[Greenbuilding] controlled combustion air supply

[jfstraube]

I understand the problem better now. I think it is a good idea to do the backdraft testing to identify this problem.  But adding another 6" sounds like you have a very leaky fireplace.  Have you tried to re-install the door gasket, adjust the door hardware or find the big hole in the fireplace?
Also, barometric dampers are cheaper and simpler than a pressure actuated damper.  Pressure sensors that can measure 10 Pa accurately over long periods are pretty hard to find.

On 2011-06-23, at 11:48 PM, Ross Elliott wrote:

> Thanks John. The builder already installed a 4" combustion air supply to the
> fireplace like you suggest, but backdraft testing indicates he needs another
> 6" hole. Although ideally it should feed directly to the fire, the second
> best place is anywhere in the house, like through a cold storage room in the
> basement, particularly if the damper only opens when needed, which is rarely
> (range hood, bath fans, dryer and central vac all on at the same time as the
> fireplace). I'm sure pressure actuated electric dampers are available, just
> not sure where. If it were my house I would just crack open a window (or
> stop vacuuming / turn down the super-sucker range hood) if the fireplace
> started smoking up the house, but NRCan has certain rules for R-2000
> houses...
> 
> Ross
> 
> -----Original Message-----
> From: John Straube [mailto:jfstraube at gmail.com] 
> Sent: Thursday, June 23, 2011 10:24 PM
> To: relliott at homesol.ca; Green Building
> Subject: Re: [Greenbuilding] controlled combustion air supply
> 
> Perhaps you can't retrofit it but most airtight wood stoves and fireplaces
> can be installed with an outdoor air supply. This de couples the chimney and
> the hole and does not need to violate the air barrier. This is what we
> always recommend and after  several house tests (and my own home) it works
> and is simple. 
> 
> Sent wirelessly from my BlackBerry device on the Bell network.
> 
> -----Original Message-----
> From: "Ross Elliott" <relliott at homesol.ca>
> Sender: greenbuilding-bounces at lists.bioenergylists.org
> Date: Thu, 23 Jun 2011 20:14:26 
> To: <greenbuilding at lists.bioenergylists.org>
> Reply-To: relliott at homesol.ca,
> 	Green Building <greenbuilding at lists.bioenergylists.org>
> Subject: [Greenbuilding] controlled combustion air supply
> 
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John Straube
www.BuildingScience.com