Outdoor Wood Furnace Info
Outdoor Furnaces - Manufacturers WITH EPA-Certified Models => Portage & Main => Topic started by: american-pacemaker on January 05, 2016, 11:33:55 AM
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I have a small amount of moisture inside the airbox and inside the door of the reaction chamber on my 250. What would cause
this ? I called Brian at P&M and left him a voicemail almost four weeks ago with no reponse so I need to fix this.
Thanks, Larry
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Are there any gaskets leaking Larry, is your flapper mechanism ok?
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Larry, if you have the clip on cover, unhook the bottom left, you might have to adjust your air setting a little but it will take care of your moisture in the air box.
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Hey Slimjim, the flapper looked like it was clean and working good. The front door gasket seals good somedays and leaks other days.
I have tried to adjust it many times to be sealed all the time with no luck. I tried to get Brian to warrenty it since it has done this since the first time it was fired up but he will not. would this cause this problem ?
Coolidge, would leaving the bottom corner create a constant draft thru the boiler ? would I need to adjust the airflow for more air
or for less air ?
Thanks for the help guys.
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It does create a small draft, but it works. Those air boxes are tight with no place for condensation to go, this if there is a small crack in the seal, the blower kicks on and air(condensation) is blown out.
You might need to add a little air to compensate for the air going out the crack.
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On occasion I get water build up in my airbox as well, and the cause is still somewhat of a mystery to me even after 4 years. ;) It seems to only happen when I use wetter wood and the weather is warm. I'm thinking long idling lets moisture build up in the airbox and the bottom chamber by the door as the stove cools down and moisture can condense, especially with a new load of wood. I am using new silicon gaskets and I know my stove is tight.
Another possibility is excessive "huffing" so the steam blows back into the airbox and condenses on the cold metal. I think this causes the water problems under certain situations.
Moisture creation varies greatly during the wood burning process as the Hydrogen components of the wood get burned off first. This means that a lot of H2O gets created during the first half of the load. Burning wood will create 1.7 lbs. of water for every 1 lb. of wood burned! During the second half of the load burn the wood is mostly Carbon (Charcoal) so the exhaust is mostly CO2 and not H2O. It seems that it's during these initial burns that the moisture issues happen when the load is light, as the water content gets boiled out and the Hydrogen burns create a lot of water as well. The exhaust is mostly steam that REALLY wants to condense on the cold metal parts.
I would think that opening the airbox a crack would cause excessive creosote problems in the tubes, especially if the load on the stove is light, as it would create a draft. It may even cause greater moisture condensing as a small stream of very cold air would be continually introduced. I would not recommend this as a solution.
Is there a way of running the stove heavy for a few days to see if idling is an issue?
What are your temperature settings?
What type of wood are you burning?
How small is it split?
How much do you load the firebox for a 12H burn?
What are your outside temperatures?
How tall is your exhaust stack?
What are your air and fan damper settings at?
Let's see if we can find a place to start troubleshooting.
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Larry,
I previously had a problem with water in my airbox too - in fact, it was water and creosote and it was gumming up the mechanism to the point that the flapper was sticking open - then more water and more creosote.
jreimer has given you excellent advice if you absolutely/positively have to get to the bottom of what is causing your water-in-the-air-box-problem.
But, if you just want something that's quick and easy and solves your problem, do as Coolidge says, unclip one of your airbox clips and be done with it.
I know it seems just TOO easy...TOO simple but, 2 years ago, I was frustrated beyond belief with my stove problems - Coolidge very generously came to my house to see what was what, we unclipped one of the airbox clips and I literally haven't had one problem with my stove since that day. Each time I clean the stove, I remove about a tablespoon of hard/crusty creosote from the bottom of the airbox, but the rest of it is bone dry.
Your mileage may vary...But seriously...do it! ;D ;D
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James, Nice too see you are still lurking. I spent a lot of time in your neck of the woods this past summer.
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Jreimer thanks for the reply and here is where were at.
1- I can try to run it hard but the outside temps have been so up and down it's hard.
2- Temperature settings are 190' with a 5' differential
3- I have a mix right now of maple,cherry,ash all between 16 to 21 percent and I throw some pine on top that is at 15 to 16 percent.
4- split size is say an average of 10 to 12 inch rounds split in half.
5- firebox load. If the temp is over about 30' maybe four splits and under 30' maybe six or seven splits. I try for just coals after 12 hours
6- I am in upstate new York and the temps have been all over the place this year. Anywhere from high sixties during the day to four
degrees at night.
7- Stack height is just one length of pipe since the boiler was installed
8- airbox settings. the bottom one is about 3 1/2 turns and the top is about 4 1/2 turns and the fan is about 1/4" gap.
Thanks for the help I sure would like to get this fixed.
James, the flapper is clean for sure. Being a machinist we use an industrial red grease at work that takes very high heat well. I keep a very thin coat on the face of the flapper and the mechanisms and that keeps them very free and creosote free.
Thanks for the help I sure would like to get this fixed.
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Jreimer...Thanks for the help I sure would like to get this fixed.
James...Thanks for the help I sure would like to get this fixed.
Have you tried unclipping one of the airbox clips yet? What have you got to lose? If you're feeling adventurous, try it for 48 hours and see what happens - if it doesn't solve your problem, you can keep searching. If it fixes it, well, woo-hoo! :thumbup:
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I don't see any problem with trying to unclip the airbox cover. If it works, great! If it doesn't you haven't lost anything.
James - Do you not get shiny creosote buildup in your tubes with doing this? I have 12' of stovepipe, so I have a lot of negative draft to be careful of.
American - 5 is a small differential. When I ran a small 5 differential during warmer weather, I believe that contributed to my airbox condensation issue for some reason. Of course it may have been just due to longer idling and not the small differential, who knows. I now run a 14 differential, but it's 0 in the day and -16 at night here now. The stove doesn't stay idle for long!
I would also try running more air. Bottom one 5 turns, top one 10-15 turns. Fan about 3/8". This could help dry out the airbox as well. As I mentioned earlier, low airflow causes "huffing" which blows steam back into the airbox during running.
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Jreimer I will try your suggestions one at a time and see what helps. Thanks
James if one of these doesn't work I will try opening one corner .
Thanks for the help guys
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Old style airbox, inside after more than a month of burning. Of course please excuse the mess it has been a long time since it has been thoroughly cleaned. Third piic you can see what I got from the exchanger tubes with wire brush. Nothing looks like this anymore after a good cleaning today. Dry airbox and just a coating of ash in the tubes.
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Wow coolidge, I wish my air box was that dry!
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Wow coolidge, I wish my air box was that dry!
Yours can be that dry too...Just unclip...Aww, nevermind. :bag: ;D
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Hi guys. I checked my air settings this weekend and found the lower setting was only out two turns. I readjusted that and will check tonight and see if this fixed the or helped the problem.
Coolidge my heat exchanger usually looks just like yours with a heavy coating of the very dry gray ash. Is that just how it
should be ?
Thanks, Larry
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That's pretty dirty, I don't usually go that long between cleanings, brush the tubes weekly and clean everything every two weeks.
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Well it just hit me too. Last night I opened the back door of my boiler and noticed creosote had been running out of my airbox. Opened up the airbox cover and it was full of water. It had been dry as a bone for a month, and I didn't do anything differently yesterday.
It's one of those mysteries....
I'm suspecting it was from "huffing" as every surface was caked with gooey creosote. I think it huffs if I stack my splits too loosely and I was in a hurry yesterday morning.
I'll check again tonight and report back.
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There has got to be some heat coming from the back of that airbox area, now you are introducing cold outside air, condensation. Just like the roof of a house, vented, if you unclip the lower left corner.
No more gooooooo :thumbup:
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I had a similar problem this fall with water in the air box. I found out that the set screw on the actuator shaft had loosened up. There was a little bur left on it so it was intermittent. I would shut the switch off and listen for the flapper to "clang" and it didn't. I then opened the flap manually and the shaft didn't move. Tightened the set screw and its been fine since.
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Put a drop of blue (low strength) PermatexTM thread locker on that set screw. ;)
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Well the airbox was mostly dry by last night. I took more care in stacking yesterday so I don't think it was huffing as much. Now I have to clean all that creosote off the mechanisms so it won't stick open. :(
With the spruce I'm burning I think it's important to get a tight stack. Otherwise it seems to burn too quickly and overwhelm the oxygen supply.
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Hi Guys, I cleaned the boiler last night and after adjusting the airbox settings it looks like I got rid of the moistu
jreimer, I tried burning a stack of smaller diameter twisted wood yesterday and ran into problems with it. When I got home
the boiler was down to 179' with about a quarter of a load of wood still. As the load burned it never fell in on itself and was hung up and didn't burn :bash:
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I know, the bridging issue is very frustrating. Not only can the fire go out, but it makes for a very dirty burn and lots of elbow grease trying to clean the creosote out of the tubes! My splits are causing big issues with this.
I'm tempted to try putting something like a heavy steel plate on top of the wood after filling it to keep forcing the wood down. I guess one issue would be trying to reload when the wood is not completely exhausted. How the heck would you get the steel plate out of the way?? Probably wouldn't work.
Any other thoughts??
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So I'm still not exactly sure what causes the moisture problems in the air box, but I do have a solution.
I connected an insulated pipe from the intake of the fan to the top of the boiler to draw warm air into the air box during burns and to pre-warm the air if there is any air leaking in during idling. I also insulated the air box with some R20 fiberglass batts I had lying around. Keeping the air box warm has prevented any moisture from condensing. Problem solved. The air box has been dry as a bone, even with some occasional huffing from burning too small wood pieces during the shoulder season.
I'll try to post some pics later.
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This image is of the back of the stove. I peeled away a covering layer of fiberglass insulation so you can see some of the setup. I used some flashing to make a funnel from the fan intake plate to the 4" insulated hose. My goal is to make a more elegant Styrofoam cover for the air box, but I wanted to test this proof of concept first. So far the results are promising.