use a T&P relief valve rated for both temperature and pressure

or a "Flame Failure" where the valve fails to open despite receiving the proper 24V signal

As a functional equivalent to the S87K1008/U

It is recommended to inspect the existing fan blade hub and set screws for wear during the motor swap to ensure a secure fit on the new shaft

requiring both inputs for proper operation

Lochinvar & A.O. Smith 100111584 Pump Circulator 320788-704 use a T&P relief valveThe Lochinvar & A. O. Smith 100111584 Pump Circulator is a critical OEM replacement part designed for high efficiency hydronic heating and domestic hot water systems. Built to withstand the rigorous demands of commercial and residential boilers, this high head circulator pump ensures consistent fluid velocity and thermal distribution across the heat exchanger. It serves as a direct replacement for legacy part numbers such as Lochinvar ARM2801 and A.