I recently installed a new electric 40 gallon hot water tank at my mother’s house last week only to find that is soon began discharging water from the factory default 150 PSI pressure relief valve. The water pressure within the area is extremely high which requires a switch to a 175 PSI pressure relief valve to remedy the problem. However, I was not able to locate a long shank (2 ½”) 175 PSI pressure relief valve anywhere to fit the new hot water tank. (Only short shank 175 PSI valves). As a result, I purchased several brass couplings and extensions to modify the short shank 175 PSI valve just enough to fit the new hot water tank. This was initially just a temporary fix until I was able to find the time to plumb a new pressure reducer to curb the beastly water pressure with in my mother’s house… which I have already installed and completed. However, my question to you is NOT… will this modification work and whether it is SAFE… but why isn’t this a SAFE long-term modification? Every local-yokel plumbing “expert” stated “I wouldn’t do that if it were up to me!” However, after some further thought, I began thinking that there wouldn’t several fail-safe’s have to break for this to be a hazardous condition?
1. If the 175 PSI pressure relief valve’s settings were increased to even double the PSI settings (350 PSI) wouldn’t it still blow the relief valve before blowing the tank?
2. For the above to occur… wouldn’t the hot water tank’s thermostat have completely stick/fail? (This is a brand new high end “energy smart” hot water tank).
3. If the hot water tank’s thermostat did fail… would the 30 amp breaker do it’s safety turn off role due to electrical over heating and surge?
By no means… do I propose to sound like a plumbing expert whatsoever. However, common sense tells me that my modified 175 PSI pressure relief valve is a safe long term solution and that it seems highly unlikely that the above fail-safe could occur resulting in a hazardous condition. However, I am taking the time to “Ask TOH” in regards to this matter!