Outdoor Wood Furnace Info
Outdoor Furnaces - Manufacturers with NON EPA-Certified Models Only => Home Made => Topic started by: jackel440 on March 09, 2009, 03:33:08 PM
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I was over picking up a load of hay,and my hay guy has a corn boiler that heats all his buildings and house.I was checking it out and noticed that the pumps are mounted to the lines coming from the bottom of the tank.I take it you would be pushiing water away from the furnace correct?So his setup would be pulling water from the bottom of the boiler.I would think you would want to pull your hot water from the top of the firebox,and return the cooler water to the bottom of the tank.That way it would absorb heat as it circulated back to the top of the tank.
I am still designing my stove and trying to decide on how i want my water paths to be.Plus be the most efficient.
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I was over picking up a load of hay,and my hay guy has a corn boiler that heats all his buildings and house.I was checking it out and noticed that the pumps are mounted to the lines coming from the bottom of the tank.I take it you would be pushiing water away from the furnace correct?So his setup would be pulling water from the bottom of the boiler.I would think you would want to pull your hot water from the top of the firebox,and return the cooler water to the bottom of the tank.That way it would absorb heat as it circulated back to the top of the tank.
I am still designing my stove and trying to decide on how i want my water paths to be.Plus be the most efficient.
jackel, i have pondered this exact thing for a long while (at times) and i don't think it matters much..if you pull the water off the bottom and your aquastat is on top then you will be pushing cooler water to the aqastat that would result in a longer burn time ( i think the bottm feeder would mean that the whole tank would need to get to the set temp before the aqastat would shut off the damper)
if you pull the water off the top of the boiler than the aquastat may be satisfied sooner
i like you are planning have a home made stove, i piped mine so i could switch easily if i wanted too but have never done it as i feel pulling the water off the top is safer...i have fears of dirts and rust entering the line if you were to "suck" from the bottom. I feel (at least i am hoping) that as the cooler water is pushed intot he bottom of the stove that is moves slow enough to the top that fine particles that could hurt my pump or clog my lines settle out. I do have a filter in the house but it is after the pump
so right now my vote is "off the top" for longer life of the pump
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I think I will be setting mine up to pull off the top of the tank.I think you maybe right on any contamints settling out before the pump if it's at the top.I didn't consider the thought of dumping cool water in the top causing the aqua stat to create longer burn times.
I don't want to create longer burn times or make the furnace inefficiant.
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imnot sure dumping in the top would make it inefficient. it would just make it so the whole tank would be up to the same temp, it would burn longer but it may stay shut off longer as well..ii am not sure but i do think you may pick up more solids in the water pulling from the bottom
i will consider (in my next stove) pulling water from the very front of the stove near the top adn dumping in the back at the bottom..this may deter any "hot spots" of where water does not move much
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In the two stoves that we have,we take the water from the bottom and return it to the top.The return line extends to the front of the stove at the loading door end.The thermometer is at the top at the loading door end also,and the water temp.is the same there as it is at the outlet for the pump.So I think the mixing is pretty good this way.
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I had thought of using a pipe inside the jacket to direct the water to circulate under the bottom and then up the other side toward the top.I was think'n this would cause the water to move around inside the tank so there would be no stagnant areas.
I suppose it would not matter anyways.I expect there is also the chance the water could stir up sediment on the bottom too.
I have no experiance with these pumps so I don't know what to expect for the output to be like.I don't know if the water will shoot out or just flow slowly from them.I would know that to decide if it would make the water turbulant enough to stur stuff off the bottom.
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jackal..the "bottom" doesen't have to be the bottom you are building your own. the bottom may be a nipple 3 inches from the true bottom or what ever you like
also you could weld in a coupling in a few spots that you may want to experiment with and just put plugs in them.
and by all means, report your findings to us all
as for pumps stirring things up..i guess that depends on the pump . i think the taco pump i use goes up to 28 gal per min. but i am not sure about head lose and such on my 250 foot one way run but even if it was half that, 14 gal out of a 1 inch pipe might cause some stirring action?
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jackal..the "bottom" doesen't have to be the bottom you are building your own. the bottom may be a nipple 3 inches from the true bottom or what ever you like
also you could weld in a coupling in a few spots that you may want to experiment with and just put plugs in them.
and by all means, report your findings to us all
as for pumps stirring things up..i guess that depends on the pump . i think the taco pump i use goes up to 28 gal per min. but i am not sure about head lose and such on my 250 foot one way run but even if it was half that, 14 gal out of a 1 inch pipe might cause some stirring action?
WillieG
Your right since i am building my own the position of the bottom can be changed.I hadn't planned to put the bottom nipple right on the bottom.I thought i might put a clean out at the very bottom to be able to check the bottom for debri.
I might just weld in extra nipples so I can experiment if i want to.Atleast they would be there for future use if I needed them for something else.
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I believe the reason for pulling off the "bottom" is to keep from starving your pumps.
and gravity helps to force feed your pumps. drawing off the top leaved little room for error
if the water level drops.
just my 2 cents.
ouch..
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Good point.
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Another point well taken.I didn't even think about the extra pressure to help the pumps.Also if it was low on water it would definatley remove the problem of running low on water,and sucking air into the system.
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I think drawing from the bottom would also get better mixing of the water.
Is the hottest water next to the water jacket and cooling as it rises and mixes.
If it were a storage tank and you wanted to get stratification yes pull from top
return to bottom.
Heatmor returns to left top and draws from right bottom
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i do agree on drawing from the bottom as to not starve your pump but i also think drawing off the top does not have to be the top 3 inches
and if you boil over and lose that much water (with the thin water jackets i have seen on a lot of these stoves) the pump may be the least of your worries
and i have never really thought of the extra pressure on the pump...my pump is 250 feet from my stove in the basement so i guess it is about as low as you can go
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Hey Bill,,, I was looking at the picture of you plumbing,,,,,, Is that an electrical connection just to the right of the pump? If so,,, what is it? Temperature sensor??
Was thinking of adding a filter to my system. After reading about pulling off the top vs. bottom, and the thoughs of sediment, weld spatter, etc. in the water, I think it would be a wise investment. I use them in my domestic water in my house,,,, one with a 15 micron sediment filter, and one with a 5 micron charcoal filter. They do a good job.
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yes mark..the wire is a temp gauge (got the idea from someone here) it also works well fro checking my radiant floor temp
also with the filter i usually change it every fall and run all my water through it till it starts to get cold..then i open the bypass valve and let some get buy to ensure a good water flow in the cold weather,
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I like the idea of a filter in the circuit.A lot of neat ideas and theorys are being tossed out here guys.I am gonna have to start writing this down and keep a better record of ideas to implement in my design. :thumbup:
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Old thread but thought I would add that household water filtration is normally on the cold water side then into your hot water system. Not sure how the filter elements would hold up to the heat over time. May shorten life at the least. you could filter water going back into the boiler when it is colder. Just a thought.
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Old thread but thought I would add that household water filtration is normally on the cold water side then into your hot water system. Not sure how the filter elements would hold up to the heat over time. May shorten life at the least. you could filter water going back into the boiler when it is colder. Just a thought.
I definitely agree with you. Actually, I did this before and fortunately, as of now I have no problems of using my water filtration. The process of cycle is very clear and nothing to worry about.
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I only read the first handful of posts and the last few of this thread. I think the reason for the water being taken out of the bottom and the return going in the top is to keep the water moving around inside the furnace better. Hot water wants to go up, cold water down, so if you put cold water on the top of the hot water, it will move from the top of the stove to the bottom, thus moving water inside the stove. This is supposed to help prevent deposits from stuff in the water which leads to corrosion.
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my homemade is built with 2 returns ,one coming in side, one in rear. like a swimming pool concept.both are low on tank. the heat from fire box creates a convection and pulls water up as it rises to top . i have a inspection hatch on top and have seen this happening. one benefit of circ pump on botom is no fear of cavitating pump if water is low .
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The main reason for putting your return in the top would be because that is where most of the heat is absorbed from the firebox. The best design is to have your supply about 3 inches above the bottom and the return coming in the top on the other end. This does two things, first it puts the coldest water at the point of the highest heat from the fire giving it a better heat transfer basically making the furnace more efficient. Second it causes a mixing of the water in the tank keeping an even temp throughout your tank. This is more important if you are using stainless steel however it is a good idea with any stove.