How should I use my wood stove to heat household water?
 

I am planning on getting a Kitchen Queen wood cookstove with optional coil loop that goes through the firebox to heat water. I am planning on routing it to a storage tank directly above on the second floor using thermosyphoning. I have a few questions for the off-grid experts here:

1. Would you use an open or closed loop system? Would it make more sense to run some sort of antifreeze through the loop and heat the water by induction?

2. I'd like to have an insulated storage tank on the second floor that is impervious to corrosion. Do you know of any good insulated composite tanks suitable for potable water?

Thanks!

Re: How should I use my wood stove to heat household water?
 

Interesting subject. Difficult solution, unless you just buy a couple 12 quart stock pots and set then on the stove;

Re: How should I use my wood stove to heat household water?
 

This is just an opinion.....

1. I would think heat loss is going to be an issue with an induction system. No matter what, you are losing heat in transfer to the tank and at the tank itself. Heating antifreeze to heat a tank to heat the water. Heat the water and get it into a tank. Then to worry about keeping it hot.

2. Stainless steel tank and myself I would think about some type of masonary component as a thermal barrier. I would think you are going to want the tank as close to the cookstove as possible (i.e. behind it) to maybe capture any radiant heat off the stove. Side benefit is you have a huge heat sink for winter warming.

Ever think of a rooftop solar system? Your wood consuption will be quite large heating water year around this way not to mention heating a house in 90 degree summer weather.

Re: How should I use my wood stove to heat household water?
 

I was thinking about perhaps a propane water heater that would function as a storage unit in the winter and actually a heater in the summer. Solar water heaters are still too far out of my price range.

Directly above the stove is a loft to the second floor landing where the water heater will be exposed. It will benefit directly from convection.

Dangerous
 

A propane water heater that benefits by convection in the winter could not have insulation. For summer use insulation would have to be reinstalled. If I were to have a pressurized water system with coils around the flue, I would install two pressure/temperature relief valves to be safe.
I have heard of a gas water heater leveling a single story building. It must have had a plugged relief valve and very little water.

Re: Dangerous
 

The propane water heater would still be tied into the wood cookstove via a coil using thermosyphoning. Sorry I wasn't clear on that.

Here is the Kitchen Queen coil hook up:

http://www.kitchenqueenstoves.com/ki...s/ash/back.jpg

Re: Dangerous
 

They can be bombs..

If the safety relief valve ever fails, and as stated
if the tank is not full.

And that goes to all hot water tanks.
No mater how they are heated....!

Re: Dangerous
 

I thought about this once when my water heater broke.

If you want a storage tank, I would go with the tank from a broken water heater. It is obviously designed for this task. They are very well insulated, they can take some pressure, and you should be able to get one for free or the price of scrap. Just put on a new pressure value at the top there to be safe.

I'm not sure exactly what the big picture is here. Somehow you have to get cold water into your firebox heater when the storage tank gets low, and also get water out of the storage tank. I could imagine a system that works given the cold water coming in pressurized and that pressure remaining through the system until the tank, you'd just have to regulate the flow through the firebox so the water had time to heat.

Perhaps you'd be best with a shutoff valve on the water input, and one more before the storage tank. Both could be opened when your fire was raging and this would allow you to fill the tank, then you close them manually when the tank is full. After than you'd have to pressurize the tank on your own, or rely on gravity for your shower if the tank is high up enough.

Re: How should I use my wood stove to heat household water?
 

The problem with this kind of system is all the variables you might encounter.
What if it's real cold and your water supply is inoperable? Can the cookstove heat the house without damaging the water system?
Will the coils be damaged if they are heated dry? You have to realize that you might be dealing with maximum temperatures in the neighborhood of 800 degrees farenheit or more.
How closely would such a system be monitored?
I don't know the monthly cost of operating a well insulated 30 gallon propane water heater but I don't think it's much. I have a tankless propane water heater and it hardly uses any propane. I don't recommend them, though. Next time I'll just get an efficient 30 gallon (which is the smallest you can buy)propane water heater and adjust it to the lowest setting.
SHTF? You would be surprised how easy it is to deal with the stock pots. I could easily live like that year round if I had to, as long as I was physically able to cary the pot to the shower.

Re: How should I use my wood stove to heat household water?
 

I have not done this...

Either weld up a rectangular box or use header tubes top and bottom with a parallel tube array (tubes run vertical) and feed cold water return at the bottom of the box or array and hot water from the top.

Just insulate the header tank very well. A bottom line from the header tank goes down to the bottom of the heating system. The hot water from the heating array goes to the top of the header tank.

Keep the lines as straight as possible and keep them large. No less than 3/4 inch and don't hesitate to go larger.

I drew up a solar hot water collector for some college kids living in a bus one time, but they didn't have the money to buy the pipe...

Hypothetical cheap solar hot water...

Use the black ABS (not available everywhere - but you can ship it in) in 3" size. Ordinary Ts and 90 degree bends - off the shelf components. It is available in ten foot lengths and could be used full length or cut in half as your area allows. Use a 55 gallon drum for the header tank set up on a platform; plumb the bottom of the tank directly to the solar heater at the bottom and run a line from the top of the solar collector manifold to a point midway or 2/3 up the drum. This top line needs to be always covered with water or the thermosyphon will stop.

This was summer and they wanted a shower that could be shared. They had an adequate water supply gravity feed to the proposed site.

This entire thing could be inside a greenhouse type structure (obviously) but this was proposed for a summer to five month usage.

jcb

Re: Dangerous
 

On a thread here brio said how they did it...
It was a passive convection system.

Yes using a water jacket that your stove heat's
the water and then draws water from the jacket from
the top of the jacket to the tank.

Use a small pump to make the transfer to the tank,
It is not complicated in practice but to type it
may be.....

fresh water into the bottom of the water jacket on the stove.
draw hot water from the top of the jacket and pump
to the tank....
From the bottom of the water tank, draw water using
another pump to circulate water from the tank to the bottom of the
water jacket on the stove (fresh water to the bottom also)

And tap for use from the top of the tank..

I may modify this post..Later,,,

Think missing something!

Can say I can think of a working convection system
that uses convection to make it work (no pumps)
But trying to work out a way to re-circulate the water
in the tank to the water jacket to keep the heat up in
the tank without using a pump...

Next......:beer:

Re: Dangerous
 

Presumably the Kitchen Queen coils are made of thick 316 stainless steel. Tn..Andy had a stainless coil in a fireplace grate for many years which he used to heat his home, you might consult with him regarding the durability of such coils under a variety of conditions. Even then, a fireplace is a couple hundred degrees cooler than the inside of a woodstove.
Imagine cold water on the inside of the pipe and 800 degrees on the outside.....or imagine the pipe empty and the stove at 800 degrees. I wonder how long such a system could last.

Re: Dangerous
 

As long as the temp is below the melting point and the s/s
and it can keep its property's (ever over heat a s/s pan
and ruin it) there maybe no problem as long as the temp
does not change the metal of the coils..

There is a critical temp that s/s will change its property's
and not sure without searching what that is.

Re: Dangerous
 

Ok, I think I understand what you are saying. You would have no water pressure though (other than by gravity), correct?

I can see that working if your tank is up high enough. I'd also have a shutoff(s) between the stove and the tank, so you could hold the hot water inside without it circulating out and possibly cooling down.

Re: Dangerous
 

Right!! hot water is lighter than cold...

Gravity is your friend...

Edit: You can and will have water pressure from your supply...

Re: How should I use my wood stove to heat household water?
 

Hoarder:

I think the loops they use in stoves are stainless steel.....I sorta doubt boiling them dry would harm it.....plus, if he had a tank of water in a thermosyphoning loop, there should always be water on the coil anyway....only way his tank is going to empty is by pressure being supplied by the house supply side, short of a leak, OR getting it too hot and boiling out a lot of the tank via an open pop off valve, there should always be water in the tank

Look for an industrial scrap yard and find a stainless steel tank....also check with milk equipment supply places for something. I found a stainless tank like this and converted it with a stainless flue up the center to make a wood fired water heater. MAKE SURE you get a pressure rated tank.

Here's the one I did:

http://www.digistash.com/data/026a39...3_p126099.jpeg

Here's an online place that has lots of used tanks:
http://www.wohlassociates.com/cat.asp?id=89

In your case, I'd wrap it with fiberglass insulation.....mine is just going to be used as I heat it, no need for storage/on demand hot water.

Definitely need a check valve....two can't hurt.....also put a small expansion tank at the top of the system,( Amitol 50 bucks at Home Depot) because you won't have a way to control temp ( and thus expansion ) and a check valve on the cold water inflow from the house supply.

Expansion tank:

http://base0.googlehosted.com/base_m...3885a3ab&hl=en


You're probably also going to need anti-scald mixing valves AT each point of use in the house, because again, you will have no control over the temperature of the hot water....it might be 100 one day, and 180 the next....( remember, hog scalding water is only 145-150 )

ALSO, gauging the AMOUNT of hot water is going to be a real challenge....you may produce too much, too little, etc....you're almost certainly going to have to have a backup system ( if for warm weather alone )....

SO, by the time you get done with all that, you might find a tankless propane water heater is the way to go. :biggrin:

EDIT: By the way, the fireplace loop I used was NOT stainless....it was black iron pipe and I went thru two of them in 25 years....the weak point was the number of welds required at the manifold....I never burned thu or had a leak in a actual pc of the pipe.

Re: How should I use my wood stove to heat household water?
 

You have first hand experience, I don't.
Maybe kitchen Queen puts the coils off to the side, rather than directly in the fire chamber. It would be more trouble free that way.

Using two handle faucets would be a good idea, I don't think regulation would be a problem because although the source temperature might vary day to day, it wouldn't change rapidly like on my tankless heater.

I would avoid using any plastic pipe anywhere near the tank or stove, and use galvanized in the direct vicinity of the stove rather than copper sweat joints.

Re: How should I use my wood stove to heat household water?
 

Even using two handled faucets will get you scalded, I think. Problem is, you turn it on, and unless you wait for the water to come from the tank, and go ahead and start using the water, you could be in for a real surprise when the hot water does arrive.


And if Kitchen Queen doesn't use a stainless loop, leave it out, and buy one from these folks....they make them just for wood stoves:

http://www.hilkoil.com/product.htm

Here's another company that sells them....complete with "how to" on installing:

http://thermacoil.com/

http://thermacoil.com/images/thermosiphon.png

Re: How should I use my wood stove to heat household water?
 

Thanks Andy...

I was having fun with this..

Knew someone probably had it figured out already,
just knew it could be done..

Was using some old oilfield equipment design elements
in part a gas drying unit using glycol that used
convection to circulate the glycol with out a pump..

It was fun while it lasted.(side note , made me think
of some really neat systems)

It is simple, Your example on your post is perfect...

Gd

Re: How should I use my wood stove to heat household water?
 

Countryside Magazine just featured an article on this in their Jan/Feb issue.

Looks like they have it available online to read:
http://www.countrysidemag.com/issues...cookstove.html


If you guys dont get this magazine you should! Lots of good info in it, I look forward to getting mine every other month!

Re: How should I use my wood stove to heat household water?
 

These stainless coils Tn...Andy found look like the solution. The only possible problem is that it may get too hot. Water heaters generally do not have an extra plugged hole where you can install a guage. You would have to check it by running some water. I would get the smaller thermocoil and a larger propane water heater for this system. If it got too hot you could peel off some insulation for winter use. I would add a bypass with isolator valves for summer use of the propane water heater. Also I'd install a drain at the bottom of the loop for whenever you need to drain your system to prevent freezing when you're gone or to work on it.
It would be nice to get feedback from someone who has tried this sytem.

Try it SLV and report back!

Re: How should I use my wood stove to heat household water?
 

If you pull out the heating elements on and electric heater carcas, you have plenty of threaded holes for extra guages and lines.

Re: How should I use my wood stove to heat household water?
 

I would want to be able to use the water heater in the summer.

Re: How should I use my wood stove to heat household water?
 

I was planning on actually installing a drain under the back of the wood cookstove to permit me to drain the reservoir and pipes if we are gone in the winter. All of my plumbing will be made this way.

It will be a while before I get to that point. I'd love to done with it at the end of this summer, and I'll keep everyone posted on progress in my homesteading thread.

Re: How should I use my wood stove to heat household water?
 

Can you weld??


</slv>

Re: How should I use my wood stove to heat household water?
 

http://yukon-eagle.com/FURNACES/THEH...1/Default.aspx

http://www.fluemiser.com/

http://www.lehmans.com/store/Stoves_...___26845?Args=

Re: How should I use my wood stove to heat household water?
 

Yes... basic stuff, why?

Re: How should I use my wood stove to heat household water?
 

Nothing really just having a thought about
doing home mods on stuff.

I love working with metal!
Give me a set of prints and the space
to work with and watch out!

Part of my life was spent as a welder/fitter,
pipe and structural steel fab.

You made a comment in your post that
made me think if it were mine I would be
dragging out the equipment and get after
it.

But had no other agenda at all .

Sort of thinking out loud using a keyboard.

:beer:

Edit:

A big part of my welding/fitting time was
oil field equipment and making pressure vessel's
some could call it being a boiler maker (sp?)
Have about 10+ years doing it.
So adding fittings to a tank started me
thinking.....

Sometimes maybe not a good thing??

</slv>

Re: How should I use my wood stove to heat household water?
 

I'd love to learn to be a better welder. I think I'll get a chance to hone those skills when I start putting together my '29 Model A hotrod... first the house.

Re: How should I use my wood stove to heat household water?
 

For sheet metal,

Use tig.

Less heat input and holds down the warping,
Mig is o.k..but more heat to deal with..and that
= warping.
</slv>

Re: How should I use my wood stove to heat household water?
 

thanks for the info.

i'm only in the brainstirning stage but this thread tells me i need to plan plenty ahead because i'm going to do hotwater with some salvage solar panels + now i see this needs to be integrated with my woodstove[& maybe elect/gas backup].

i acknowledge grung of theoildrum for the following plan ...for the solar i plan an open system w/ solar heated h2o into a large holding tank[heat exchanger].

a small solar/electric panel driven pump would set the solar system in motion- h2o from holding tank up to panels. [gravity feed back to tank- no low spots re freezing]

my cold water would go into a coil[copper one say 120' 3/4 in the holding tank/heat exchanger this [pre] heats water prior to elect/gas heater.

that's my plan for now- prior to reading this thread.



? so coil in my woodstove to heat exchanger or to hotwater heater like is typical. i'd think water heater. thanks.

also i weld & have some stainless-- approximate thickness/size pipe of the thermo coils? i didn't find specs on links.

open to redesigning solar but $ limited.

Re: How should I use my wood stove to heat household water?
 

I just used an El Sid pump and a 1/2" copper coil loop wrapped around the flue of the wood stove, its controlled by a t'stat on the HWT. Its a 12 volt, 10 watt pump that is seal less, magnetic drive. Draws from the bottom of tank (tee fitting on drain valve) and tee'ed into the hot water outlet on top of the HWT. Pump is piped in the bottom return line from the tank to the stove.

Pretty simple, really.


http://www.siliconsolar.com/shop/sol...ing-Pump_T.jpg