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Heater motor wattage?
Posted: Wed Mar 18, 2015 2:03 pm
by tony g
Does anyone know the wattage of the heater motor so I can spec a new type of resistor for it. im looking at Arcol units as we have them at work. The resistance of the stock unit is around 1.5 ohms and thats easy enough to find in a modern type but obviously no good if it cant take the current needed.
Cheers
Tony
Re: Heater motor wattage?
Posted: Wed Mar 18, 2015 8:39 pm
by Edin Dundee
I can easily measure the current going through the heater on all settings if you can wait until the weekend.
Re: Heater motor wattage?
Posted: Thu Mar 19, 2015 7:09 am
by tony g
That would be great Bill if you can thanks for that
Tony
Re: Heater motor wattage?
Posted: Thu Mar 19, 2015 12:15 pm
by Jon Tilson
Err isn't it just ohms law?
I reckon it drops the volts by half on low speed so 6 volts across 1.5 ohms...
Gives a current draw of 4 amps, so needs a rating of 24 watts....
Jonners
Re: Heater motor wattage?
Posted: Sun Mar 22, 2015 12:23 pm
by Edin Dundee
Hi Tony,
The motor takes 2.5 amps on full speed and 2 amps on half speed. Alternator voltage was 14V. The schematics show the resistor wired in series with the motor in one position and not used in the other position. Dunno if the schematics are accurate, it's too cold to mess around any further.
2 amps, 1.5 ohms, I Squared R losses of the resistor will be 6W.
Here's a pic of the resistor, seems quite chunky for 6 watts.....but then again the design is 60 years old!
IMG_5434 by
edindundee, on Flickr
Re: Heater motor wattage?
Posted: Sun Mar 22, 2015 4:35 pm
by tony g
Thats awesome Bill thank you very much.
Tony