Outdoor Wood Furnace Info
General => General Discussion => Topic started by: csmart94 on January 03, 2013, 06:25:10 AM
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I built my own owb. Uses a couple old lp tanks. I think my firebox is too small because im not getting the burn time id like to see. Its a 125 gal lp tank that is about 24 diameter heating about 200 gallons of water. One thought I had was to slow my forced air furnace blower down to stop the sudden drop in water temp and useing alot of wood to recover in a short amount of time. let me know what what you think. thanks
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Make no difference really, it takes x number of btu's to keep your home at let's say 73 degrees. Your home will still require that same number of btu's regardless of how fast the fan is running.
Some installs are done where the fan never shuts off and a zone valve or "close t" are used to allow heat into the coil t certain times.
Seeing you built your own stove, which is fine, but makes me hope you didn't build your own underground line as well???? I've been around this stuff a lot and never have seen a homemade line that was worth burying
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yes I did but together my own lines. Guess I didnt think that to be an issue if they temp drop is drastic when the fan kicks on.
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yes I did but together my own lines. Guess I didnt think that to be an issue if they temp drop is drastic when the fan kicks on.
Is your pump running all the time? If so that's fine but good insulated lines are a must, if it's kinda hanging on just by losing heat to the ground then when it calls for heat it kills it....
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If you want to stop the sudden drop in temp, I would put a bypass valve between the pipes on the heat exchanger and adjust it till it is how you want it. Should work better than playing with the fan speed.
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If you want to stop the sudden drop in temp, I would put a bypass valve between the pipes on the heat exchanger and adjust it till it is how you want it. Should work better than playing with the fan speed.
That is true, but when times are cold it's either the boiler stays warm or the house does, right?
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Yes i circulate water all the time. That is why i thought the fan speed would take care of some of the issue. I looked at my furnace and the fan is set to slowest speed. So I thought to try opposite of what i was thinking. Bumped it up to the speed at which normal heat would run.
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is the sudden drop in temp you are talking about a sudden drop in temp of the boiler itself and unable to recover what the house is using? if so then a boiler with 200 gallons of water and a good fire going that can not keep up leans towards a lot of square feet and or a poorly insulated house and /or underground lines as well
if the sudden temp drop is only from one side of the exchanger to the other than i would suspect low gpm
???
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Blower should just run longer.
Will still probably burn the wood up as fast but will keep the water from getting as cold suddenly.
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Sounds like there is more info needed really, I don't see how you can kill 200 gallons of water so quickly, I think as with every other self made line set that would be one place I would be highly concerned about.
Willieg has had some experience with that as well
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Willie yes the return line off the exchanger is considerably cooler when the furnace is running. Its a 007 taco pump which i think is 20 gpm. Im about 80 foot total from boiler to exhanger.
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Willie yes the return line off the exchanger is considerably cooler when the furnace is running. Its a 007 taco pump which i think is 20 gpm. Im about 80 foot total from boiler to exhanger.
Well there is one major problem, I'd never run an 007 hardly any distance at all, they'll only do 10-12 ft of head...
Hopefully you don't have 3/4" lines to boot???
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So far the furnace is funning at a shorter duration, this house is only 7 years old so insulation isnt the issue.
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Willie yes the return line off the exchanger is considerably cooler when the furnace is running. Its a 007 taco pump which i think is 20 gpm. Im about 80 foot total from boiler to exhanger.
Your probably down to 1-3 gallons per minute if you have many elbows. 007 won't do 20gpm I don't think if it had a 1 ft run with no restrictions
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What size is your pex?
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Yes i do have 3/4 off the boile to1 inch underground then 3/4 in house
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Your flow is killed........
You need something like a 25-10 pump to handle that, you barely have any flow the way it is...
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It's hurting you in more ways than just that as well, I'd be afraid to say what your return temp back to the stove would be if it's already considerably cooler out of the coil, of course it's probably robbing some heat from the supply line as it goes back out
You would only want the water difference from in and out of the coil to be around 20 degrees max
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What do u recomend
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Willie yes the return line off the exchanger is considerably cooler when the furnace is running. Its a 007 taco pump which i think is 20 gpm. Im about 80 foot total from boiler to exhanger.
Your probably down to 1-3 gallons per minute if you have many elbows. 007 won't do 20gpm I don't think if it had a 1 ft run with no restrictions
A 007 can do 20 gpm if you have a few feet of 2" pipe. (Something that will never happen on an OWB)
I would guess the same 1-3 gpm range that it is running.
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With you having that distance and some 3/4" piping involved I'd reccomend a GPD25-10SFC, would run you about $175 to your door.
If you wanted to try to save some change you might find a good 011 or something like that online, but the pump I was pricing you is a 3 speed, you can kind of adjust it to suit yourself.
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I have no used pumps at this time, RSI may have a used one that would work for you
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Ok ill let you know. I really appreciate all the info, its been a great help as i scratch my head. I love figuring out problems but sometimes i get discouraged. Thanks again
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Ok ill let you know. I really appreciate all the info, its been a great help as i scratch my head. I love figuring out problems but sometimes i get discouraged. Thanks again
The pump probably isn't the only issue, but it won't be possible to correct anything else as long as that's messed up and severly under sized
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A 0011 taco should be big enough?
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I think the 011 will do about 31' of head, so yea I'd think so
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Ok well i bought my pump from menards so i thought they might take it back and ill get the 0011 they have them in stock
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Pumped changed to the 0011, im guessing i still need to change my underground pipe cause i am still useing more wood than i think i should.
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Yup, like I said, the pump had to be fixed to be able to start fixing other issues. There is numerous line choices for you to choose from.
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what do you recomend, if i buy something, it might need to lay ontop of ground untill spring. Is foam filled better than the wrapped?
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It might be, it's just a matter of what your willing to pay
Heat loss on a good quality 5 wrap is as good as a quality foam filled, but the casing on logstor maybe tougher.
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A good quality 5 wrap is likely 7.50-8.25/ft
A quality foam filled product like logstor is more along the lines of 14/ft
Logstor has a few more features than thermopex, another quality foam filled line
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I redone my lines today, bought thermopex and got it in the ground and hooked up. Supose to get cold tonight so we will see how much better it is. I hope to get 12 hours out of a load. Thanks for all the info. Fyi I didnt dig up the old line yet but was close and yes the dirt was warm so I was loosing a lot of heat there.
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Yup, you'll do much better now if your dirt was actually warm lol. :thumbup: