Water jacket/coil on cookstove for hot water?

[electrathon]

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

The danger is without circulation you are boiling water in the coil and still have cold water in the tank. The danger of scalding is off the chart. The system is not safe as set up. I agree, you may get away with it, just like smoking and not wearing a seat belt.

It seems like you have not read most of our conversations over the last year. My coil can easily be moved into the firebox and it would skyrocket the BTU transfer. Remember how you keep saying that is not safe (like in the stove we are talking about)? Cooling of the combustion area of the stove can increase creosote build-up and stovepipe emissions. I get virtually all of my heat from the wood stove in the winter time. It is necessary to use a preheat tank so that I did not have to burn my stove all summer long.

The fact that the system functions does not make it safe. I have personally seem hundreds of stoves that are installed in a manor you feel are unsafe (can we say barrel stove) that have been used to heat houses every day for years/decades without a single issue.

 

[electrathon]

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.

No, an open system can not be plumbed back into a pressurized system. OK, anything can be done, it is just not reasonable to do it.

A water supply line controlled with a float (toilet) valve could be easily used to keep the tank full.

 

[electrathon]

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.

What in the heck? My system is perfectly balanced to max out at a safe temperature and provide virtually all of my hot water in the winter months. It does exactly what you just said it needs to do.

 

[electrathon]

Here is a basic picture of what you need to do.

 

[bholler]

Cooling of the combustion area of the stove can increase creosote build-up and stovepipe emissions

No taking to much heat from the stove at any point will cause creosote buildup. It doesn't matter if it is the firebox or not.

The danger is without circulation you are boiling water in the coil and still have cold water in the tank. The danger of scalding is off the chart. The system is not safe as set up. I agree, you may get away with it, just like smoking and not wearing a seat belt.

No there is still a free flow from the coil to the tank that will not happen.

It is necessary to use a preheat tank so that I did not have to burn my stove all summer long.

Well no there are about 100 other ways to plumb it so you dont need to burn all summer.

The fact that the system functions does not make it safe. I have personally seem hundreds of stoves that are installed in a manor you feel are unsafe (can we say barrel stove) that have been used to heat houses every day for years/decades without a single issue.

So you are saying that there has never been a failure of a barrel stove that resulted in a structure fire? I have seen 2 personally. Now how many accidents have this water heating system on the kitchen queen caused? I am basing my opinion on years of experience in the field working on thousands of stoves. How about you? You are also apparently forgetting that the kitchen queen is ul listed which means it has been very thoroughly tested for safety. If it is so dangerous how did it get through the testing process?

What in the heck? My system is perfectly balanced to max out at a safe temperature and provide virtually all of my hot water in the winter months. It does exactly what you just said it needs to do.

Yes yours is balanced which is good but to me the btu input does not seem near high enough to actually supply hot water just enough to preheat which if that is all you want that is fine. But the op was asking for a water heater not a preheater.

 

[Rusnakes]

Here is a basic picture of what you need to do.

Electrathon, wouldn't that be a pressurized system then (based on that picture), since the cold water is plumbed in to the coil and storage tanks?

 

[Rusnakes]

Electrathon, wouldn't that be a pressurized system then (based on that picture), since the cold water is plumbed in to the coil and storage tanks?

Or thinking about it more...b/c it has a separate line out of the bottom of the storage tank in that pic, which creates a viable loop to allow for thermal siphoning in the water coil-storage tank portion of the system.

 

[bholler]

Electrathon, wouldn't that be a pressurized system then (based on that picture), since the cold water is plumbed in to the coil and storage tanks?

Yes that is a pressurized system

 

[electrathon]

Electrathon, wouldn't that be a pressurized system then (based on that picture), since the cold water is plumbed in to the coil and storage tanks?

Yes. The only reason I can imagine that you would not want a pressurized system is if you do not have running water in your house. The system pressure is whatever your house has from the city water or your well. This can be from about 30 to 90 PSI. If your tank is above the stove, it will self circulate. Lower than the stove you will need a pump and a solar temperature differential controller to run the pump.

 

[Rusnakes]

That was what I was guessing from my first post, but I didn't take into consideration the back flow/loop to the cold line to recirculate into the coil for thermal siphoning. Makes total sense.

I talked with my brother who is pretty handy with plumbing stuff and he recommended an expansion tank with that model above. Wonder if that would be smart or overkill.

 

[bholler]

I talked with my brother who is pretty handy with plumbing stuff and he recommended an expansion tank with that model above. Wonder if that would be smart or overkill.

Yes you would want an expansion tank for sure

 

[bholler]

That was what I was guessing from my first post, but I didn't take into consideration the back flow/loop to the cold line to recirculate into the coil for thermal siphoning. Makes total sense.

I talked with my brother who is pretty handy with plumbing stuff and he recommended an expansion tank with that model above. Wonder if that would be smart or overkill.

In order to do a pressurized setup that will work safely even if the power goes out you really need to know quite a bit about thermal dynamics to balance the system. If you have to much btu input you will pop the releif valve making a mess and it could be dangerous. to little and you will need a secondary water heater like electrathon.

 

[electrathon]

Real rough numbers if you heat 50 gallons of water up 50 degrees there is about a cubic foot of expansion. You already should have an expansion tank on your water heater, add another one for the preheat tank. If you are not going to use a preheat system (it is generally one of the better ways to plumb it) you can use your exiting water tank. You need to lower the thermostat setting as low as possible and use a tempering valve to prevent scalding if you go this way. It will not be as efficient if you do not use a preheat design, but it can be done. Your water temperature coming out of the faucet will tend to very in temperature without a preheat tank. With the preheat tank the water is warmed to operating temp, then it flows through the main tank, generally the elements will stay off, they should only come on when it is sitting and has thermal loss.

 

[bholler]

You already should have an expansion tank on your water

I totally agree with you on this but surprisingly most people do not have one for some reason. I don't understand why not they don't cost much

 

[electrathon]

I totally agree with you on this but surprisingly most people do not have one for some reason. I don't understand why not they don't cost much

I work in a water department in a small town. We have people calling complaining about thermal expansion causing issues in their house often. In the old days there was not a single check at the meter and the city system would function as the expansion tank. Now we add the check for water quality/safety issues and there is no place for the expanded water to go unless there is a dripping faucet or a running toilet (very common). Thy also help with water hammer issues.

 

[begreen]

In order to do a pressurized setup that will work safely even if the power goes out you really need to know quite a bit about thermal dynamics to balance the system. If you have to much btu input you will pop the releif valve making a mess and it could be dangerous. to little and you will need a secondary water heater like electrathon.

The relief valve should be plumbed to a drain or outside. Having scalding water splashing about is not a good plan, especially if it's near a hot stove.

 

[bholler]

The relief valve should be plumbed to a drain or outside. Having scalding water splashing about is not a good plan, especially if it's near a hot stove.

Yes that would be best but then you have to worry about it freezing up also

 

[electrathon]

The relief valve should be plumbed to a drain or outside. Having scalding water splashing about is not a good plan, especially if it's near a hot stove.

Yes, it is plumbing code. If there is an overheat the valve starts chattering and letting water out. The drained water is required to go down the drain or to the outside. Many houses are flooded because people do not properly plumb in their water tank.

 

[bholler]

Yes, it is plumbing code. If there is an overheat the valve starts chattering and letting water out. The drained water is required to go down the drain or to the outside. Many houses are flooded because people do not properly plumb in their water tank.

I have never seen that in the plumbing code. I am not saying you are wrong by any means I just have never heard of it and honestly have not ever seen a furnace or water heater plumbed that way even on new construction which was inspected.

 

[electrathon]

Yes that would be best but then you have to worry about it freezing up also

That is why you can use the drain or outside. The drain is generally considered the safest option. This same issue happens with condensate off of instant hot water heaters and high efficient furnaces.

 

[bholler]

That is why you can use the drain or outside. The drain is generally considered the safest option.

Good point

 

[electrathon]

The relief valve should be plumbed to a drain or outside. Having scalding water splashing about is not a good plan, especially if it's near a hot stove.

I have had my system in since 2013 and I have never had a drop of water out of the relief valve. I can see my temp and pressure at the stove (and temp at the tank) and have only watched it climb during an extended power outage. Very rare here. The UPS can carry the pump for 3-4 hours. I was going to start the generator but it was time to go to work so I let the fire die out. Power came back on about an hour later. I have 64PSI on the system so boiling point is at about 290 if I remember correctly.

 

[begreen]

It only takes one accident in an unusual circumstance to teach a painful, life changing lesson. Be safe.

 

[bholler]

I have had my system in since 2013 and I have never had a drop of water out of the relief valve. I can see my temp and pressure at the stove (and temp at the tank) and have only watched it climb during an extended power outage. Very rare here. The UPS can carry the pump for 3-4 hours. I was going to start the generator but it was time to go to work so I let the fire die out. Power came back on about an hour later. I have 64PSI on the system so boiling point is at about 290 if I remember correctly.

so you rely on power to keep the temp down? I would absolutely never do that personally

 

[electrathon]

so you rely on power to keep the temp down? I would absolutely never do that personally

Only sort of. I rely on power to make the pump work. My tank is lower than the stove so it needs a pump to circulate the water. It can be done with check valves and boiling water (a percolator system) but they are quite dangerous. Plus they barely work. Water is circulated with pumps all the time and has been found to be very safe.