Water heating

[awoodman]

When running a coil inside fire box is their any condensation problems?
I have a Quadrafire stove and a space beside it to put a 40 gal. tank
no pump needed.
I have a propane tankless hot water heater in my house I want to preheat
water to it.

 

[Slow1]

I advise extreme caution on this front based on reading I've done on this subject.

From what I have read (sorry, can't dig up references right now), heating water from a stove is generally a bad idea if you have other alternatives available. The basic reason is that if you put the coils in the firebox, the water pulls a LOT of heat out of a fire, thus you end up having a hard time keeping the fire up to a proper (i.e. clean) burning temperature. If you put the coil outside the firebox (i.e. near the flue gases) then you end up cooling down your stack too much and have draft issues and associated increased issues/dangers there (think nasty dirty chimney eh?). Not saying it can't be done - however, from what I have seen you really need to design it VERY carefully with an eye to several factors that may not be obvious at first blush.

If you go forward with this project I hope you share your experience!

 

[savageactor7]

I wish a savvy inventor would study and tinker with this cause it seems to me that the stove top heat could be reclaimed...good luck to the woodman.

 

[webbie]

I've used external coils with some success.....for instance against the rear of a stove - in between the stove and a shield.

I used to have them made up by a company that made the finned copper heat exchangers for inside boilers - they have a lot of surface area.

Another option is to DIY using "U" copper fitting, so you have a serpentine which goes back and forth a few times. This type of system is likely to convect well to a nearby tank where most of the water is above it. If you DIY, use higher temp solder just to be sure......also make certain you put a PR valve on the system.

 

[Slow1]

That makes sense - putting it outside the firebox and the flue would seem to keep it from 'stealing' too much heat from the proper operation of the stove.

 

[awoodman]

The Quadrafire has to many obstructions in the air space on the sides and back of the stove
for an external aplication. For an external use I would have to lay coils directly on the top of the stove.
And would condensation off the coils rust the stove top?

A company sells a stainless U that goes in the fire box. Just wondering if soft copper tubing
would work and if their is any condensation problems.

A hot set-up would be to have coils runing through fire brick on the inside of the stove.

 

[awoodman]

Bump it up maby some one has tried this?