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Replacing an old bathroom fan Answered

This is an idea someone may be able to use, but it does not quite rise to what I would want to do as an Instructable.

A widow friend has two bathrooms, each with a very dated bathroom fan in need of replacement. I was able to mount the works (fan motor, fan blade, and mounting plate) for the new fan onto the old mounting plate after modifying the old plate. This saved me hours of work in a very hot confined attic when time and tools available to me were quite limited. Had I torn out the carcass for the old fan and tried to put the new fan carcass in its place, I would have needed to fashion a wooden framework for mounting the carcass that would fit just right between the ceiling joists, all so the fan would be properly centered above the existing hole in the ceiling. 

The mounting plate for the new works was just a bit smaller than that for the old works. The height and diameter of the new fan cage were very close to the dimensions of the old fan cage. I began by using a cutting wheel on an angle head grinder to cut through the old mounting plate around the circumference of the old fan cage. Then I positioned the old mounting plate over the new works and its mounting plate.

The glass dish that would cover the light bulbs fastens to a shaft that screws onto a threaded stud centered between the corners of the new mounting plate. I sighted across the corners of the mounting plates so the threaded stud was centered. I clamped the two mounting plates together and drilled four holes for 10-32 screws 1/2 inch long and secured them with nuts and lockwashers. (I did need to cut out part of the new mounting plate so the fitting for the two electrical outlets [fan and light] were accessible to plug in both the light and fan cords.) Had the glass dish mounted to the works differently, I would have used measurements from at least two sides to the center of the fan's shaft to position the new mounting plate on the old.

Once the two mounting plates were held together with four screws it was a simple matter to put the works into the old carcass and plug in both the fan and the light to their respective receptacles. There was no question the works would fit because they were attached to the old mounting plate that had been taken from the old carcass.

The round opening in the ceiling drywall bordered on being too large to be covered by the escutcheon for the new cover/light fixture. I added some drywall spackling around the edges to close any imperfections and gaps.

For me this was an idea that worked and saved me a lot of time.



Nice idea. Anything to save a trip into the furnace called a attic this time of the year. As Fall approaches, its not a bad idea to inspect all the vent caps on the roof for obstructions. Dryer vents are a safety issue.

Your attics in Las Vegas must be especially torrid with heat about this time of this year! Thanks for the words about checking vents for obstructions.

My wife and I had a meal out last night with our son-in-law. During our discussions he mentioned he had replaced a bathroom fan located between the first and second floor where an attic was not an option. He had come up with the same idea I used and described here.

Thanks for looking.

Torrid is not the word. With all the protection from fiberglass insulation you become drenched in perspiration in minutes. With my heart condition I can't go up there in the summer months. Yesterday was a record 115 degrees.

If it is 115 deg. F. on the street, temperatures in an attic would have to be crowding 150 deg. F. I am supposed to be in Las Vegas in November for The SEMA Show (automotive manufacturers) at the Convention Center. It should be more comfortable then.

November is very nice in Vegas. Bring your swim trunks. Are you with a manufacturer? SEMA is tough to get into unless you're in the business.

I am a tag-along. My son-in-law and his father build cars. They invited me to come with them.

SEMA is an interesting experience. My son-in-law and his father have a list of vendors with whom they want to talk. Being with them means running from one booth to another and then standing around for 30 to 45 minutes while they discuss some technology they may use on a car. I was there last year, too. I enjoyed it a bit more when they took their free stuff (ball pens, bumper stickers, booklets, etc.) to FedEx for shipping home and I was free to go where I wanted to go. It was then I got to seek out vendors whom I wanted to ask a question. Fortunately, there is a guidebook for discovering what vendors are there and then finding their booth. This year my son-in-law's father is building a '67 Ford Mustang fastback to display. It is all about gathering name recognition to gain future customers.

Nice project, I'm sure your neighbor appreciated it.

As suggested by Kiteman, a photo or two would have mad it easier for some of us to visualize. One question: did this fan have ductwork (flex hose)?

Bill, when I get back to Vancouver after a few weeks near our kids in East Tennessee, I think I may pull down the inner works from one of our bath fans and make an Instructable. One of the mounting plates will need to be represented by a piece of thin cardboard.

One of the advantages of fitting the new inside works to the old fan's mounting plate is that I did not need to be concerned about where the vent ductwork fastens to the new fan housing. The ductwork and connections for the old fan box or carcass remained undisturbed. Check back. I will try to concoct a simple drawing that may help.

Didn't you take photos? That would make a great instructable.

I took no photos. Thanks. I could possibly make drawings, although details will vary with different makes and models.