Thermostat Bad?

Happy Monday, I Hope everyone had good weekend. My Tstats were shut off all weekend due to very mild temps outside. My system is single zone FHW with settings at 160/180 and differential of 15. The burner kicked on way to often with the stats off. The circ pump never kicked on, but the FHW water rising on its own made the house extremely warm to 75*. Am I possibly looking at a bad thermostat? Or should I shut the ball valve which is 12" up on the main supply of heat coming from the boiler and let it just heat what's inside for the domestic water? The system is a Utica set up for cold start and is only in it's 2nd season. But the tstat is older than dirt. THANKS! -
-Bob

 

Since posting earlier this morning, I have calculated my burner kicking on 3 times per/hr and each time it stays on for a 3 minutes burn. Could I just be overreacting to the mild temps and the hot water rising to the baseboards without the circulators or tstats calling for the heat. I also borrowed one of those digital thermal laser temp guns to compare the temp of the water coming out of the main heat supply line and it was with 5 degrees of what the gauge temp was on the front of the boiler. THANKS.

 

I Put in a new stat today to eliminate that as the culprit. It was another mild day and we were sweating again. I put a platic screwdriver to the Taco circ pump and listened to see if it was pumping even tho the stat was off and the circ pump was not pumping as well it should not when the stat is not calling for heat. BTW my pump is on the supply side. I am still confused as to why the boiler water is traveling all the way up to the baseboards and overheating the house. Am I missing something here? Is this just natural gravity feeding of the boiler water? THANKS.

 

Something here doesn't add up. If your system is set up for cold start, it should not fire at all if the thrermostat is not calling. You speak of domestic hot water: If there is a domestic coil, the boiler is not likely set up as a cold start. Presuming a domestic coil & not cold start, the most likely problem is a stuck flow check.

 

Grady, you are correct. It is NOT set up for cold start. Is there a flow check inside the circ which is on the supply side? The only other flow check valve I have is on the return about 5ft from the bottom of where it returns to the boiler. The hot pipes do not stay hot all the way to the return, mainly stay hot for 3/4 of the run. THANKS.

 

It is unlikely there is a check valve in the circulator. Some boilers, however, come with circulators with built in check valves. You can verify this yourself by looking at the data plate on the circulator. If it lists the model as a 007FC, it has a built in check valve. If you end up replacing the flow check & it is threaded onto the pipes, do not use teflon tape. A teflon containing pipe dope is ok but the tape often flakes off & gets under the seat of the flow check leaving you with the same problem you have now.

 

Grady, I just went downstairs and it is a Taco F5 circ. The only other hardware on the supply side is just before the circ where the expansion tank is attached to the air scoop. Is there a check inside the scoop? THANKS.

 

There is no check valve in that circulator. It sounds like you don't have one at all. That would be an installation issue. There should be one on any system that needs to stay hot in the summer.

Ken

 

Shall I install one on the supply side before the circ or after the circ? I do have a ball valve about 12" from the top of the boiler supply that has always been open. Can this be closed for summer months ? And if I can close this, would I have to lower the water psi while it is closed? THANKS

 

You really should have a flow check. You can close the ball valve to stop the heat now but you can't close it all the time. The flow check either needs to go in a horizontal pipe or a universal flow check can be used at the top of the supply riser from the boiler and be used as an elbow. You would not have to adjust the pressure either way.

Ken

 

Thanks so much Ken , I will install the flowcheck tomorrow. I will put it in the horizontal run before the circ. You guys are the best.
-Bob

 

Thank you also Grady! If your ever in NH , I owe you a native trout dinner.

 

You have a deal.
Just one word of caution on the ball valve. If it is between the boiler & the expansion tank, do not close it. If downstream of the tank, OK.