Questions about the need/requirement for a expansion tank

[three_jeeps]

The gas hot water heater in my house rusted through on the bottom - time for a new one (it lasted 19 years!!!)
The plumber that came over said that my system needed an expansion tank. I understand the rational for an expansion tank but not sure my system warrants one.

From what I've read, it is required on a contained system. A contained system is any water system that has a backflow protection device installed on the incoming water supply of the building. Makes sense because you want a buffer to accomodate any excessive expansion.

I checked the incoming line to my house, and the only thing in the main line is a pressure regulator after, and in close proximity, to the water meter. I didn't see any check valve in the line.
I therefore believe that my system is not a contained system...true? I am fairly certain that a pressure regulator is not a back flow device so it makes no sense to install an expansion tank (?).
So the following questions:
1. Does my system require an expansion tank?
2. Is current plumbing practice to make all residential systems a 'contained system'? or is it 'good practice' to install an expansion tank in non-contained systems?- the rational for this escapes me...

Thanks for any insight.
J

 

[Twowaxhack]

Some codes require expansion control on all systems.

My local code only requires thermal expansion control on closed systems

Some PRVs have a bypass valve allowing the system to be open. Some don’t…..

If you want to know if your system is experiencing thermal expansion there is a simple process to check for it.

1. Make sure there are no leaks or drips in the system and all automatic valves are turned off ( ice maker )

2. Install a pressure gauge on the system. You can get the type that attach to a hose Bibb

3. Run enough hot water to make the water heater fire off.

4. Close the faucet and again make sure there are no leaks or drips in the system. Do not use any water.

5. Watch the pressure gauge as the water is heated by the water heater. If your system is closed the pressure will start climbing.

 

[Mitchell-DIY-Guy]

PRV? You need an expansion tank. No need for further testing.

 

[Twowaxhack]

PRV? You need an expansion tank. No need for further testing.

That’s not necessarily true. It depends on his pressure and type valve.

He may not even need the PRV, and not all PRV’s close the system.

I suggest you read more......

 

[Mitchell-DIY-Guy]

@Twowaxhack : No. that's a period at the end there. No.

If there is a PRV in the house, it's because it needed it. No builder, plumber, or anyone of sound mind in an initial build is going to put one in as a lark. They put them in because the AHJ, code, or local practice says so. I can tell you with certainty that here, even if the plumber or builder could save a few bucks by putting in a PRV with integral thermal bypass, the plumbing inspector would say, "Nice. Put in the tank and reschedule an inspection." END OF STORY. All that testing you suggest is a waste of time. It also ONLY measures a point in time, and nothing else.

So, the OP has a PRV. The PLUMBER says he needs an expansion tank. So, put the tank in.

Of course, the OP @three_jeeps doesn't indicate where he is. He's best consulting with the local plumbing inspector for the town/county/AHJ and posing the question to them not here. The reason for that is simple: what they say is the rule. Doesn't matter what I say or you say.

 

[Twowaxhack]

@Twowaxhack : No. that's a period at the end there. No.

If there is a PRV in the house, it's because it needed it. No builder, plumber, or anyone of sound mind in an initial build is going to put one in as a lark. They put them in because the AHJ, code, or local practice says so. I can tell you with certainty that here, even if the plumber or builder could save a few bucks by putting in a PRV with integral thermal bypass, the plumbing inspector would say, "Nice. Put in the tank and reschedule an inspection." END OF STORY. All that testing you suggest is a waste of time. It also ONLY measures a point in time, and nothing else.

So, the OP has a PRV. The PLUMBER says he needs an expansion tank. So, put the tank in.

Of course, the OP @three_jeeps doesn't indicate where he is. He's best consulting with the local plumbing inspector for the town/county/AHJ and posing the question to them not here. The reason for that is simple: what they say is the rule. Doesn't matter what I say or you say.

Sorry mr home inspector, you’re mistaken.

I say that often to home inspectors in real life and now on the internet.

Plumbing conditions can change. People install things they don’t need......

That’s why professionals TEST rather than assume. But home inspectors don’t test........so I usually end up correcting their assumptions.

 

[Twowaxhack]

We had entire neighborhoods that when they were built required pressure reducing valves.

Then a few years later about 10 new developments started in the area.

The water pressure went from 125 psi down to 65 psi in the span of a year.


I removed MANY pressure reducing valves in those neighborhoods and still do on occasion left over from 2007.

So while they were once useful, now they’re not.

 

[three_jeeps]

Thank you for your replies. When I purchased the house a number of years ago, the water pressure seemed very high. I called the local water company and they came out and checked the pressure. IIRC, it was around 75 psi. They said the pressure in the house should be between 45-60 PSI. I contacted a reputable master plumber who installed a PRV. Pressure was set to ~ 55PSI. This was done about 15 years ago.
J

 

[Twowaxhack]

Thank you for your replies. When I purchased the house a number of years ago, the water pressure seemed very high. I called the local water company and they came out and checked the pressure. IIRC, it was around 75 psi. They said the pressure in the house should be between 45-60 PSI. I contacted a reputable master plumber who installed a PRV. Pressure was set to ~ 55PSI. This was done about 15 years ago.
J

Max water pressure is 80 psi for a residence.


You don’t need the PRV if the pressure is still below 80 psi.

Depending on the type PRV, if it has a thermal bypass, you don’t need an expansion tank if the test proves the system isn’t closed and your code doesn’t require it.

@Mitchell-DIY-Guy Are you still reading ?

 

[three_jeeps]

@Twowaxhack : No. that's a period at the end there. No.

If there is a PRV in the house, it's because it needed it. No builder, plumber, or anyone of sound mind in an initial build is going to put one in as a lark. They put them in because the AHJ, code, or local practice says so. I can tell you with certainty that here, even if the plumber or builder could save a few bucks by putting in a PRV with integral thermal bypass, the plumbing inspector would say, "Nice. Put in the tank and reschedule an inspection." END OF STORY. All that testing you suggest is a waste of time. It also ONLY measures a point in time, and nothing else.

So, the OP has a PRV. The PLUMBER says he needs an expansion tank. So, put the tank in.

Of course, the OP @three_jeeps doesn't indicate where he is. He's best consulting with the local plumbing inspector for the town/county/AHJ and posing the question to them not here. The reason for that is simple: what they say is the rule. Doesn't matter what I say or you say.

I am in PA.

 

[Hamberg]

I am in PA.

Which county? Local jurisdiction may require.

 

[three_jeeps]

Which county? Local jurisdiction may require.

Allegheny, City of Pittsburgh
I've run into situations where the city has certain restrictions/requirements on plumbing and electrical that the county is silent on.

 

[Twowaxhack]

If you’ve seen what I’ve poured out of old expansion tanks you wouldn’t install one unless you had to have it.

 

[Hamberg]

Allegheny, City of Pittsburgh
I've run into situations where the city has certain restrictions/requirements on plumbing and electrical that the county is silent on.

Other side of the State - Montgomery County, they require them here (assuming you'd actually pull the permit and have it inspected!?)