[EdFNJ]

Just about everything I have read online says a thermal expansion tank on a water heater should be installed on the COLD side. I even read the instructions (online) from a T.E.T. manufacturer that says the same thing.

The thermal expansion tank on our electric water heater is on the HOT side. Is there a specific reason for this or can I safely move it to the cold side?

Reason is, I want to install a recirculation pump on the HW side and there is no space without either moving or removing that T.E.T.

Thanks

[Tom53]

I found this article, which could explain some of the confusion


Where to install a thermal expansion tank

Typically there are two water systems in a home, one is the cold water supply and the other is the hot water supply. The main point of separation is not the water heater as you might suppose, it is the supply valve that is just upstream of the water heater, usually leading to the cold side flex connector. A second valve on the downstream side, (after the hot side flex connector), is not a point of separation since the water heater is part of the hot water supply system.

Your thermal expansion tank must be filled with cold water but must be installed into the hot water system.

The proper place to install your thermal expansion tank is downstream of the water heater's inlet control valve and upstream of the water heater.

By placing it there you keep it filled with cold water and the water heater's supply valve which is used to isolate the water heater and the hot water system will also isolate the thermal expansion tank. For full isolation install a second valve down stream of the T-E tank.

[EdFNJ]

Thanks. Yes, I had read that article as well. It, like just about every other article I read says it should be installed on the COLD side. That's why I am wondering why ours is on the HOT side. I thought maybe there was some "special" reason they did it that way (hot side) here in T.V.

[Topspinmo]

When my water heater was replaced it was on the cold side and the plumber said it goes on the cold side. IMO the reason it's there is to prevent pressure surges from outside water supply. People have had defective expansion tanks and it has blow the fitting off at the wall which most have they cheap twist on connectors. I say it goes on the cold side if you ever have surge in pressure this cushion it. So closest fitting don't take the quick pressure rise? That was i under stand it???

[EdFNJ]

That seems to be the general consensus so I am going to move it. Piping is easy here since it's all cpvc pipe. All cut and glue. No twists (except for the NPT thread on the top of the W.H.).

I also learned something online. It's not a HOT WATER HEATER, it's just a WATER HEATER since it heats COLD water not HOT!!!

😁😁😁

[Tom53]

There could be several reasons for the way it was installed. It could be confusion over the "hot water system", or the "degree of difficulty" in the original installation. It's there for the pressure rise during the heating cycle, so it should work on either side, but the life expectancy may be shorter on the hot side depending on your temperature setting.