Expansion Tank Question


Fellow inspector!I have a question about expansion tanks on closed
water system.Is it correct that an expansion tank be installed on a closed
water system to be installed on all water heaters?I read in National plumbing code that on a closed water system(were their is a water regulator valve installed)that an expansion tank is required for thermal expansion.

Anyone know the correct answer


My understanding is that the installation of a regulator or other device that prevents backflow to accomdate expansion requires an expansion tank or pther approved means of handling expansion in the system.

Do you follow the IRC or UPC? As far as I can tell, an expansion tank is required only on a boiler, by the IRC.

Here is what the UPC says. . .

608.3 In addition to the required pressure or combination pressure and temperature relief valve, an approved, listed expansion tank or other device designed for intermittent operation for thermal expansion control shall be installed whenever the building supply pressure is greater than the required relief valve pressure setting or when any device is installed that prevents pressure relief through the building supply. The tank or device shall be sized in accordance with the manufacturer’s recommendation.

Most water heaters require an expansion tank if a closed loop setup is used.
Without it TPR valves and tub or sink valves will very often drip when a hot water circulation pump is turned on…

In ky they were requiring expansion tanks on water heaters if you installed a back flow preventer.

I went to do an inspection at a home where the water heater was an electric heater.It had no expansion tank and the T&P drain was routed through the wall and a 90 deg.elbow that went up then crossed through the ceiling at the subfoor area then down the oppsite wall to discharge outside.I called this an area of concern.The T&P valve was aready rusted & leaking.The owners called a plumber and he said the w.heater was up to code.I’m not a code enforcer,but this is a improper installation.Any feed back?

:lol: :lol: :lol: Up to code?!:lol: :lol: :lol: The plumber must be a comedian. How can you monitor discharging with the pipe terminating outside? How can you trust a deteriorated TRP? How can you trust upward piping to properly remove discharges (especially with an upward right angle elbow)? I’d pose those questions to the plumber if possible and explain the correct answers to the client.

The vast majority of our overflow legs terminate outside. The local AHJ no longer allows the overflow leg to run upward, as they used to for many years, but they still terminate through the wall and outside in many installations.

The vast majority of tanks I see lack overflow legs all together. All the piped ones I have seen dispense onto the foundation floor. Of course, the climate differences may explain our different experiences.

here in maryland, (this info came from a county plumber who came to check my findings that the listing agent didn’t think was correct, the drain exited into a sanitary tub and not outside, and had no check valve)
expansion tanks have to be installed on all new 2005-2006 HWH’s that are on city water, and those that don’t have them will have to have them installed within the next 8 or so years to prevent backflow to the main line that may rupture if correct valve is not installed on water main to house.