I recently had a Panasonic Whisper Series bath fan installed in my bathroom by a plumbing/HVAC company and wired up by a separate electrician. The fan starts up extremely slowly: it sounds like nothing is happening until 5-10 seconds after the switch is thrown, and it takes about 45 seconds to reach full speed.
Here is a video I made to demonstrate: https://youtu.be/X2nrfbXdfRU (note: if I'd had the cover off, the video would show the fan won't move at all for 1-2 seconds after throwing the switch).
Unfortunately, I don't know the exact model of the fan, but I believe it to be a FV-0510VS1. The plumbing/HVAC people didn't tell me and didn't leave any manuals with me. It seems to have a FV-0510VSB1 motor assembly, as that model number is referenced on a the Spanish part warning sticker I can barely make out.
The electrician that hooked it up said that "all Panasonic fans are like that." Is that true? I'm skeptical because I can't imagine anyone would want a fan that works that way — I thought it was broken the first time I tried it.
What's going on with my bath fan? Is there any way I can fix it to start up more quickly? Is there some kind of setting or could I hire another electrician to wire it up differently?
Best Answer
To make these fans quieter, the fans are designed to not create as much turbulence, which means they "slip" more when the air is not moving already, i.e. when you first turn them on. In addition the Panasonic fans have a built-in damper that prevents the cold air from flowing back into the room when the fan is off, so before it can move air it must get that damper to open, and when it is just starting there is not enough air pressure yet to open that damper. All of that can give you the impression that they are not yet working, but they are. This is likely just something you need to learn to live with, i.e. turn the fan on as soon as you enter and maybe use a timer to have it run on a while after you leave.
That said, there are a couple of things to check;