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Tim H.
Tim H., HVAC Professional
Category: HVAC
Satisfied Customers: 3971
Experience:  Experienced in all aspects of HVAC, both residential and commercial.
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My mpd35st-nm won't stay lit. I didn't use it after initial

Customer Question

My mpd35st-nm won't stay lit. I didn't use it for years after initial installation and then tried to no avail. Pilot won't stay lit. I have held it on for 10 minutes straight to get the solenoid warm, but still goes right out. When I open the glass, I can get it to stay on, but not always. And I have gotten the pilot to stay on long enough to to light the fire with the glass open, but it'll still go out. Even with the glass open, it goes out after a few minutes. I thought it was starved for o2. Any ideas?
Submitted: 1 year ago.
Category: HVAC
Customer: replied 1 year ago.
Problem solved already. Did not receive an answer yet. Would I receive a refund? My $16 PayPal was automatic so that I wouldn't lose my place in line. Just let me know. Thanks for your time - Dave
Customer: replied 1 year ago.
Nope. Flamed out again. Ran normally for about 10 minutes with glass closed. Then poof. I'm stumped! Ugh!
Expert:  Tim H. replied 1 year ago.

Hi, I'm Tim and I'm an HVAC expert here to assist you with your questions. Please provide all information I request as it makes it more difficult to troubleshoot something when I'm not there onsite. Essentially, you become my eyes and ears. Thanks for the opportunity to help. At the end of our dialog, you will have a chance to rate my service, but please wait until we are finished and you're satisfied you have all the information you need.

Have you tried replacing the thermopile??

Customer: replied 1 year ago.
It could have been faulty? It's never been (stayed on) used and the pilot and gas shut off.
Expert:  Tim H. replied 1 year ago.

Sometimes a thermopile will need replacing just from sitting too long. I've seen this happen many times.

Customer: replied 1 year ago.
Strange. The other identical fireplace in my house was installed at the same time and works perfectly still. Ok. I'll see about getting a replacement.
Expert:  Tim H. replied 1 year ago.

The majority of times, this is what it is.

Customer: replied 1 year ago.
Ok. Hope so. Available through Lennox only, or is it a common stock item at a hardware store and a diy install. I'm an electrician so this isn't far from my wheelhouse.
Expert:  Tim H. replied 1 year ago.

See here.

Expert:  Tim H. replied 1 year ago.

These are universal.

Customer: replied 1 year ago.
Sounds good. Thank you. I'll get one and cross my fingers
Expert:  Tim H. replied 1 year ago.

Since you're an electrician, here is a piece on millivolt testing to help determine if thermopile is bad.