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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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😄 I have an older lennox gh efficiency furnace, I not sure

Customer Question

Hi !😄 I have an older lennox high efficiency furnace, I not sure what model number, natural gas. My programable thermostat calls for heat but the furnace does not immediately come on, especially when it's cold. It does come on however but the interval between running and not, even though the thermostat is calling for heat is long and varies as the day progresses. Cooling side works fine. Any thoughts ?
Submitted: 1 year ago.
Category: HVAC
Expert:  airheatman replied 1 year ago.

Sounds like issue may be in thermostat.If you connect R and W wires together bypassing thermostat, will heat come on every time?

Customer: replied 1 year ago.
Not sure, and I'm not where I can check this right now. I can try later today and get back to you. Is there a time limit on our conversation?
Expert:  airheatman replied 1 year ago.

There is no time limit just come back when ready. If we can bypass thermostat and make heat come on when it should be but is not, we will know thermostat is problem, not sending signal to furnace.If not we will concentrate on furnace

Customer: replied 1 year ago.
Ok, thanks! I'll get back later today 😊
Expert:  airheatman replied 1 year ago.

We will go from there.