Runaway Boiler !!!

[ejhills]

I'm running a Tarm Solo MB55 for the first time this winter and I ran into an unexpected turn of events.
With a good bed of coals, and the boiler temp at 140-180, my flue temp will skyrocket into to 700's.

It was these last few days and all this gusty wind. If my bottom draft is open just the tinyest bit. A sustained gust of wind will draw the fire right of the box and barely touch the temperature. But that freight train just pulls the flames right on up. This can happen in less than a minute.

Then the wind is gone....

And all that heat comes slamming back down into the firebox door. Insert large puff of smoke.

Now I can truley appreciate why those doors have those heavy latching handles.

So I think my chimney is too tall but of course other experiences of the group are definately appreciated.

8" diameter Flue and lets say 42' of chimney

Normally I do ok but these gusty 15-20mph winds have been brutal.

Help

 

[ISeeDeadBTUs]

Instal a wind turbine and heat with electric

 

[Eric Johnson]

Usually the big puff of smoke occurs when your draft door closes, causing a buildup of explosive, oxygen-starved wood gas in the firebox. Then, when it gets enough air (usually at the chimney connector) it explodes, causing puff-back, or a series of puff-backs. If you open the loading door at this stage, it will blow up in your face, occasionally with enough ignition to burn off your eyebrows and other hair.

Sounds to me like you're probably experiencing some variation on that theme. Maybe what's happening is that the excess draft caused by the wind is pulling the draft door closed, allowing the gas to form, and then igniting it when it lets up and the door opens back up. Poof!
'

 

[ejhills]

OK... so excess draft in high wind conditions

This is what happens first, before the puff.

What can be done to reduce excess draft?

 

[machinistbcb]

well you can add a barometric (spelling ?) damper to help control the draft. I had one on my old conventional wood boiler, but I never really liked it.

 

[NNYorker]

Running a Econoburn 100 with a barometric damper (Field Controls Type RC) installed. I live on top of a big hill surrounded by open areas surrounding the house. Wind blows 95% of the time. Winds with gusts as high as 45mph last week -- boiler maintained set temp within +10* most of the time. Barometric dampers and Tarms have been discussed here with mixed thoughts, but this setup seems to be the norm in places other than the U.S.

 

[Eric Johnson]

You could put a conventional cast-iron damper into your exit pipe and keep it adjusted for conditions. Since you're down there operating the thing anyway, might as well give yourself the option of controlling the draft. I always had dampers on my conventional wood-fired boilers, and don't think I could have operated them very effectively without them. A CI damper runs around $5 at most hardware stores.