backdraft damper location??

[Der Fuirmeister]

Is there a general rule or suggestion for locating the backdraft damper? Is one required? For instance, right now I burn in a furnace and do not have one. I have zero creosote problems and have plenty of draft which is controlled at the furnace air inlet. The furnace has no draft fan.

When changing to a draft fan type boiler will the fan push smoke out the damper???

Can I locate the damper in the ash clean out opening which is lower down the chimney than the flue inlet from the boiler???

 

[pybyr]

Is there a general rule or suggestion for locating the backdraft damper? Is one required? For instance, right now I burn in a furnace and do not have one. I have zero creosote problems and have plenty of draft which is controlled at the furnace air inlet. The furnace has no draft fan.

When changing to a draft fan type boiler will the fan push smoke out the damper???

Can I locate the damper in the ash clean out opening which is lower down the chimney than the flue inlet from the boiler???

With my Econoburn, they specifically recommend a barometric damper, and I put one in. Mine is at the chimney end of the flue pipe, not the boiler end- it is on a TEE with the arm of the TEE facing down into a 90 degree elbow, and then the damper in the elbow. I did it that way so that (a) the cool air introduced by the barometric damper would not cool the length of the flue pipe between the boiler and chimney; and (b) so that the damper would be vertically lower than the horizontal flue pipe, so as to minimize odds of smoke coming back out the damper. So far, so good- 0.02 draft per Econoburn's recommendations, no backdrafting out the damper except in those instances when the boiler does a huge "puff" of wood gas following a loading- and I am learning how to avoid and minimize those puffs by the technique I use when loading.

 

[LeonMSPT]

Have to do what makes you happy and safe feeling. My New Yorker came with instructions that said, "draft exceeding .04 inches can lead to overheating flu and chimney, run away fires." It also said that the BDD is "required". Then they directed that the BDD be "located within two feet of the back of the boiler".


Draft is one of the weirdest things... because it's "different" at different locations on the boiler and piping system. If I put the damper five feet away, the rapid movement of air into the BDD is going to "draw" on the boiler at a higher rate than the damper is set for. The fluid movement "pulls" harder on where the resistance is.

So, advice?

Start with the instructions included with your boiler and work from there.

 

[pybyr]

I run a Bacharach full sized draft gauge full time, sitting on top of the boiler, and measuring the draft about a foot from the boiler, since I figure that it is the draft at/ "through" the boiler that is the main thing for boiler efficiency/ operation- even though it's of course important to maintain enough draft throughout the system to make sure that all of the combustion products go up the chimney. It's interesting and informative to watch the draft as I get the burn going.

I've got a moderately long but steadily-uphill sideways run from boiler to chimney flue- and I verified with Econoburn that this is OK (and it seems to work fine) but since chimneys rely on the heat of the combustion gases to keep it all moving, I just could not see putting the damper right at the boiler where it would allow cool air to enter the rest of the run

 

[LeonMSPT]

Working on purchasing and installing a Dwyer #25. My chimney tugs like a tractor... 35 ft tall, 6.5 x 6.5 inch stainless liner. I don't worry much about cooler air entering the chimney or the flu pipe. I consider the pipe and chimney past the damper as being about the same. Once the gasses pass the BDD, stack velocity and concentration of volatiles and particulates plummets. There isn't much "opportunity" for things to stick in the first place.

Been burning a good two months, and about halfway through the season. I've cleaned the chimney connector pipe a few times so far. It gets well polluted because I go from coal to wood to coal once a week. Fly ash and condensate is nasty... thickens up and sticks well. Though, I've never even 1/8 inch of stuff off the inside of the pipe.

I run a Bacharach full sized draft gauge full time, sitting on top of the boiler, and measuring the draft about a foot from the boiler, since I figure that it is the draft at/ "through" the boiler that is the main thing for boiler efficiency/ operation- even though it's of course important to maintain enough draft throughout the system to make sure that all of the combustion products go up the chimney. It's interesting and informative to watch the draft as I get the burn going.

I've got a moderately long but steadily-uphill sideways run from boiler to chimney flue- and I verified with Econoburn that this is OK (and it seems to work fine) but since chimneys rely on the heat of the combustion gases to keep it all moving, I just could not see putting the damper right at the boiler where it would allow cool air to enter the rest of the run

 

[Der Fuirmeister]

LeonMSPT, I'm not familiar with the New Yorker WC90. I assume that's a boiler? Does it have a draft fan?

PYBYR, Does your Econoburn have a fan that pressurizes the primary chamber on the front end like the EKO, or does the fan work on a vacuum basis from the back side like the Wood Gun?

Just wondering if this has any affect on the backdraft damper...........

 

[pybyr]

PYBYR, Does your Econoburn have a fan that pressurizes the primary chamber on the front end like the EKO, or does the fan work on a vacuum basis from the back side like the Wood Gun?

Just wondering if this has any affect on the backdraft damper...........

yes- it's kind of like a USA-built, built-for-stout variant of the EKO and Tarm downdraft designs, with the blower pushing air into the firebox and the refractory/ secondary

I seem to get really good draft regulation with the damper in the location that I mentioned above, in this thread

 

[LeonMSPT]

Old style wood/coal boiler, water jacket design. Has a combustion blower that pushes combustion air into the ash area under the grates up through the coal when it's running. Had alot of issues with puff backs and gas explosions initially, until I put the damper on. Since then it's only happened once... still haven't managed to wrap my head around it.

Had door vents open all the way... I suspect the "fire" was below the gas charge for a period of time and it was drafted into the chimney connector and flu, then when it contacted flame it went off... With the door vents "cracked", the flame hangs lower in the firebox about 6 inches above the coal... grows and shrinks, but hangs on through the entire demand cycle, then settles down on top of the coal, occasionally flaring up and then settling back out. So long as it's burning off without blowing my chimney connectors apart and causing minor heart attacks it's fine by me.

LeonMSPT, I'm not familiar with the New Yorker WC90. I assume that's a boiler? Does it have a draft fan?

PYBYR, Does your Econoburn have a fan that pressurizes the primary chamber on the front end like the EKO, or does the fan work on a vacuum basis from the back side like the Wood Gun?

Just wondering if this has any affect on the backdraft damper...........