Need help with old garage heater

[tschaeff321]

I inherited an Emerson Electric Co. Manufacturing number: LUH-A-03-22-00-00-51, Serial # U-78558, 240 volts.
I used a dryer cord to hook it up to 220. When I turn it on, the fan comes on and the heating element starts to heat. After about 30 seconds, it shuts off. Can anyone tell me where to start.

 

[tschaeff321]

When I pull the back cover off, there is a loose copper wire coming from a torpedo shaped piece of copper attached to the outside housing for the fan.

 

[American Locomotive]

You're really going to need to post some pictures...

 

[tschaeff321]

The first picture shows the copper wire poking through hole in upper left. The second shows the torpedo shaped object the copper wire connects to.

 

[Done That]

I believe the bulb is a sensor for a thermostat...it looks like it was probably removed from the front of the unit, but that's a guess on my part. It would have been filled with a "charge" that would create pressure changes against an internal bellows to signal changes...pretty old school stuff.

The current Emerson division making these is Chromalox, maybe that will help as you sort through this.

I'm attaching an image of what I'm thinking the thermostat control probably looked like...but I'm not suggesting this is the exact part you need.

 

[tschaeff321]

Thanks

 

[American Locomotive]

Either the thermostat control has failed, or it's overheating hitting the high temperature limit - or the high temperature limit switch has failed.

 

[LS6 Tommy]

The "copper wire" on the front is a capillary tube that used to be on the t-stat. The T-stat has been broken off or removed. The other end of the "copper wire" is attached to the "torpedo", which was the original sensing bulb for the T-stat. The previous owner probably removed the t-stat, jumped it out and was just using and on/off switch. The fan should not come on immediately, it should come on shortly after the heating element heats up and should run for a short time after the heating element shuts off to cool it down. Sounds like somebody may have messed with the wiring. Short cycling usually is a bad limit switch. Is there a wiring diagram under the back access cover or can you post some pics of the wiring and controls inside the cabinet?


Tommy

 

[tschaeff321]

I ordered a thermostat from Chromalox. Model # LUH-TK1 (SPST)/LUH-TK2(DPST). I am having trouble deciphering the wiring instructions which show 8 different wiring diagrams, none of which seem to be my model (LUH-05-10-2401P).
Thoughts?

 

[LS6 Tommy]

To wire it according to your unit diagram, you need the DPST stat. Just put L1 on one terminal of the stat and L2 on the other.

Tommy

 

[tschaeff321]

When I hooked up the thermostat to L1 and L2, the Main Panel breaker blew. Trying to sort out the wiring inside the unit. I ran the blue thermostat wire to one hot leg which is also connected to a wire coming out of what I think is a limiting switch. The other side of the limiting switch has a wire running up to a wire nut which connects with a wire from the fan motor and several from the heating coils.
The black thermostat wire ran to the other hot leg along with a wire from the fan motor.