Proper water pressure


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Old 05-26-11, 08:51 PM
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Proper water pressure

Just had a main water line replaced due to storm damage. The plumpers put in PEX tubing and connected to the old glavinized pipe with a pressure regulator. Before the damage of the old main water line we had good pressure (do not know what the pressure was) now the PEX is connected and a water pressure valve was put on. Now pressure will be good when the faucet or washing machine is on then dies down to a small stream of water. I checked the pressure on the outside faucets and the washer faucets and the pressure is at 110 psi. and when faucet, shower, toilet, washer, etc is turn off or filled with water there is this roaring noise until the pressure is built up again. I've never heard or seen this in a old home or even a new home. So what do we do next? Like to be a little educated when I deal with the plumber again. We also have been without water for over 5 weeks so a quick response would be helpful.
 
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Old 05-26-11, 10:20 PM
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Hi.

I will try to answer best I can.

Sounds like you had the main line from the street to your home replaced?
And it was replaced with a Pex/plastic/poly type pipe?
And your home has old galvinized pipes?

1. The pressure to the home should not be over 80 psi. This pressure reducing valve that was installed should be lowered to 80psi max. This is not going to help your pressure issue any.

2. Because they added this device, if it was not there before, has made your homes water system a closed system. A thermal expansion tank is needed. Should be installed at the water heater cold side after the water heater shut off valve.

3. Your pressure lose if most likely your galvinized pipes. They corrode inside, and close up. So a 1" pipe turns into a 1/2" pipe. Now you dont have the volume of water. The pressure will be there when you first open the faucet, but as the water runs the flow and pressure drop. Try watching the gauge and see what the pressure says wiyh water flower from some faucets.

4. How big of a water main did they run? Sometimes during replacement a old 1/2 line is replace with 1/2 because some people dont know better. I would have asked for the main to be 1" if it was me. Gets you more volume(gpm)

5. Possibly when they tied in they loosened some crudein your old pipes and its either clogging the galvinized lines somewhere, or it may just be at your aerators at the faucets, showers, etc... If at all faucets in home, hot and cold, it sounds like the main in the home.

6. You could try blowing your lines with compressed air. It may help, or make it worse it you dont know how to do it. Otherwise I would recommend repipe the whole house with pex.

Summary:
80psi max in home. (Pressure valve is adjustable)
Thermal expansion tank at HWH
Check size of main
Check for blockage in galv pipes and aerators
Check pressure with fixtures running. (post back here)

Hope that helps

Mike NJ
 
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Old 05-27-11, 09:16 AM
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Proper water pressure

Mike,

Thanks for getting back to me so quick. We've been cleaning the crude out of the aerators thoughout the house so there was quite a bit of rust/crude and the main PEX line is a 1" diameter line. I do have a pic of how they connected the PEX to the galvanized pipe and pressure reducing value, but cannot find a way to do this on this site.

Ken
 
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Old 05-27-11, 09:29 AM
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Old 05-27-11, 07:06 PM
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Originally Posted by kenzen View Post
Just had a main water line replaced due to storm damage. I checked the pressure on the outside faucets and the washer faucets and the pressure is at 110 psi.
This is a city water supply? 110 psi is double what it should be. My guess is your measurement is off. How did a storm damage your water line?
 
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Old 05-27-11, 09:19 PM
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Proper water pressure

Mike,

As part of the massive storms that blew through the south our neighborhood had high straight lines wind and a microburst in my neighborhood, blew down 23 trees in a small area. Anyway a large oak fell and tore out about 12 feet of my main water line.

So had a new main water line put in, by the way it did take 5 weeks before we had water, and PEX line 1" diameter was put in as well as a water reducing valve. Even at 110 psi. for example, it takes a small load of clothes about 1.5 hours to wash, my shower (which has a water saving head) hardly has a spray.

Ken
 
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Old 05-27-11, 10:49 PM
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Many (most?) residential pressure reducing valves have an inlet strainer and yours (if fitted) may be partially plugged. You will have to turn off the water ahead of the PRV in order to remove and clean this strainer.

The other possibility is that the PRV is defective and not properly opening the valve when downstream pressure drops. If the pressure downstream of the PRV rises to street pressure when there is no flow the PRV is definitely defective.
 
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Old 05-28-11, 05:56 AM
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Proper water pressure

Okay, so let's the valve's screen is cleaned and I still have the same issue what next? The plumbing company has been out twice so far and will be out again more and likely. One guy indicates that the galvanized pipes are the problem, but before the new main water line and new PRV we had running water with no pressure issues.

I've cleaned out all the screens and aerators in the house except the screen of the PRV so I'll do this when I return. So if I do this and the problem stays the same what are the aternatives at this point besides replacing the galvinized pipes which would cost $3500 at this time. Having the pressure problem is being more frustrating then not having water for 5 weeks, having massive trees down in yard, distroyed garage, and leaking roof from the tornado and hail damage which ocurred 2 days after the first storm.
 
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Old 05-28-11, 12:10 PM
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You need to be able to read the pressure on both the inlet and outlet of the pressure reducing valve (PRV) before being certain of anything. Ideally you would use two pressure gauges but one will suffice. The pressure gauges do not need to be highly accurate but they do need to be repeatable, that is to always go to the same reading when the same pressure is applied. If you have two gauges then they should read the same when the same pressure is applied to either gauge.

When no water is flowing the gauge on the inlet side of the PRV will be reading the street pressure. The outlet side pressure should be in the area of 60 to 75 psi. If the outlet pressure is the same as the inlet pressure then the PRV is leaking through and needs to be rebuilt or replaced. (This is assuming that the adjustment screw has not been turned all the way in.)

When water IS flowing the gauge on the inlet side may drop a bit but the outlet pressure should remain in the 60 to 75 psi range although a slight drop is normal. If the pressure drops below 60 psi then either the PRV is too small or it is malfunctioning. This malfunction could be a partially plugged inlet strainer or a defective regulating valve. If the inlet pressure drops significantly, to near the outlet pressure, then the supply from the water utility is choked from either the utility's valve not being fully opened or the new PEX piping being too small (internal diameter) for the service.

If the pressure readings on both sides of the PRV are normal under both no flow and full flow conditions then the galvanized piping in your house is the problem. This can be further determined by taking pressure readings at the furthest tap in the house under both no flow and full flow conditions AFTER first determining the PRV and supply piping are not the cause of the problem.
 
 

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