Pressure regulators and expansion tanks

If you find a water pressure regulator on the property, do you automatically call for an expansion tank at the water heater if one is not present?

In all the states where I’ve worked in real estate, I’ve only found one expansion tank on a water heater, and that was here in San Diego back in 2002 or so.

I recently met a home inspector in Washington who always calls for an expansion tank if one is not present and there is a pressure regulator on the property.

Haven’t heard of this requirement before and cannot find such a requirement in any of my books at the moment.

Thanks for the guidance.

I’ll also try to check with some plumbers here later today.

It is required here, and I call it out .

The existence of a regulator does not automatically make it a requirement. It’s a bit more complicated than that.

608.3 continued. . .

In addition to the required pressure or combination pressure and temperature relief valve, an approved, listed expansion tank or other device designed for intermittent operation for thermal expansion control shall be installed whenever the building supply pressure is greater than the required relief valve pressure setting or when any device is installed that prevents pressure relief through the building supply. The tank or device shall be sized in accordance with the manufacturer’s recommendation.

Sorry , I am speaking of water heaters in general at install, and not referring to with pressure regulators.

I don’t call out “requirements”. It is, however, a safety concern so I do.

I don’t agree that it’s a safety concern.

If your relief valve setting (whether on the heater or supply) is 150 psi (example) and your street/supply pressure exceeds 150 psi, the expansion tank is just a means to prevent opening of the relief valve when the system is closed - i.e. no water running.

Even with regulators, a closed system can gradually build up pressure equal to supply pressure. Eventually, even with an expansion tank, the relief valve will open if the system remains closed.

Even with drain pans , we have a lot of high rises , so it depends on your area.

Yes the tpr should be enough in a home , one would think.

They are required with backflow preventers.

Hey, Bruce.

Define a “backflow preventer” in your area for me. Thanks.

Hey, Jeff.

What do you think about this:

I haven’t seen you around for a while Russel. I hope life is good for you and yours. :smiley:

I’m a different Bruce, :smiley: but I’ll answer…

In my area, it is a double-check valve.

PEX piping…

As my wise old grandmother said, “If you get too many negative people ni your organization, find a new organization.”

from your link differant page:D

where have you been? hope all is well

I think they’re trying to sell you and expansion tank :mrgreen:

Like you, I have see exactly 1 expansion tank during my career as a Home Inspector.

I don’t think they’re a bad idea, but until I get some definitive information that shows me the great benefit of having one, I will not be recommending their installation on a standard residential system. Also, the methods for determining their necessity, are well beyond our normal scope.

I don’t know if it is code in Tyler, but I see expansion tanks on every home built in the last 10-15 yrs. My own home has one.


I do not see them very often here either. And on a home with PEX piping I think it would not be necessary at all.

The scenario does not occur much here, so I have not seen a bunch either. Expansion tanks here are not needed unless your next door to the pumping station and then a pressure relief is required at the pressure reducing valve. A backflow preventer is only required if you have a residential fire suppression system or an irrigation system (around here). Of course, special circumstances demand a judgement call by the AHJ.

From what I’ve seen in the last 2 years you could ask 12 AHJ’s and get 12 different answers. You could even ask 2 different code inspectors in the same AHJ and get 2 different answers.:wink:

I would agree with this in theory. PE and PEX allow for plenty of expansion. . .