Weil Mclain Gold GV keeps shutting Off

[3ne]

I am new to this forum and need some help. My 6 year 3 month old Weil Mclain Gold GV4 boiler has been acting up.
First I lost heat this past Tuesday. Called my regular HVAC repair guy out. After about an hour of checking, found out that my circulator pump was not running. Only the by-pass pump was running the system.
Got a new circulator pump installed the next day. System got back on and ran for about 30 minutes and then shut off.
The LED's were flashing the trouble: 'TSAT CIRC' which reads 'Frozen boiler water prevention activated'. In this mode the circulator pumps keeps working but the gas gets shut off. My repair guy messed around a few minutes then shut off the power for 45 secs as noted, turned it back on and the unit fired up again.
There lies my problem. The boiler keeps shutting down after approximately 30 minutes( I have timed it on several occasions). So for the past couple days I am running down to the basement to reset the boiler.
Should I replace the water temperature sensor ? I have now zipped tied it to the main return pipe in its original location to see if it needed to make better contact with the pipe.
Is my GV4 circuit board faulty? Once the house temperature reaches the set point it shuts off the unit and the LED is all green.
Also I have noticed that the temperature on my thermostat goes about 5 degrees below the set point before it calls for heat to refire the unit. Does my programmable Thermostat need replacing? it is only 1.5 years old.
Let me know your thoughts.

[jadnashua]

If the thermostat has batteries, make sure that they are good. I think that that message indicates that either the outside sensor or an internal one things there's a possibility of freezing because of the input, and is trying to ensure that the water in the pipes doesn't freeze, ruining the system.

[3ne]

My batteries were replaced at the start of the season last fall.
This morning got up to a cold house 61. Went down to the basement again reset. Did that for 4 times at 30 minute intervals the went to church. Got back at about 10:00 and my furnace is still running
Kept running until it hit target at 70 now i am waiting to see when it will kick back on.
Anyone out there have had this happen?

[Tom Sawyer]

Make sure the dip switches on your thermostat match the control boards specifications.

[jadnashua]

Many of the smart thermostats out there can be configured to control multiple heating system types. To work properly, that must be set according to the heating system type you have. then, some also let you adjust how tight it should control the temperature from maybe as little as 0.25-degree to maybe a couple of degrees before it turns back on again. Some also have a lockout to prevent the system from turning back on again after a short off cycle. So, careful setup can tweak it to your system's needs and your desires.

On some electronic thermostats, the batteries are essentially backup and only get used when the power is off to maintain the memory and settings; on others, it actually runs the thing and doesn't use the 24vac input for anything other than switching. So, if you have a long power outage, the batteries that could have easily lasted a whole year, may go fairly quickly. Doesn't hurt to check them.