expansion or pressure tank

I picked up a 2 gallon pressure tank to use as expantion tank for my 40 gallon HWH. I then found a unit labled as an expantion tank near the HWH in the same store. They are the same make and look the same other than paint and stickers. The other difference is the expantion tank came with a saddle valve to hook it up to a pipe. It was only $2 more so I figure that is the added cost of the junky valve that comes with it. Are they the same? I am thinking I am fine with the pressure tank I bought.

My piping is copper/pex mix. The tank is steel. I have a dialectric fitting sitting here that fits the tank. Should I use it? Also I was considering instalint the unit with a pex line up to it to help take up any movement. Is this good or over kill?

I don't know if the tank you got is an expansion tank or not. It sort of sounds like it is. Does it have a Schrader valve(like a tire) that you can add or release air pressure with? If so, it probable is an expansion tank. Saddle valves are crap and should not be used for anything. A Watts expansion tank does not come with a valve or fitting to connect to the supply line; you have to buy a tee adapter that will go in to the cold water supply line and that the expansion tank will screw onto. For example, my supply line is 3/4" copper, so I bought a copper adapter that had two 3/4" female ends that soldered into the supply line and a threaded end that the tank screws onto. If your line is Pex, you will have to get the proper fittings for Pex. If it's copper, you get a copper fitting of the proper size.

Expansion tank...

It sounds like one is for the waterheater.. the one with the 3/4 outlet...


the other one sounds like something that replaces the tank that sits under your kitchen sink for a reverse osmosis system.

I should have been more clear. The tank I got is a 2 gallon pressure tank for a well system. It has an air bladder and the schnider fitting. The inlet is 3/4" pipe thread. The Expantion tank looks to be built identicle except for retail packaging and including the saddle valve I would not use any way.

tank

It can be an expansion tank, a presure/storage tank, or an accumulator. The use determines what it is, not the construction of the tank.

hj said:

It can be an expansion tank, a presure/storage tank, or an accumulator. The use determines what it is, not the construction of the tank.

Click to expand...

Cool, I just wanted to make sure there was no real difference internaly.

Thank you.

The only thing I can think of is the precharge might be different, but you should check and adjust the pressure as part of the installation regardless.

An expansion tank for a boiler, since the water is not potable, might not be as clean inside, but that is a totally unsupported guess.

tank

When purchased the tanks would be equally clean. It is only after being in use that the contents might be contaminated.