Outdoor Wood Furnace Info
All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: abide on October 09, 2013, 08:47:03 PM
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I have posted a couple other questions earlier about a Shaver that was part of a property I purchased this summer. Being a foreclosure I am unable to ask the previous owner how it worked for him...so I am kind of winging it. Today I did my first test fire. I got the temp up to 165 fairly easily. I installed the Ranco mod so I am confident that temp is accurate. I then turned on the indoor system and started the circulator. Being as I just repressurized the indoor radiators the temp had to come way up. Looking at my indoor boiler the temp raised at a good pace until it hit 110 then it just kind of stalled there and the outdoor unit ate up the wood pretty quick (4 hours). Is it normal to have a 55 degree differential between the two sides of the heat exchanger? The unit is 50' from my house and today it was 60 outside so there was not a large demand. I am new to having a baseboard hot water system but it seems to me that my boiler/radiator temps should be closer to 150?
Rod
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Don't sound normal to me, but that seems like a tough one to figure out, could be partially air locked or pump severely undersized, but the fact it ate up so much wood so fast has me scratching my head on that, because if it wasn't using up the heat the wood woulda lasted a long time.......
What kind of underground pex do you have?!
The delta t across the exchanger is indeed huge but how did u have such a large demand for heat today, it should have ran you outta there quick haha
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The underground appears to be homemade (insulated in corrugated pipe). I see no signs of water as best I can tell. Would I be better to shut off all radiators and then let it come up to temperature?
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What size is the heat exchanger? If it is way undersized it could easily have 55 degree differential.
Was the return water to the outdoor boiler hotter than that?
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When you say radiators are you meaning cast iron as they hold a lot of water and will take a bit of time to stabilize, if you have lots of them it will take more time.
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I have numerous cast iron radiators. The house is 2500 sq. feet. The way I see it there are only two options. The heat exchanger is dirty or undersized or the underground lines are wet. It is my thinking that if the heat exchanger is not doing its full job my burn times should be extended. Therefore I am leaning towards the underground lines being deficient. Last night at 2300 I loaded up the boiler with many large rounds at 0630 this morning the fire was largely coals and ash. The indoor boiler never got above 110 last night. The return water off the exchanger back outdoors seemed very cool. Thoughts?
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Are you feeling your lines at the stove or at the boiler!?
If its hot on one side of the exchanger and cold on the other, that heats going somewhere, and I agree if they werent putting out heat your burn times should be going the other way....
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I should also add that my circulator is designed to only run on demand. Therefore it is not continually pumping water through underground. My pipe seems pretty hot at both stove and boiler. Does anyone with bad underground lines have similar experience? The run is only 40-50 feet.
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What would be airlocked? Circulator on inside, outside or heat exchanger. Seems to me the heat is going somewhere...but where?
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Try shutting off the pumps on the indoor system and see if it can keep up to temperature with the OWB pump running. If it does then it isn't the underground pipe.
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Yea I've seen that happen but it sounded like you were saying the the water was arriving hot at the heat exchanger and being real cool simply by going through it.
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Gonna have to start checking some temps with a thermometer or perhaps heat gun......
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I should also add that my circulator is designed to only run on demand. Therefore it is not continually pumping water through underground. My pipe seems pretty hot at both stove and boiler. Does anyone with bad underground lines have similar experience? The run is only 40-50 feet.
what if you turn it on pump full time circulating full time to and from boiler ? and shut off other pumps in house? get a dig temp gauge and get readings..... see if you are loosing temp in pipeing.....? is it plumed right on boiler? and circulating it the right way? just trying to give ideas...
kelly
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I am currently heating water back up right now. Hopefully this evening I will test running outdoor circulator with indoor turned off. I need to get a heat gun soon. The stove holds temperature remarkably well when there is no call for heat. So I have a baseline...In 50 degree temps how much wood should I go through to heat 2500 sq. feet?
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unsuccessful test last night. One thing I found...Since the OWB went unused and empty for several years, a large deposit of scale formed on the inside of the pex piping. I installed a filter on the pump but this does no good when the contaminants are in the pipe and can flow freely downstream and clog the heat exchanger. Today I will move wye filter from pump to heat exchanger supply. I will do this after I reverse the flow on the exchanger to push any debris back into OWB. This problem was confirmed by a visual inspection of exchanger. When I cleaned out the exchanger last night and restarted the pump the pipe got almost too hot to touch for the first 30 minutes or so then the temperature gradually declined. This should solve my temperature problem, however, I don't know if this will fix the consumption issues. One idea I have is that the reduced flow of water causes all heat to be lost in piping. Since the flow then never gets to stop the continuous cold return causes the wood to be consumed faster.
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CLR works OK but you can purchase a commercial coil cleaner for domestic hot water coils from your local supply house that is much stronger
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CLR works OK but you can purchase a commercial coil cleaner for domestic hot water coils from your local supply house that is much stronger
I wish we had a supply house anything close to what I have.... The little hardware stores here wouldn't know a coil from a space ship lol
If the flow was so slow tho, it wouldn't be able to pull heat from the boiler, when flow is to slow often the problem is I'm getting good burn times but not keeping up with temp in the home... I think there is more issues at hand here than low flow..
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Sorry for the delay...My basement flooded as we received 10" of rain in the last couple days. I started my experiment again by running the OWB circulator with the internal circulator powered off. I also have the indoor radiator system drained at the moment while I replace a few valves that were stuck or leaking. Last night I got the OWB temp up to 160 where it is set to operate. Once this was achieved I ran the pump and regularly emptied the WYE filter which I just relocated to the heat exchanger supply side. The first 3 times I emptied the filter I got a good amount of scale that was shaped like the curve of the piping. The fourth time there was very little. I am sure I will have to closely monitor the filter for the immediate future, however, it seems like I got most of the deposits flushed from the line. So...about 14 hours ago once the set temp was reached I continuously ran the water through the underground pipes and heat exchanger. As of now the load I put in the firebox is probably about 30-40% consumed and the water is holding temp well. Based on this I don't think I have much of a problem with my underground lines. I am thinking my problem was the result of a clogged heat exchanger. If the lines were bad with the latest rain we had it would have been very noticeable now since the water table is very elevated at the moment.
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It might be worth getting a temp gauge in the house so you know the temp of water getting in the house,
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Sorry for the delay...My basement flooded as we received 10" of rain in the last couple days. I started my experiment again by running the OWB circulator with the internal circulator powered off. I also have the indoor radiator system drained at the moment while I replace a few valves that were stuck or leaking. Last night I got the OWB temp up to 160 where it is set to operate. Once this was achieved I ran the pump and regularly emptied the WYE filter which I just relocated to the heat exchanger supply side. The first 3 times I emptied the filter I got a good amount of scale that was shaped like the curve of the piping. The fourth time there was very little. I am sure I will have to closely monitor the filter for the immediate future, however, it seems like I got most of the deposits flushed from the line. So...about 14 hours ago once the set temp was reached I continuously ran the water through the underground pipes and heat exchanger. As of now the load I put in the firebox is probably about 30-40% consumed and the water is holding temp well. Based on this I don't think I have much of a problem with my underground lines. I am thinking my problem was the result of a clogged heat exchanger. If the lines were bad with the latest rain we had it would have been very noticeable now since the water table is very elevated at the moment.
I the heat exchanger was clogged? How did it exchange heat and where did it go?!
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I ordered an infrared thermometer yesterday and will use it to assess the temps on the supply and return brass fittings. My test load ran for 36 hours at set temp with the underground lines being used throughout. I believe the lines are not the problem. Unfortunately I will not have the new radiator valves installed until wed/thurs if all goes well. I feel much more confident that the next test run will go well. I will report back as soon as it is ready. Good info on the bypass for the filter. I will be looking into that. Also I was pricing out pipe thermometers and may include them in the final configuration.
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Fired up the boiler yesterday and it seems to be working well. Last night the temp got right around freezing and the house maintained 72. Wood consumption does not seem to be excessive. I believe my problem was the clogged heat exchanger and burning somewhat punky wood. One concern I have is the indoor closed loop system does not seem to get hotter than 120. Although this was able to maintain temp in the house it seems kind of low for colder temps that are on the way. I guess time will tell. I received my infrared thermometer and the temp drop on the underground lines does not seem to be more than a couple degrees.
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One more question...My underground lines are 3/4" poly butyl. Total run is ~80 feet one way. Half underground/ Half basement. I converted both ends to pex and used the crimp fittings which have a brass insert that goes inside of piping which further reduces diameter in small spots. Could the smaller piping be hindering my ability to transfer BTU's?
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No mixing valve. Just 13 cast iron radiators coming off a loop in the basement.
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One more question...My underground lines are 3/4" poly butyl. Total run is ~80 feet one way. Half underground/ Half basement. I converted both ends to pex and used the crimp fittings which have a brass insert that goes inside of piping which further reduces diameter in small spots. Could the smaller piping be hindering my ability to transfer BTU's?
Yea the overall line size is a problem
3/4 flows half the btu of 1"
But I'm not buying we've found all the issues yet, if your heat exchanger was clogged, you should have had crazy long burn times with no heat getting into the home. When it's clean, more btu flow, which means more can be transferred, if its partially clogged, water slows and btu flow is killed, the heat had to be going somewhere... Just not sure where n how yet lol. Good luck :thumbup:
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Changing out the lines is unlikely this fall. Could I get a higher capacity pump? Right now I am running a taco 007. I also upped my temp setting to 180 instead of 165.
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I just reloaded the boiler. If I wouldn't fiddle around with it so often it would probably equal out to a 20-24 hour burn time. The wood I am burning is somewhat punky so it probably goes up faster than normal oak wood. I found an online calculator that determines your plumbing head by your pipesize. If I did my math correct it figures out to be 50 feet. I used the numbers for pex assuming that poly butyl is probably very similar (80' of 3/4" x 2). Assuming I need 100,000 BTU's (high end) I need close to 10 GPM. I am not even in the ballpark with my setup. Possible corrections I can make for little time and money are changing over the 40' of piping in the basement to 1" pex. With the cost of a taco 0011 being over $200 I will probably just spend the $500 on newer underground piping.