Yep - that's Part F regs - 30 over a hob - 60 elsewhere - though they're minimum flow rates, no harm in exceeding them.
Since you have 3 peed settings, it's definitely a variable speed fan. It kind of depends how the fan is currently controlled, whether it's pulse width, or variable resistor.
Quote from: SamT on April 04, 2019, 05:10:30 pmYep - that's Part F regs - 30 over a hob - 60 elsewhere - though they're minimum flow rates, no harm in exceeding them. Depends if there's an open flued solid fuel / oil burning / gas stove nearby; I'll see your Part F and raise my Part J!
Since you have 3 peed settings, it's definitely a variable speed fan. It kind of depends how the fan is currently controlled, whether it's pulse width, or variable resistor.I'm guessing you could probably get away with just wiring another speed controller in series, but it might be possible just to dump some power by sticking a reasonable sized resistor in line?
Quote from: Fultonius on April 04, 2019, 11:47:29 pmSince you have 3 peed settings, it's definitely a variable speed fan. It kind of depends how the fan is currently controlled, whether it's pulse width, or variable resistor.I am not an electrical engineer, but my prodding of their remains suggests that 3 speed extract fans often have 2 sets of windings - small and large. So you could get low speed by energising the small windings alone, medium from the large windings, fast by energising both?
Quote from: moose on April 05, 2019, 07:13:14 amMoose is right. There's a first time for everything! It's often hard for me to make an informed judgement... my job means I see a vast array of equipment... unfortunately it's usually burned away beyond recognition!
Moose is right.
Quote from: moose on April 05, 2019, 07:13:14 amQuote from: Fultonius on April 04, 2019, 11:47:29 pmSince you have 3 peed settings, it's definitely a variable speed fan. It kind of depends how the fan is currently controlled, whether it's pulse width, or variable resistor.I am not an electrical engineer, but my prodding of their remains suggests that 3 speed extract fans often have 2 sets of windings - small and large. So you could get low speed by energising the small windings alone, medium from the large windings, fast by energising both?I'm an electronic engineer, slightly different to electrical.Moose is right. It's an AC motor not DC, if it were DC then fultonius would be right.It's very hard to change the speeds of this type of motor. I think reducing the number of windings would do it but that's no easy task. Reducing the voltage to the thing might do it but it would very quickly be unhappy with the wrong voltage and also you're playing with 240v and it not easy to just make volts disappear.The little white box in your picture is just for LEDs I think.My recommendation would be buy a lower wattage fan part and wire that in. And like Paul b says check it's not something rattling making all the noise.A lot of guessing in that post and as always I could very easily be wrong.