Water jacket/coil on cookstove for hot water?

[Rusnakes]

Has anyone out there effectively installed a water jacket or coil on their cookstove for use in your domestic hot water system? We are considering a cookstove for the kitchen area and have the opportunity to build a system if it is feasible. I read literature from Obadiah's on the topic and I went from "this seems doable" to "we'd probably blow up the house".

Thoughts/experiences?

 

[bholler]

Has anyone out there effectively installed a water jacket or coil on their cookstove for use in your domestic hot water system? We are considering a cookstove for the kitchen area and have the opportunity to build a system if it is feasible. I read literature from Obadiah's on the topic and I went from "this seems doable" to "we'd probably blow up the house".

many cook stoves come with them already. And yes it can work the problem I have found is that if they heat water well that water is usually taking enough heat out of the system that you have problems with creosote buildup due to the lower exhaust temps

 

[Rusnakes]

many cook stoves come with them already. And yes it can work the problem I have found is that if they heat water well that water is usually taking enough heat out of the system that you have problems with creosote buildup due to the lower exhaust temps

Hadn't considered that as a problem, but that is something to strongly consider. I remember reading somewhere that the water jacket option assumed about 40% or so of the overall BTUs. One of the other worries at our end is balancing the need for a "large enough" firebox (for decent longer burns/less standing over the stove) and the heat output of the stove itself (we already have another stove and want the cookstove for just the kitchen area. And, we like the classic style versions, too (like the Heartland, Elmira...vs. the Kitchen Queen, etc.).

I know that the vast majority of the cookstoves sell a water jacket option, but the actual mechanics (and possible failures) with it leave us with great pause.

 

[bholler]

The kitchen queen is a much better unit than the heartland elmira ect.

 

[coaly]

The Kitchen Queen has a stainless U shaped pipe inside firebox for heating baseboard, radiant floor or a hot water holding tank.
It was made to circulate through the optional reservoir on the back, but you will find it makes too much hot water and over humidifies the house. So the reservoir gets enough heat from the stove edge it sets on unless you use it as intended as the reservoir being your only hot water source. With the coil added to the tank it can boil 24 gallons an hour. If you are on 1 floor, you need a small circulator pump, if heating a floor above, it will circulate naturally as the heated water rises, flows through the radiation and back to be reheated. This can be an "open" system with tank you fill manually or pressurized fill with a 10 or 15 pound regulator. The later also uses a relief valve plumbed just like a boiler.(expansion tank, oxygen separator or scoop, regulator auto-fill valve)
As long as you install a pressure / temperature relief valve on a pressurized system you will be safe. NO isolation valves between heating coil and relief valve that could be closed. I have a faucet on the side of mine in the kitchen as well that supplies enough hot water all winter for the kitchen.

Here's a very good book for kitchen boilers;
http://www.archive.org/stream/kitchenboilerco00unkngoog#page/n72/mode/2up

Pex tubing is very easy to install and you must use the tubing for heating systems with oxygen barrier in closed systems. I oversize it to 3/4 to reduce friction and get circulation through entire home without pumping.

The Kitchen Queen is my only heat source for close to 2000 square feet. It is used as the oven, cooktop, clothes dryer and humidifier all winter.
We have a commercial Garland range and my wife prefers the wood oven since it is always 300 or above and ready to go.They bake and cook better in the oven than conventional ovens since they do not use air circulation around food staying moister inside and never drying the food out. They are the ultimate wood stove. You won't find another brand with a larger tank, and most don't circulate UNDER the oven first when on bypass to prevent the tar, goo and creosote found under ovens that circulate the normal route, over, down, under.
Search for my posts with keyword Kitchen Queen for threads with pictures and more info such as thermostats and summer operation.

 

[coaly]

I clean once during the heating season, but it could take a season or two to learn the stove. I learned to keep the oven door closed until completely up to temperature since there is always circulation around the oven. It's not the path of least resistance, but flue gasses are allowed to circulate. Overnight this adds to the heat output but can cool the chimney with too much surface area extracting heat. I only need the extra BTU for extremely cold nights. There is a bypass directly up chimney from firebox to open in the morning that allows chimney to heat up fast, so there are ways to reduce creosote formation. I could probably get by with cleaning at season end, but cleaning with a Soot Eater from the bottom is so easy, I keep it clean for less resistance in the flue and a quicker responding stove.

You definitely want a 6 inch insulated flue. The stove has recently passed UL with reduced 6 inch pipe. The warning about reducing in the old manuals was due to having enough draw around oven, using smaller than the 7 inch outlet. Mine has worked fine with 6 inch. It may not achieve over 600*f. oven temp, but I never needed it that hot. The thermometer goes to 1000 and you could reach 800 if you tried. It gets too hot in here with prolonged oven temps. over 400.

 

[Rusnakes]

At 26 gallons an hour, that is a LOT of hot water. So if you have a reservoir + external storage tank system (just for hot water use) vs. a radiant heat system (for whole house heating, thus lots of cooling off of the water coursing through the house) and you run your stove 24/7 in the winter, I assume there is some way to deal with the excessive amount of hot water produced? I mean, I *love* hot baths, but even I couldn't use that amount of output.

Here's what I kind of envisioned for our entire hot water system in a I-have-never-put-something-like-this-together-before kind of thinking. We are in Michigan, so we would probably use the stove reliably from about October through May for cooking/heating. We also have a Jotul F55 in the main section of the house, just for heat. This cookstove stove would go in the furthest back portion of the house (think back mud room area attached to our kitchen; we will likely bust out the wall to have it all one space):

Cookstove with water coil, on first floor of house
Reservoir on back (size dependent on model/brand)
Water storage tank plumbed in a few feet higher than the stove (we have room to build a "closet" to store this in that mudroom area space)
Storage tank plumbed to interface with our main hotwater tank in the basement
Main hotwater tank is plumbed to fixtures in house (for us this is 3--bathtub, kitchen sink, mudroom sink)

We also wanted to create a summertime hotwater system using a solar hot water system. That would be down in the basement, plumbed to the main hotwater tank.

We have mulled over the Kitchen Queen many (MANY) times. I had read that they can burn you out of the house, which is one reason (besides aesthetics) that we didn't consider it for this area. Total sqft-age for this portion of the house is about 800 or so feet, then a door, then the rest of the house (about 1500 ft heated by the Jotul). We also have a backup propane furnace.

 

[electrathon]

Are you heating domestic water only or trying to produce baseboard/floor heat? The BTU's taken from the stove will be drastically different if you want baseboard heat. It is way easier to just get domestic hot water. If done properly it is not that hard to set it up. It is done all over the world and used to be done in America. It can be dangerous, just like burning wood can be dangerous. Done properly it is not any more danger concern than a woodstove is. It will basically be a solar water set-up except that you will be using the stove as the heat source instead of the sun. I have a long explanation on the forum about my system. I am hooked into a woodstove above the heat baffle plate, so your system will produce a lot more heat a lot faster than mine does.

I can answer many direct questions you have.

 

[electrathon]

Your storage tank should be higher than your stove, more height, better circulation. No pump is needed for this set-up. The cold water inlet to the normal hot water heater is diverted into the inlet side of the new pre-heat tank (water fills cold into the bottom) Hot water out (from tank top) goes to the cold water inlet of the house water heater. Circulation loop to the stove goes cold water out (tank bottom) to the lower inlet pipe on your water coil. Upper water out on the coil goes to the top of the tank. If you install solar you use the same storage tank as you are using for the stove, you just need to install a "solar wand" into the tank for the glycol part of the system. You need a check valve on the inlet side of the stove, this helps with the "push" of the heated water. You need an overpressure valve set on the outlet side of the coil, drained to waste or outside. You need an expansion tank on your system, a water heater expansion tank will work (you should have that already).

 

[coaly]

At 26 gallons an hour, that is a LOT of hot water. So if you have a reservoir + external storage tank system (just for hot water use) vs. a radiant heat system (for whole house heating, thus lots of cooling off of the water coursing through the house) and you run your stove 24/7 in the winter, I assume there is some way to deal with the excessive amount of hot water produced? I mean, I *love* hot baths, but even I couldn't use that amount of output.
We have mulled over the Kitchen Queen many (MANY) times. I had read that they can burn you out of the house, which is one reason (besides aesthetics) that we didn't consider it for this area. Total sqft-age for this portion of the house is about 800 or so feet, then a door, then the rest of the house (about 1500 ft heated by the Jotul). We also have a backup propane furnace.

The coil when used to heat water in the tank is good for a large Amish family. That's what it was built for.
When you have other domestic hot water and don't use enough, you don't install the coil. It will over humidify the house since it is a vented tank.

I went with the 480 and it is in the center of open floor plan house. I built it to heat with a centrally located stove which was a Fisher at the time. Cooking on a freestanding wood stove is hard on the legs heating up, and we wanted a larger cooktop. The Queen has full size brick thickness across the front so your legs don't heat up standing over it for long periods of time. The firebox door is a double wall with intake air between inside and out, so it doesn't heat up as well. Put a fan at the floor blowing cool air into the stove room. I would still favor the 480 over 380 due to a smaller firebox and smaller oven.

 

[electrathon]

The Kitchen Queen has a stainless U shaped pipe inside firebox for heating baseboard, radiant floor or a hot water holding tank.
It was made to circulate through the optional reservoir on the back, but you will find it makes too much hot water and over humidifies the house. So the reservoir gets enough heat from the stove edge it sets on unless you use it as intended as the reservoir being your only hot water source. With the coil added to the tank it can boil 24 gallons an hour. If you are on 1 floor, you need a small circulator pump, if heating a floor above, it will circulate naturally as the heated water rises, flows through the radiation and back to be reheated. This can be an "open" system with tank you fill manually or pressurized fill with a 10 or 15 pound regulator. The later also uses a relief valve plumbed just like a boiler.(expansion tank, oxygen separator or scoop, regulator auto-fill valve)
As long as you install a pressure / temperature relief valve on a pressurized system you will be safe. NO isolation valves between heating coil and relief valve that could be closed. I have a faucet on the side of mine in the kitchen as well that supplies enough hot water all winter for the kitchen.

Coaly, What is the coil made our of that is in the firebox? Specifically is it meat the low lead standards for domestic piping and can it handle domestic water pressures (100PSI)? 15 PSI is boiler pressure, but is he is going to run a preheat tank to the domestic water heater he will exceed that many times over. Also the over boiling of water can be easily controlled on a system running household water pressure. My system never tops 120 degrees no matter how long the stove is running. You may get hotter than that, but these systems generally level off at some point, depending on the system design and piping. Depending on house pressure boiling temp will be about 250 degrees. Solar system designers understand this and it is part of the design.

 

[bholler]

What is the coil made our of that is in the firebox?

Stainless as he mentioned in what you quoted

Specifically is it meat the low lead standards for domestic piping

Yes it is made for domestic piping.

piping and can it handle domestic water pressures (100PSI)?

That I dont know for sure but after seeing how they are built it would really surprise me if it couldn't.

My system never tops 120 degrees no matter how long the stove is running.

If it only reaches 120 max how much hot water can it supply? certainly not enough for any sort of radiant heating

 

[electrathon]

electrathon said: ↑
What is the coil made our of that is in the firebox?
Stainless as he mentioned in what you quoted

↑
Specifically is it meat the low lead standards for domestic piping
Yes it is made for domestic piping.
That was my question. There are many alloys of stainless and many are not rated for domestic piping.
↑
piping and can it handle domestic water pressures (100PSI)?
That I dont know for sure but after seeing how they are built it would really surprise me if it couldn't.
I figures it likely could, but the system seems to be designed for open water heater heating and then there were comments on 10-15 PSI, way to low for domestic water, but great for boilers. You know how it works, if it is not rated for it then it doesn't matter if it works. It just matters what the UL rating says.

↑
My system never tops 120 degrees no matter how long the stove is running.
If it only reaches 120 max how much hot water can it supply? certainly not enough for any sort of radiant heating
I do not use my system for radiant heating. I heat domestic hot water. The BTUs needed for domestic hot water are far fewer than radiant heat uses. If you are having overheat issues on a domestic water system one solution is to add some baseboard heaters to dump heat and heat a cooler part of the house.

 

[coaly]

3/4 pipe size schedule 40. Just like black iron, made of stainless.

It sets on clips pre-installed in the firebox on oven side.

The stove comes with square plates bolted across the pre-cut holes.Simply remove bolts and plates, screw together pipe and elbows and double nut to firebox rear;



The kit is made to only circulate to the stainless tank on the back. The coil takes water from the low side of coil that comes from the hotter firebox side of tank and hotter water exits from coil into the oven side of tank raising the temperature of only the 24 gallons in the manually filled tank.It will boil that tank from a cold fill in one hour.

I pointed out to the builder that this diagram is incorrect. You want the rising hot water from coil in firebox to return to the cooler side of tank on oven side as shown below. He didn't know it was on-line. Ed Semmelwroth from Antique Stoves is a good friend and uploaded things on-line for him including the entire Kitchen Queen website.

This is the correct connections from the website as well;
This is the kit for tank connection. I replaced hoses with stainless flexible water heater connectors. Screws right on to the 3/4 male pipe nipples that come with the kit, also stainless.

Here's my kitchen faucet;

I also added the white support which is a shelf bracket to hang scraper, poker, and other utensils in the kitchen. Those are onions drying on a clothes rack behind stove.

Onion season.........

I raised my tank with a half inch solid aluminum shim as a heat sink all the way across tank for more support and more surface contact from stove top to tank. The outlet box on the back houses the bypass slider for quick starting without circulating exhaust across stove top. The added heat it absorbs into water tank is in place of the water coil in fire box. That is the hottest part of stove and doesn't seem to cool the exhaust noticeably. The bypass is also used in summer for stove top cooking without heating the entire stove.

Most Kitchen Queen owners self insure through the Amish Church, so the UL rating is only for Englishers. My added thermostat would negate the UL Rating anyway. That's the best feature of the stove and new ones now are adding it as a listed option. Mine was procured at cost and a test subject. I posted the pics on a thread here years ago fabricating the thermostat. Back then it was only used and available to the Amish. It was just retested and passed with improvements, so they are now being offered on the new version.

 

[bholler]

That was my question. There are many alloys of stainless and many are not rated for domestic piping.

It is listed for domestic water production so I would assume it is ok for that.

I do not use my system for radiant heating. I heat domestic hot water. The BTUs needed for domestic hot water are far fewer than radiant heat uses. If you are having overheat issues on a domestic water system one solution is to add some baseboard heaters to dump heat and heat a cooler part of the house.

I know that but my point is that if there are only enough btus to get it to 120 max how does it supply enough hot water even for domestic use? I know it couldn't in my house.

I figures it likely could, but the system seems to be designed for open water heater heating and then there were comments on 10-15 PSI, way to low for domestic water, but great for boilers. You know how it works, if it is not rated for it then it doesn't matter if it works. It just matters what the UL rating says.

Yeah I dont know what they are rated for all of them I have worked on were open systems mainly because they were in Amish houses without power or running water.. There is one we work on in an English house but it is just an open system to they just gravity feed for the bathroom and kitchen

 

[electrathon]

I know that but my point is that if there are only enough btus to get it to 120 max how does it supply enough hot water even for domestic use? I know it couldn't in my house.

How hot do you have your heater set? 120 is plenty hot for domestic water. 50 gallons of 120 degree water is far more hot water that 10 gallons of 200 degree water. A lot safer too.

If you are asking why the water is not hotter than 120 degrees, I will respond with why is your living room not 600 degrees when the stove is. It all has to do with BTU transfer.

 

[bholler]

How hot do you have your heater set? 120 is plenty hot for domestic water. 50 gallons of 120 degree water is far more hot water that 10 gallons of 200 degree water. A lot safer too.

Yes 120 is a fine temp but if that is the max that your stove can heat to as you say how can it possibly keep up? I am talking about btu input which if your tank maxes out at 120 if left untouched there is not much in the way of btu input there.

I know about btu transfer just fine I just dont see how you have enough btu transfer into the tank to keep up with even moderate use if it only has enough btus to get up to 120. And btw when I was heating water with coal previously it heated much higher that 120 but I put in a mixing valve to keep the water to the taps at a constant safe level.

 

[electrathon]

Yes 120 is a fine temp but if that is the max that your stove can heat to as you say how can it possibly keep up? I am talking about btu input which if your tank maxes out at 120 if left untouched there is not much in the way of btu input there.

I know about btu transfer just fine I just dont see how you have enough btu transfer into the tank to keep up with even moderate use if it only has enough btus to get up to 120. And btw when I was heating water with coal previously it heated much higher that 120 but I put in a mixing valve to keep the water to the taps at a constant safe level.

Remember that this is a preheat tank, I have said many times that the coil in my stove robs very little BTUs from it. The coil is above the baffle plate, not in the firebox. The preheat tank is 50 gallons, if it is anyplace near 120 my instant hot water heater will stay off. If it is at 100, the instant hot adds only about 10 degrees. Water normally is about 50 degrees around here so the energy is a fraction to only raise it 10 instead of 60 degrees (i keep it set on 110. I also likely have some thermal loss to the basement, the preheat tank is a standard electric water heater. Any loss of heat transfers to the house.

I am sort of surprised that you are not bashing on the above coil set up. There is no circulatory loop, it is a simple peculator system. You will initially have water boiling inside the coil with cold water still in the tank. l am puzzled at the tank set-op It would be so simple to have a basic circulatory system. It would work better and be far safer than how it is configured. The water faucet is on the inlet side of the coil, I am guessing that is because the top of the coil is typically scalding, so drawing water from the inlet side possibly tempers the boiled water with inlet water.. I see this system as functional but horribly dangerous. Possibly heating water with a circulation system is not permitted in the Amish rule system?

 

[Rusnakes]

Are you heating domestic water only or trying to produce baseboard/floor heat? The BTU's taken from the stove will be drastically different if you want baseboard heat. It is way easier to just get domestic hot water. If done properly it is not that hard to set it up. It is done all over the world and used to be done in America. It can be dangerous, just like burning wood can be dangerous. Done properly it is not any more danger concern than a woodstove is. It will basically be a solar water set-up except that you will be using the stove as the heat source instead of the sun. I have a long explanation on the forum about my system. I am hooked into a woodstove above the heat baffle plate, so your system will produce a lot more heat a lot faster than mine does.

I can answer many direct questions you have.

We were just looking to have it for domestic hot water use only (sinks, shower). My concern with the cookstove boiler option is that, unlike a solar hot water system, where you have a maximum heating temp and then you can have it shut off and drain back to the storage tank (since the domestic water isn't heated in the collectors; the water in the solar hot water system is and is passively conducted to your domestic system), the cookstove boiler option heats your domestic hot water directly, which means it is sitting in the coil until water is used to move it along in the system. At least that is what I am envisioning thinking about this type of set up.

I'll look your system up in the forums. Sounds interesting.

 

[electrathon]

We were just looking to have it for domestic hot water use only (sinks, shower). My concern with the cookstove boiler option is that, unlike a solar hot water system, where you have a maximum heating temp and then you can have it shut off and drain back to the storage tank (since the domestic water isn't heated in the collectors; the water in the solar hot water system is and is passively conducted to your domestic system), the cookstove boiler option heats your domestic hot water directly, which means it is sitting in the coil until water is used to move it along in the system. At least that is what I am envisioning thinking about this type of set up.

I'll look your system up in the forums. Sounds interesting.

You must have a water storage tank, preferably a preheat tank for the domestic water system. You can not have water boiling in the coil, circulation is a must.

 

[bholler]

I am sort of surprised that you are not bashing on the above coil set up. There is no circulatory loop, it is a simple peculator system. You will initially have water boiling inside the coil with cold water still in the tank. l am puzzled at the tank set-op It would be so simple to have a basic circulatory system.

Every one I have worked on has a cross over line between the two tanks so there is a loop or they had a separate tank that was a loop as well I agree the system shown with two unconnected tanks doesn't make sense. But that is not what I have seen in the field.

I see this system as functional but horribly dangerous.

I agree without a crossover between the tanks it wont be as functional but I don't see the danger you are seeing at all.


The fact is that this system is tested and works to supply all of the hot water for families not just to preheat their water.

 

[bholler]

You can not have water boiling in the coil, circulation is a must.

Yes absolutely.

 

[Rusnakes]

You must have a water storage tank, preferably a preheat tank for the domestic water system. You can not have water boiling in the coil, circulation is a must.

So, I guess my question is...what if your water is already at a high temp in the storage tank and you don't use hot water all that often? Does it keep working its way to boiling? If not, then I would expect there was some temp regulator and drain back in the system to keep the coil from boiling your water to oblivion. (Sorry, I am no expert in plumbing, so apologies if I sound dunce with this...trying to learn the limits of what a system could do to see if it would be a good fit here).

 

[bholler]

So, I guess my question is...what if your water is already at a high temp in the storage tank and you don't use hot water all that often? Does it keep working its way to boiling? If not, then I would expect there was some temp regulator and drain back in the system to keep the coil from boiling your water to oblivion. (Sorry, I am no expert in plumbing, so apologies if I sound dunce with this...trying to learn the limits of what a system could do to see if it would be a good fit here).

No if you have enough btus to boil the tank it will boil it and blow the pressure relief valve. That is why the system needs to be designed right with enough btu input to supply the needed water but not to much that it will boil it. In the systems i have worked on they are open systems that are gravity fed so it if boils it boils but there is no pressure built up. Pressurized systems are much more complicated and potentially more dangerous.

 

[Rusnakes]

No if you have enough btus to boil the tank it will boil it and blow the pressure relief valve. That is why the system needs to be designed right with enough btu input to supply the needed water but not to much that it will boil it. In the systems i have worked on they are open systems that are gravity fed so it if boils it boils but there is no pressure built up. Pressurized systems are much more complicated and potentially more dangerous.

So, you would just boil off your water in an open system, but plumbing in back to your main hot water heater (since it would be a the pressurized loop) is the problem.

Am I to assume that you could plumb in a cold water line then to these systems or is this a "fill by hand" setup? In coaly's pics above, I see no cold line in to that system.