more questions about heating water on a wood stove.

[mx842]

My other post about heat exchangers died but I was still wondering about how to make enough hot water to keep my floor loops from freezing this winter. I have this wood stove that at one time had a 30 gal boiler sitting on top of it. I gave up on that setup after spending countless hours rebuilding it and still not being able to make enough hot water without being a slave just to keep it running and keeping enough wood to feed it.

Time has caught up with me again and I'm looking at winter again without finding the time to build my new system. What I have now is almost the same setup only to a smaller scale. The new SS tank that sits on top of the stove holds only about 5 gals of water. I have a 40 gal electric water heater that I have placed beside the stove and want to move the water from the stove top into the water heater then pull water out of that to send over to my manifold and into the floor.

I'm out there all day and don't mind keeping it going and also keep an eye on it to see what's going on until I get an idea of weather or not this will work at all or weather I need to do something else. I don't need to send 120 degree water to the floor just enough to keep the slab from freezing. I get enough heat off the stove to keep most of the building warm enough to work in and I could probably cut another door or window in the room that the stove is in and that may just do the trick without putting warm water into the floor. I guess I want to see what I can get out of this thing and hopefully learn a little something in the process.

I have read this site for a long time and have gotten a lot of ideas for when I do my other boiler but after reading hundreds of pages they all sort of get mixed together and my brain can't seem to put all the pages together. I'm wondering what the best way to plumb the hot water heater to get the best results. I am using a Taco Red Baron pump to send water over to my floor loops that are around 1600 feet of 1/2" pex.. I took the pressure valve and the drain valve out of the tank for the 2 in pipes and the two out pipes. I plan to T out of the pressure valve and put the pressure/temp valve back into the system and also use a T where the drain valve was so I can stub in another drain valve and have another in or out port.

My question is where would you put the water in and out piping and what ports would you put the water going in to and out of the water heater?

My other question is on this Taco pump, as long as the pump is running I have no leaks but as soon as I cut the power to it water runs out of the pump housing and out of the weep hole. Is that normal?....( I wouldn't think so) should there be check valves before and after the pump to keep this from happening or is there something else I'm doing wrong? Thanks for your help.

 

[Seasoned Oak]

Sounds like an internal seal in that pump. I usually just replace those pumps when they start leaking. They are about $75 Its nice to have shut off valves on each side of the pump so you dont have to drain the whole system.

 

[mx842]

Sounds like an internal seal in that pump. I usually just replace those pumps when they start leaking. They are about $75 Its nice to have shut off valves on each side of the pump so you dont have to drain the whole system.

Thanks........And I'm not trying to be combative but I think we are on a different wavelength. Where can you get a 1/8th hp bronze taco 113 inline circulator pump for that kind of money? I've seen them priced anywhere from $600.00 to $1300.00 over the web depending on who had it. Most I've seen are in the $800.00 range.

I always put inlet and outlet valves on pumps and you are right it sure makes servicing a pump a lot easier. I was wondering if it would help if I put inline check valves on the in and the out to keep the water from trying to back flow when the pump is shut off? The seal kits are not that expensive, in the $50.00 range and I replaced them once but the pump still leaked once I shut the pump off. I know you can ruin a seal set quickly if they are run dry but I tried to get all the air out of the piping and the lines as full as I could before starting it up. I always put my pumps down as low as I possibly can so that there is less chance of them running dry for long periods of time. It's really weird, it only leaks when it is shut down and will run 24/7 and never leak a drop.

 

[maple1]

You're pretty overdone in the pump department, I think.

Check the price of a Grundfoss 15-58 3 speed.

 

[Seasoned Oak]

I use these
http://www.nationalpumpsupply.com/0...ith-1-25-hp/?gclid=CPOS2pet48kCFdAXHwodMQEKXg
$77
Taco has SS and bronze pumps around the $200 range

 

[mx842]

You're pretty overdone in the pump department, I think.

Check the price of a Grundfoss 15-58 3 speed.

Yeah, I knew it was a bit much for this setup but that's all I have right now. I do have a 1/6th hp Lochinvar E8B that I bought on e-bay but it had a bad seal in it when I got it. I bought it and kept it a long time before I got a chance to try it out so it was no need to fuss at the seller. actually I'm not sure if it's the seal or not I didn't see it leaking but it was making a loud scraping or squeeking noise so I shut it off and pulled it off then put this Taco pump on. I pulled the Lochinvar apart but didn't see anything that looked out of place or where it was rubbing anywhere then put it back together and tried it again but it still did the same thing.

The Taco pump has a 11/4" in and out flange that I have necked down to a 1" inlet and then necked down again to 3/4 that goes to my manifolds. It seemed to work ok with the system I had last year at least as long as the boiler was making heat. I remember one time a cold snap sneaked up on me and the floor got really cold. It was down to 26 degrees on the surface in places by the time I finally got it going and after about 4 hours it had come up to 45 degrees. The problem was that the return water was so cold it was killing the boiler but it got me through the rest of the winter.

 

[Highbeam]

Really, if I were you, I would blow out the water and mothball the system. Sounds like you are comfortable with the woodstove heat.

 

[mx842]

I use these
http://www.nationalpumpsupply.com/0...ith-1-25-hp/?gclid=CPOS2pet48kCFdAXHwodMQEKXg
$77
Taco has SS and bronze pumps around the $200 range

Thanks for that link. I may just get me one of those. I like that it doesn't use very much power to run on and the cost is nice also.

 

[mx842]

Really, if I were you, I would blow out the water and mothball the system. Sounds like you are comfortable with the woodstove heat.

No really....Yes, I do like the feel of a wood heater when it cold outside. Nothing warms you up like a wood burning stove but my problem is that the only place I can put a stove is in a room I built just for the boiler and my big air compressor. I didn't want it in the main shop because it would take up too much room and I didn't want to have to cut a hole through my nice new medal roof.

I had thought about building one that would fit through the wall where I could load it from the outside and have the flu pipe exit out the same way. That way I could keep the mess outside and still get the benefit of the heat off the sides of the stove. I was going to run about 100' of 3/4 or 1" copper tube around the top with a thin skin layer of medal over that to circulate water through to make heated water for the floor that would heat my machine shop, my closed off office, and the cleaning room and spray booth on the other end of the building. Right now with the stove in the back of the building it was closed off from the rest of the space but I have since cut a hole for a doorway going into my sand blast/ paint booth and that let a lot of the heat to reach some of the back part of the building. Most of this area doesn't have tubes in the floor but it's nice to have a little heat back there as right now it's just being used as a storage area and some of the stuff stored there doesn't need to freeze.

I had planned on cutting a window through the wall where my air compressor will live and put a fan unit to pull air through where my air cooling coil and air dryer is. I could use this to pull the extra warn air that is trapped in the equipment room through this opening and out into the main shop but then I remembered why I wanted to put the air compressor in it's own space somewhere in the back of the building out of the way.......the darn thing makes a lot of noise! If I cut a hole there all that noise would come in along with all that nice heat and the trade off didn't add up. I cut an opening in the other corner next to where the stove is now and that should allow for a good circulation through the whole back part of the building and into the main part as well. Even then that's not going to supply enough heat to keep the front part of the building from freezing up if it get really cold.

So far this year it's been really warm for this time of the year. It's been in the 60's and the 70's for the past couple weeks and they are saying it's supposed to be near 80 on Christmas day. Hopefully the whole winter will be like this and then get warm but I wouldn't count on it.

 

[mx842]

I'm in the process of tearing out all my old black iron piping that I had run from my equipment room to my manifolds. I never did get an answer of how to pipe the water heater to my stove so I just went ahead and piped it in the way it looked like it should be. I removed all the fittings in the water heater and installed a T in to the bottom drain and one in the side of the tank where the safety valve was located. On one side of the T at the port where the safety valve was I reinstalled the pressure valve and the other side I placed a union and from there I went from the 3/4" that was in the water heater tank to 1" copper and down to the out port or hot side of my stove top heat exchanger.

From the bottom of the water heater tank where the drain was I came out with a T where one side I placed a boiler drain valve and on the other side I came out with a short nipple to a 3/4 union then went to 1" copper over to the in side (cold side) of the stove top heat exchanger. I positioned the water heater tank so that I could route the cold side return line across the top of the stove where it could pick up some heat on it's way back to the heat exchanger on top of the stove.

Then I piped the two top ports, the hot and cold water heater ports to my manifolds. I wasn't sure about how or where to place my pump in relation to the hot and cold ports on the water heater but went ahead and came out of the tank with a 3/4 union then stepped it up to 1" then over to a 1" valve
valve and into the out side of the pump. In other words the water will travel up from the pump to the cold side port in the tank. I did the same on the hot port, came out with a 3/4 union then stepped up to 1" copper then over to a 1", 4 way brass T. I put a small air separator on the top and small expansion tank on the bottom. The other two ports of the 4 way I put 1" unions to 1" copper for the supply from the tank to the manifolds with this 4 way in-between.


The return water from the manifolds is 1" copper back to a 1" valve and into the suction side of the pump. My only concern is with having to rely on natural hot water rises cold water falls circulation system to carry heated water the the 40 gal water heater what is going to keep the water flow from the pump from trying to push water back into the heat exchanger or messing up the natural flow in and out of the heat exchanger? I almost have my roughly 190' of 1" copper that goes from the pump to my manifolds run, and hopefully once I check for leaks I can fill it up with water for a test run.


I sure wish I could get some kind of answer on my concern with regard to the pump over the natural flow idea I have going on here and what effects it may or may not have.

 

[mx842]

Okay, Thanks anyway...........Yesterday after checking for leaks in my new piping system I filled the old girl up. I flushed the old cruddy looking water out of the loop system in my floor that had came from using that black iron pipe in the past with a open system. Then I filled the loops with new fresh water and got as much air out as I could then hooked the new 1" copper to the manifold. I started my circulation pump for a final check for leaks in the system. After I let it run for about an hour to be sure my air bleeders had gotten the rest of the air out of the lines I decided to go ahead and put some fire in the firebox to see what would happen.

I went around the shop and cleaned up a little and I put all the paper trash in the stove and I had a pile of OSB scraps in the corner that I use for kindling and I threw in several pieces along with one old dry, about 6" round by about 23" long log that was also laying on the floor. I didn't want to really load it up the first time until I could find out what was going to happen. I opened the draft and lit her off and went to the fridge and got me a bud lite then sit in the corner next to the back door with my hand held temp light. I didn't really think I might need an excape route but what the heck.

After about 15 minutes I could start to feel some heat coming off the sides of the stove, went in and got another beer and as I walked by the stove I could see that the sweat that had formed on the outside of the copper pipe from the really cold water I had filled the system with had started to dry up. I touched the hot pipe coming off the out port of the stove top heater and it was getting warm about half way up the line and in about another 15 minutes or so I could feel that the hotter water had already started to flow into the hot water tank. I threw in a couple more pieces of OSB I had laying there and in about 45 minutes more there was heated water now flowing out the tank and into the supply lines to my manifolds. About 3 beers later (about a hour +/- a little ) I had 65 degree water flowing into my manifolds about 85 feet away. I didn't put any more wood in the stove and this morning I went out there about 8:00 AM and the hot water tank was still warm to the touch.even with the circulating pump running all night.

Now I know all this will change when the temps go down as it was in the high 60's yesterday but at least I found out that this setup will heat water and with a few mods here and there should get me through the winter. I have to add some more pipe to the outside of the stove pipe, figure out some kind of control system, maybe add a little insulation to the stainless steel tank on top of the stove and maybe a little around the buffer tank, then get a new circulating pump that I can stop and start without it leaking all over the floor.

All and all I'm pretty pleased with the way it worked out to this point and with a little tweaking I think this will work out just fine. Thanks for all your help.

 

[mx842]

Merry Christmas to everybody! I've been busy the past couple days so I didn't have time to post the pictures I promised. This is a few of what I have going on. It's supposed to get colder next week so hopefully I can give it a good workout to find out just how it is going to work in real life.

4X 6 ss sq tube cut in pieces with end caps tacked and ready to weld

Top front section welded with pressure and temp gauge bung hole welded in place

Tank welded up with stove pipe connection welded in place

In and out ports welded in place. bottom port is 1" in port, top is 1" hot out port, center is 3/4" pressure test port

The makings of a stove pipe, schedule 40 black iron showing the damper section

Air vents for copper tube runs

Manifold copper tube connection

Copper tube runs along walls

Water heater connections at top of water tank

Circulator pump

Pressure testing piping system

side view of stove top heater and water heater tank

Hot pipe going to water heater tank

 

[mx842]

A few more pictures. Water tank and heater piping

 

[mx842]

We got another cold snap and I have had the chance to try out my new stove top water heater. It's working pretty good now that I moved the circulator pump over to the manifold rather than right at the storage tank. The storage tank got hotter faster that way but I was just barely getting flow through my manifold.

I took off that old Taco circulator and put on an old Bell & Gossett 100 series pump I got pretty cheap from a friend. It doesn't leak when it's not running like the other one was so now I can add some kind of control on the pump with hopes that I can control the water temp going in to and out of my floor loops.

I have two problems that I need to address. One is that the little stove top water heater makes the water a little too hot to put in the floor during the day when I'm in the shop and able to keep the fire stoked. It heats the storage tank to around 145 degrees even with the circulator running. I have been trying to figure out how to cool down the supply water but haven't come up with a solution yet or better to say I haven't wanted to shut the system down to try to make it better while it is cold outside.

I have several three way tempering valves that I can add into the supply but can't decide if I should add one at the manifold or at the storage tank. I'm thinking it would be better to put it at the manifold but one other problem I have is that I'm making creosote especially at night when the last load of wood burns down to just a bed of coals and it's not adding enough heat to keep the storage temp up enough. I know I could probably use more storage but is so close to where I would like it to be I think I can fine tune it a little to get me through the winter. Cleaning this new stove pipe is not much trouble but I would like to make it draw a little better because it smokes up the shop pretty good when there is not a good hot fire going in the firebox and I open the door to add wood. In the morning it's really bad when the stove top tank has cooled down.

My manifolds are in a small office space that I partitioned out in one corner of my shop. I have another smaller 30 gallon water heater that I want to pipe in right over where the manifolds are that would give me a little more storage and that may be enough to get me through the night a little better. Especially if I can figure out how to temper the water down a little going into the manifolds and letting the storage water get a little hotter. The water temp coming out of the stove top heater stays at around 140 degrees during the day or as long as there is an active fire going on in the firebox.

I'm thinking that if I could figure out where to pipe in a mixing valve and come up with some kind of control on the cir pump that I should be able to get the storage water up to 170 maybe even 180 degrees before I load it up for the night. Wishful thinking??? I don't know LOL...........

 

[maple1]

I can't imagine the stove being able to put as much heat into the water, as the floor can take out of it.

So, broadly speaking - I would likely just send more water into the floor, if the tank gets hotter than you'd like.

 

[mx842]

Well that's my problem. The stove is making 140 degree water and I'm thinking that is probably too hot to be dumping into the floor. I would like to calm it down to around 80/90 degrees going into the floor and let the storage temp get up to 170/180 or so with hopes my supply water will last through the night. The way I have it now is great during the day while I can trow in a couple sticks of wood every hour of so but when I pack it full at night and cut the draft down it likes to make creosote. I know more storage would be best answer but I'm just trying to get through this winter until I can do better.

I was just wondering if I added in a mixing valve to lower the temp going into the floor and letting the storage temp go up a little that hopefully there would be at least warm water left in the morning to not be dumping so much cold water in the stove top heater which is adding to the build up of creosote. if that makes any sense. LOL

 

[maple1]

Is the water being pumped into the floor at the same time as the water is getting to 140°?

 

[DoubleB]

I think @maple1 is saying that your slab becomes your storage. Pump water through the slab at the same time you're generating heat, and it won't get too hot for the big slab. Instead of letting your tank store X amount of Btu's to deliver to the slab overnight, just put those X Btu's into the slab while you're burning. Slab gets a couple degrees warmer while your burn, but as you don't burn it will cool the couple degrees without freezing and be the same result as adding a mixing valve.

Also, I notice you asked above about the former pump that leaked while idle and didn't leak while running. First thing that crossed my mind is that you either may currently have, or may have had in the past, a situation where you are pulling a vacuum on the suction side of the pump. In a former life I recall that most pumps put the pump seal on the suction side (so the seal isn't on the high pressure discharge end). However, if the suction side of these pumps pull the water pressure below atmospheric, then air wants to enter the seal, even though the seal is flooded internally. This can cause the seal to fail. Some condensate pumps can be specifically designed so that the seal is on the discharge side so that is always flooded, but that's not what you have in your picture above.

In your pictures it appears that your pressure tank is quite a distance away but on the suction side of your pump, is that right? So that's the suction side is the right idea, but if your distance is too long and tank pressure too low, or if you have a valve between the tank and pump suction that ever was closed while your pump operated, you drew a vacuum on you suction and might have brought air into your pump seal that could have sprung your leak.

Maybe your situation is different, but that's where I would start.

 

[mx842]

Is the water being pumped into the floor at the same time as the water is getting to 140°?

Yes it is, by the time it gets through the roughly 90 or so feet of 1" copper pipe it maybe has lost a few degrees but depending on how I keep the fire going in the stove that's about the average if I keep it hot. I have been keeping the temp down by not putting wood in the stove as often, basically just keeping a big layer of coals going and every hour or so throwing in a couple pieces to keep them going.

 

[maple1]

Can you measure more temps?

Not sure exactly where you're measuring the 140 at, but you should also measure the temps of the water going to & coming back from the floor. And maybe into the top of the stove tank.

I am almost 100% certain that the floor should be able to take way more heat than the stove is making. So I am thinking that the floor loop is not pulling the heat from the tank like it should - the floor flow could be coming in the bottom of the big tank, going straight up, then back out to the floor, in sort of a column-like flow. And since the stove flow is only convection, and has quite a bit of horizontal direction to it, I don't think it's flowing very much, which would make a small area of the hottest water at the top of the tank. Or in other words, you might have two separate flows going on that aren't mixing much.

 

[mx842]

I think @maple1 is saying that your slab becomes your storage. Pump water through the slab at the same time you're generating heat, and it won't get too hot for the big slab. Instead of letting your tank store X amount of Btu's to deliver to the slab overnight, just put those X Btu's into the slab while you're burning. Slab gets a couple degrees warmer while your burn, but as you don't burn it will cool the couple degrees without freezing and be the same result as adding a mixing valve.

Also, I notice you asked above about the former pump that leaked while idle and didn't leak while running. First thing that crossed my mind is that you either may currently have, or may have had in the past, a situation where you are pulling a vacuum on the suction side of the pump. In a former life I recall that most pumps put the pump seal on the suction side (so the seal isn't on the high pressure discharge end). However, if the suction side of these pumps pull the water pressure below atmospheric, then air wants to enter the seal, even though the seal is flooded internally. This can cause the seal to fail. Some condensate pumps can be specifically designed so that the seal is on the discharge side so that is always flooded, but that's not what you have in your picture above.

In your pictures it appears that your pressure tank is quite a distance away but on the suction side of your pump, is that right? So that's the suction side is the right idea, but if your distance is too long and tank pressure too low, or if you have a valve between the tank and pump suction that ever was closed while your pump operated, you drew a vacuum on you suction and might have brought air into your pump seal that could have sprung your leak.

Maybe your situation is different, but that's where I would start.

I guess basically......... that has been what I have been doing. I just never thought about it that way until put it that way. My only concern is how hot the water could get if I really kept a good hot fire going. How hot is to hot to be dumping into the slab?

You are probably right about the leaky pump but it was that way when I first installed it, in fact it leaked before I even started the pump. I had it hooked into a big old water storage tank I built and had it piped where it pulled water out of the tank from the bottom then went through the boiler. My plan was at that time to heat that tank of water during the day and at night pump that hot water through the loops by another pump. On the first startup as soon as I opened the in and out valves at the pump it started pouring water from out of the little weep hole.

I bought that pump on e-bay as a slightly used but great condition pump but didn't get to try it out for a long time after I bought it so I didn't even bother the guy I got it from. I think I have seen those seal kits on e-bay form $70 to $100 dollar range so that's what I plan to do to see if I can get it going.

I've made a few changes to the system since I posted those pictures. As I said I removed the pump from the room the stove is in to over where the manifolds are. I wasn't getting enough flow through the loops the way it was but it heated the water tank faster that way. Now I'm getting good flow through the loops and I can tell the floor is getting warmer but I have been careful how I keep the stove fired to keep from getting the water too hot and that's what I would like to change.

Your question about the pressure tank and the distance to the pump. Actually the way it was then was that the pressure tank was on the supply side going to the manifolds. It really isn't that far maybe 15' of pipe is all. The way I have the system piped is the water flows through the stove top heater out the hot side and up to where the pressure valve was on the WH. It flows into the 3/4 pressure port (hot water) and out of the tank through the 3/4" drain port at the bottom of the tank by natural flow.

The supply side I had it piped where the inlet to the pump was fed from the return water from the manifold through the pump and up to the 3/4" inlet port on the tank. Then out of the 3/4" outlet port on top of the tank then over to my expansion tank and air valve before it exits the boiler room and out to the manifolds. Now basically now everything is the same except the pump has been moved over the where the manifolds are and the return water goes directly into the cold wader side of the tank and exits out the hot port. I'll try to get some more pictures of the way it is now once but I have been holding off until I could shut it all down and make some final changes. I want to add a couple of good pressure and temp gauges over at the manifold and also pipe in my other hot water tank along with a mixing valve if needed. Right now it feels too good in the shop to shut it down now.

 

[mx842]

Can you measure more temps?

Not sure exactly where you're measuring the 140 at, but you should also measure the temps of the water going to & coming back from the floor. And maybe into the top of the stove tank.

I am almost 100% certain that the floor should be able to take way more heat than the stove is making. So I am thinking that the floor loop is not pulling the heat from the tank like it should - the floor flow could be coming in the bottom of the big tank, going straight up, then back out to the floor, in sort of a column-like flow. And since the stove flow is only convection, and has quite a bit of horizontal direction to it, I don't think it's flowing very much, which would make a small area of the hottest water at the top of the tank. Or in other words, you might have two separate flows going on that aren't mixing much.

I have those SS manifolds that have temp gauges on the supply and return. Each loop has little adjustable flow meters on the supply and each loop on the return has it's own flow valve where you are supposed to be able to control the flow of each loop. For what it's worth I really don't know just how accurate any of those little gadgets are because no matter how you adjust any of the flow meters it always looks like the flow is the same. Right now I have all of the loops wide open.

As far as reading the temps. I have a temp and pressure gauge on the stove top heater which seems like it is fairly accurate. I'm thinking those little temp gauges on the manifolds are not all that accurate. They have always read higher that I think they should. When the temp gauge on the stove reads 140 degrees the gauges on the manifolds are reading around 160. I have one of those hand held red dot readers but they don't tell much as to actual temp inside the pipe because I get different readings that are all over the place depending on where you point the laser. I do know if I grab the hot side pipe going into the manifold it pretty hot. I can hold my hand on it but after a few seconds it gets a little uncomfortable to hold on to so I know it's pretty warm.

 

[DoubleB]

the pressure tank was on the supply side going to the manifolds.

This sounds like a problem (without seeing the system in person, of course.) In general you want the pressure tank near to the pump inlet, otherwise you can draw a vacuum on the pump inlet and have a dry seal. Not to mention cavitation. Not sure if your new setup avoids this or not, but you might look into that.

 

[maple1]

I have one of those hand held red dot readers but they don't tell much as to actual temp inside the pipe because I get different readings that are all over the place depending on where you point the laser.

Those things don't measure shiny surfaces very good - copper included. Spray a big spot of flat black paint where you want to measure (BBQ paint is good), that should fix that. If it's a decent gun to start with, that is - you should be able to tell that by seeing what it reads at your good temp guage. After spraying a spot of aforesaid paint, that is.

And after reading again, it seems your only reliable thermometer is in the stove top box, and that's where you're seeing 140. I am thinking most of your issue is not enough convection flow around that loop. There is quite a bit of horizintal to that. Can you turn that box around 180° so the fittings are closer to the hot water tank? Then you could get a lot of the horizontal out of the flow.

But I would first get good temp readings at all points mentioned above - that should tell you what's happening with the heat. In & out of the box, the tank (both loops), and the floor.

 

[maple1]

And, I re-read some again - how much pressure is in this system? Don't think I saw that mentioned either - might have missed it though.