Help with Williams direct vent wall heater.

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  #1  
Old 01-03-15, 03:52 PM
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Help with Williams direct vent wall heater.

I'm having the same problem as the original poster. Williams direct-vent wall heater. The pilot light stays lit, but I can't get the heater to turn on.

Voltage is 260mV with the thermostat both on or off.

I removed the pilot tube and did my best to clean it, but no effect.

I think it was hooked up to a low voltage thermostat, but I just hooked it up to a millivolt thermostat.

Any ideas?


Separated from... http://www.doityourself.com/forum/ga...l-furnace.html
 

Last edited by PJmax; 01-03-15 at 04:19 PM. Reason: started new thread
  #2  
Old 01-03-15, 04:28 PM
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Welcome to the forums.

Hopefully you'll get my PM and follow us to your new thread.

Your voltage reading is very good. It tells us that your pilot generator is probably ok as well as your pilot flame.

When you activate your thermostat that 260mv should immediately drop to under 200mv or so. It sounds like your thermostat isn't making contact. You can take the two wires that go to the thermostat and short them together. That should bring the burner on.
 
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Old 01-03-15, 05:44 PM
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Thanks for your assistance. I just tried your test. Lit the pilot light and tested the voltage at 300mV. Shorted the TH/TP and TH terminals at the furnace, and the pilot light went out. What do you think is going wrong there?

Shorting the cables at the thermostat end doesn't do anything, which makes me think the cable run is open somewhere. But before I address that, I'd like to see if I can get the furnace running.
 
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Old 01-05-15, 03:15 PM
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Any idea why the pilot light goes out and the main burner doesn't light when I short the TH/TP and TH terminals?
 
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Old 01-05-15, 06:23 PM
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Are your connections similar to the diagram below ?

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Old 01-05-15, 07:34 PM
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PJ I believe he needs at least 560 mv at the power pile before the gas valve will open..........
 
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Old 01-05-15, 11:00 PM
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yep, looks like that. yes, it does.
 
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Old 01-05-15, 11:07 PM
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There are several types of pilot generators and I believe most of these Williams units use the 340mv. one.
 
 

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