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Thread: Dumping into Pressurized Water System?

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    DIY Senior Member molo's Avatar
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    Default Dumping into Pressurized Water System?

    Hi everyone,

    This forum seems to deal with expansion tanks and maintaining pressure more than the others, so I am posting here.

    I am considering installing an open top storage tank on the top of a wood-stove. When the water reaches a certain temp. i would like to be able to introduce it to our 82 gallon hot water tank. We are on a well with an expansion tank. Is there a way to do this that is not causing excessive wear on the system?

    Thanks for any replys!
    "Any American who is prepared to run for President should automatically, by definition, be disqualified from ever doing so."
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    DIY scratch-pad engineer leejosepho's Avatar
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    Quote Originally Posted by molo View Post
    ... an open top storage tank on the top of a wood-stove.
    First be sure that either the stove will support the weight or that the tank has its own support over the stove.

    Quote Originally Posted by molo View Post
    When the water reaches a certain temp. i would like to be able to introduce it to our 82 gallon hot water tank.
    Many complications there, but you might be able to use a demand pump, a couple of check valves and some thermostatic and pressure sensors to ultimately push the heated water into the line just past your water heater.

    Quote Originally Posted by molo View Post
    We are on a well with an expansion tank. Is there a way to do this that is not causing excessive wear on the system?
    Yes, use check valves so the pump and everything else ahead of your water heater never even know they are getting an occasional break!

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    Radon Contractor and Water Treatment 99k's Avatar
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    Please explain your concept here because it doesn't make much sense to me? You are going to boil a large vat of water (like making maple syrup) and then repressurize it and move it to a HW tank? Have you thought about all the moisture in the house? What happens if you don't have demand for hot water ... you'll still be boiling. There are systems that use a closed coil, so perhaps you could add one on top of the stove. Better do plenty of research and have safety systems in place ... boiling water / steam is extremely dangerous.

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    Plumber Cass's Avatar
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    Personally I think the effort and cost to do this will exceed your expectations and the end result will not be cost effective...

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    Plumber Cass's Avatar
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    You could also contaminate your water system very easily and I would strongly recommend against doing this for that very reason...

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    Moderator valveman's Avatar
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    You can't just pump into a water heater. It is a closed system with no expansion, and there is no place for the water to go. You might put a coil of copper in the pot of boiling water. Then use a hot water circulating pump to draw the water from the bottom of the hot water tank, push it through the copper coil, and then back into the top of the hot water tank. Circulating the water from the hot water tank through the coil in the kettle of boiling water, will transfer the heat to the water in the hot water tank, without actually using the water in the kettle. A circulating pump will not have to build pressure, and can be very small, like maybe a 1/12 HP.

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    DIY Senior Member molo's Avatar
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    Quote Originally Posted by 99k View Post
    Please explain your concept here because it doesn't make much sense to me? You are going to boil a large vat of water (like making maple syrup) and then repressurize it and move it to a HW tank? Have you thought about all the moisture in the house? What happens if you don't have demand for hot water ... you'll still be boiling. There are systems that use a closed coil, so perhaps you could add one on top of the stove. Better do plenty of research and have safety systems in place ... boiling water / steam is extremely dangerous.
    Hi,
    I burn wood to heat my house. I want to place a stainless steel container on the stove (load-bearing capabilities of floor and stove in mind). I will fill this container perhaps with a direct line. I will then bring the water to a temperature (not boiling, perhaps 120 F). Then through another permanently installed line incorporate it into the existing 82 gallon hot water tank that is part of my expansion tank pressurized well system. The stainless steel tank will have an opening at the top so as to prevent excessive pressure build-up in the event that the water is left to boil (unlikely). There are alot of designs out there that include circ. pumps, aquastats, mixers, pressure relief valves. I would like to avoid these mechanical devices so that I have better control over the operation and avoid a closed system. The concern that Cass brought up about contamination could most likely be avoided by a closed system, but then the excessive pressure concern goes way up. I have been thinking about the contamination concern and am yet to decide if the stainless steel tank with direct lines into and out of is sanitary. The moisture concern isn't very high because the home is so dry with the wood heat and I won't be boiling the water

    Any ideas for getting this water to my taps?

    Thanks!
    "Any American who is prepared to run for President should automatically, by definition, be disqualified from ever doing so."
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    Moderator valveman's Avatar
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    I have mine set up exactly as witch has described. You just have to be careful you don't make steam. I have extra pressure relief valves and a large expansion tank. Notice the brown circulation pump that draws water from the bottom of my water heater, sends it to the coil on the wood burning stove, then puts it back at the top of the water heater. I think putting the coil in the pot of boiling water would also work, and may keep it from being able to produce steam.
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    DIY Senior Member molo's Avatar
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    With the closed system on a circ. pump I'm wondering how you keep it from getting too hot? For example, how do you keep your hot water tank from being full of water that is hotter than the standard 110-115 degrees? I have little ones and can't take the chance of any scalding. Regarding the pressure relief valves they would absolutely be neccesary. I would still be super nervous about a blow-out because I've seen pics of systems that got too hot, and the exploded pipes. I even remember the pic that Master Plumber Mark posted of an exploded gas hot water tank.
    "Any American who is prepared to run for President should automatically, by definition, be disqualified from ever doing so."
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    Moderator valveman's Avatar
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    I did not connect the copper coil directly to the wood burning stove. The coil is behind the stove, in the semi-enclosed area designed for a fan. The coil stays about " from the back of the stove, and is not touching metal anywhere. Then I connected the thermostat in the water heater in series with a thermostat behind the wood stove. When the water in the hot water tank is cool enough to close the switch on the thermostat, and the thermostat on the back of the wood stove is hot enough to close a switch, the circulation pump comes on. If the fire goes out, and the thermostat on the wood stove opens up, or the water in the tank is hot enough to open the switch on that thermostat, the pump goes off. I have to manually switch off the power from the thermostat in the water heater to the electric heating coils, to heat water with the wood stove.

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    DIY Senior Member molo's Avatar
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    Quote Originally Posted by valveman View Post
    I did not connect the copper coil directly to the wood burning stove. The coil is behind the stove, in the semi-enclosed area designed for a fan. The coil stays about " from the back of the stove, and is not touching metal anywhere. Then I connected the thermostat in the water heater in series with a thermostat behind the wood stove. When the water in the hot water tank is cool enough to close the switch on the thermostat, and the thermostat on the back of the wood stove is hot enough to close a switch, the circulation pump comes on. If the fire goes out, and the thermostat on the wood stove opens up, or the water in the tank is hot enough to open the switch on that thermostat, the pump goes off. I have to manually switch off the power from the thermostat in the water heater to the electric heating coils, to heat water with the wood stove.
    I'm still headed in the direction of a stove with mounted tank(s) similar to what the old cookstoves use to have with their water reservoirs.
    What they didn't have in those old homes was a pressurized system. If I can get through the sanitation concern (which I hope to do with a ss tank and permanently fixed intake and exit copper lines) I might be able to do this. Perhaps two tanks to receive the finished water that I could alternate from day to day.
    Last edited by molo; 12-10-2008 at 10:51 AM.
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    That's all folks! Gary Slusser's Avatar
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    If you run the cold water feed line to the water heater to a stripped down water heater tank sitting by the stove first, like an 80 gal, and then the outlet from this tank to the inlet of the heater, you'll have nice hot water out of the heater for quite awhile before running out. And no problems with boiling or anything else because the old heater tank is nothing more than a large wide spot in the pressurized cold water feed line to the real heater. And you don't need a pump etc. but I'd plumb a new T/P valve in the old tank.

    Any chlorides in your water will corrode SS.

    I did that (in 1973) with an over/under (two on their side) 55 gal metal oil barrel wood burner I built in my basement and a stripped naked 82 gallon gas water heater set up off the floor on 3 bricks. You used to be able to buy a kit for the burner; a door with a draft control for the bottom barrel and a fitting to get the smoke/heat out the top of that barrel into the top one and then another fitting for the stove pipe out the top of the top tank and 4 legs for each barrel.

    You may not be able to or want to do that.

    In case you'd like to know how I did it, or ideas... I put both in a 3'+w x 6' tall by 6-7' long galvanized sheet metal box with a frame of 1/8" x 3/4" x 3/4" angle. I extended the draft control on the burner out through the door of the box with 3" pipe about 4" long and had a normally closed (in case of a power outage) temperature operated draft control and a another temp controller (high temp safety) in the box to maintain the burner temp. That controller also controlled a fan (on/off) so I could send hot air into my forced hot air heat system, otherwise the heat just rose into the system and it was all control with the upstairs thermostat. I tended the burner 2-3 times a day with dry split oak up to IIRC 40" long. I heated the 2 story 4 bedroom house, with 5 kids, and most of all our hot water use with that for about 8-9 years. I tore out the original oil fired forced air converted coal furnace and used nothing but the wood burner all winter in north central PA. When I shut down the heater at the end of winter, that old heater still tempered the 45* cold water to like 55-70* which saved electricity for the 80 gal electric heater. I used to get 40' trailer loads of logs and would cut split by hand and stack them. I started to go around cutting down some trees for people but gave up on that after a few; tha twas real work.
    Last edited by Gary Slusser; 12-10-2008 at 06:19 PM.
    Gary Slusser Retired (= out of business)
    Click Here to learn how to correctly size or program a water softener.
    CAUTION, as of Nov 12 2013 all YouTube videos showing how to rebuild a Clack valve have an error in them that can cause damage.

  13. #13
    DIY Senior Member molo's Avatar
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    Quote Originally Posted by Gary Slusser View Post
    If you run the cold water feed line to the water heater to a stripped down water heater tank sitting by the stove first, like an 80 gal, and then the outlet from this tank to the inlet of the heater, you'll have nice hot water out of the heater for quite awhile before running out. And no problems with boiling or anything else because the old heater tank is nothing more than a large wide spot in the pressurized cold water feed line to the real heater. And you don't need a pump etc. but I'd plumb a new T/P valve in the old tank.

    Any chlorides in your water will corrode SS.

    I did that (in 1973) with an over/under (two on their side) 55 gal metal oil barrel wood burner I built in my basement and a stripped naked 82 gallon gas water heater set up off the floor on 3 bricks. You used to be able to buy a kit for the burner; a door with a draft control for the bottom barrel and a fitting to get the smoke/heat out the top of that barrel into the top one and then another fitting for the stove pipe out the top of the top tank and 4 legs for each barrel.

    You may not be able to or want to do that.

    In case you'd like to know how I did it, or ideas... I put both in a 3'+w x 6' tall by 6-7' long galvanized sheet metal box with a frame of 1/8" x 3/4" x 3/4" angle. I extended the draft control on the burner out through the door of the box with 3" pipe about 4" long and had a normally closed (in case of a power outage) temperature operated draft control and a another temp controller (high temp safety) in the box to maintain the burner temp. That controller also controlled a fan (on/off) so I could send hot air into my forced hot air heat system, otherwise the heat just rose into the system and it was all control with the upstairs thermostat. I tended the burner 2-3 times a day with dry split oak up to IIRC 40" long. I heated the 2 story 4 bedroom house, with 5 kids, and most of all our hot water use with that for about 8-9 years. I tore out the original oil fired forced air converted coal furnace and used nothing but the wood burner all winter in north central PA. When I shut down the heater at the end of winter, that old heater still tempered the 45* cold water to like 55-70* which saved electricity for the 80 gal electric heater. I used to get 40' trailer loads of logs and would cut split by hand and stack them. I started to go around cutting down some trees for people but gave up on that after a few; tha twas real work.
    Hi and thanks for the reply Gary,

    I wanted to ask you about your suggested design. What would be the location of the tank at the woodstove? On it or next to it? The first tank is serving more as a preheater for the final one?

    I've got a few years worth of firewood under roofs right now and want to heat the water while I'm heating the house.

    Thanks!
    "Any American who is prepared to run for President should automatically, by definition, be disqualified from ever doing so."
    Gore Vidal.

  14. #14
    That's all folks! Gary Slusser's Avatar
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    I had my tank directly behind the barrel burner. Yes a preheater or tempering tank. Put it only a few inches from the stove, up off the floor a few inches. I would not put anything on the stove. I think that's asking for trouble of some kind sometime.

    You could do the same thing with a 100' coil of say 3/4" copper supported above the stove a few inches and maybe add a cover like a piece of sheet steel or aluminum above it maybe 3" to hold the hot air a bit before it goes up around it.
    Gary Slusser Retired (= out of business)
    Click Here to learn how to correctly size or program a water softener.
    CAUTION, as of Nov 12 2013 all YouTube videos showing how to rebuild a Clack valve have an error in them that can cause damage.

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    Master Plumber Redwood's Avatar
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    your idea as presented is not doable for several reasons the biggest being the open container and cross connection with potable water supply.

    Maybe what you need to do is think about one of these.
    wood burning boilers

    Maybe this will stop NH Master's head from exploding...

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