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  1. #1
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    Default CPVC hot-water piping issues

    I am a new inspector. It is the 1st time I see CPVC piping for hot/cool water. Is there anything I should comment properly?

    The heater is electric.

    Thanks a lot.

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  2. #2
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    Default Re: CPVC hot-water piping issues

    I have no problem with the material. I saw a condo with it, yesterday, One thing to look for is that it is properly supported and the the glue isn't gooped all over the joints. Excess glue can actually weaken the plastic.

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    Default Re: CPVC hot-water piping issues

    Its approved for hot and cold water in most if not all areas.


  4. #4

    Default Re: CPVC hot-water piping issues

    It is an approved material. However it does become brittle over time and it is subject to freezing and cracking so depending on your location you may want to include additional information.
    Also the loop that connects what appears to be the cold supply to the relief drain pie has some device I could not see well and do not know why it is there?

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    Default Re: CPVC hot-water piping issues

    That there TPR discharge pipe should not be connected to anything except the relief valve.

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    Default Re: CPVC hot-water piping issues

    Is that some sort of air hammer control device at the top of the "T" on the cold water inlet?

    I, too, have never seen that.

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    Default Re: CPVC hot-water piping issues

    I see your located in Canada. As far as I know CPVC is approved in all US states. I see it mostly in manufactured homes. I occationally see it older homes, homeowners install it becasue it's easy to work with. Be aware of the diffences between CPVC and PVC. PVC pipe is not rated for hot water temperatures, and in most cases it's not allowed for residential plumbing. In most areas PVC is allowed be used for the incoming water supply line. Also be aware that CPVC feezes and cracks more easily than most other materials. It should be well insulated if it's located in a crawlspace or unheated area.


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    Default Re: CPVC hot-water piping issues

    Quote Originally Posted by Trent Tarter View Post
    In most areas PVC is allowed be used for the incoming water supply line.
    Most codes limit the use of PVC for water service piping from the meter (outside the house) to the outside edge of the foundation wall (not inside the house), which is where the service shut off valve is also usually located.

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    Default Re: CPVC hot-water piping issues

    CPVC was very popular with DYI'ers in BC before poly B arrived on the scene.
    I would describe the piping. Also this comment - Amateur plumbing, so there may be hidden defects.
    I would call for that discharge tube to be corrected.
    That must be a pressure relief valve to the right of the check valve in place of an expansion tank, with a discharge tube connected to the TPRV. He should have simply run two separate pipes for discharge.

    That device on top of the cold pipe is a vacuum relief valve missing its plastic hood.

    Last edited by John Kogel; 01-16-2013 at 09:38 PM.
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    Default Re: CPVC hot-water piping issues

    Why do I have the weird feeling someone tried to create a hot water convection loop. I have a funny feeling the device in the vertical position is a check valve and the TPR piping is running down the side of the water heater and tying into the drain valve. I hope I am completely wrong as this could be a possible ticking time bomb since the TPR would fail to work properly if needed... tick-tick-tick

    The odd part on top of the "T" after the shut-off valve might be a vacuum relief valve??? Which might explain the possible "Y" strainer check valve before it... why it's there, no idea... other than I think they had parts from a boiler and did the best they could with a water heater... it's just a guess...


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    Default Re: CPVC hot-water piping issues

    A Vacuum Relief valve at or near the water heater is standard practice here. It prevents the tank from siphoning out if there is a loss of water pressure.

    The check valve at the supply pipe allows pressure to build up in the system. Coupled with aging plastic pipe, it is potential trouble.

    The device to the right is not a substitute for an expansion tank or valve situated where it is, AFAIK. A real plumber should check it out.

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    Default Re: CPVC hot-water piping issues

    Could that be a trap primer? That's what it looks like from here.

    Jim Robinson
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    Default Re: CPVC hot-water piping issues

    Quote Originally Posted by John Kogel View Post
    A Vacuum Relief valve at or near the water heater is standard practice here. It prevents the tank from siphoning out if there is a loss of water pressure.

    The check valve at the supply pipe allows pressure to build up in the system. Coupled with aging plastic pipe, it is potential trouble.

    The device to the right is not a substitute for an expansion tank or valve situated where it is, AFAIK. A real plumber should check it out.
    I have never seen a vacuum relief valve on a water heater. Is that common or required in Canada?

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    Default Re: CPVC hot-water piping issues

    I'm sure it varies place to place, usually you will not find vacuum relief valves on top fed water heaters, at least around here. I believe bottom fed heaters require them, and I've heard of them being installed on units that are above fixtures, but those could be requirements from the manufacturers. You might also come across them in areas where storage tanks are used, but those are few and far between around here.


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    Default Re: CPVC hot-water piping issues

    Quote Originally Posted by Mike Kleisch View Post
    I'm sure it varies place to place, usually you will not find vacuum relief valves on top fed water heaters, at least around here. I believe bottom fed heaters require them, and I've heard of them being installed on units that are above fixtures, but those could be requirements from the manufacturers. You might also come across them in areas where storage tanks are used, but those are few and far between around here.
    From the IRC:
    - P2803.7 Vacuum-relief valve.
    - - Bottom fed tank-type water heaters and bottom fed tanks connected to water heaters shall have a vacuum-relief valve installed that complies with ANSI Z21.22.

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    Default Re: CPVC hot-water piping issues

    Quote Originally Posted by Lon Henderson View Post
    I have never seen a vacuum relief valve on a water heater. Is that common or required in Canada?
    It is common enough to appear to be required here, if that makes any sense to you. Yes, required in my little corner of Canada.

    I don't scream blue murder if the VRV is not installed, just note that it is not there.
    I have read that modern top feed heaters have a hole near the top of the feed tube which breaks the siphon. I suppose the hole could be rusted shut. So could the valve.

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    Default Re: CPVC hot-water piping issues

    Quote Originally Posted by Jerry Peck View Post
    Most codes limit the use of PVC for water service piping from the meter (outside the house) to the outside edge of the foundation wall (not inside the house), which is where the service shut off valve is also usually located.
    Typically I see PVC used on private wells, not from city meter to home.


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    Default Re: CPVC hot-water piping issues

    Quote Originally Posted by Jerry Peck View Post
    From the IRC:
    - P2803.7 Vacuum-relief valve.
    - - Bottom fed tank-type water heaters and bottom fed tanks connected to water heaters shall have a vacuum-relief valve installed that complies with ANSI Z21.22.
    I "cough" didn't know that. I just saw a bottom fed hot water storage tank that didn't have a vacuum relief valve. Does this code cover passive storage tanks, too?

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    Default Re: CPVC hot-water piping issues

    Quote Originally Posted by Lon Henderson View Post
    Does this code cover passive storage tanks, too?
    If the passive storage tank is bottom fed and connected to a water heater, yes.

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    Question whazzat?

    Is that some sort of backflow preventer with atmospheric vent that is tied into the TPR discharge?

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    Default Re: CPVC hot-water piping issues

    Quote Originally Posted by Jerry Peck View Post
    If the passive storage tank is bottom fed and connected to a water heater, yes.
    The storage tank is being fed from a boiler that heats both the domestic use water and the water used for the radiant floor heat. I rarely see these bottom fed heaters or storage tanks. It turns out that the system was put in with a permit and inspected. Apparently, the city inspector didn't know a vacuum relief valve was required with this configuration, either. This discussion was timely for me.

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    Default Re: CPVC hot-water piping issues

    My father had CPVC installed in their house when was built in 1970.
    The only other option was copper at the time and CPVC had just been approved in their county. Is a ranch with crawl space, 5-4 foot head room. No pipes are insulated and never a leak or freeze up and in the Atlanta, Ga area. Was there not long ago and the pipe still are in great shape.
    My dad had told me that my grandfather, who's house was across the street originally had copper pipe, but that he was diagnosed with cooper sulfate poisoning was then determined coming from the copper pipe in the house and they ripped out all the copper and put the CPVC in my grandfathers house afterwards did not have the health problems anymore so my dad had decided to use CPVC also for his house.
    Well that was the story.


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    Default Re: CPVC hot-water piping issues

    In 16 years of inspecting, I have never seen a water heater plumbed like hthis. Could someone explain to me what a vacuum relief valve is / does?

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    Default Re: CPVC hot-water piping issues

    Quote Originally Posted by Benjamin Thompson View Post
    In 16 years of inspecting, I have never seen a water heater plumbed like this. Could someone explain to me what a vacuum relief valve is / does?
    Post #11, it lets a bit of air in if there is negative pressure in the plumbing pipe (vacuum).

    This only happens if there is a failure of pressure in the lines of course. But if this happens, the tank could empty and the electric elements would burn out, not sure about gas burners.

    On a plumbing forum, somebody suggested the tank would collapse if water drained out and a vacuum was created in the tank. I suggest the water would not drain out if the vacuum was that strong. Air would be forced back up the pipe, IMO.

    There is normally a black plastic cap on top. Here's a pic new construction and old. The second tank is in a basement. It would take some terrific vacuum to suck water from that tank out to the street, wouldn't you say? .

    I think the valve's real purpose is to facilitate draining of the tank. You don't need to open a tap. Lazy people in the plumbing industry maybe pushed for those things to be mandatory.

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    Default Re: CPVC hot-water piping issues

    Quote Originally Posted by John Kogel View Post
    I think the valve's real purpose is to facilitate draining of the tank. You don't need to open a tap.
    Nope, the purpose is to avoid back feeding into the tank when pressure is lost, think of it as basically being the same thing (it is) and serving the same purpose (it does) as a hose bibb atmospheric vacuum breaker (it is a atmospheric vacuum breaker).

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    Default Re: CPVC hot-water piping issues

    Thanks, Jerry. So it is a good thing and everybody should have one, right?

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    Default Re: CPVC hot-water piping issues

    Just a little observation from California. Does anybody else think the strapping is inadequate to prevent side movement of the tank and the resultant pressure on the now brittle plastic piping? What about the pressure buildup with no expansion tank and a check valve on the incoming line?


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    Default Re: CPVC hot-water piping issues

    Quote Originally Posted by William Cline View Post
    Just a little observation from California. Does anybody else think the strapping is inadequate to prevent side movement of the tank and the resultant pressure on the now brittle plastic piping? What about the pressure buildup with no expansion tank and a check valve on the incoming line?
    Strapping is a regional requirement. Not required here. It may surprise non Coloradans, that we get micro earthquakes around 3.0 occasionally.

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    Default Re: CPVC hot-water piping issues

    I was taught that “Vacuum Relief Valves” and “Vacuum Breakers” are different devices.

    In basic terms:

    Vacuum Relief Valves (eliminates vacuum when it occurs) allow air into the system to prevent siphoning, to prevent a water heater from draining empty and operating while dry, or prevent the possible collapse of tanks, such as fiberglass ones (pic). They are designed to sit under constant pressure and are only needed to allow air in, and not provide backflow protection as water does not flow through them.

    Vacuum Breakers (prevent vacuum from occurring) prevent the backflow of water into the system, since water flows through them, thus contaminated water does not enter the water supply. These would normally be installed at the points of discharge after shut-offs, such as a hose bib, above mop sinks, or anywhere you want protection of the water supply to end. And, assuming nothing elaborate is required. Regular Atmospheric Vacuum Breakers are not designed for constant pressure and could fail to provide backflow protection if installed before any shut-offs.

    This fiberglass storage tank was bottom fed, with no relief valve:




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    Default Re: CPVC hot-water piping issues

    Thanks, Mike. So we are back to the device in the OP's and my pics is an anti-siphon device which is most likely redundant in a top fed water heater? And even more so when the tank is on a ground floor or in a basement?

    Nice pic, BTW.

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    Default Re: CPVC hot-water piping issues

    Quote Originally Posted by John Kogel View Post
    Thanks, Mike. So we are back to the device in the OP's and my pics is an anti-siphon device which is most likely redundant in a top fed water heater? And even more so when the tank is on a ground floor or in a basement?

    Nice pic, BTW.
    Yup, I agree, and relief valves are not required on top fed units around here. I can see the need if the tank is above the fixtures, say on a 1st floor, and you have a sink in the basement??? Same idea as siphoning gas out of your neighbor's car into a gas can, high to low. And, this is why we always turn off the water heater when draining lines kids. Plumbers I know open the highest faucet and the lowest facet to let air in to drain the lines, otherwise you might be waiting awhile, and you can still hear the water heater gurgle a little bit sometimes.


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