In alt.home.repair, on Thu, 30 Jan 2020 03:21:22 -0800 (PST), Cindy
Hamilton wrote:

On Wednesday, January 29, 2020 at 8:57:39 PM UTC-5, micky wrote:
Do electric roof fans rust enough that they must be replaced?

My fan, in the pitched part of the roof, looks like new from the inside.
The plastic top, the metal screen**, and the metal frame below the
screen. all look perfect.

**Not wire screening but sheet metal with a lot of holes in it.

But the roofer who came yesterday wants to replace it, because he says,
it's rusting.

He also says the new one will be better, new thermostat, new humidistat.

My current thermostat works fine, I never take steamy showers or baths
so I don't need a humidistat.

I'm a little curious. Do steamy showers or baths affect the humidity
in the attic space that much? My bathroom vent fan exhausts to the
outdoors, so I've never thought about the humidity that might leak
around the fan housing. (The attic access--right outside the bathroom--
has a gasket.)

Cindy Hamilton

That's a good question. My fans, from two bathrooms side by side,
exhaust to an inch or two below the roof ridge rail. (I'm not sure where
the first floor fan vents to. Maybe I'll look) Not sure why, maybe it
saved a little money not to have 3 holes in the roof, three vents, and
the trouble of roofing around them.

But the instructions that came with the fan talked about running the fan
after one took a steamy shower. Because I guess, the humidity would be
bad for the wood in the attic. I don't know if home-priced humidistats
existed in 1983, but the instructions might have mentioned them too.

One of the bathrooms had a separate switch for the fan, and two of the
first things I did were, in the bigger bathroom, put in a light over the
sink and in the housing for that light, put a switch for the fan, which
I promptly turned off and havent' turned on since then. The new light
was half way between the ceiling light and the wall switch, which had
also controlled the fan. (And still does. The fan won't run unless both
switches are one.)

And in the powder room, it was going to be too hard to put in a wall
switch so I just unplugged the fan, in the ceiling. That fan is meant,
iiuc for odors, and of course there are none.

When my mother moved to Baltimore, to an apartment whose bathrooom(s?)
had no windows so they put in a fan, I put in a switch for each, a
pull-chain right through the housing. I was like a typical tenant who
considers the changes he makes improvements and not damage. The
apartment never complained. I had asked my mother and she hated the
fan's noise as much as I did, even though it wasn't much noise.