Hi all.
I have a Continental CHMF200 wood furnace, the blue brother of the Napoleon HMF200. Overall, I like it... but I've been dealing with the issues of using a wood furnace in this house for three years now.
One major issue is draft - I have an 8" double wall internal chimney that rises ~45' above the level of the furnace in my basement. At the chimney base, there is an 8" to 6" adapter, from which 6" is run to the stove.
For reference, the stove manual calls for 0.04" - 0.06" of draft at max, with strict warnings to NEVER allow above 0.10" of draft go through the stove.
I installed a Dwyer Mk. II manometer a few years ago, and found out that my draft would range from 0.08" at the best of times (not cold out, still air) up to 0.2-0.3 when there was cold or a decent wind blowing across the top of the chimney. Needless to say, my flue temps were fairly high, and I was going through wood like no tomorrow with fairly low heat output - the heat was all going up the chimney.
To combat this, I installed a 6" barometric damper (https://www.grainger.ca/en/product/p/WWG45DX61) as permitted in the manual, and calibrated it for -0.06" vacuum. It does a good job of making sure the draw through the appliance remains stable and within tolerance, and in turn I get much more controlled burns, incredibly higher heat output into the plenum and ducts, and the wood lasts 2-3x as long in the firebox.
However, the downside of this is that I am sucking large amounts of heated room air up the chimney through the draft control. This has killed my flue temps - a hot fire maybe raises the chimney temps to 185-200* (although after a year, I am only seeing minimal creosote accumulation). More importantly, I'm aware that the stiff breeze of warmed room air traveling up the chimney is being replaced by ambient outdoor air.
Does anyone have thoughts as to what an appropriate 'next step' would be here?
I really see two options at this point:
1. I run a second outside air supply to the barometric damper, so that I'm at least not putting house air into the chimney. This would lower flue temps even further, and the run would be *very* inconveniently placed.
2. I install an old-fashioned manual damper between the barometric damper and the chimney to restrict the draft further - ie, do a 'bulk' restriction of the draft, and just reduce the barometric damper to a 'fune tuning' role.
Any further thoughts?
I have a Continental CHMF200 wood furnace, the blue brother of the Napoleon HMF200. Overall, I like it... but I've been dealing with the issues of using a wood furnace in this house for three years now.
One major issue is draft - I have an 8" double wall internal chimney that rises ~45' above the level of the furnace in my basement. At the chimney base, there is an 8" to 6" adapter, from which 6" is run to the stove.
For reference, the stove manual calls for 0.04" - 0.06" of draft at max, with strict warnings to NEVER allow above 0.10" of draft go through the stove.
I installed a Dwyer Mk. II manometer a few years ago, and found out that my draft would range from 0.08" at the best of times (not cold out, still air) up to 0.2-0.3 when there was cold or a decent wind blowing across the top of the chimney. Needless to say, my flue temps were fairly high, and I was going through wood like no tomorrow with fairly low heat output - the heat was all going up the chimney.
To combat this, I installed a 6" barometric damper (https://www.grainger.ca/en/product/p/WWG45DX61) as permitted in the manual, and calibrated it for -0.06" vacuum. It does a good job of making sure the draw through the appliance remains stable and within tolerance, and in turn I get much more controlled burns, incredibly higher heat output into the plenum and ducts, and the wood lasts 2-3x as long in the firebox.
However, the downside of this is that I am sucking large amounts of heated room air up the chimney through the draft control. This has killed my flue temps - a hot fire maybe raises the chimney temps to 185-200* (although after a year, I am only seeing minimal creosote accumulation). More importantly, I'm aware that the stiff breeze of warmed room air traveling up the chimney is being replaced by ambient outdoor air.
Does anyone have thoughts as to what an appropriate 'next step' would be here?
I really see two options at this point:
1. I run a second outside air supply to the barometric damper, so that I'm at least not putting house air into the chimney. This would lower flue temps even further, and the run would be *very* inconveniently placed.
2. I install an old-fashioned manual damper between the barometric damper and the chimney to restrict the draft further - ie, do a 'bulk' restriction of the draft, and just reduce the barometric damper to a 'fune tuning' role.
Any further thoughts?
