you really have your heart set on doing something like this be sure to install a mixing valve so you prevent any amount of "ultra hot" water from reaching any of your water fixtures...

 

[Medman]

I agree with Jim - I did this during the summer. Insulate the tank, wrap all of the lines you can see, even under the sinks. Add heat traps and use a mixing valve on the tank outlet so that the tank remains at a higher temp (more ueable heat in the tank). This is a low cost solution that has an immediate and noticable effect.
Now if I could just get that teenage girl of mine out of the shower...

 

[farmersam]

It can work. My parents house is baseboard hot water. Dad took copper and wrapped it around a Standard(brand name) pot belly stove. Then wrapped it with a think sheet of copper.

Necessary components: pressure relief valve, expansion tank, and a 'dump zone'. Dad's dump zone was a reznor heater...basically a finned radiator with a fan behind it. Hooked to a thermostat with a lead on it, which was attached to the copper pipe. Dad could heat the entire house (3 bedroom rancher, 2 stories) with that stove instead of his natural gas boiler. This was a closed loop system, of course.

Other throughts? I'm thinking about the same thing in my house. I don't want to use electric hot water. Electric in Appalachia = coal burning.

 

[Gooserider]

I agree with Jim - I did this during the summer. Insulate the tank, wrap all of the lines you can see, even under the sinks. Add heat traps and use a mixing valve on the tank outlet so that the tank remains at a higher temp (more ueable heat in the tank). This is a low cost solution that has an immediate and noticable effect.
Now if I could just get that teenage girl of mine out of the shower...

Simple - add timer that after N minutes shuts off the hot water line, and cross connects it to the cold water line... Bet she won't stay in long after that.... Might need to get better earplugs than you use with the chainsaw though, as she might get a trifle noisy.

Gooserider

 

[jjmelt]

Thanks for the replys


I would add all the saftey items you all mention. I was going to draw what I think would work then ask you all to look it over. I have a oil burner with a zone to a boiler mate for the DHW I was thinking of tapping into the return of the boiler and just let the water from the stove circulate through the boiler. When a thermostat calls the circulators will turn on and the boiler will only turn on if the stove isn't keeping up.
If the copper is laid aginst the stove the water won't get hot enough when it goes through 50' of piping?
Not sure what you mean about the electric water heater. Are you saying I should eliminate the tank and buy an electric HW heater and insulate it and all the pipes? Insulating tanks is no problem I have a spray foam machine.
What is an effective heat trap?
We have 4 girls that love the shower. My boiler turns on just to make HW. The wood stove in the house pretty much heats the house.

 

[jjmelt]

I'm just copying what I you guys are doing with the gasification boilers. I just wont be as efficient. Like I said before storage will be coming as soon as I find a tank.
Found a bunch of used 500 gal propane tanks in Indiana on Ebay. A bit to far for me to drive

 

[WES999]

Here are some pics of a project I am working on, a water heater for my old Fisher stove. I made a heat exchanger form 3/8 ridged copper tubing and two pieces of of 3/8 aluminum. It is placed on the stove top, The water is circulated through the heat exchanger by a Taco pump, the pump is controlled with an temp controller with a thermocouple in the heat exchanger.

This is a non pressurized system so there should be little risk of burst pipes, but I have added a relief valve just in case.

I have run a preliminary test and was able to heat about 20 gal of water from RT to about 150* in about 2 hr.
There is still a lot of work to be done, tank and line need insulation etc.

 

[jjmelt]

Similar to what I want to do. However I will be pressurized (10- 15 PSI)and lots more tubing around the stove. It looks like you have about 20' of tubing. I was looking to get 200' around the stove. so can I assume I would have 10 times more? Some type of concrete poured arounf the tubing should help with the heat transfer. They must make something that won't rot out the copper. I also have some old cast iron basebord I was thinking of using. Somehow wrap the stove in the baseboard.

 

[Fred61]

I tried this a few years ago and spent alot of money and alot of energy for very poor results. After my initial coil failed to produce enough hot water I reworked it two more times and still had poor results. I was able to get my 100 gallon tank up to about 140* in about three days, running the stove wide open. 100 gallons of 140* water doesn't go very far. A byproduct of this was that I sucked so much heat off the stove, I couldn't get it to burn properly. I always had a cold smokey fire.

 

[farmersam]

Fred,

How much tubing did you use, and was it directly in contact with the stove or was there an insulation material between the stove and tubing?

Sam

 

[kabbott]

Here are some pics of a project I am working on, a water heater for my old Fisher stove. I made a heat exchanger form 3/8 ridged copper tubing and two pieces of of 3/8 aluminum. It is placed on the stove top, The water is circulated through the heat exchanger by a Taco pump, the pump is controlled with an temp controller with a thermocouple in the heat exchanger.

This is a non pressurized system so there should be little risk of burst pipes, but I have added a relief valve just in case.

I have run a preliminary test and was able to heat about 20 gal of water from RT to about 150* in about 2 hr.
There is still a lot of work to be done, tank and line need insulation etc.

I have a Fisher similar to the one in the pic that I converted to a "boiler". I have a water jacket on the back and top and a 6" pipe about 3 feet long through a
larger pipe that captures heat from the outlet(afterthought to lower stack temp). I don't have good hard data but estimate 60-80,000 btu peak.
the "peak does not last very long and if you need this output maintained you better be prepared to carry a lot of wood. It is very inefficient, the stack temps are
still high( 600 ish ) It has heated my home and DHW for 2 going on 3 seasons but I am looking at building/buying a gasifier.Last year I used 7-8 cord of wood(ouch!)

If you are serious about making hot water I would find another route.
Whatever you decide be SAFE, steam is no joke!

 

[Fred61]

Fred,

How much tubing did you use, and was it directly in contact with the stove or was there an insulation material between the stove and tubing?

Sam

Sam,

I had one of those stainless coils from hilkoil http://www.hilkoil.com/ running through the firebox and about 39 feet of 3/4" copper on the outside. The insulation was over the outside of the copper tubing.Not much of the copper was in contact with the stove surface. It's good because if it all was in contact, the stove would not have burned at all. The stainless coil in the firebox would get a thick, hard, crusty coating that needed to be chipped off quite frequently.

 

[jjmelt]

Well I still want to try it. You all might cring but I was going to just tap into the oil burner flue to see if it works before I invest in pipe. I was going to test with the boiler off so I don't have both run at the same time. Any other problem with that I'm not aware of?

 

[Gooserider]

Well I still want to try it. You all might cring but I was going to just tap into the oil burner flue to see if it works before I invest in pipe. I was going to test with the boiler off so I don't have both run at the same time. Any other problem with that I'm not aware of?

Aside from the fact that it is a direct violation of the stove makers instructions, and breaks every fire and insurance code in the book????

There is a real reason why they say that you should NEVER share a flue on a wood burning appliance... First off, It is possible for one appliance to backdraft through the other, filling the house with smoke and CO. Secondly it is claimed that the combustion gasses from the two appliances leave different and incompatible residues, which can combine in ways that are corrosive to some chimney materials, are ignition prone (as in chimney fire) and build up more rapidly than either would alone...

(Note also that if you do have a problem, it is really doubtful if your homeowners would pay up because you were doing stuff in violation of code...)

Gooserider

 

[jjmelt]

Don't all the combo furnaces share the same flue?

 

[RobC]

AHONA has refurbished tanks and include heat exchangers. There is a guy in Penn. That does the same and I think you can get them at the $200 / $400 range. His name has been on this site, just can't think of it. Leddog has had some Michigan. Where are you at ?

 

[jjmelt]

I'm in NEW York just outside the city. The tank was going to the next project, If you remember who the guy is I would like to know.

 

[RobC]

Will get back to you later to day. I tried doing a google already and didn't catch him. Maybe some one will catch this post and remember. Try searching on this site some body had posts of his sales yard not too long ago.

 

[Gooserider]

Don't all the combo furnaces share the same flue?

Yes some do, but they are then tested and rated for that application, with designs to prevent the problem mentioned, any special requirements for the chimney specified, and so on...

Gooserider

 

[RobC]

This is the guy. The ad is from Lancaster Farming.There a few posts on this site with his name mentioned. I think you can get them just as they are or he will do work to them if you want.
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