My water heater has a pressure relief valve attached to the top, with a downspout that drains on to the floor. There is a second release valve on the hot water distribution pipes, this one drains to the ground outside. what is the purpose of this second valve? Is it a code requirement?
My intuition is that is is designed to trip before the heaters release valve so water is blown off outside instead of on the basement floor. The distribution release valve is set to 125 psi, but I can't find a set point labeled on the heaters valve.