# D-vent versus B-vent with heat-recovery ventillator



## cyberiad (Dec 17, 2009)

Some B-vent gas fireplaces seem to have high specified efficiency. An example would be, some ads for Monessen say their B-vent units' efficiency is "up to 80%".

I understand the B-vent will create negative pressure and draw cold air in the house, so high efficiency can be a bit of a joke, depending. But maybe a heat-recovery ventillator could equalize the pressure and pre-heat the incoming air? 

Bottom line is I want the occasional option of opening the fireplace doors, if that's reasonable and practical.


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## summit (Dec 17, 2009)

any extra air circulation system can potentially mess up a bvent stove in a tight house... I have found folks with system like that often have a problem with the spill switch tripping because of the negative pressure holding low exhaust rates in the spill hood.


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## cyberiad (Dec 18, 2009)

Is there any practical way to actually get 80% efficiency from a B-vent gas fireplace?

(Monessen lists efficiency as "up to 80%" for all their B-vent gas fireplaces.)


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## DAKSY (Dec 18, 2009)

Bottom line is I want the occasional option of opening the fireplace doors, if that's reasonable and practical.

You can open the doors on a Direct Vent or a B-Vent, but for aesthetic purposes only. 
There will STILL be a piece of tempered or pyroceram behind the doors.
Both are sealed combustion chambers.
The difference is how that combustion air gets in...


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