Customer reported that the relief valve on their oil/wood boiler was discharging. Upon inspection, we operated the boiler to its high limit and observed that the relief valve did not discharge during testing; however, there was evidence of prior discharge, as water was present in the bucket beneath the valve. Boiler pressure was found to be at 25 PSI. Checked the expansion tank and determined that it has failed, leaving no room for system expansion as the boiler heats, which likely caused the relief valve to release. Presented the customer with estimates for replacement of the expansion tank and relief valve, as well as the addition of a drip leg to the relief valve outlet for safety. We are scheduled to return in the morning to perform the recommended repairs. For the interim, the aquastat was turned down to 160°F to limit boiler temperature overnight. The customer has been advised that if the supply zone shutoff valve leaks when closed during service, an additional estimate will be
