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percy 03-13-2014 11:34 AM

Retro Ventilation Vancouver BC
There is practically no air movement inside our 1200 sq.ft. semi-attached (strata) bungalow which is unusually dusty, humid, and prone to mold formation. A sealed, radiant gas fireplace easily heats the house, while electric baseboard units control condensation and the 3 bedrooms. Air exhausted by kitchen, bathroom and dryer fans is replaced with fresh air leaked in through windows and doors. Siding and window upgrades have cut down the leaks, possibly adding to this problem.
My solution is to draw fresh air from under the eaves into a 50-60 CFM fan mounted in the attic forcing the air into the house through a HEPA filter, then through a fan/heater, and ducted into the bedrooms, hoping to create enough positive pressure inside the house to insure that humid air, dust and mold spores leak from inside to outside. Nice theory. Has anyone had practical experience with it?

yuri 03-13-2014 12:30 PM

I would recommend you look into a proper ventilation system like a HRV or in your climate you may be able to use a ERV. Lifebreath makes the best ones IMO. I have a LIfebreath HRV. Googe Lifebreath. It explains what they are nicely on their site (click on products). 1200 sq ft you probably should use a 150-155 cfm unit. That is what I have. THe 100 cfm may be too small. ERVs will freezeup in colder climates but I doubt Vancouver will have that problem. There should be a climate chart on their site.

percy 03-13-2014 06:47 PM

Retro ventilation Vancouver BC
Thanks Yuri: Heat or energy recovery is not the vital concern in Lower Mainland BC that it would be in say, Winnipeg. It does get below freezing here up to 2 - 3 weeks per year, and the lowest setting of the Valor gas fireplace easily handles the coldest weather here in this 1200 sq.ft. building. You may be correct on the need for 100 CFM - I was figuring on the Canadian recommended and theoretical 0.3 air changes per hour when stating 50 - 60 CFM. There is a lot of rain here and humidity is rather high year-round but for six months of the year, the windows can be opened at night to let fresh air in. Even with climate change, AC is not a real necessity here yet.
I want a simple/maybe stupid, and cheap solution to stale, humid, dust and mold spore-laden air. Just pumping sufficient clean HEPA-filtered air in to the point where all leaks are from inside to the outside - seemed a simple way to solve the problem. I'd like confirmation that some DIY person tried the idea and it worked - or didn't. Thank you for your suggestions.

beenthere 03-14-2014 05:10 AM

A draw back of your solution may be that the air in the bedrooms won't know its suppose to go outside. Instead it will go through the wall recepts and switches along ith the door under cut if they are under cut, to the hall or other areas along the bedrooms.

Good luck with your project, and please keep us updated.

percy 03-14-2014 09:10 AM

Retro Ventilation Vancouver BC
Thank you BeenThere: Maybe our concepts differ. The bedrooms are at one end of the house, the living-room at the other. Ideally, the outside air would be pumped into the living-room to slightly pressurize the whole house, get heated and mixed in by the fireplace and find its way through the house to the leaks in sliding aluminum windows in the bedrooms, breaches in the vapour barrier, etc. It is a strata house and we are not free to put new openings in the walls. Existing openings could be used - an unused exhaust fan opening in the hall ceiling outside the bedrooms, a kitchen exhaust through the soffit, the dryer exhaust through a wall, electrical receptacles in the bedroom ceilings. The air in attic is spore-laden and not a good source of fresh air even with HEPA filtration. The fan could be mounted there but intake air should be supplied and distributed through ducts and the filter located inside the drywall (e.g.hall ceiling) for easy access.

yuri 03-14-2014 10:40 AM

There is no cheap simple easy way to do what you want IMO. There is a whole home dehumidifier from Lennox that you could have installed and bring in outdoor air and dehumidify it and then supply it to your rooms. Would have to find a Lennox dealer with some imagination but it could be done. IMO you need some sort of dedicated system with supply ducts to your rooms. This could be done by this unit or if you want ventilation only then the small ERV 120 ERV from LIfebreath that they use in condos may work. HEPA filters are very expensive and plug up quickly. cost $50 to $150 depending on the shape and size etc and last about a month.

If you have a gas water heater with a chimney then you got to be VERY careful you don't pressurize the house or monkey around with the pressures or you may get CO poisoning if the chimney loses its draft etc. Some homemade system could kill you if done improperly.

SPS-1 03-14-2014 11:55 AM

A simple solution would be to just open a couple of windows. One window on one end of the house, another window on the opposite end.
If you have mold issues, that is more likely related to a water leak, rather than air circulation.

percy 03-14-2014 07:44 PM

Retro Ventilation Vancouver BC
Hi Yuri:
I was involved in designing an air system 45 years ago to maintain 1/2 inch w.p.air to keep dust out of a foil rolling mill. It worked, but unlike our rancher, the air circulation in the building was superb to begin with, and the outside quite dry (Alicante, Spain).
You may be right and I have to go the expensive ducted route, but before I do, I'd like to try pumping in enough treated air to assure that most if not all leaks are outwards. I wondered if anybody had tried this simple, low cost approach.

Hi SPS-1:
Of course we do open windows and air the place when it's not too cold to do so. The humidity (and temperature) rapidly drops, but dust is still a problem. Our most serious mold issues occurred after some of the wood siding was replaced with fibre-cement on two walls without roof overhang protection. The material (HardiePlank) is OK, but the installation and finish was not up to what was recommended. The joints were unflashed as required, and there was no caulking under window and corner trim. Once caulked and painted properly, and moldy fibreglas insulation replaced, the mold issues all but disappeared (condensation on aluminum window frames can still lead to mold formation if not addressed).

percy 06-11-2014 08:01 AM

retro vantilation Vancouver BC
Simply pumping fresh, filtered air pumped into a house apparently will provide a healthy air change rate, and lower staleness, dust, humidity, and mold. A commercial unit, Nuaire Drimaster, can do this for less than $500 - but seems to be available only in Britain and Ireland. Works like our vacuum cleaner - sucks in air (from the attic), filters it, and exhausts it into the house. Anyone know of a North American equivalent?

yuri 06-11-2014 08:18 AM

1 Attachment(s)
Fantech makes lots of good inline fans. You would need to build a filter box for it.

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