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Rick
Rick, HVAC Supervisor
Category: HVAC
Satisfied Customers: 20775
Experience:  40+ yrs. experience as a licensed oil & gas technician.
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I have a Weil McLain CGi direct vent boiler approx. 13 years

Customer Question

I have a Weil McLain CGi direct vent boiler approx. 13 years old. The boiler temp reaches the limit temp before the call temp is met.
JA: I'll do all I can to help. How long have you been dealing with this?
Customer: It seems since the boiler was replaced as part of a major renovation.
JA: Just to clarify, are you working with a contractor?
Customer: Not yet
JA: Do you plan on doing the work yourself?
Customer: Yes
JA: Anything else we should know to help you best?
Customer: I replaced the 30 psi relief valve that was relieving and I found it was rusted. It was only a year old. The pressure temp gauge was also replaced because it was inaccurate. I am replacing the gauge after about a year again after I checked the pressure on one of the bleed valves.
Submitted: 3 months ago.
Category: HVAC
Expert:  Rick replied 3 months ago.

Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue. If my initial response doesn’t answer your question then let me know and we can continue our conversation.

It's normal operation for the boiler to reach the limit temp before the thermostat is satisfied. This will happen most of the time particularly when it's very cold out. The burner shuts off on limit but the pump continues to run as long as the thermostat is calling. After the burner has been off for a while the water circulating through the system will cool off and the burner will come back on.
If the relief valve is discharging you probably have a failed expansion tank that should be replaced.

Expert:  Rick replied 3 months ago.

In light of the above what is your question?

Customer: replied 3 months ago.
The relief valve was replaced and the pressure is about 18 to 20 psi
Expert:  Rick replied 3 months ago.

That pressure is OK but you need to watch the pressure when the boiler gets up near limit temp. Relief valves don't just leak on their own. They leak if the pressure gets too high (over 30)or if someone flips the lever up and the valve doesn't reseat properly.
Do you have more questions?