Hello,

I have a 55gal water heater and is supplied, and outputs via copper flex lines. There is standard copper coming out of the wall, a shutoff, then flex to the water heater supply, then flex out back up to the wall, where there's another threaded connection.

So, my question is, can I just get a threaded T connection, thread that onto the shutoff on the cold supply, then screw the expansion tank to that, and the flex line to the second "outlet" of the T?

Basically, I'd just be inserting a T between the current shutoff and flex line connection. The expansion tank would be on a horizontal "run", with it above the piping.

So:
Tank
| |
Pipe->Valve->T->SupplyToWaterHeater

The other option I can think of would be to install a T on the water heater inlet, and put the tank on the upward facing part of the T, and then reconnect the supply line to the horizontal part of the T.
Tank
| |
Pipe->Valve->SupplyToWaterHeater->T
| |
Heater

Thoughts? The disadvantage to the second option is being able to strap the expansion tank to anything. The first option, I should be able to strap it to the wall... in the second option, it would just be kind of self-supporting.

Currently I don't have an expansion tank. The water heater is new, and has a TandP valve on it, so there's no worry about exploding, but I'm curious why the previous owner didn't have an expansion tank installed since it should be required.

Thanks!

This is NOT an answer, just a follow up (since I can't seem to edit the original question.

Those attempts to diagram didn't really work. See below... in both cases, the expansion tank is installed on a side of the "T" that faces up... in one case, that's on the perpendicular part of the T (example 1) and on the other, it's on the parallel side of the T (example 2). By that I mean, if the water was flowing in a straight line, the T would have an inlet and outlet that are parallel, and a outlet that would be perpendicular (can't think of a better way to describe it).

Pipe->Valve->T->SupplyToWaterHeater

Pipe->Valve->SupplyToWaterHeater->T

I usually install a 3/4" brass tee on the cold inlet of the tank, install the expansion tank onto the top of the tee and then install a short brass nipple into the side of the tee and connect the flex supply to the nipple.

Oh, okay! And all of this would be threaded? Do you secure the tank to the wall at all?

Yes, you can install T on shut off valve. This is the simpliest approach to making connection for Expansion Tank. Just make sure you have enough room for the tank itself above the heater. Sometimes there is lots of pipes, and also vent, disallowing ET installation.

Let us know how you did...

Can do. I'm probably going to be doing this around the beginning of next month, but I'm going to head to the local hardware store today and see what this project is going to run me.

The only thing I wonder about now is, it looks like my household water pressure might be in the 90-100psi range, and various places on the net say either that's fine (that household pressures can run upwards of 110 and not be a problem), or that it's high (that they should be 50-80psi). Will the tanks take that pressure? I don't get any knocking in the pipes (I used to get a bit when I used one faucet until I insulated them), and I haven't had any problem with failing appliances, so...

I'm going to call the local utility tomorrow (Monday) and see what they say.

Thanks!

House pressure on the inside of the house should be no higher than 55 psi. You will need pressure regulator to reduce incoming pressure, like Wilkins 60 or Wilkins 700 units. Expansion tank serves different purpose.

If I were you, I would first install pressure regulator. You may not even need Expansion Tank.