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Phil
Phil, Mechanical Engineer
Category: HVAC
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Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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1100i 7 amp fuse blows when thermostat calls. When I replace

Customer Question

1100i 7 amp fuse blows when thermostat calls for heat. When I replace fuse while the thermostat does not call for heat, the main exhaust blower runs. All three fans spin freely as does the auger feed motor. What else can I check?
Submitted: 1 year ago.
Category: HVAC
Expert:  airheatman replied 1 year ago.

Disconnect wires where they connect to thermostat and twist them together .Lets see if fuse pops again if unit woks.

Customer: replied 1 year ago.
I had disconnected the thermostat at the stove and verified the circuit makes/breaks as I adjusted the thermostat.
Expert:  airheatman replied 1 year ago.

I am wondering if the short is IN the thermostat.That's why I say connect the wires together leaving thermostat out of the circuit and see if heater will work without popping fuse.

Customer: replied 1 year ago.
Ok, need to go purchase more fuses . Will take about 30 minutes
Expert:  airheatman replied 1 year ago.

I would get a few.Until we find source of short. Sometimes the only way to locate is by process of eliminating components until it no longer shorts.

Customer: replied 1 year ago.
I measured across thermostat input terminals at the pellet stove and measure a dead short...
Customer: replied 1 year ago.
Wife went to purchase fuses.
Expert:  airheatman replied 1 year ago.

If you remove wires from thermostat and touch the wires together, will unit work?

Customer: replied 1 year ago.
ok have fuses- fuse blew when shorting across thermostat input to stove.
Expert:  airheatman replied 1 year ago.

Do you see a wiring diagram on stove you can send me a picture of?

Customer: replied 1 year ago.
Unfortunately, there are no wiring diagrams or schematics provided.
Expert:  airheatman replied 1 year ago.

Let me verify something. Do I understand that with no call from thermostat the exhaust blower is coming on?

Customer: replied 1 year ago.
that is its normal operation. When unit is first powered up, the exhaust blower will run for a few minutes, even if unit does not call for heat.
Expert:  airheatman replied 1 year ago.

OK so exhaust blower stops after a few minutes and just sits idle?

Customer: replied 1 year ago.
Expert:  airheatman replied 1 year ago.

I am suspecting board may be the issue.Was looking for a wiring diagram.You can start unplugging components until fuse does not blow, but I think any relay that might short is built into the board.

Customer: replied 1 year ago.
I pulled the circuit board and noticed the short across the thermostat terminals clears. So, I suspect the failure is likely on the board as well. Do you have a schematic of the control board?
Expert:  airheatman replied 1 year ago.

Unfortunately I do not .Was looking online but haven't found one. That's why I was asking if you had one.

Customer: replied 1 year ago.
Is there anything more you can offer?
Expert:  airheatman replied 1 year ago.

I can open to other experts to see if they have ideas.

Customer: replied 1 year ago.
WIll that cost extra?

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