Blower Accessory Not Turning On

[Ramin]

I have a Hearthstone LP gas-fired direct vent heater (Sterling-Ht 8532 - with the remote) and blower (95-57320). The heater works fine however the blower never turns on. The blower has a variable speed switch on the left and an on-off-t'stat switch on the right of the heater. No combination of things I have tried (with the heater on or off) has worked.
I am the second owner of the heater (was installed in the house when we bought it) and I have never seen the blower work. I removed the blower from the unit but I'm not sure what to troubleshoot.
It looks like from the power line there is a connection from the variable speed switch and another connection to a place on the heater. Is anyone familiar with how the blowers function and what could be wrong (haven't seen any fuses anywhere...). I'm very new to this so any advice would be helpful. Thanks!

 

[DAKSY]

Try bypassing the blower rheostat & thermodisk plugging the unit directly into an outlet. That will tell you if it's getting power or not. If it doesn't work that way, the motor's probably shot. If it DOES work, then the problem is either in the rheostat or the t-disk. You should be able to jump the t-disk by removing the wires to & from it & connecting them together with a double ended male spade. If it works then you know it's the t-disk. If it doesn't work then, the only thing left is the rheostat.

 

[Ramin]

Thanks. I got the blower to function by jumping the two wires. I am trying to figure out where the signal is supposed to come from to jump those wires (when properly connected) and why it isn't working. Any ideas on how to troubleshoot why the fan isn't getting the signal to turn on?

 

[DAKSY]

Here's the Tech Manual for that blower model from the Heartstone site. Scroll thru til you come to the wiring diagram...Good luck & I hth

 

[Ramin]

Thanks again.

From what I can find it looks like it is the snap switch that isn't working. I'll have to see I didn't reach the correct temperature for it to turn on or it isn't working at all. The good news is that it should be much cheaper to replace if I need to (although I didn't look to see where I can get them yet).

 

[Ramin]

For anyone else with a similar problem this was a good post that describes how the snap switches work.

https://www.hearth.com/talk/threads/pellet-stove-tempature-limit-switch-help.11404/

 

[DAKSY]

You can easily test the snap-switch (aka Thermodisk) with an open flame. Remove it & hold the disk section to a lighter or match or even a candle. Listen for a small metallic 'tink.' You will have to be in a relatively quiet location as that sound made by the disk when it closes is almost inaudible. If it DOES work, then make sure the disk section is in contact with the stove body, or it won't get hot enough to actuate...

 

[Ramin]

I did that and I heard a click. I put some thermal grease on the back of the snap switch and put it back together and it all works now. Oddly the placement of the snap-switch is near the bottom of the back where it is much much colder than a few inches higher. It seems odd that it would be placed somewhere where it takes much longer to get hot. Is that normal?
The fan will switch on and off during operation now. After the fan runs for a few minutes it seems to cool down in that area enough to switch back off (with the fire running).

 

[DAKSY]

I did that and I heard a click. I put some thermal grease on the back of the snap switch and put it back together and it all works now. Oddly the placement of the snap-switch is near the bottom of the back where it is much much colder than a few inches higher. It seems odd that it would be placed somewhere where it takes much longer to get hot. Is that normal?
The fan will switch on and off during operation now. After the fan runs for a few minutes it seems to cool down in that area enough to switch back off (with the fire running).

They try to place the t-disks so the firebox is good and hot when it actuates. Contact with the stove body is IMPERATIVE. If any air passes between the t-disk & the stove body, the t-disk will cool, open & stop the blower. Sometimes you need to "tweak" the t-disk mounting bracket to assure good contact...