Need positive pressure in house.

[astro]

Positive Pressure in house
Customer has a son with extreme allergy problems and wants have a constant positive in the home with extremely filtered air. We installed the best filtration system with UV that Lennox makes, but he wants air flowing out and not in the windows. I suggested an outside fresh air intake going through the filter and leaving the fan in the "on" position. Any other thoughts???
Thanks, Brad

[green jumper]

Pressurizing a house isnt the best of ideas, it'll reduce iaq for his house. Having a good filter as well as controlling the air exchange into his house through an hrv and running it through a filtration system is a better idea, running the fan constantly will help as well with air exchanges through the filter.

If he doesn't already, tell him to spend money on hardwood floors, new furniture leather preferably and a new mattress.

[Carnak]

i would get an inline fan with a speed control, a filter system in tight frames that do not bypass air, something pleated as a prefilter on something like HEPA as a final filter.

If you live somewhere humid positive pressure is great but you have to treat the air as you bring it in.

http://i32.photobucket.com/albums/d41/a_bee_normal/WTF.jpg

[bigbird]

carnak, you use that contraption in your kitchen to chase hurricans away?????

Hi BRAD, it`s been a long time.

[Carnak]

i used it in the atttic bird. about to replace it with an ERV

I shut it off and tape up the inlet hood during hurricanes :)

[beachtech]

has he been tested to see what the source of his allergies are?

that would be a good place to start, then you know what you are up against as far as airside, of it could be as simple as something he is doing routinely... you'd be amazed to find out some of the things that cause allergies ;) i have them as well...

[beenthere]

Deleted your duplicate thread in general. Don't make duplicate post.

[teddy bear]

Pressurizing a house isnt the best of ideas, it'll reduce iaq for his house. Having a good filter as well as controlling the air exchange into his house through an hrv and running it through a filtration system is a better idea, running the fan constantly will help as well with air exchanges through the filter.
.
How does pressuriziing your home reduce indoor air quality? Pressurizing your home reduces infiltration from stack effect and wind but does not eliminate infiltration. In normal leaky homes, pressurizing a home during windy cold weather will over-ventilated the home. During warm calm weather, pressurizing the home delivers much needed fresh air. Infiltrating air is not filtered while make-up air can easily be filtered and blended with house air. The bigger concern is maintaining <50%RH in the home to prevent mold, dust mites, and other bioloficals from growing. In green grass climates during wet cool weather, supplemental dehumidification is needed to maintain <50%RH. A whole house ventilating dehumidifier with a MERV 16 air filter may be a good starting point. They are able to blend filtered fresh air into the home, while maintaining <50%RH throughout the home.
In arrid climates, a fresh air inlet on the return of the air handler and a large MERV16 filter with the fan "ON" maybe adequate. The other issue is how much air is required. For normal people, an air change in 5 hours is considered adequate. Some suggest an air change in 3 hours as optimum.




If he doesn't already, tell him to spend money on hardwood floors, new furniture leather preferably and a new mattress.

With fresh air ventilation and maintaining <50%RH, comfortable furnishings are usable without concern for mold and dust mites. Fresh air and maintaining low humidity are the biggest issues. Rugs that are musty and loaded should be discarded. Water flooding basements with carpets should be avoided. American Lung ass. is a good reference for facts regarding IAQ issues.

Regards TB

[Carnak]

pressurizing reduces natural infiltration and can over power the stack effect and wind effect if the home is tight enough and I have been in countless homes where this happens in Canada and several homes down in the tropics.

I have a customer here who was worried about when the planes spray for mosquitos and I have his place pressurized so that you feel cold air leaking out of any cracked open window or door.

In commercial buildings, infiltration is usually neglected in load calculations as there is controlled ventilation tipping the balance to a desired positive or negative.

If you pressurize with clean treated air, you will keep out 'dust' etc

You cannot pressurize swiss cheese however, so if you want to keep out exterior allergens, you are going to have to tighten up your building in the first place. Might be hard to do if you are a cheesehead with a tendancy towards cheese products. Glad I am not in Wisconsin.

Sealing the holes reduces the pathways in so it is a 'no brainer' that it is a good defence.