expansion tanks and no pressure reducer

[mike pontiero]

I've been on a few job sites recently and noticed different plumbing contractors installing expansion tanks on water heaters but there was not a pressure regulator or reducer existing. I thought expansion tanks were installed only if there was a pressure regulator installed. Is this a new practice, plumber's preference, or just an added safety step? I guess it can't hurt. Anyone have any input?

[Billy Stephens]

I've been on a few job sites recently and noticed different plumbing contractors installing expansion tanks on water heaters but there was not a pressure regulator or reducer existing. I thought expansion tanks were installed only if there was a pressure regulator installed. Is this a new practice, plumber's preference, or just an added safety step? I guess it can't hurt. Anyone have any input?
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Watt's Manufactures Installation Instructions Specifies one is required. ;)
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[Billy Stephens]

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Watt's Manufactures Installation Instructions Specifies one is required. ;)
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Oops
* more detailed instructions.
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[mike pontiero]

Expansion tank is required or a pressure regulator is required. Point is Plumbers are installing expansion tanks even if a pressure regulator is not there. Is that going to effecy anything?

[mike pontiero]

If a home is not getting excessive pressure, then a pressure regulator would not be needed, right? There are alot of homes in Ohio that I have seen without a pressure regulator.

[Billy Stephens]

Expansion tank is required or a pressure regulator is required. Point is Plumbers are installing expansion tanks even if a pressure regulator is not there. Is that going to effecy anything?
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Mike,

The Manufactures Installation Instructions state They Are Required to Properly Install there Product.( as well as a back flow valve check valve.)

If there product is not installed as per the Instructions ( even in Ohio ) it is not Properly Installed.

If there is a water pressure spike that exceeds 150 psi. and the expansion tank bladder ruptures then Watts ( don't know about other Manufactures ) disclaims any damages because there product was Improperly Installed.

[Scott Patterson]

It is very likely that you will find a check valve at the meter. You might check with the local utility to see if they have them in place. If this is the case then you need an expansion tank or valve in place as it is then a closed system.

[Ed Garrett]

Speaking only to the idea behind installing an expansion tank past the water heater ... this installation is limited to addressing ___SMALL___ amounts of heat expansion.

It is not intended as a water hammer device nor is it intended to absorb any inrush of pressure from the supply side.

It is Only intended to prevent a pressure buildup resulting from operation of the water heater (most commonly tankless water heaters with rapid temperature rise). Obviously, in order to prevent pressure buildup there must be a backflow valve somewhere...otherwise pressure will equalize back to the supply....

...If the tank is being installed without a backflow, it will not hurt anything in the system ... it will simply be another part of the entire system subject to the same burst pressures.

Water heater installation is suppose to include a backflow valve. Pressure Regulating is a different "option" dependent on supply conditions. Be careful to differentiate between the two as most "pressure regulators" only regulate in one direction and are __NOT__ backflow valves.

Some pressure regulators work on "flowing" water (turbulent flow designs) and pressure can build through the regulator when flow is shut off (equalization of pressure on both sides of regulator).

If you find an expansion tank w/ a water heater, it should be installed downstream from the Water Heater and a backflow valve should be located on the water heater supply. Some of these specifications are energy specs rather than system safety so you could see variation in "interpretation" depending on your energy codes. The backflow near the water heater on the supply side is intended to stop heated water from thermosiphoning back into the supply. If it is not there, I would call it out as an energy issue even if "thermostatic" couplings (plastic lined couplings with an integrated baffel) are being used.

Ed

[Richard Moore]

Ed...much of what you just posted is just wrong.


It is Only intended to prevent a pressure buildup resulting from operation of the water heater (most commonly tankless water heaters with rapid temperature rise).
Tankless water heaters only operate when water is flowing, when the faucet is opened, so there is no pressure buildup.


Obviously, in order to prevent pressure buildup there must be a backflow valve somewhere...otherwise pressure will equalize back to the supply....
It's the PRESENCE of a backflow valve that can create high pressure and prevents pressure equalizing back to the supply...which, in itself, is not a bad thing.


Water heater installation is suppose to include a backflow valve.
I think you are confusing heat traps with check valves.


Be careful to differentiate between the two as most "pressure regulators" only regulate in one direction and are __NOT__ backflow valves.
No, most pressure reduction valves do indeed effectively act as check (backflow) valves.


Some pressure regulators work on "flowing" water (turbulent flow designs) and pressure can build through the regulator when flow is shut off (equalization of pressure on both sides of regulator).
Huh?


If you find an expansion tank w/ a water heater, it should be installed downstream from the Water Heater and a backflow valve should be located on the water heater supply.
Wrong! Every manufacturers instructions state that the thermal expansion tank should be on the supply side.


The backflow near the water heater on the supply side is intended to stop heated water from thermosiphoning back into the supply. If it is not there, I would call it out as an energy issue even if "thermostatic" couplings (plastic lined couplings with an integrated baffel) are being used.
...and the rest of us wouldn't.

[Scott Patterson]

Sorry Ed, I have to agree with Richard.

Where did you learn what you posted? I'm curious who has told you all of the this. I hope that it is not from a home inspector training school

[Ed Garrett]

Thank you for the corrections Richard.

Despite my initial statement I did not stick with "only".

re: water heater and location of the "expansion" tank, it is on the cold water supply to the water heater as you say. I was thinking of work done on a hydronic system where we installed a "hydronic" expansion tank in the heat loop to handle thermal expansion. This is a closed system plus circulation pump all past the water heater. Mfg specified an expansion tank between the Heat Exchanger in the forced air unit and our hot water source. Forgot we had to special order one to handle the temperature range. Again, should have stuck with the "only"....

Ed