10 replies to this topic

[mini-man-dan]

Hi All
Just considering if it would be possible to convert a single speed heater fan into a variable speed or twin speed.
I've come up with the idea of using a 'potential divider' circuit, where at 50% power both variable and fixed resistors have the same resistances. This would then allow you to have the fan on absolute max and absolute min.
I could use a variable resistor (potentiometre) that is either linear (so moves left to right) or circular (like a volume knob on a stereo etc) then put some kind of limit on it so it doesn't keep spinning.
Does anyone think this would work? I'd probably use an SPi heater (more powerful) to do it, just seems a cheaper and more unique way of installing a heater that works!
Any comments appreciated
Dan

[johnbest981]

A Member on here called 'tadleysimon' has just turned his heater into a twin speed one using a resistor.

I've never heard of a variable one, but there was a pretty good thread on the single to twin conversion, i'll see if i can find it.

good luck though! a variable one would be all kinds of cool.

[Milner08]

I dont think your going to be able to find a small enough Variable resistor which can handle the current the heater needs.
You can do it using two high power resistors to give a potential divider though.

TM

[mars red mike]

What if you used the 3 position switch and resistor unit from a rover metro/100?

[Paul Wiginton]

Very early MK1s had variable speed controlled by a twirly rheostat. I had one on my Sprint, being 1960, until I turned it more into a race car

Paul

Edited by Paul Wiginton, 18 February 2010 - 03:42 PM.

[SolarB]

Hi All
Just considering if it would be possible to convert a single speed heater fan into a variable speed

Yes, but it would take a bit of work.

or twin speed.

Dead easy.

I could use a variable resistor (potentiometre) that is either linear (so moves left to right) or circular (like a volume knob on a stereo etc)

Motors take quite a bit of power, you'd require a substantial pot to run the heater.

If you want a simple two speed fan you need a watty resistor. A 3R3 reduces the speed to a sensible level, mount it like this so it dumps the heat into the heater case.

 DSCF2311_b.JPG   87.49K   45 downloads

[tadleysimon]

yer the twin speed conversion is dead easy. i just used the same type resistor as above but a 2r2, got a new switch and stuck a heater switch panel on from roofless.

variable speed would also be dead easy with one of these.
http://cgi.ebay.co.u...=item27aec36c9f

also see this thread
http://www.theminifo...x...5&hl=heater

[rusty789]

There are a few ways of lowering the voltage.. At a guess i'd think you'd want atleast 9v on the slower speed..

But I think it could be done with a lower wattage resistor, what current does the motor draw?

I did also think of this but havent got round to it yet..

I might have to have a play this weekend...

John can I borrow your old heater still?

Edited by rusty789, 18 February 2010 - 08:13 PM.

[Brams96]

Is it possible to swap the normal mini heater with a more modern cars one (non-mini) that is more efficient? I'm guessing all it would need is some plumbing and some different brackets? The reason I ask is more modern cars seem to clear the windows quicker and better that our little mini heaters. It's something I've been considering.

[tadleysimon]

There are a few ways of lowering the voltage.. At a guess i'd think you'd want atleast 9v on the slower speed..

But I think it could be done with a lower wattage resistor, what current does the motor draw?

I did also think of this but havent got round to it yet..

I might have to have a play this weekend...

John can I borrow your old heater still?

yes you can use a much lower wattage resistor, it was just much easier to get hold of the one that i did. and its not exactly huge.
if you read the thread i linked to there some maths in there.
apparently a heater motor draws about 2 amps

[zef]

Very early MK1s had variable speed controlled by a twirly rheostat. I had one on my Sprint, being 1960, until I turned it more into a race car

Paul

Would it look something like this? I've been wondering what this is since I got my Elf.  27062009086.jpg   380.08K   20 downloads