I installed a new Honeywell 7-day programmable t-stat today on my heat pump.
It seemed to work fine all day but this evening I smelled a creosote
Type smell in the house and attick where the unit is located.

I checked the attick for signs of fire, smoak etc but did not locate
Or see anything suspicious.

Any ideas? could this smell be related to t-stat?

Is there operation test code that can be entered into the unit for
Operation check ?

Please advise?

Thank you, SteveH

Was your old thermostat malfunctioning? Perhaps the system is activating auxiliary heaters that have been unused for some time, and dust is burning off the strings. I hope this is the case... D.I.Y. HVAC is risky business.