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I have a Weil McLain cg 4 natural gas furnace, the pilot…

I have a Weil...

I have a Weil McLain cg 4 natural gas furnace, the pilot stays lit all the time but the furnace doesn't start

Contractor's Assistant: Did you double-check the thermostat? And what about the pilot light?

The pilot is lit, but doesn't turn off even when the automatic damper cycles

Contractor's Assistant: Do you plan on doing the work yourself?

Yes, I have two of these furnaces, and have worked on them before

Contractor's Assistant: Anything else we should know to help you best?

I am thinking the Mercury flame sensor or the main gas valve may be bad, even when I turn the gas valve to off on the unit, the pilot stays lit, the only way to shut off the pilot is to shut off the main

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Answered in 2 hours by:
11/11/2017
Daniel Plourde
Daniel Plourde, HVAC Technician
Category: HVAC
Satisfied Customers: 453
Experience: I've been in the HVAC buisness since 2008 working on residential, commercial, and industrial buildings
Verified

hi i am dan i can help you with this. from the testing that you have done it sounds like the gas valve is your problem, especially since when you turn the nob to off the pilot stays on that is an indication that something internal in the valve is broken and stuck on pilot mode. i would recommend replacing the gas valve. if you have any more questions about this please let me know or if this helps you i would appreciate it if you could rate me on my service by selecting one of the 5 stars on your page.

Daniel Plourde
Daniel Plourde, HVAC Technician
Category: HVAC
Satisfied Customers: 453
Experience: I've been in the HVAC buisness since 2008 working on residential, commercial, and industrial buildings
Verified
Daniel Plourde and 87 other HVAC Specialists are ready to help you
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Customer reply replied 6 months ago
Hi Dan, I believe you are right, I tried " rapping" on the gas valve, and the furnace started! Are there any serviceable parts inside the valve that could be causing the problem?

unfortunately there are no serviceable parts to the gas valve. whenever they are bad it requires replacing the whole valve.

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Daniel Plourde
Daniel Plourde
Daniel Plourde, HVAC Technician
Category: HVAC
Satisfied Customers: 453
453 Satisfied Customers
Experience: I've been in the HVAC buisness since 2008 working on residential, commercial, and industrial buildings

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