Blower and draft

[ecolbeck]

The stack draft on my evaporator does not seem to be able to keep up with the blower I use ( around 150 cfm). I end up with sparks and ash coming out of every little crack and around the cast iron door and the little space between the pans and the stack. I throttle back the blower so that stuff isn’t flying around the shack but then I feel I’m getting sub optimal evaporation rate. The stack is 7” diameter connected to a 8” metalbestos chimney which has the standard cap on top.

Is this just a normal problem that everybody has to deal with or is there something I can do to improve this situation? Do those of you who use metalbestos use the standard cap or does that cap restrict the draft too much?

[tcross]

I would ditch the cap and probably add another section or two to your chimney. that should help increase your draft. i had to get my chimney above the peak of my roof by a good 2' in order to get a real good draft.

[maple flats]

What size is the evaporator? If it is smaller than 2x6 that stack should be good, on a 2x6 it could be marginal. As tcross said, get rid of the cap and add more stack. Above the roof you can just use single wall pipe. If you add more than an additional 2' you may want to brace the stack.

[eustis22]

interesting..in my new shack, the top of my stack is below my peak.....I should extend it above the peak, huh?

[ecolbeck]

Hi, thanks for responses. The evap is 18x63. Stack is proper diameter and quite tall (20+ft). Sounds like the cap might be the biggest issue?