Jump to content




Restricting a motor (fan)

Guest Dane

Recommended Posts

No a standard fan.

Ive got a log burner stove, and damn it throws some heat out!

What im currently working on is a ducting system to take heat from one room to the next (i will have a plenum chamber) 1 6" inwards, and then 3 4" out)

Ive got the fan, but i want to reduce the speed of it.

I got a Fan control unit, and turned it right down but its still quite a lot of air flow.

Does any one know how i can restrict it even more?

I was told a resistor inline prior to the control unit, but never worked on anything like this before.

Any ideas? or Links to items :)

Link to comment
Share on other sites

if you have the matching controller to the fan and the slowest setting is not slow enough then i'd suggest your now looking at mechanical flow restriction such as a damper

or a smaller fan

Link to comment
Share on other sites

You can change the size of the capacitor on the fan to slow it down, the capacitor is there to effectively skew the phase on the motor and make it turn on a single Phase motor so by adjusting the capacity of the capacitor you can reduce or increase the speed, might take a bit of experimentation to get the right capacitor, but they are pretty cheap from somewhere like RS or Maplins, so have a look at the capacitor that is on the fan and get some different ratings to try.


Link to comment
Share on other sites

hmm i had it in pieces and didnt see a capacitor. As i looked for that already.

its not a "domestic" fan.

It is quite powerfull.

The controller drags its speed down drasticly, (it is not the "right" controller for the fan, again, its not a domestic fan.)

Its actually a fan that i used for forcing air through grain on a farm (my dads a retired farmer)

We need something with some force due to the lengths of the runs, "domestic" fans are no where near enough flow rate.

Link to comment
Share on other sites

Just blank of half of the fan inlet then adjust from there. If the fan inlet is cold use a bit of cardboard (I'm assuming it's a centrifugal fan with mesh over the inlet), if it's hot, a bit of steel - but if it's hot, your fan probably wont last long.

Link to comment
Share on other sites

Like Riggy says, some kind of damper in the ducting would do it. Ask whoever supplied you with the duckting if they have dampers that you can fit in it, they probably manufacture something to suit. No mechanical engineers on here?!


You need some duckting baby... Daffy the rapper!

Link to comment
Share on other sites


This topic is now archived and is closed to further replies.

  • Create New...

Important Information

Terms of UseWe have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.