Hey guys,

I'm installing a new indirect hot water storage tank and taking out the old NG hot water heater, along my other upgrades. Extent of the changes will involve replacing all the pipes from the 1.5" water main (aftet the meter).

I left a water pressure gauge on the current water heater for a couple of days: pressure stays constant at 60psi, and max dial just barely touches 70psi. City water. So that confirms there's currently no backflow preventers of any kind. There is currently no expansion tank or basically anything else other than a meter and shut-off valve.

The question is, should I install an expansion tank on the cold side, or should I even go as far as adding a water pressure regulator? Is this a good idea for future-proofing, or waste of money? 60psi is on the high-end, but still within range. I do believe the indirect heat storage tank is exempt from any local plumbing code.

Also planning to install the Honeywell AMX series Mixing Valve on the storage tank.

Thank you all in advance for your time.

The storage tank is probably NOT exempt, because it is a heated vessel. You do not need a pressure reducing valve, so why would you want to install one, and if you did, THEN you would also need an expansion tank which you also do not need at this time.

I agree the WPR is probably not necessary since your variable street pressure is pretty steady under 70 psi (80+ would throw a flag). If you have ANY backflow or check valve device on your main supply you need to install an expansion tank.

Keep an eye on the TP valve for a while. If you notice any dripping or emission from this an expansion tank is a good idea. These are relatively cheap and easy to install. I recommend anyone on city/municipal water use one due to enhanced backflow prevention happening now on their end which did not exist as much when these infrastructures were originally designed. Thermal expansion could be absorbed by systems which now no longer can. If in a well situation, your bladder tank can accept some of the brunt as well so th need is not as great.

Now, should I do a heat trap on the storage tank? Any thoughts?

I realize that I don't have a need to a tank and a WPR right now as my house doesn't have any one-way valves, but future-proofing was my main concern. I guess I'll skip it for now and add it down the road if the situation changes.