On Jul 10, 5:23*pm, Lee B wrote:
Current house came with a whole house fan (not an attic fan, but the
kind in a hallway ceiling that sucks air into the attic). I was happy to
see that because I really liked the one in my old house. However the one
in the old house had a variable speed dial on it, and the new house's
fan has just one speed - high and loud with a simple off/on switch.

Is the variable speed a function of the fan itself or can that be added
at the switch? I'd definitely be having an electrician do it, but I'm
just trying to figure out if it's even doable, or if I'd end up needing
an entire new fan. And if so, would replacing an existing fan and switch
be difficult (ie cost me an arm and a leg)?

Your fan motor will be an induction motor because they are quiet and
cheap. The speed they run at is frequency dependent. It's possible
to make motors that have in effect two windings and hence two speeds.
There are mickey mouse devices that cut the voltage to make the motor
run slower but this causes heating effects in the motor it might not
be designed for.
There are also electronic inverters that rectify your alternating
current & then output any frequecy you like. So the motor can be run
at a wide range of speeds but they are fairly expensive.
If tthere are belts linking you fan and motor, you might consider
changing the pulley ratio. It's quite hard to determine what ratio
you would need.