Now I would want a lot better information. Does this unit draw fresh air into the house and pass it across a heat exchanger to recover heat from the exhausted air or does it simply rely on a leaky house for the make-up air? I mean, why would you heat or cool the air in your home then blow it outside? Certainly such a unit would cost much less to run and remember your clothes dryer and your bathroom exhaust fans already perform that service for you. Your heating and/or cooling costs though will go up by deliberately dumping up to 176 CFM outside. A much cheaper and more efficient method would be just to open a window.
As for drawing warm air down into the basement I am pretty skeptical. It certainly can be done but really you want a chase or duct directly from an upper ceiling. There are low cost in-line fans for this purpose but never forget that warm air rises. Finally, a 1200 square foot house is 9600 cubic feet. with a basement that is 19200 cubic feet including the basement. Divide that by 176 CFM (cubic feet per minute) and you get a house air change about every hour and 50 minutes. They install the thing in the basement because it is easiest. This is often also where they install air-to-air heat exchange ventilators and generally because it is easier but probably the best place for them is in the attic space. You generally install a ventilator because your building is very air tight and for reasons of health you want to bring fresh air into the building. Generally you pressure balance an air exchanger to be just a little negative so that you don't risk driving warm moist air in the winter into the walls and insulation. You generally draw air off of high moisture generating areas like bathroom ceilings or kitchen ceilings and vent it outside. You then pull fresh in through another vent located several feet away from the outlet and pass that across some form of heat recovery system hen discharge the fresh air near the cold air return of your furnace so the fresh air will mix with the furnace air and be distributed evenly through the building. You don't make a direct connection with the cold plenum of the furnace because you don't want the pull of the furnace to unbalance the system. The heat exchanger allows you to recover some of the heat or cold from the air you are exhausting. They generally have a variable speed system which accelerates the fans when humidity rises above some determined level and you can have timed speed controls in places like bathrooms for the same reason you use bathroom exhaust fans. I installed mine in the attic and dropped the condensation hose into the sewer stack. When it is 30 or 40 below there is a lot of condensation from the exhausting air and this unit also requires a defrost cycle which cycles from time-to-time in cold weather. The heat recovery efficiency is severely reduced as outdoor temperature decreases too. This building is two stories in addition to the basement, I have receiving ducts on all levels. I put the intake and outlet on the side furthest away from the driveway and about as high as I could get them to minimize the likelihood of sucking in exhaust and other fumes. Certainly this system does help control humidity in the house.This house though is really very air tight with double wall exterior construction and a poly envelope between the walls with 4 inches of insulation on the inside walls and 6 on the outside walls and 18 inches in the roof. I surrounded the exterior of the basement with 3 and a half inches of extruded Styrofoam and under the basement floor of the addition.I couldn't insulate under the original basement floor or pull the poly air barrier under it but the rest is all sealed. Artificial ventilation is necessary under those circumstances. I also run the furnace fan continuously. This too helps keep temperature more even and of course helps to distribute the fresh air though in the summer we generally leave windows and doors open most of the time. Leave your humidifier running. after about a week it will settle down. relative humidity is always higher in a cooler place just because cool air cannot hold nearly as much moisture between the molecules of slower moving gases as can fit between the faster and more widely spaced molecules of hotter gasses. I don't know if this is helpful in understanding or not. I would be curious though to know about this device and what it really is made of and what it includes. It sounds like a very over priced bathroom fan to me. Dale Leavens. ----- Original Message ----- From: Scott Howell To: [email protected] Sent: Monday, May 11, 2009 10:48 AM Subject: [BlindHandyMan] more on humidity Folks, in my quest to be sure I have a good handle on this humidity stuff, I ran across something called Ez Breathe. This system claims to exchange air in the home as opposed to pulling air over coils and the like. Thus the air is exchanged over the entire home, costs $2 to $4 as opposed to the $30 that conventional dehumidifiers cost to operate. The difference is in the price, which is about $1,500. Now the unit apparently has a humidistat and a fan that can create a negative pressure at 176 CFM at 31 Db noise level. The purpose of installing in the basement is to pull air from all levels and vent them outside of a six-inch hole in your home. They claim it also pulls warm air down to the basement and this unit sits on the floor so it is pulling air down to the floor. So, I'm curious if anyone is familiar with this or knows anything at all. In my questioning of the sales rep, she seem to have sound info and I'm not saying the system is bad, good, or worth the cost. I'm more curious if it sounds reasonable at all. Seems to me that would running the fan in the furnace accomplish some of the same goals? Maybe just installing a fan that vents to the outside would do the same thing for less money? Just wondering and hey exchanging air can't be a bad thing in any event, but not sure the cost is reasonable. tnx [Non-text portions of this message have been removed]
