[Greenbuilding] Back to Rumford fireplaces, tight homes & backdrafting

[Drew A. Gillett P.E.]

http://www.tamtech.com/products.htm paul raymer at formerly weather energy 
systems developed just such a device (an airtight motorized damper working 
in conjunction with an exhaiust fan for circulating air from passive solar 
greenhouses to the house). it was not a big seller due to cost and lack of 
passive solar greenhouses)  and the link above shows the current version of 
products that are for sale.

for now best bet is a sign saying "open window when fan in use"

----- Original Message ----- 
From: "Keith Winston" <keith at earthsunenergy.com>
To: "Greenbuilder list" <greenbuilding at listserv.repp.org>
Sent: Tuesday, December 05, 2006 9:08 PM
Subject: Re: [Greenbuilding] Back to Rumford fireplaces,tight homes & 
backdrafting


>I think it's a huge mistake that we've all been lead to believe the
> bigger the exhaust fan (kitchen, bathroom) the better. And I'm
> incredulous that no fan manufacturer has figured out a direct-vent
> option of any kind associated with their fans (i.e. an electronically
> controlled make-up vent in the kitchen, to keep from depressurizing the
> rest of the house, and only on when the fan is on, perhaps even to the
> same level).
>
> I'm sure it'll happen soon. Maybe.
>
> Keith
>
>
> Tom St. Louis wrote:
>> Builder has installed Rumfords in two SIPs homes. The homes are so tight
>> that when the kitchen fan is turned on, the chimney backdrafts (even with
>> the combustion air supply open at the side of the fire box), this gets 
>> worse
>> as more fans and the clothes dryer are turned on. Even the 'supposed' 
>> sealed
>> combustion Rinnai on-demand water heaters backdrafted. Oh dear!
>>
>> More make-air sources are going to be added or maybe a larger single 
>> source
>> possibly behind the kitchen stove. Looking at adding sealed glass doors 
>> to
>> the Rumfords to add extra insurance to prevent backdrafting.
>>
>> Will a wood fired Rumford firplace work having air-tight sealing
>> ceramic-glass or other high temp glass doors with outside combustion air
>> source? Can they be converted to gas log Rumfords with airtight sealed 
>> doors
>> and still work?
>>
>> Big reminder for everyone.........
>> Add up all the maximum CFM capacities of all exhaust air fans and 
>> appliances
>> in your buildings while still at design stage, then plan and specify 
>> make-up
>> air source(s) equal to worst case for air being sucked out. Must have
>> incoming make-up air equal to what is being exhausted.
>>
>> Add an adjustable barometric type or electronically controlled damper to
>> allow needed make-up air to prevent backdrafting or sucking air through
>> cracks in the building envelope. Some homes with those modern stainless
>> steel 700 to 1500 cfm kitchen fans or down draft stove fans would require 
>> a
>> fan to bring make-up air in.
>>
>> Tom
>>
>>
>>
>>
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>>
>>
>>
>
> -- 
> Keith Winston
> Earth Sun Energy Systems
> Hyattsville, MD 20781
> 301-980-6325
> send me mail at
> keith at the company below
> www.EarthSunEnergy.com
>
>
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>