Thermostat help

[marinelife]

I put in a new thermostat and am having an issue

When I test heat/cooling the fan does come on but the heat takes 30 seconds or more to start then it runs for 10 seconds or so and shuts off for 20-30 seconds.
It may shut off twice then finally turns on and stays on until the temp is correct.
It is gas furnace made by lennox. Any ideas?

[ghurlag]

Was it running fine with the old thermostat?

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[marinelife]

yeah the old one worked as long as we did not want to change the temperature.
I have already went and swapped the new one for another new one.
Both new ones act the same but are the same model!

So a new model maybe in order!

[marinelife]

See you skip a year of getting in cleaned and find out you needed it. The Flame Sensor was dirty :)
Now the new thermostat and furnace are working correctly.

[ghurlag]

yay!!!