[moved] Space Heater Fan Controller

[Woznet]

First time on edaboard and my first time attempting a mod like this, I am hoping to be able to get some guidance to finish this mod successfully and safely.

Space Heater: Comfort Zone CZ448 (I could not find a homepage for Comfort Zone)

https://www.amazon.com/Comfort-Zone-CZ448/dp/B007X5J7X6

Electrical Specs for Space Heater: 120 Volt AC, 60 Hz, 12.5 Amp, 750/1500 Watts, 5120 BTUs

Goal: Adjustable fan speed

I think what I need to do is add a potentiometer (I think that is the right term, I want something to control the fan speed) to allow me to adjust the fan speed of the space heater. The Space heater has 3 settings on the dial Fan, Low, and High (low and high determine if the fan turns off when the temperature reaches a certain point based on the thermostat dial)

I am unsure of which specific potentiometer I should get or if there is a different part that I need. I also am unsure of where to insert the potentiometer in the electrical circuit.

Any links to tutorials for electronic hobbyists or for something like this project would be great.



Photos of the space heater -

 

[srizbf]

First time on edaboard and my first time attempting a mod like this, I am hoping to be able to get some guidance to finish this mod successfully and safely.
....

Goal: Adjustable fan speed
.....
I think what I need to do is add a potentiometer (I think that is the right term, I want something to control the fan speed)
.....
I am unsure of which specific potentiometer I should get or if there is a different part that I need. I also am unsure of where to insert the potentiometer in the electrical circuit.
.....

Welcome to the forum.
Hope your stay will be pleasent here.

You can insert a speed controlling device ( it cannot be a potentiometer for such fans).

The power specification details of the fan is to be known, so that other members can suggest you the solution.

 

[chuckey]

The fan motors in these sort of heaters are normally shaded pole which are not adjustable in speed. To confirm this, open up the heater and inspect the motor. A shaded pole motor has a rotar of iron laminations with no brushes (bits of carbon that slide in to make contact with a segemented piece of copper ("the commutator") and a coil on the fixed part (the stator). Often a piece of bare copper wire is riveted to the iron laminations close to a gap, where the rotar sits.
Frank

 

[BradtheRad]

To adjust fan speed only, could be a light load. A triac can do the job.

One of my early projects was a controller for a fan attached to our wood stove. I purchased a triac from Radio Shack. I added a potentiometer and resistors. I did not use the schematic printed on the small package. I barely knew what I was doing. It worked only because the load was light ('squirrel-cage' type fan), I think.

The control broke when I hooked it up to a window fan. Possibly because I did not install a heat sink.

What will happen by slowing down the fan? Will heated air go horizontal more, or vertical more? I think vertical. Do you want this?

- - - Updated - - -

I don't think my triac-type control can work with most fans. The squirrel-cage type works because I was lucky in that case.

 

[Warpspeed]

Just slowing the fan will probably cause the resistance elements to overheat and probably burn out pretty quickly, if the plastic case does not melt first.

There is usually a bimetallic over temperature cut out to prevent this.
So controlling just the fan is not realistic.

You need to control both fan and heating element together.
Best way to do that is buy a suitable potentiometer controlled triac power controller, and just plug that into the power lead going to the fan heater.

A Chinese made router speed controller, should have a suitably high power rating.
Buying one will cost less than the parts to make it yourself, so its just not worth considering as a do it yourself project.

This is the type of thing readily available on e-bay: