installation of expansion tank/ pressure relief valve

[plumbob]

Is a pressure relief valve needed in line prior to the addition of a expansion tank of water heater; what size tank necessary with 60 gal. water heater. Any unforeseen difficulties with do-it-yourself job?

[G. LoesherParticipant]

You had better already have the relief valve on the water heater. And the expansion tank is to help the relief valve work better, it is not the reason for needing one.: Is a pressure relief valve needed in line prior to the addition of a expansion tank of water heater; what size tank necessary with 60 gal. water heater. Any unforeseen difficulties with do-it-yourself job?

[G. LoesherParticipant]

: You had better already have the relief valve on the water heater. And the expansion tank is to help the relief valve work better, it is not the reason for needing one.: : Is a pressure relief valve needed in line prior to the addition of a expansion tank of water heater; what size tank necessary with 60 gal. water heater. Any unforeseen difficulties with do-it-yourself job?The EXPANSION tank has nothing to do with the T&P relief persay as the Temperature /Pressure relief valve is designed to operate at a pressure of 150 PSI or a temperature of 210 degrees. To properly size this T&P you must take the cubic foot input of the natural gas and convert it into the BTU rating and then size the relief valve accordlingly. What the expansion tank does do is allow for the normal expansion of the hot water during the heating process. Pressure temperature relationship As the water is heated it does expand and on old piping systems this could create a problem especially is someone was stupid enough to install a check valve on this system. Normally expansion of the hot water should not be a problem if you on city water with no back flow preventers installed in the system. The hot water stratification will not put undo stress on a properly designed piping system. By installing a heat sink as per ASME section IV and the model plumbing codes this should never be a major problem. The relief valve is there ONLY as a safety device and never as an operating controller. The T&P is unique in the fact it does the job of several devices in one. A relief valve is used on hot water systems and a POP or safety valve is used on Vapor systems such as compressed air or steam. The T&P works for excessive pressure and or temperature as a hot water tank with and Air pocket can readily explode. If you happen to go to the top of this page to PLUMBVIEWS You can read several articles about the importance of hiring ONLY a Master Plumber/Gas Fitter. Anyone without a license could end up killling you and everyone around you. Would you go to an unlicensed doctor? or a doctor who only learned on the job by watching someone else who learned by trial and error? Just saying Plumbing in most states means the person must be licensed and insured. This is for your protection. Did you know that not all T&P are ASME OR AGA rated and some have no way of testing their operation? Did you also know that the proper discharge piping arrangement of the T&P is just as important as the valve itself? If you didnt know these things YOU had better call a Lic Master plumber and ask to see their license. Accept NO EXCUSES. A tech is NOT licensed and your taking your life in your own hands allowing unqualified/unlicensed stumblebums in your home .Good luck… Sylvan

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