Faulty Thermostat? Or normal operation?

Frankfog2

Does a thermostat shut off immediately when the temperature is reached? Or does it continue to run even after? When my thermostat is going from 65-68 in the evening. The thermostat would read 68 and the boiler would continue running for an additional 5-10 minutes until finally clicking off.

PeteA

is it a programmable thermostat? It could be set up incorrectly for a different type of heating system than what you have installed. I noticed that some of the Honeywell thermostats will run a degree or two past the set temp based on the heating type selected at the programming step. This may be to allow a degree or two run up for forced air syatems vs hot water or steam systems. Just a thought because I did find this to be the case at my sisters house.

Frankfog2

PeteA said:

is it a programmable thermostat? It could be set up incorrectly for a different type of heating system than what you have installed. I noticed that some of the Honeywell thermostats will run a degree or two past the set temp based on the heating type selected at the programming step. This may be to allow a degree or two run up for forced air syatems vs hot water or steam systems. Just a thought because I did find this to be the case at my sisters house.

hey! 
I have a Honeywell RH6360 set up as follows
120-2
125-0
200-3
205-12
Wake 68
Leave 65
Return 68
Sleep 60
Would changing 120 (the programmable to non programmable be beneficial)

pedmec

You might want to elaborate on what type of system you have. It just might not be the thermostat. Some systems are set to run a little while after by the boiler control to remove the heat from the heat exchanger to the system. You can delay the circulator shutdown to gain that excess heat instead of it cooling down and wasted to the flue.

HVACNUT

If the boiler has a triple aquastat and the heat demand is satisfied but the boiler temperature is below the Low Limit setting, then the burner will continue to run until it meets that temperature setting. 
If the boiler has a dual aquastat, then then burner will run to High Limit regardless of heat demand.
If the boiler has a cold start high limit only aquastat but TT is jumped out, then it will maintain High Limit regardless of heat demand. 

John Mills_5

Many digital stats keep running when they hit the set temp. My Honeywell Prestige IAQ does and about any others I've seen do as well.