Noisy Whirly Birds

January 7, 2004

Q. We have a bit of a problem that I hope you will be able to shed some light on.
We live in a doublewide manufactured home; it is of 1976 vintage and an area of 1344 sq. ft. The previous owner installed two whirly bird fans on the roof,One is located at the front of the roof and the other at the rear. As you are aware I am sure, we sometimes get fairly stiff breezes here to say the least. The whirly birds do not require much of a wind to start them going and therein lies the problem. There cannot be much more than a foot or two between the roof and ceiling as the roof is of a very shallow pitch and made of metal. The fans make a heck of a racket and also in colder weather, we notice quite a substantial draft from back to front of the house down the hallway. The bedrooms at the rear of the home are also quite chilly, also perhaps part of a draft problem we have.

The first question is, with such a small space between the outer roof and the ceiling, would you think that the fans are of much benefit in summer or winter?

Being a metal roof, if they are of no benefit, are we asking for disaster in trying to remove them. (ie) leaking roof?

We are also going to be replacing an aging thermostat, which is currently located in the kitchen. We plan on relocating it to the hallway. Can we almost be assured that with the draft down the hall, the furnace will run overtime.

I should also add into the fray that the windows should also be replaced but being on a pension almost an impossible expense. I do realize that they certainly do not help matters and that they may indeed be a big part of the problem.

Larry & Wendy
Lethbridge, AB

A: My suggestion would be to cover the units with a heavy duty plastic bag for the fall and winter months. I seldom recommend whirly bird vents on a modular home because by and large, the ceiling is not draft proofed and can become drafty during the cold months. A basic rule of thumb on a modular home built to factory specs is that if extra venting were required, it would have been put there at the time it was built.

Try covering the vents instead of removing them at this time, it is less costly and it will give you a chance to experiment.

I’d leave the thermostat where it is until you have covered your vents. You are right in assuming that if your thermostat is moved to a colder or drafty location, it will call for heat and bring your furnace on more often. Usually, you’d want the thermostat located near the area that you spend most of your time.