Closed plumbing systems & expansion tanks

[Brian E. Kelly]

Originally Posted by jfunderburk

A builder of a new home is claiming that there is no backflow preventor present on the home and thus no expansion tank is required.

Isn't a backflow preventor integrated into this pressure reducer? Notice the one-way arrow.

Attachment 28482 Attachment 28483

The arrow indicates flow, but does not necessarily indicate ONE WAY flow.

I usually call this a regulator, but that is not important. High pressure enters the up stream side and the pressure is reduced passing thorough the device to an acceptable pressure.

Now, if for any reason the pressure is raised on the down stream side (house side) of the regulator there is no way for it to go back wards through the regulator until the pressure over comes the up stream side (Street side) pressure. And more than likely that is a LOT pressure to overcome or a regulator would not have been installed in the first place.

[Jonathan T. Hittle]

THERMAL EXPANSION CONSIDERATIONS

Installing a pressure reducing valve creates a closed water system. Thermal expansion occurs
in a closed system when water is heated and pressure builds up. A thermal by-pass designed
into the reducing valve can dissipate the expanded pressure back to the service main.
When the system pressure in a closed system increases to a pressure greater than the supply
pressure by just one pound, the o-ring on the stem will flex (see Fig. A) and allow the excess
pressure to be relieved to the supply side until pressures on both the system and supply sides
are equal. When a faucet on the system side in used, thus lowering the pressure, the valve
opens as soon as the system pressure falls below the set outlet pressure, typically 50 lbs.
The valve and the system then return to normal as shown in Fig. B above. The PRVH features

a ball and seat type of check valve as a thermal by-pass but the principle is similar.


I have a State of Ohio Backflow license and I thought I would put in my two cents. Remember backflow requirements vary by municipality and state.

[Bruce A. King]

When did the IRC start requiring a thermal expansion device? 2003?

[Joe Funderburk, CMI]

Originally Posted by bking

When did the IRC start requiring a thermal expansion device? 2003?

It's in the '03 IRC. Here's how it's worded there (P2903.4):

"...an approved device for thermal expansion control shall be installed on any water supply system utilizing storage water heating equipment whenever the building supply pressure exceeds the pressure-reducing valve setting or when any device, such as a pressure-reducing valve, backflow preventer or check valve, is installed that prevents pressure relief through the building supply..."

That's worded differently from 06. If I had read that first, it would have answered my question. Seems plain that a pressure reducer requires a thermal expansion device.

[Brian E. Kelly]

Originally Posted by jfunderburk

It's in the '03 IRC. Here's how it's worded there (P2903.4):

"...an approved device for thermal expansion control shall be installed on any water supply system utilizing storage water heating equipment whenever the building supply pressure exceeds the pressure-reducing valve setting or when any device, such as a pressure-reducing valve, backflow preventer or check valve, is installed that prevents pressure relief through the building supply..."

That's worded differently from 06. If I had read that first, it would have answered my question. Seems plain that a pressure reducer requires a thermal expansion device.

Thanks Joe, I did not want to leave my chair.

And I read it the same as you do.

[tsaunders]

Orange piping is usually reserved for fire suppression systems. If the label on the piping is NIBCO, they are a manufacture of fire sprinkler system piping
Usually the water service would be black.
Very strange

[Wayne B. Wilson]

Well the valve you had shown does not have a back flow with it
Some come with one , Some even have a pressure relief valve. I would say a thermal tank will be in order . The arrow shows the direction of flow some what like valves . Ever seen a valve put in back wards It will reduce flow a fair bit.

[Joe Funderburk, CMI]

Originally Posted by tsaunders

Orange piping is usually reserved for fire suppression systems. If the label on the piping is NIBCO, they are a manufacture of fire sprinkler system piping
Usually the water service would be black.
Very strange

It's PEX isn't it? Is there anything wrong with using it for residential potable water?

[Joe Funderburk, CMI]

Here's something you may wish to use. No charge. Modify to suit your needs.

"The water heater does not have an approved device for thermal control installed (an expansion tank or pressure relief valve). The device's purpose is to prevent spikes in water pressure due to water heating that could damage the internal components of a water heater, cause a leak at the temperature-pressure relief valve, or cause a leak at plumbing fittings elsewhere in the home. Recent changes in today's commonly accepted standards require such a device when a new water heater is installed, but there is no standard that requires an upgrade to an existing unit. Regardless, installation of a thermal expansion control device is recommended to prevent the types of damage described above. A reference document about expansion tanks is attached at the end of this report for your information."

Here's an attachment I include with my reports when I cite this: http://www.aohomeinspection.com/pdf/...on-control.pdf

[Bruce Thompson]

good call on the orange line. i believe it is fire suppression

[Bruce Thompson]

Ok, now I'm not sure. I vaguely remember fire suppression piping using glued joints.

Anyone else got any ideas? Obviously a fire suppression system (if the house had one) would need to be regulated just as the potable system.

[Bruce A. King]

Thats Red Nibco Durapex, lots of used in homes around here, actually the best PEX on the market IMO.

http://www.nibco.com/assets/PEX%20Spools%20NPI.pdf

Look at all of Joe's picture, you can see how it looks redder in some areas, it is kinda orange but the flash on most cameras really makes it look bright orange.

[Brian E. Kelly]

Originally Posted by tsaunders

Orange piping is usually reserved for fire suppression systems. If the label on the piping is NIBCO, they are a manufacture of fire sprinkler system piping
Usually the water service would be black.
Very strange

NIBCO makes everything.

[Michael Leavitt]

I know this is an older 2009 thread, but this InterNACHI thread came up in my Google searches, and the issue raised is an important one that I feel inspectors need to better understand.
In an effort to clear up the confusion shared in the thread above, the typical Watts residential pressure regulator is NOT a backflow prevention device that turns an older home’s open system into a closed system. When you read the specs of the popular Watts Series LFX65B Water Pressure Reducing Valve it clearly states, “Provision shall be made to permit the bypass flow of water back through the valve into the main when pressures, due to thermal expansion on the outlet side of the valve, exceed the pressure in the main supply.” This means that when the house side water pressure exceeds the street pressure that the pressure regulator is designed to bleed pressure back towards the street’s water main... Pressure regulators are NOT backflow prevention devices.
Talk with your local water departments to see how they are handling the closing of older home plumbing systems. Some are taking care of it at the street, some at the meter, and some are doing nothing at all for existing homes until a new water main is installed. It varies from water department to water department. When an older home’s open system becomes a closed system with no thermal expansion device installed, then the water heating cycling strains the water heater’s TPR valve to bleed off the pressure with each cycle. This extra use of the TPR can cause failure creating the first step needed for explosions. Now all you need is for the thermostat or overheating sensors to fail and the electric elements or gas flame will cause the house to go boom and me to have to document yet another catastrophic news story for www.WaterheaterExplosions.com. Let’s all strive to put a stop to the needless water heater explosions.
Hope this helps!
Michael Leavitt - Orem, Utah
www.WaterheaterExplosions.com

[Bruce A. King]

Thanks Michael,

I did some more research into this back in 09 but put it in this other thread:

http://www.nachi.org/forum/f22/therm...unty-nc-43644/