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Re: GBlist: Re: HRV
Buzz Burrell wrote:
> The house is what needs to breath. (How much air diffusion is optimal
> for a wall is a very complicated and controversial separate issue.
> much easier to install an HRV than it is to waste valuable brain time
> studying the problem).
I have to disagree in part or at least rephrase - I think an HRV is an
ad hoc or bumper solution (and one that I think will breed a whole host
of problems in the future). Fungal and bacterial growth in ductwork is a
leading cause of SBS and difficult to control as ductwork can provide a
good breeding ground for fungal activity. Fungal spores from 1 micron in
size enter from supply air. A HEPA filter if tightly fitted can prevent
entry but if not maintained can actually exacerbate the problem.
Microbial activity inside the ductwork is difficult to control as the
conditions that cause the activity are unseen and can be unpredictable.
HRV may be a necessary solution at this point but I think brain time
should be always reserved for a more fundamental understanding of basic
materials. Cementious and masonry materials have an interesting ability
to recover heat, retain moisture and transfer air. Moisture retained in
and traveling through porous rock has been shown at a biological level
an ability to host activity that can remove toxins from the air that are
not normally water soluble. In other words there is a potential for
indoor air purification as a function of materials used (another 'living
I am looking for some specifications for duct preparation, installation
and maintenance schedules that are designed to minimize potential for
contamination. The installation is for air supply, exhaust and heat
recovery as a retrofit in an old house (4500sq.ft) for a MCS person. I
originally wanted to manage supply and exhaust passively and manage heat
recovery with an air to water exchange (heating is hydronic) which I
still think is feasible but am having trouble with the general design,
anyone have any suggestions or worked on something similar.
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