BIG FANS WITH LOUVRES MOUNTED IN YOUR HALL CEILING

These are the big propellers with louvres – You will find them with direct drive and belt drive  - belt drives reduce the fan speed and make them quieter.  These are hard to insulate in cold climates. Home Depot, Lowe’s, Triangle, LL Building Products, Marley, SystemAir (Dayton/Grainger), Air Vent and Sears are sources for these big fans.

SUPPLIERS OF LARGE HALL CEILING FANS (SIZES)

Note – on average, the 24 inch is 5500 CFM, 30 is 6000, 36 is 10,000, 42 is 14,000, 48 is 18,000. BD is belt drive, DD is direct drive)

Air Vent (24, 30 DD and 30, 36 BD)

GAF/LL Building Products/Master Flow  (24 DD and 30 BD)

Marley Engineered Products/QMark (20,24,30 DD and 24, 30, 36 BD)

Dayton (24, 30, 36, 42 BD and 24, 30 DD)

Triangle Engineering  (24, 30, 36, 42, 48 BD and 24, 30 DD)

Ventamatic/Cool Attic (24, 30, 36 BD and 24, 30 DD)

SMALLER INSULATED HALL CEILING MOUNTED FANS WITH DOORS

These designs are smaller fans in boxes that are well insulated. Tamarack supplies these and is one of only 2 suppliers with R38 insulated ceiling connections.

SUPPLIERS OF SMALLER HALL FANS WITH DOORS

AirScape (1000, 1700, 2500, 3500 AND 4400 CFM)

Tamarack Technology (1000,  1450, 1600, 3400 CFM)

RAFTER MOUNTED DUCTED FANS

These are the quietest – the fans that mount up in your attic and pull air through ducts. You can get these with very good insulation. AirScape, Tamarack, QuietCool, Comfort Cool, RE Williams and Invisco supply these quieter systems.

SUPPLIERS OF RAFTER MOUNTED DUCTED SYSTEMS

AirScape (1532, 1700, 2800 AND 3800 CFM)

Comfort Cool (1000, 2000, 2700 AND 3000 CFM)

Tamarack Technology (1100, 2200 CFM)

QuietCool (1000, 1200, 1500, 1700, 2000, 2250 and 2850 CFM)

Note that QC offers larger CFM but those systems just use multiple fans. The largest single fan QC makes is 2850 CFM. Note also that QC is the first to offer super low wattage systems. As an example, the 2850 takes just 177 watts!

Invisco (5800, 7400, 10,300, 14,500, 18,200 CFM)

Invisco is the first to offer these large fans attic mounted and ducted. Invisco also has the most effective insulated dampers that offer up to R60 insulation.

R.E. Williams (1850 CFM with 4 8 inch inputs from 4 ducts) These 8 inch ducts are not competitive with the systems shown above.

HOW TO DETERMINE THE RIGHT CFM FOR YOUR HOME

There are opinions all over the internet about how much CFM is right. The US government suggests 3 CFM per square foot of home. Airscape has a calculator. QuietCool says use their QC1500 for each room. Invisco says calculate it based on 2-3 CFM per square foot BUT only for those rooms that get hot. I say use 2 CFM for your whole house square footage. And don’t worry about your ceiling height unless it is over 10 feet. If it is, just increase your CFM by the percentage over 10 feet that you have. For instance, a 12 foot ceiling height would add about 20% to the calculated CFM..

TESTING CFM ON A REAL ROOM

I have tested some systems and have posted some tests on YouTube.The most interesting is the test using a big room I built out of plastic sheet  in my garage. It had a 10 foot by 12 foot floor with 8 foot walls. I used it to show exactly how much time it takes for a 1600 CFM whole house fan to suck all the air out. The video is at the left here.

So if your home is 2500 square feet and the ceilings are 8 feet high, the volume is 2500 times 8 or 20,000 cubic feet. The QC1500 is rated and guaranteed to pull 1500 CFM so it should pull all the air out of your home in 20,000 divided by 1500 or 13.33 minutes.

In practice, air moves from the window to the duct opening, cooling the air as it moves, but not all the hot air will be pulled out in 13 minutes. Some of the cool air will be pulled out as well. But don’t worry about that detail. All of the systems I have seen do a good job of moving the air. The time it takes to make you feel cooler will depend on the number of windows open and the temperature of the outside air.

Be sure to take advantage of my free advice. I will be happy to advise you on the best systems for your home.