Water heater pressure valve issues < Zman1234 > 2018-03-27 14:44 GF apt building last tenant on 2nd floor away from main water line in water heater pressure release valve started blowing a month or so ago so had "the plumber" replace pressure valve. He had to move the heater to access it because of another water heater too close. Week later water heater leaking so replace water heater. Pressure release valve on new heater blowing, the tenant does take hour showers. The plumber puts in a regulator at the meter and tests at 55psi. Confirmed. New water heater still blowing I have clear hose into 5 gal pail not too bad but $1800 later the same problem is a load of ****. The manufacturers manual says that an expansion tank should be fitted but the plumber insists on the regulator it will solve your issue. It didnt. So I am thinking of putting the expansion tank on I have sweated lotsa pipe. Also thinking about connecting the two water heaters with a stainless washer hose to the clean out bibbs to act as an expansion tank. Tank is turned down to warm now and the latest pressure reading is 118 I have the dial meter. Any inputs? the house is older and has galvanized and copper in various configs everywhere and is a pita.