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Domestic Hot Water set up

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  • Domestic Hot Water set up

    After much research and a certain amount of guess work, I have decided to pull the trigger in setting up a thermo siphon system to my cook stove for domestic hot water purposes. The idea is to have it all connected to an electric water heater that can be also utilized on days when the stove is not active and during summer months. It will be switched for that purpose. There will be a second - identical water heater also in the system, but it will be inactive. Its purpose is strictly for storage so that the stove does not overwhelm the first tank... that, and I love to take HOT baths.

    I am open to suggestions or opinions as to whether any one thinks this is a viable endeavor - or not. Diagram is attached here: hot water.pdf

  • #2
    Did you do this? We gave up as everyone we tried to hire to plumb the system was chicken about it. I have the piping in back of the wood stove for a 2nd water heater but just stopped mid stream

    Comment


    • #3
      We did. Have had some set backs getting the water supply hooked up to the house though (new construction) so unable to say if the endeavor has been successful yet. Hope to have resolved in the near future. I will let you know.

      Comment


      • #4
        We used it in our home for about 10 yrs.in the Yaak.
        Background- We were totally off grid, fresh from suburbia, wanting to live sustainably in as pure an environment as I could find with plenty of fresh air and water.
        Grew up in Detroit as a Motor City Mad Man working in the Auto Shows for Chevy Creative Services and as a contractor, building for top level Detroit Auto Executives and CEOs.
        Have a strong background in design/engineering, all phases of construction, both commercial and residential, Licensed in MI as a General Contractor, Builder, HVAC and Hydronic Boilers including Steam Certification's.

        Pros.
        1. Free hot water all the time your using your stove for heating.
        2. Works great with solar hot water. Combined Themostorage systems work great in areas that have a lot of fog, inversions or cloud cover in the winter, but plenty of sun in the summer and shoulder seasons.
        3. If your remote, no power, off-grid other than what you can make, this is the "Ticket", .
        4. Folks have been doing this for hundreds of years and are still doing it in Europe, NZ and Aussie Land, down under. (Nothin new under the sun here. Plenty of info on how, just read any Journeyman Plumber Text Book from the turn of the century. Entire cities like Detroit, Chicago, NY, Boston, Philly are heated this way.....still to this day folks. Steam, it used to do everything, before electricity. We just forgot how.) We show you how right on this site and we have helped more than I can remember do this. Where we lived in the Yaak, lots of folks heat their water this way and are happy to show you how. We have extended that hospitality to you in this website. Here is the link where you will find out how, we have tried to make this as easy as possible for you, without getting into hot water ourselves. The info is out there, we just put it together in a way that should make sense, you choose how you want to go. Very simple system that can supply running hot water for the entire family.)
        5. If it is done right, it works flawlessly with no power requirements. (The safety valves that protect your system is the same system that is used on every hot water tank in North America, the PTV Pressure, Temperature Valves, are different, though so beware of using a standard hot water tank PTV, those are designed to be used only in an emergency. You need a commercial duty unit designed to work over and over again without losing its ability to seal propely and sense water temps and pressure. Scale build up can affect PTV so check them regularly to insure they work.)
        6. If your tired of bathin in the crick or creek depending on where you live, this is far better.
        Cons.
        1. Everyone if afraid of hooking up something don't understand, they know pumps and controls and little else because that is all they have ever installed. Risist there insistance that you use pumps to make it work, you don't need a pump. If you cant do it yourself, fooooorget it! (PS I show you how on this site and will be making a video series soon about it and expand it to include solar hot water. Read our info and take a deep breath and get to work, you don't know if you don't try. Just remember these general rules, twice as much rise as fall minimum, your upper bung on your Range Boiler should be twice as high as the inlet into the heat exchanger installed in the firebox so it will gravity flow. Do not use any check valves like swing valves, especially pressure types that have a spring in them, in your thermo loop coming to and from the stove. Never install any valves unless they can be pad locked open when the stove is in use. A child accidentally shutting the valve can reak havoc if shut when the stove is in heating mode. Use 3 - 30s or 2 - 45 degree elbows instead of a 90 to reduce restriction as much as possible so nothing impinges the natural flow of the hot water. Use Stainless Steel inside the firebox and 3/4" or 1" copper in your thermo loop. Never use PEX! This system will operate at far hotter temps than any typical hot water tank does. YOU MUST INSTALL THERMAL MIXING VALVES IN YOUR DHW SYSTEM OR ANTI SCALD FACETS AT EVERY SINK!!!!!!!!!!!!Install unions and pressure relief valves and drain tees at the stove so the system can be drained and the stove moved for annual maintenance. If you purchased your stove and system from Obadiah's you can call me and I'll do my best to help you understand how this works, so it gets installed properly. If you need an complete passive hydronic design, we can do that for a fee that will carry everything you need for permits and installation. We can even provide all the parts, for an entire hydronic heating systems. However we do not recommend converting stoves into boilers, unless they are designed to do so. We are now testing the new SOPKA North Hydro which has a factory installed boiler and we have been offering the ESSE Ironheart with Hydronic heating for many years, see the article for design and pictures of a Ironheart installed with both Domestic Hot Water DHW, and Hydronic In-floor Radiant Heating by one of our clients who specializes in these types of installations in California incorporating Solar Hot Water.
        2. The system will gain BTUs into a Stone Lined Range Boiler that sits somewhere near the stove on the floor. There is a water loop from the stove to the side of the Range Boiler where the water circulates without any pumps utilizing the Laws Of Thermodynamics, (Heat Rises/Cold Drops) to move the water. There is no modulating the heat flow, once the internal heat exchanger is sized and installed. You need a heat exchanger inside the firebox that does not capture more BTUs than you can use. So size appropriately, which is the tricky part of all this. The larger the Bather Load, the more BTUs you need to capture and store until you need them. Once you have a fire going in the firebox, its intensity in creating Infrared Rays is what will heat your water. A Flat Sided Water Jacket will capture 10 times the BTUs of a coil. In a Nutshell..... the hotter the fire, the more hot water you will be making, You cant have one or the other, there is no way to shut it off without building steam which will build pressure until something, hopefully a safety valve releases and the pressure is safely released in a properly designed system. You will need to be able to monitor the water temp inside your range boiler from as many places a possible on your Range Boiler Tank, (RBT). A temp gauge on the lower side will tell you the water temps in the bottom of the RBT and one on the upper side will help you see the differences in the Thermo-zones inside the RBT. Having another telling you how hot the water is coming out of the tank. As the tank stores BTUs it does so from the top down. Top being the hottest zone, bottom being the coldest zone. You should have a second regular hot water tank somewhere in the loop, can be anywhere, in the basement even, if you have a pressurized domestic water system. The way this works is when you open the tap anywhere in the house hot water comes out of this normal hot water tank you bought at your local small business like a hardware store. Gas, eletric does not mater, it should be sized according to bather loads and can provide hot water to your home when your not burning your wood cookstove and making hot water, you turn it on and take the range boiler out of the loop so your not heating it. When you open a tap hot water comes out of the second hot water tank which acts as a buffer tank cooling down the water coming out of the Range Boiler to a more reasonable temp. You should install a Thermo Mixing Valve in your system if you don't have Anti Scald Fixtures installed by local code. These measures prevent scalding hot water from coming out of your faucets. VERY IMPORTANT!!! As the hot water is flowing out of the hot water tank, the cold water inlet is being feed by the hot out side of the range boiler, so the water going in to this second water heater is being pre-heated by the RBT. This means there is no need for the burner to kick on because it is being fed with hot water. You can also turn it off, or just set it low and the RBT will do the rest. When the tap is open that hot water coming out started as the cold water going into the bottom of the RBT. This cools down the RBT each time you use hot water.
        3. You must watch the system constantly and use hot water whenever the system gets too hot or it will release the PTV valve and dump all the hot water in the RBT into the drain, (MAKE SURE TO PLUMB THIS OVERFLOW INTO SOMETHING OTHER THAN YOUR FLOOR!!!!!! A DRAIN IS A MUST AS THIS WATER IS COMING OUT AT OVER 200 DEGREES!!!!!!) So in day to day life you will have a full hot water system when you get up in the morning and the stove has run all night and everything has been properly sized to store the BTUs you made. Those that like a morning shower take one and use as much hot water as needed if they are not sharing with others and don't need to do some laundry. You go about your day and re-stoke the fire, it builds heat. You come home from work and either take another shower, do some dishes, something to use the hot water. All is fine if you have a system set up properly sized to accommodate your lifestyle. If it is making too much hot water you will loose it and when you want to take a shower the water will be cold and you will not be happy. So spend sometime figuring out your bather load and how many gallons of hot water your actually using in normal day to day life. If that will change we can plan for it ahead of time if we know in advance.
        4 If your system is not properly set up you will either not have enough hot water which is very frustrating, or too much which can make you feel like your a slave to your hot water system.
        5. Insurance Companies, best not to even go there and just plead total insanity and said it was something "you found on the internet that some guy named Woody said he had made work well for his family" . It does work and now you know the ins and outs of actually living with this type of DHW system. If you have done your homework well enough, only you can make the choice to travel the free hot water from your woodstove, road. Keep us posted and hopefully some others will step up to the plate and share their experiences.
        Domestic Hot Water is a fantastic option for many woodstoves and cookstoves. But how does it actually work?

        Comment


        • #5
          Continuing on after establishing a few important consideration, I have had a chance to study the design that you provided.

          First let me congratulate you, very well thought out and would work great with two range boilers, or other heavy gauge SS or Galv. steel NON insulated tanks that can dissipate the heat.

          Pros- Inexpensive way to do this, short term, average life span, 3 yrs, max 5 yrs.

          Cons- Does not hold up well, over time as glass lined water heaters have very thin inner tanks and are insulated, so they tend to get too hot too fast and then dump, causing massive expansion and contraction issues inside the tanks cracking the glass inner liner. Water seeps in behind this barrier and the tank rots out in less than 3 yrs. (Used to do it this way and recommend doing it this way, until time proved the flaws) You would be better off with two old fashion galvanized well pressure tanks in my opinion if you cant afford Range Boilers. This can be had cheap but can be hard to find because of their scrap value. They are very heavy! Best to ask well drillers, demolition companies, habitat for humanity Re-Use Centers and places that sell junk may have some around. They were installed before the switch over to bladder tanks for well pressure control. They stood about 5 to 6' tall and about 24 -36 in dia. Weigh about 3-500 lbs.

          Range Boilers are designed to do a specific job based on a bygone era. In the day they were as common as glass line hot water tanks are today. Stone lined tanks can take the higher temps better and helps protect the steel tank longer, from corrosion. A Range Boiler can last 50 yrs, some are still in use after 75 yrs that I know of.
          Tanks must be heavy gauge steel and have passed at least a 120psi pressure test. The PTVs must be as specified in the materials list we provide in the link I provided.

          Please answer a few questions about what your doing so I can help size it appropriately as described above, the true key to this is only making as much hot water as you can use.
          1. Where are you installing these tanks, the drawing does not define if your going up through a floor, or if this is on a different plane?
          2. How many folks and how many gallons of hot water do you need?
          3. Is there any way we can dump some excess heat somewhere that could use it by running a loop that would kick on either a small circ pump or thermosipion to a wall hung water to air radiator?

          Here is some pictures of my installation and a DHW Boiler we designed and built next to a small range boiler with its own firebox, that we are now looking at re-introducing.



          Thanks,

          Comment


          • #6
            Geez Woody... Thanks for the great advice! I sincerely appreciate it. It must've taken you longer to compose that message than I spent building my system.

            First let me answer your questions:

            1. Where are you installing these tanks, the drawing does not define if your going up through a floor, or if this is on a different plane? Tanks installed on the floor above and 5 ft to the right.
            2. How many folks and how many gallons of hot water do you need? Two mostly.
            3. Is there any way we can dump some excess heat somewhere that could use it by running a loop that would kick on either a small circ pump or thermosipion to a wall hung water to air radiator? Not presently. Could be done, but with difficulty

            I have some questions for you:
            1. I believe that I read somewhere in your literature on the subject to use a swing (not spring) check valve just before the cold water recirculates back into the heat exchanger to keep freshly heated water from going up the cold pipe. Am I remembering this correctly? I do have this swing check currently installed, level and true. It can easily be removed.
            2. I do have pex installed in the hot loop. However, It is six feet away from the stove with 3/4" galvanized pipe in between. The pex is rated for 200* with 80 p.s.i. In your opinion, do you think this will still present a problem?
            3. The 2 fifty gallon ceramic lined hot water heaters (tanks) are already installed. I suppose this will have to suffice until one or both of them fail as you have described. My questions is this: What will the symptoms of this failure be? Small leak? Flood? Catastrophic explosion?...
            4. My stove is a Waterford Stanley. I purchased the WS boiler, side shelves and Ventis chimney system from Obadiah's. Question: considering the WS boiler (small) filling into 2 fifty gallon water tanks, do you really think we will have too much hot water - thus springing the PTVs?
            5. Regarding the PTVs: I just picked some up from Lowe's. I would the assume that they are not the commercial grade that you described above. Where can these commercial grade PTVs be purchased and how can I tell the difference?
            6. Can I burn my stove with the heat exchanger installed and no water in the system - or will it damage the SS heat exchanger?

            I did install the drains, temp guage and unions as you've described. It is good to get confirmation on those items.

            Thanks again for your feedback.

            Comment


            • #7
              I have some questions for you: See answers to your questions below.

              Why didn't you say you bought your stove from Obadiah's..... you qualify for VIP treatment now. If you liked me before, your goin to love us now. Email me, I'll give you my cell # and you can call me anytime.
              1. I believe that I read somewhere in your literature on the subject to use a swing (not spring) check valve just before the cold water recirculates back into the heat exchanger to keep freshly heated water from going up the cold pipe. Am I remembering this correctly? I do have this swing check currently installed, level and true. It can easily be removed. I no longer recommend any swing valves at all be installed in any passive system, only systems with pumps.
              2. I do have pex installed in the hot loop. However, It is six feet away from the stove with 3/4" galvanized pipe in between. The pex is rated for 200* with 80 p.s.i. In your opinion, do you think this will still present a problem? Depends, in my experience these systems can get up to 230 degrees under pressure. When PEX gets too hot it gets really soft and will blow off the fittings. If you want to risk a flood of hot water in your home, it is up to you. I now only use copper for my entire systems and use PEX for lower temp applications, like gas and electric boilers that turn on and off.
              3. The 2 fifty gallon ceramic lined hot water heaters (tanks) are already installed. I suppose this will have to suffice until one or both of them fail as you have described. My questions is this: What will the symptoms of this failure be? Small leak? Flood? Catastrophic explosion?...Again that depends, could just start leaking slowly, could split in half at the seams, depending on what the situation ends up being that brings it to the failure point, pressure or corrosion. There should never be an explosion, but a deluge of hot water is possible, but very rare.
              4. My stove is a Waterford Stanley. I purchased the WS boiler, side shelves and Ventis chimney system from Obadiah's. Question: considering the WS boiler (small) filling into 2 fifty gallon water tanks, do you really think we will have too much hot water - thus springing the PTVs? Your tanks are insulated, so they wont bleed BTUs and will continue to build heat until used. I don't know your bathing or cleaning habits, so I have no idea how much hot water you need. That heat exchanger in the Waterford I would estimate produces 12,000 BTUs per hour of hot water, every hour on the hour that the Stanley is burning. Here is the formula, One BTU is the amount of heat energy required to raise one pound of water by 1ºF. Water weighs 8.33 pounds per gallon so we can calculate that one gallon of water requires 8.33 BTU to raise the temperature 1ºF.
              5. Regarding the PTVs: I just picked some up from Lowe's. I would the assume that they are not the commercial grade that you described above. Where can these commercial grade PTVs be purchased and how can I tell the difference? The difference is the pressure and temperature they will release at. Also they are made differently so that they do not degrade with use, whereas the ones on the typical water heater are designed to be used less than a handful of times as they are emergency releases and should never be needed on any hot water tank that turns on and shuts off based on a thermostat. Some will trip at 30 lbs of pressure, others at 100-150 lbs. What are you running your water pressure at? If 50 lbs then you want a 100 PSI unit Watts # 274683 model # 174A
              6. Can I burn my stove with the heat exchanger installed and no water in the system - or will it damage the SS heat exchanger? No it will damage the heat exchanger and the entire system. NEVER RUN ANY HYDRONIC SYSTEM UNDER HEAT WITHOUT WATER.....EVER! Only a water reservoir that sits on the back of a cookstove without any internal plumbing running to the firebox, can be used empty without damaging anything.

              Comment


              • #8
                Oh dear... I think I have unintentionally mislead you. I purchased my Waterford Stanley boiler from you as well as the Ventis chimney system. A couple of years ago, a close friend of my wife stepped up and offered her WS cook stove. She purchased it in the 90s but chickened out installing in their cabin. I picked it up for $1700 still in the crate. (I love telling that story!) So, I probably don't qualify for the VIP treatment. Hopefully with the purchases made you can still throw a bone of advice my way once in a while... That being said: It is hard to believe you could offer better service than what has been provided in dealings with your staff. Sarah was very accommodating in helping me understand what components were needed. The prices were very reasonable. Larry helped me track down the boiler and side shelves direct from WS. Come to think of it - considering what Waterford Stanley charges for that little heat exchanger, perhaps I should quality for the VIP treatment.

                We should have the water system up and flowing within the next few days. I will keep updating this post as events progress. Hopefully others can learn from my success/failures. Me thinks there is a fair amount of interest in the subject of producing DHW from cook stoves.

                Thank you again for sharing your wisdom. It is very much appreciated.

                Comment


                • #9
                  Me thinks yer correct. me also thinks this is a liability land mine field, so me must be careful! I like you and I tend to take care of my friends, so your still free to call me, just don't tell anyone
                  Thanks for all the compliments, we are a family business and have a great staff that actually care, strange concept these days, but it works for us.....
                  I actually have a water jacket around here somewhere for a Waterford Stanley Cooker that when I find it, will duplicate so the price will too. We build our own water jackets and are looking for one that people have and can provide pictures and measurements of so we can duplicate them for folks with stoves where the MFG has gone out of business. Waterford was sold recently so were watching carefully to see where that goes.
                  Your willingness to engage, ask questions and step out of the box, make providing this information to others possible. I am willing to invest my time and effort here, in this fashion, so it will be here in the future when I'm not. I don't see mainstream embracing these systems, unless they have no other choice.......so me doubts that anyone else will step up to the plate and help folks do it properly.
                  As far as the wisdom part, having a quest for knowledge is the fuel that drives me. Searching for it, outside the box, is where I'm most comfortable. Developing what I learn into practicality, is what stimulates my own development as an individual. Sharing the fruit of my accomplishments, as well as failures, with those who are on similar paths in life, feeds my soul and completes my purpose for living life, with gusto, guts and guns! Only a truly free man can know Life, Liberty and the Pursuit of Happiness. Freedom comes from Self-Sustainability, not the bank, or the government, or the utility companies, smart meter hanging on most US homes today.......

                  Comment


                  • #10
                    ...I think we're on the same page here. Will be in touch.

                    Comment


                    • #11
                      OK... After many frustrating set backs, i finally got water to my house so that i could test this set up. Here is my first after action report:
                      ​​​​​Burned the stove at a respectable temp for approx 5 hrs. The water jacket did its job and hot water did rise to the storage tanks. This i know because i installed a temp gauge at the top of the run right before the hot water entered the tank. However, I do not believe that any cold water returned to the jacket to complete the heating cycle. This i suspect as there was virtually zero storage of the hot water. After a few hours i turned on a hot spigot in the house and only had a burst of hot water for a couple of seconds. After more time had elapsed, I released some water at the top of the tank at the PTV. Another burst of screeching hot water came out. Again, only for a couple of seconds followed by very tepid water.
                      As we discussed earlier, I did install a swing check valve at the bottom of the return line, right before the water re enters the jacket. My next move will be to remove this check valve this allowing completely unrestricted flow in the circuit.
                      My property is remote so I have to work on it in fits and spurts. I will update again when more info becomes available. In the mean time, any advice or suggestions will of course be welcomed.

                      Comment


                      • #12
                        Wiser, Happy New Year!
                        The check valve is your issue for sure, not sure if it is the only issue. Detailed Pics would be helpful for me to help troubleshoot. Or just call me and I'll walk you through the rest of the way.

                        Comment


                        • #13
                          It works! We cooked water most of the day. Stew and cornbread for supper. Soon had 50 gallons of hot water that served for two showers and cleaned up dinner. Life is good!

                          Still to be determined is how well the glass lined tanks will hold up to the heat and cooling cycles as Woody described earlier. Also will have to tinker on how to manage together with the electric. I still need a couple of fittings before i can integrate the 2nd tank. All of this will just take trial and error. I will keep updating as issues of interest arise.

                          A couple of observations:
                          • Right now we are just hooked up to one 50 gal tank. I was surprised at how quickly hot water filled it. Once the 2nd tank is put into service, it will help with containment of all the hot water being created but it will still take a fair amount of diligence to be sure things don't get too rowdy.
                          • I have always planned on installing a tempering valve. Now it is urgent.
                          Thanks Woody for your awesome advice and insight. If you have any questions I'd be happy to tell you all about the experience. I tried to upload some photos but your server didn't like the size.

                          Comment


                          • #14
                            Thanks Wiser,
                            Yes size is an issue, we need them no larger than 1000 x 1000 pixels and not a ton of resolution, so they upload semi fast for our folks on dial up and satellite.
                            You can also PM me for my email address and we'll edit and post them for you.

                            If a picture is already online, all you have to do is hit "Control C" (Copy) when your on the picture, and "Control P" (Paste) when your on the line on this site, in this forum, logged in, and have an open thread you have started, on your screen. The picture should appear here, that easy, as it was already optimized for the other web page.

                            It will be interesting to see how well your domestic hot water tanks hold up, having a second one will definitely help give you a better buffer between as you said,
                            "Rowdy Time". Keeping the tanks from blowing their PTV, will be critical, the best way to deal with that issue is always more volume, so your on the right track.

                            Keep us posted!

                            Comment

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