Slow down Fan on Eber Water heater

[Whiterose]

I have an Eberspacher D5W which heats water and this is then circulated to a matrix fan which blows warm air out into cabin.Not as good as an air heater , however that’s what I have.The thing is the fan is very strong and too “windy” ie can I slow fan down so amore gentle flow of air comes from the matrix?
Cheers Friends

 

[William_H]

Fans are peculiar things in that they require a lot of speed to do anything. Or put another way a small drop in voltage to the motor will give a small drop in RPM and a large drop in air movement. The answer to your question is to fit a small resistor in series with the fan perhaps with a switch. You need to buy a range of resistors (5watt wire wound) not expensive but robust. Start with trying 1 ohm then 2.2 ohm then 3.3ohm. Fit all 3 in series with a total of 6.5 ohm to get the effect. You want a speed that will still move plenty of air but which is a lot quieter. You might need a switch because the higher voltage when you are on shore power will be a lot different to out on an anchor with battery going down. Switch of course will bypass the resistor(s) for full power.
good luck olewill

 

[Ian_Edwards]

You could fit a motor controller, which is designed to control the speed of a DC motor.

Google - 12 volt dc motor speed controller - and you find a whole range of them available online, starting at around £5 each.

You'll need to know the current drawn by your heater fans (put a multimeter in series with the fan motor on a 10 amp range), it'll be in the range 2 to 5 amps at a guess. then buy an appropriate one from the web.

example here, but this is only 3 amps, so you need to check before you buy.

http://www.ebay.co.uk/bhp/motor-speed-controller

 

[Whiterose]

Thanks Olewill
Fair winds

 

[Whiterose]

Thanks Ian
Will check it out
Cheers
Rich