Extractor fans

[ppppenguin]

We're refitting our kitchen at the moment using Ikea units. THe cooker hood has a 3 speed extractor which is horribly noisy. I reckon all cooker hoods are far too noisy so the obvious answer is to get an external fan and remove the fan in the hood. So far so good.

It would be nice to use the 3 speed controls in the hood to work with the external fan. I don't think it's possible but please let me run it past you all.

The fan in the hood has 3 taps on the motor which is of unknown type. The resistances all add up sensibly so I'm pretty sure it is actually 3 taps. The external fan has a capacitor, not sure if it's start or run, on what look slike it could be a motor with an external rotor. So definitely no direct compatibility.

The external fan didn't like a dimmer switch very much. The speed wandered up and down when set to half speed. Possibly a trailing edge dimmer would do better. A variac worked fine but is not a practical solution. Can I do anytihng by switching different capacitors? Or any other ideas?

PS: The fan/motor in the external fan is made by Blauberg BL-B190A-2X-A01-01 rated at 60W. USes a 1.5uF 450VAC cap.

[boater sam]

We used to slow such motors by wiring a choke in series. The ones out of fluorescent light fittings work well in their various wattages to give different speeds.

[ppppenguin]

Nice idea. I didn't think a series cap was going to work well as it would likely resonate with the motor. I've got some gash fluorescents (only 4' and 5') so worth a try.

[Murphyv310]

Hi.
When I was repairing industrial cleaning equipment I found that motors that had start/run caps would blow the fuse on start up if their value had dropped or risen (which many do). Some motors before they got to the blowing fuses stage would struggle to get going but if they did inevitably they still ran at their normal speed of 1480 rpm including the normal slip.
If the motor has a cap I'd be inclined to leave the correct value, you may land up with a cooked motor or fuse blowing.

[Sinewave]

We fitted ours with Ikea untis, very nice units and a good sizing.

We went for a Hotpoint cooker hood which I don't find too noisy.

[ppppenguin]

Finally got round to sorting the cooker hood properly. The speed switching is so simple I don't know why I didn't think of it before. Old fashioned GLS lamps in series. The first tests suggest 60W for the lowest speed, 100W for the middle speed. The top speed is mains direct to fan.

Wired it all up using a small plastic box to take the lampholders. I used various Painton connectors that I had around for the interconnections.

[Refugee]

Have you thought of gutting a desktop fan for the motor and switching. They are usually three speed.

[Crackle]

You can get these speed controllers for fans. I am not sure if you need to have a special fan to go with this so that it can be controlled.
https://www.tlc-direct.co.uk/Products/BGVSFC.html

Mike