Thermostat possibly?

[mhgcsuper]

I have a Lennox heat system. It will not come on or go off with the thermostat setting. If you set the thermostat up about 10 degrees and turn the fan to on instead of auto it will come on. Then in order for it to turn off you have to flip the breaker for the fan motor (since there is no fan off, just on and auto). It is a lennox complete heat boiler system that uses the water from the hot water heater to heat the house normally. It also has emergency heat which is what I think is coming on when I do the above. The air seems hotter than it usually is. What would cause this system to do this? Thanks.

[HayZee518]

why would you use hot water from the water heater to fill your system? usually it's a cold water feed. I don't understand this "emergency heat."
Also when you turn up the thermostat does the unit fire?

[mhgcsuper]

HayZee,
It is the Lennox complete heat HM30 system. It pulls the hot water through the heat exchanger and uses the heat from the water to circulate warm air through the house vents. I am not sure if it has 2 stage heat (primary and auxilliary) heat or not. The main problem is the thermostat will not cut the heat on or off after it has reached the desired temperature. I can set the fan 'ON' switch on and reset the breaker for the thermostat and the blower fan motor and then it will come on. It will not cut off however and the breaker has to be tripped again to cut the heat off.

[HayZee518]

that does sound wierd but check your control panel. you may have a relay with welded contacts. sounds odd that you need to trip off the breaker to shut down the fan. the breaker is there for protection not to turn on-off the circuit. the control system is 24 volt because the "stat" controls the relays and contactors.