PRV??

[mathew stouffer]

I have never seen one of these before. Is this a PRV and is it adjustible.

[Jim Luttrall]

No, does not appear to be a pressure reducing valve. Looks like this:
Watts Brass & Tubular 3/4" Back Flo Preventer LF7U2-2 3/4 (http://www.google.com/products/catalog?q=watts+dual+check+valve+backflow+prevente r&hl=en&client=firefox-a&hs=72f&rls=org.mozilla:en-US:official&prmd=ivns&bav=on.2,or.r_gc.r_pw.&biw=1280&bih=530&um=1&ie=UTF-8&cid=147699748049026334&sa=X&ei=dLjCTeGOEsfL0QGXlf3sAw&ved=0CHgQ8wIwAg#)

A simple check valve.

[Ray Norton]

That's a double check valve used to protect the municipal water supply. It is probably required by that particular Public/ Water Works Department/ Agency. They can also be required on sprinklered homes but judging by by what I can see of where that one is located the home is not sprinklered. It is not uncommon for those to be required to be inspected annually.

[Scott Patterson]

I have never seen one of these before. Is this a PRV and is it adjustible.

It is a "check" valve as Jim & Ray noted. Now with that little critter installed you now have a closed system and that requires an expansion tank or valve to be installed. I did not see one in the picture.

[Ray Norton]

I would expect to see the expansion tank at the water heater, not at the meter, to absorb the extra pressure caused by the expansion of the heated water.

[Scott Patterson]

I would expect to see the expansion tank at the water heater, not at the meter, to absorb the extra pressure caused by the expansion of the heated water.

True, for some reason I thought the WH was under the meter in that picture. I think I need to lay off the chocolate chip cookies for my afternoon snack! :)

[Rick Cantrell]

"That's a double check..."

Close.
Thats a "Duel check valve", they are not the same as a double check.

"It is not uncommon for those to be required to be inspected annually."
Duel checks are not able to be tested, therefore they are not inspected.
Double checks can be tested and are inspected annually.

But both do serve the same purpose.

[James Duffin]

I would expect to see the expansion tank at the water heater, not at the meter, to absorb the extra pressure caused by the expansion of the heated water.

Since the code in NC now requires a backup drain pan under an expansion tank under same conditions one is required for a water heater I am seeing more expansion tanks in crawl spaces.

[mathew stouffer]

James is that new in the 09 irc

[James Duffin]

James is that new in the 09 irc

In NC an expansion tank is considered a hot water storage tank so the following code applies.



504.7 Required pan. Where water heaters or hot water storage
tanks are installed in: (a) remote locations such as a suspended
ceiling (b) attics (c) above occupied spaces or (d) unyentilated
crawI spaces the tank or water heater shall be installed in
a galvanized steel pan having a minimum thickness of 24 gage,
or other pans approved for such use.
Exceptions:
L Electric water heaters may rest in a high-impact plastic
pan of at least lL16 inch (1 6 mill) thickness

2. Water heater mounted on concrete floor for floor

~

504.7.1 Pan size and drain. The pan shall be not less than
1.5 inches (38 mm) deep and shall be of sufficient size and
shape to receive all dripping or condensate from the tank or
water heater. The pan shall be drained by an indirect waste
pipe having a minimum diameter of 0.75 inch (19 mm). Pip- I

ing for safety pan drains shall be of those materials listed in
Table 605.4.

[R.A .McBride]

Since the code in NC now requires a backup drain pan under an expansion tank under same conditions one is required for a water heater I am seeing more expansion tanks in crawl spaces.
What code is N.C. under?

[James Duffin]

What code is N.C. under?



The 2009 NC Plumbing code is based on the 2006 International Plumbing Code with NC amendments.

[Tom Thompson]

True, for some reason I thought the WH was under the meter in that picture. I think I need to lay off the chocolate chip cookies for my afternoon snack! :)
Scott; Installations of expansion tanks require check valves on cold inlet to heaters making the hot system closed it's self.

[Bruce Low]

Says right on it......... Check Valve, the technical term for a backflow preventer.

The Bottom Line - Through an Engineer's Eyes

[Zibby Bujno]

Its BFP (baclflow preventer) - this particular model usually is installed at closed hydronic systems (forced hot water) and water makeup line. Since its installed on main water feed for the house, make sure all water heaters have expansion tank!! Otherwise all PRVs will be leaking.

[Mike Schulz]

James,

NC amendments., can you post the verbiage because I do alot of new construction and have not yet seen a pan under the expansion tank in an attic or garage.

Thanks

[Tom Thompson]

James,

NC amendments., can you post the verbiage because I do alot of new construction and have not yet seen a pan under the expansion tank in an attic or garage.

Thanks
It's recommended by the manufacture, they do go bad. I've had several (most) fail in 2-3 years.