Expansion Tank On Water Heater

Teetorbilt

I need to replace my water heater and have noticed that in all of the new construction that they are placing a small (2 gal.) pressure tank on top of the heater. Why?

I'm assuming that it has something to do with backflow preventers and being on city water. I'm on a well and have a big tank out back with all of the rest of the Chernobyl looking junk.

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ron schenker

I believe it works in conjunction with the Temp/press. valve to absorb extra volume and or pressure buildup in the tank. More safety for the homeowner

ATH

I installed one recently after my pressure regulator started to leak periodically. Problem solved.

Apparently, after using hot water, the cold water that replaced it would expand as it was heated. The pressure had to go somewhere. We had oreviously noticed a little weeping from the pressure relief valve on the water heater and the toilet fill valve seemed a bit weak.

We replaced both and now the weakest link in the system was the gasket on the pressure regulator.

I verified the problem before installing the tank by putting a gauge on the washer feed. I pegged the needle on the gauge!

Installing a tank was a lot cheaper than replacing the regulator. I'll probably have to do that too, soon. But I got a little more time out of it.

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Wayne
Around the House
http://www.MyPowerCouple.com

Bill

Also if the water heater is used to heat the house too you need an expansion tank

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Is it beer thirty yet
Virginia Department of Licensing
Virginia Plumbing Codes

Atricaudatus

You nailed it ATH. Here in NC this is now a code requirement, and it's for exactly that reason. As the water is heated it expands, and the tank gives the system somewhere to expand to without creatng weeps and drips at your TPV or elsewhere.

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-Rhett
Licensed electrician and plumber

Moscow

The real reason for an exspantion tank on hot water tank, is if you have a close loop system with a check valve or a backflow perventer. If you don't have both or one of the devises you will not have anyproblem.
However in some citys they have check vavles on the meters, then you have a close loop in your system and you will need a expantion tank.

Good Luck
Justin