Expansion tank install

Hey guys! I had my plumber come on Friday to look at my T&P valve issue. He did a review of the system and found that the PRV was starting to go bad. It resgistered 80 PSI and was fluctuating. So he replaced the PRV and the main shutoff valve, a 20 year old gate valve. He also replaced the T&P valve on the water heater. Over the weekend there was no water in the bucket under the T&P valve pipe. Tonight there is about a cup of water in the bucket. So it looks like I need the thermal expansion tank.

The installation seems pretty straight forward. My plan would be to run a "T" off the cold supply line just above the water heater shutoff valve. Or should I run the "T" after the shutoff valve?

The other question is how do I support the tank? I have a steel support post about 2 feet from the water heater that I could strap the tank to or make a little platform for it. My plumber suggested not running a pipe all the way to the floor. He thought that would make the tank less effective.

Any recommendations on tanks?

This seems like a fairly easy installation. Unless I'm missing something.

Thanks, Mike

Can you hang it with perforated straping from the ceiling or you can support it by placing a peice 2" ring of 3" pipe on the top of the heater and resting it there.

Based on information on this forum I purchased and installed the Watts DET-12-M1 expansion tank. I've installed the tank horizontally. Below is an installation picture showing how the tank is supported.

Is there a main cut off valve where the water supply enters the house? If not there should be. If you also have a valve for the water entering the heater like I do, then put the tank in the cold water supply somewhere between the PRV and the tank valve. If you don't have that second valve, then just put the expansion tank between the PRV and the tank. Hanging the tank vertically is the preferred method, mostly because it's easier to support from floor joist above. If that's not possible the other methods are going to work but will require some creativity to provide the support as jk60 did in the previous post. You need 6" clearance around the tank, I think it's about 11-1/2" diameter. It is a very straight forward installation, just be SURE you provide the support.

That will work.

Cass - I don't have enough room to make the T fitting and place the tank on top of the water heater.

JK60 - Did your DET-12-M1 come fully charged or do you need to charge it after you install it? How did you charge it? Pump or compressor? Also any particular reason you added a pressure guage?

Gary - I have both a mail cutoff that is about 15' away. I'd rather have the expansion tank closer to the water heater. There is a cutoff valve for the water heater as well. When the water heater was installed a year ago they put a coupling between the tank and the shutoff vavle on the supply line. My plan was to replace the coupling with a T and run a couple of feet of pipe to the expansion tank and probably mount it upright on a little shelf attached to a support post in the basement.

Thanks for all the great information.

Mike

MikeG said:

JK60 - Did your DET-12-M1 come fully charged or do you need to charge it after you install it? How did you charge it? Pump or compressor? Also any particular reason you added a pressure guage?Mike

Click to expand...

The tank comes precharged to 40 psi. Since my water pressure is at 50 psi I increased the tank pressure to about 55 psi using a small portable electric compressor, the type you use to pump bicycle tires or car tires in an emergency. The instructions for the tank tell you specifically to perform this operation prior to installing the tank, i.e. the tank must be at zero outside pressure. As far as adding the pressure gauge, it is a cheap addition and I felt more comfortable in being able to monitor the water pressure in the house as well as ensuring that the expansion tank is doing it's job.

Good luck,

Jerry

I also increased the pressure, but I use my big compressor very carefully. Mike, I think your plan will work fine although I don't think the 15' wouldn't hurt anything.

Would there be any problems with placing the tank on the concrete floor next to the water heater?

No, and that is how Watts shows it in their suggested install doc. It's easier to support!, but harder to unscrew.

Jad -

Thanks. I might build a small platform for it then. It's easier than trying to hang it. That way I could remove the platform when I need to unscrew it.

Mike