Tarm Draft Question

[lawandorder]

I have a Solo 40 that is connected to black pipe to the ceiling then attached to 12 ft of 6inch Selkirk Metalbestos. This is in a boiler room attached to the back of our garage. The Selkirk pipe goes throught the ceiling in the boiler room then up through the roof. I seem to be having draft issues, condensation and creosote on the outside of the pipe when I look at the cap and outside pipe after it exits the roof I also seem to have some wood that isnt burning through after a full burn. Smoke when I open the firebox door to load etc.. SOme small pieces of logs along the sides of the firebox etc... I did not insulate the "attic" portion of the boiler room. THere is just 6 inch insulation in the ceiling than nothing from their up through the roof. Should I Have insulated the rafters of the boiler room and side walls of the boiler room in the attic space. Will this have helped my draft and reduced condensation etc.. I have been burning good wood the past week but the creosote still looks like its there. The snow on the boiler room roof has streaks of brown running down the roof line. Looks like I may have done something wrong.

 

[twitch]

I recently installed a Solo 30 (Scandtec) with basically the same set up (boiler room in garage, ceiling heated, no insulation above, stainless double walled insulated chimney) you have and I'm having the same condensation, creosote, and smoke when loading problems.

I've found that if I set the secondary air adjustment all the way to the right prior to opening the loading door, it helps with the smoke. I'll still get some smoke if the fire is smoldering and not really hot.

The condensation problem I'm seeing is only when the boiler is up to temp and in idle. The flue cools off, and I'm getting some dripping from the pipe in the boiler room. I haven't inspected the inside of the flue or chimney yet, but the liquid dripping is more of a brown color. The wood I have isn't as dry as it should be, but I don't see any type of dripping or creosote when the boiler isn't idling or after a complete burn.

The small pieces on the sides of the firebox are typical for me when I let the fire go out, and I find that when I reload before the burn is complete, I have to use the poker and push the logs / coals to the center, over the opening to the combustion chamber.

I know I didn't really answer any of your questions, but you're not alone with what you are seeing, and I think some of it may be typical.

Scott

 

[lawandorder]

twitch- how much pipe do you have going up. I probably have 12 ft from the ceiling up through the roof to the pipe cap. I also have a two 30 degree offsets in the black pipe to get to the ceiling insulated pipe.

 

[Birdman]

I have a Tarm 40. I have 4 ft of black pipe connecting my Tarm to a Metalbestos chimney..... which is outside of house. My Tarm is the basement. I had issues with creosoot and moisture for about a week? then it all stopped. I had alot of moisture at first... dripping from the black pipe.... i had to use coffe cans tolet it drip in. I guess it just takes some time to clear up? I have had no problems since then. I was scared it was going to happen all the time..... and thankfully... it did not. It has been smooth sailing for 4 -6 weeks... except for the power out issue which filled my house with smoke in the middle of the night. I am working on a remedy for that... Let us know if your issue clears up like mine did.

 

[lawandorder]

i just went up on the roof and took the cap off looked down and saw some fine brown colored ash buildup but nothing that appeared like black flaky stuff or hard black colored stuff everything looked like a fine brown powder. I am thinking about adding three more feet of pipe which i probably could do. I dont know if this would help my draft or hurt it?? I counted up the Selkirk. I have three 3 ft sections with an offeset that has a one foot section with it.

 

[twitch]

I think that the moisture and condensation we are seeing is mostly water (from a cold flue and boiler in idle) mixed with the ash. When I checked and cleaned my HX tubes in the boiler, all I saw was the fine ash stuff, and no creosote.

It may clear itself up after the seams in the stovepipe get sealed from this stuff. I have a "T" prior to my chimney and when the boiler is idling, I can hear drops of this stuff hitting the bottom cap of the "T".

 

[twitch]

twitch- how much pipe do you have going up. I probably have 12 ft from the ceiling up through the roof to the pipe cap. I also have a two 30 degree offsets in the black pipe to get to the ceiling insulated pipe.

I haven't measured it but I'd guess 12 feet from the ceiling to the cap. I have two 90 degree elbows in my pipe then into a "T" in the bottom of the chimney. I can't imagine that the two offsets would be causing a problem. There's a link in my signature to some pics during the install to see the chimney setup in the boiler room, it's a little different now, but close. Problem with my setup is that the chimney, which was existing, is over the top of the boiler. Seems to be working, but not ideal.

 

[lawandorder]

Well decided to try more chimney added a 4ft section on top and it looks like it is really helping. Tarm seems to be firing a lot better and very lttle smoke out the door. Closed the secondary which also helped. I hope this isnt a fluke because my fire today was roaring to the point where i had to cut back the secondary a lot more than normal and it still was screamin hot...... Fingers crossed that it stays like that and my burns turn out a lot better.

 

[jebatty]

My Tarm manual recommends a chimney 20-30 feet in height. My chimney is 5 ft black stove pipe, then 18 ft of 6" Class A through an unheated attic. I exceed the minimum 3 ft above the top of the roof. If anything, I have excessive draft, as I have had to damper down the draft fan damper quite a bit.

It seems to be that always, at least almost always, condensation and dripping down the chimney comes 1) from melting ice in the chimney that collected during a cold period when the chimney was not being used and resulting from interior humidity escaping up the chimney, or 2) and more likely, wood with high moisture content., or 3) flue temp too cool during boiler operation. If I had to pick one of these, I would pick wood with high moisture content.

If you don't have a flue probe thermometer, get one and install it. I would recommend flue temp during gasification burn be no less than 400 and more probably 550-650 for most people (with dry wood), unless you have turbulators, and if so, subtract 100 degrees. The chimney needs to get hot and stay hot for good draft. A hot chimney also means that you cannot have condensation, as the chimney will boil any water off as steam.

I don't subscribe to condensation during idle periods, unless they are long and you have high moisture content wood. That moisture will boil off the wood in the hot firebox, ascend the chimney, and can condense if the chimney is cool.

 

[lawandorder]

my new friend the moisture meter has helped and i have only been using 20 % or less it looks like the extra 4ft has helped its actually ben running well this afternoon and is idling now almost burned out. I did notice that my stack temps now are 600 or better which i would only see if i left the damper open for a while. I was getting 400-600 but it seemed to be a struggle to keep it there, now it seems to want 600 degrees.

 

[jebatty]

The 400-600 is perfect, IMO. Let us know if the increased draft has solved your moisture problem.

 

[hoth2oguy]

Hi all,

glad to hear the problem seems to be clearing up. I am sure the additional length of chimney helped - a key issue is flue temperature being high enough, but velocity of exhaust gas is important too and a taller chimney pulls better.

These boilers are very efficient and, by definition, are pulling a lot of heat out of the exhaust stream. High moisture content wood and/or short or cold chimney can be the tipping point for condensation to occur. Compounding this situation in a brand new boiler is especially good heat transfer in the boiler tubes. After a bit of burning that same fine brown fly ash that you have seen in the chimney has also built up in the boiler tubes so the heat transfer is not quite as good and the flue temps stay a bit higher. Don't be surprised if the situation returns briefly after you brush the boiler tubes for the first time.

Just thought I would add my two cents, hope this helps.

Chris

Dealer Coordinator
BioHeatUSA

 

[lawandorder]

Thanks for all the replies. THe extra chimney seems to have helped out a lot put in 2/3 load at 10PM last night. House at 69 degrees and outside 4 degrees. Tarm still had coals and temp on the unit was 150 ish. So I am thinking its better. I had cleaned the Hx a few days ago and my stack temps are usually 600 plus during a burn. Now its burning hotter but should I look at turbulators or adjusting the draft fan to bring the stack temps back to the 400-600 range. I have a bit of smoke out the chimney but it may be moisture as its only 7 degrees out now. The learning curve continues......

 

[jebatty]

If you can adjust the draft to keep the burn between 400-600, that's good. Clean boiler hx tubes whenever temp seems to be moving consistently above this point.

Turbulators are good -- increase boiler efficiency and will drop stack temp about 100 or a little more. May have to adjust/increase draft, as I still recommend with turbulators keeping it 400-600. Result will be more heat from same amount of wood.