pressure relief blows!

[Chris-man]

Hey, Masters , what heppened to the insistence upon model and Serial numbers? does this rule not apply to HWHs?

I have a BRADFORD-WHITE hot water heater(cold water heater) Numbers as follows:

Model: MI 50s6ds13 (friggin stupid to use 5 and S AND L and 1 in codes)

Serial #: sm4062055

the problem is compound with this unit BUT for Now I would be indebeted to get some expert advice on presumable replacing the pressure relief valve which "blows' after I turn on the circuit breaker to MANUALLY heat the water--a real pain in itself, but now the water barely gets warm enough to shower in---Bummin! So am I correct, is this a bad pressure relief valve? If so, will you please advise me how to get it's replacement (I will list below, the numbers and such from the tag on the valve) and also, IMPORTANTLY, tell me in your experience is there some , little, or much RISK in putting a pipe wrench on this 20 year old joint and torking on it. Will I need a breaker bar? thanks. Heres the info from the tag:

Ser #: 9840N

M7STD.Z21.22

Canadian registration # 0G1893.5C

3/4 in 100XL ext.4

female on both ends thanks Gurus. Humble Handyman

[Chris-man]

Just to keep myself interested Im replying to my own post! Hey Mastahs out there--SAmauri-Appliance-Butt-kicking Gurus any words of Wisdom on my above pressure-relief inquiry? Domo. HH

[RegUS_PatOff]

M7STD.Z21.22

I'm not a Water Heater master, but

USED one on 'Bay $ 10 + shipping 270346092726

[certified tech group 51]

I don't know up there in the great white north but in the lower 48..It is called a PT valve. Pressure and temperature relief valve. It operates if the temperature OR pressure exceeds the plate rating. I do not know why you are manually turning the water heater off and on. The thermostats are automatic...If you have a thermostat that sticks 'on' you get a runaway condition, The tank over heats and the valve vents the pressure ( caused by temperature increase ) The pressure part is if the system pressure exceeds the rating, problems with the city or pump pressures....20 years old, the valve is probably stuck in place but with some heat and a good wrench it sounds doable.....If the water is not getting hot enough I would first check the elements the move onto the thermostats.......I will bet the next gubmit shut down, it is a lower thermostat that is the problem.....P.S. purchase a new set of thermostats and elements and do the complete overhaul all at once plus flush the tank from the lower pet cock.......