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Author:
Bethrose (Non-US)
New home and water heater replaced as well as pressure relief valve as every time get a bath water comes out of pressure relief valve going under wall and now trim is damaged. Had water commission check water pressure and advised about 72 psi which is great. They noticed builder installed a PRV but said was not required. I believe is considered closed system but not 100%. I read on internet if closed system should have an expansion tank which I do not have. Water commission said I should have PRV removed. Not sure what I should do! Please advise? Thank you
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Author:
stuckinlodi (MO)
I think you are correct, if you have a PRV then it is recommended that you also have an expansion tank. Having a PRV makes it a closed system.
But just to make sure we aren't getting terminology confused, the PRV (pressure reducing valve) is a separate medium-sized unit connected inline with your incoming main water line, its job is to reduce the water pressure from the city water supply and it is adjustable. And then on the side or top of your water heater is a smaller safety valve called the TPR valve, temperature & pressure relief valve. Its job is to let excess pressure or overly hot water out of the water heater by releasing water. So when you said you had a new water heater and pressure relief valve installed you meant the TPR valve, right?
If the city pressure is not too high then you can remove the PRV and not have to get an expansion tank. Water commission recommendation may be correct, and they should know what is needed and what is not needed.
What do your neighbors have? Since they are connected to the same water source and pressure do they have PRV and expansion tank, or neither one of them?
Until you can get it fixed can you place a tub or bucket under the TPR discharge to catch the water in and avoid further damage? Or attach a hose somehow to carry the water to a better place. Don't block, stop-up or close off the TPR discharge, that could lead to excessive pressure in the water heater. The new TPR is doing its job by getting rid of excess pressure inside the water heater. When the water heater heats the water the pressure inside increases. You can try adjusting your water heater temp to a lower setting if you want, that might help with the problem until you decide what to do about the PRV and expansion tank.
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Author:
bernabeu (SC)
The TPR is CODE REQUIRED to discharge to: a safe area where it will create no damage
eg. basement with floor drain - pan with adequate drainage - through wall to exterior (not recommended, but 'legal')
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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638
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Author:
hj (AZ)
quote; through wall to exterior (not recommended, but 'legal')
In this area is is "legal" and almost always REQUIRED.
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Author:
bernabeu (SC)
1.be constructed of an approved material, such as CPVC, copper, polyethylene, galvanized steel, polypropylene, or stainless steel. PVC and other non-approved plastics should not be used since they can easily melt.
2.not be smaller than the diameter of the outlet of the valve it serves (usually no smaller than 3/4".
3.not reduce in size from the valve to the air gap (point of discharge).
4.be as short and as straight as possible so as to avoid undue stress on the valve.
5.be installed so as to drain by flow of gravity.
6.not be trapped, since standing water may become contaminated and backflow into the potable water.
7.discharge to a floor drain, to an indirect waste receptor, or to the outdoors.
8.not be directly connected to the drainage system to prevent backflow of potentially contaminating the potable water.
9.discharge through a visible air gap in the same room as the water-heating appliance.
10.be first piped to an indirect waste receptor such as a bucket through an air gap located in a heated area when discharging to the outdoors in areas subject to freezing, since freezing water could block the pipe.
11.not terminate more than 6 inches (152 mm) above the floor or waste receptor.
12.discharge in a manner that could not cause scalding.
13.discharge in a manner that could not cause structural or property damage.
14.discharge to a termination point that is readily observable by occupants, because discharge indicates that something is wrong, and to prevent unobserved termination capping.
15.be piped independently of other equipment drains, water heater pans, or relief valve discharge piping to the point of discharge.
16.not have valves anywhere.
17.not have tee fittings.
18.not have a threaded connection at the end of the pipe so as to avoid capping.
if you drain it outside you SHOULD have a visible air gap inside AND a 'large bore' discharge pipe
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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638
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Author:
packy (MA)
not by massachusetts code..
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Author:
hj (AZ)
You mean MA has MORE regulations that those?
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Author:
Bethrose (Non-US)
Yes correct have a PRV on main water line and yes to other question. It seems like I should have the PRV removed because my water pressure is fine and hopefully that would not change and end up having to get back on.
Or am I better off just getting an expansion tank to absorb the water that is being released? Is there any pros/cons to either option? Thank you
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Author:
stuckinlodi (MO)
Is is odd that someone added the PRV if it isn't needed. And it is odd they didn't also add the expansion tank once they decided to add the PRV, but many may not consider the expansion tank necessary with a PRV. Something like a PRV isn't added unless they think there could be a problem without it. I suppose they could be required by municipal code and all dwellings get them regardless of actual need.
Since you have a PRV already installed if you added the expansion tank then you'd be ok if the city ever upgrades or does something and your incoming water pressure increases. But that's probably not something likely to happen.
I think adding an expansion tank is easier than removing the PRV. However the expansion tank has a rubber diaphragm inside, it moves back and forth as the water pressure changes, so it could deteriorate after several years and you'd need to repair or replace it. Not a big deal to replace it once you have one installed since the plumbing connection is already in place but it is something that you'd have to deal with. Also, the expansion tank needs to be charged with air pressure to work, that air pressure could leak out over time and you'd need to add more air. Not hard to do but something that may be required. Sort of like having a car tire with a slow leak that you need to take care of now & then.
If you consider that your water pressure is not too high, that you aren't having other problems due to how high it is then your need for a PRV doesn't exist.
Maybe you can leave the PRV in place but adjust it's pressure regulating setting upward to where in effect it is not doing anything, the incoming water would just flow straight thru? That way you can avoid having any plumbing work done. Not sure that can be done, one of the experienced plumbers here can let us know.
Just so you understand, when a water heater heats the water in its tank that water expands and tries to increase the water pressure in the homes water pipes. On homes without a PRV that increase in water pressure is "absorbed" by the city water supply piping system, since there is a direct, unimpeded connection from your house to the city water system (except in rare cases where your water meter has a check valve). But with a PRV installed that increase in water pressure in your home water pipes can't get back out into the city water system and get absorbed. That's why they call it a "closed" system in a home with a PRV installed. So as the water heater heats the water the pressure increases until the water heater TPR valve (safety valve) opens to let excess water out to reduce the pressure back to a lower level. If you add the expansion tank it will absorb that excess water pressure and the water heater TPR valve does not open.
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Author:
bernabeu (SC)
simply install a bypass around the PRV and leave it open
==============================================
"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638
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Author:
Bethrose (Non-US)
I found out the PRV I have does have a bypass so would you recommend an expansion tank? Thanks
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Author:
stuckinlodi (MO)
If you open the bypass so that your water flows thru the bypass instead of thru the PRV then your house water supply plumbing is connected directly to the city water supply, it is no longer a "closed" system so you won't need an expansion tank. The excess pressure when your water heater heats the water will get absorbed by the city water supply system. Do you know how or can you find out how to set the bypass so it is open and water flows thru it? Open or turnon the bypass and see if the water stops leaking from the water heater safety valve (TPR).
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Author:
Bethrose (Non-US)
The PRV is one part and the bypass is built in it so do you mean to turn the bolt to open it up more and by doing this it opens it up?
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Author:
stuckinlodi (MO)
No, don't adjust the PRV bolt. I thought you meant you already have a bypass pipe that goes around the PRV.
The bolt on the PRV is for setting the pressure you want in your home's water supply plumbing. A typical PRV has a range of 25psi to 75psi, generally you set it at 50 psi but can make adjustments if needed. As the bolt is screwed in (turned clockwise) the water pressure in the home is increased. Many PRV's today have a builtin bypass feature to help reduce the effect of increased water pressure when the water heater heats its water. But this type of internal bypass is not perfect.
I think what bernabeu meant earlier when he said to install a bypass was to have someone add a new pipe that goes around the PRV. That type of bypass would eliminate the effect of the PRV completely and give you an "open" system. If the new bypass pipe that is added has an inline shutoff valve you would leave it open but could close it in the future if you wanted to start using the PRV.
If you can talk to a local plumber ask which would be lower cost: to install a bypass pipe around your PRV (or remove the PRV) or to install an expansion tank. See what he says.
Can you post a photo of your PRV?
This is roughly how a bypass pipe around the PRV would look:
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Author:
Bethrose (Non-US)
No I do not have the bypass like photo, only the PRV. It is an Apollo USA model and supposedly they said the bypass is inside. But obviously it doesn't work very well. I will get a plumber and do what you suggest as better option. Thanks
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Author:
stuckinlodi (MO)
Tell your plumber what you are trying to fix (water leaking out of water heater TPR safety valve), that the water commission guy said a PRV is not needed in your neigborhood and that you don't have an expansion tank. So you either need an expansion tank added OR the PRV removed or bypassed. He should understand fully what you need and be able to give you quotes on the cost of your choices. If you'd like to keep the PRV installed just in case it is needed in the future then have him leave it in place and add the bypass pipe around it.
He may say that leaving everything like it is and adding an expansion tank is the easiest and lowest cost thing to do. That would also take care of the water leaking from the TPR. Make sure you understand the possible maintenance chores that go with having an expansion tank, they last several years but can fail and need to be replaced. If the plumber does install an expansion tank be sure he puts it on the cold water side of the water heater, not the hot water side.
Also ask him to take a look at your water heater TPR drain line and see if it can be routed differently so it doesn't cause any more damage to the wall like it has been doing. In many places it is ok to run it outside the building or over to a foundation sump.
Good luck!
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