How I Made My Bathroom Fan Smart

When I moved into my house, it came with this and old fan in the bathroom to keep the moisture down when you’ve had a shower, the bathroom itself is in the inside of the building and doesn’t have any external walls / windows, so the fan is really important to keeping it dry and non-moldy.

The original extractor worked well enough, but I’ve never really been that happy with it; it’s kind of noisy when running at full speed and has a trickle mode that runs it at low speed all the time – ostensibly this is to keep the room fresh, but in reality, means that the room Is always cold in the winter. It’s also not very well installed – is the case not fully closed on the fan focusing, and when I tried to close it up tightly the fan scraped the inside of the case and made an awful noise.

More recently the humidistat that makes it speed up automatically stopped working, meaning that after a shower the room would stay damp for hours afterwards. I’ve tried taking the fan apart and cleaning it in case it was just dust and grime of the sensor. But that didn’t help, so I set about replacing it. This being 2021 with nothing better to do, I decided to make it smart and control it from software.

After some research, I used a Manrose MF 100T inline fan, looking down the spec sheets, it is quieter, more electricity efferent and moves more air than the existing solution so seems like a great fit.

Photo of installed extractor fan in attic with inlet and outlet tubes.

To control the fan, I used a Shelly 1 relay – I’ve used some Shelly 1 PM relays in a couple of other places that I’ll write about soon, and I’ve so far been super happy with their ease of use and reliability.

It was all connected up as shown in this schematic:

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