Boiler relief valve

tandrews

Ok - this seems silly but I need clarification. Been a long time since I worked on a boiler. I always understood that a hot water boiler had a pressure relief valve for overpressure conditions; an aquastat for water temp setting; and hopefully, a high temperature limit control. In looking at a university presentation for boilers, it states that hot water boilers have a temp/pressure relief valve - not pressure only. I thought that pressure relief valves for boilers are rated for use up to about 250 degrees but did not believe that they would activate based on temperature or pressure. How is that even done without the temp stem like on a water heater temp/pressure relief valve. Can someone educate me please? Thanks.

GGross

Boilers for space heating make use of a pressure relief valve. Perhaps the university presentation got their terms mixed up, made a typo, or were perhaps talking about large commercial water heaters, which are technically boilers as well, we just commonly call a piece of equipment a "boiler" when it is used for space heating, or indirect water heating, or both

hot_rod

There are some combined systems out there that share DHW and heating appliance. Maybe that is the case with needing a T&P?

tandrews

Thanks very much for the response - it is along the lines of my thoughts. Appreciate it!