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Old 07-20-14, 02:52 PM
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Need a sunday slueth

Hello,

We have been struggling with water problems at our 7-year old house, that seem to have gotten slowly worse over the last year or so. So now, I did some investigating and came up with a relevant diagram.

Our house is fed by a water meter w/ 1" PEX line, and water coming in is about 55 PSI. It reduces to 3/4" line, runs through a pressure regulator I found with my hand going inside the drywall, and feeds the water heater/branches out. The water heater says 50PSI, but my problem can be summed up with this observation: when I activate cold water at point 1 and 2 (e.g., flush a toilet and turn on the hand tap), water pressure drops to about 10 PSI at the water heater. Hot water feeds presumably do the same thing. If i turn on water at points 3,4,5, (e.g., flush a toilet and run a bath while the dishwasher is on), not a drop of water comes out of points 1 and 2.

So basically, at my house, there can only be basically one thing using water at a time. I called the water company and they want me to turn the water regulator nut all the way down into the water pressure regulator, i doubt that would fix anything but i could be wrong.

Does anyone have any ideas for me?

Thanks!!,
 
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Old 07-20-14, 04:03 PM
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Unless this is a fairly new house OR someone recently replaced the service piping from the water meter to the house it is unlikely you have PEX for that service line. PE (polyethylene) IS often used for service lines.

The internal diameter of PEX piping is somewhat smaller than the equivalent in copper and that will reduce the flow rate and subsequently the dynamic (while flowing) pressure. For that reason PEX is usually upsized for main lines. Since one-inch copper is now the "standard" for water service if you have only a 3/4 inch PEX line you are already undersized.

Water pressure decreases with elevation by a little less than 1/2 psi per foot, I think it is 0.433 to be exact. That means with a forty foot rise the top-most outlet would have about 20 psi less pressure than at the meter. Coupled with undersized piping that could be a significant drop.

Your 55psi at the inlet to the pressure regulator is normally sufficient for any two story house provided an adequate supply of water (questionable due to the undersized piping from the meter) and it also is low enough to preclude the necessity of a pressure regulating valve (PRV) in your system.

That you have an increase in pressure to 80 psi at the water heater while only experiencing a high of 60 psi before the PRV tells me that you either have no expansion tank on the water heater or that the expansion tank needs servicing or replacement.

Screwing the adjustment on the PRV all the way in will effectively stop the PRV from regulating to a lower pressure although the PRV itself may be malfunctioning sue to dirt or wear. If it has a strainer (most do) then a clogged strainer would seriously affect flow rate and dynamic pressure. Personally, if it were mine with those water pressures I would completely remove the PRV.
 
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Old 07-20-14, 07:20 PM
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thanks furd

A couple questions: i would need to call a plumber for the 3/4" pex line, unless I read up on it and buy the crimpers, i don't feel confident to install behind the wall unions. Perhaps i have a dual backflow and pressure regulator, i can only feel it out with my hand and can't see it, but that might explain the 5PSI drop or so i see on the other side? Anyway, if i splice it out, is there something else i could put in its place that would serve to block a chunck of metal or something nasty straight to my house? I feel so exposed wtih nothing between the meter and me!

For the water heater, i have an expansion tank, but my water gauge may only have read 80PSI for a split second, don't know, i've never actually seen it above 50PSI despite checking many times, yet hte red needle didn't lie. It is only a n of 1 though, i can try a few more times? The tank is 7 years old now, i suppose best to just replace the whole thing, I just checked my pressure releif valve and at least that seems to be working well.

Yes, it is angering that only 1/2" lines travel upstairs to the bathroom, i'm not sure it would matter all that much though in the end because i think my g/m rate is really low. I can't remember, but when i ran my sprinkler lines 5 years ago, i think i was at like 4 g/m?
 
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Old 07-20-14, 07:46 PM
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First of all, your PRV should have never been "buried" inside the wall as it WILL need servicing at some time. You would be best to cut out the wall for access and then install an access door. Relatively inexpensive plastic doors that are held in place by spring action are available at the big box mega-mart homecenters in the plumbing department. Nicer doors (even stainless steel) are available from Internet supply companies.

You need a shut off valve before the PRV and if you have one then removing the PRV is easy. You can use "Sharkbite" unions to add a short piece of 3/4 inch PEX where the PRV is now located. Having the access door will allow you to periodically "check out" the Sharkbites although they are very dependable when installed according to the instructions. Your worries about "something" coming through the water service piping are unfounded as nothing solid that can harm anything would ever get past the meter. Oh, the 5 psi pressure drop through the PRV is entirely normal and simply the nature of the beast.

As for the expansion tank on the water heater it may simply need to be serviced. Remove the cap from the air valve (looks like a tire valve) and quickly press in the pin. If you get water then the internal bladder is shot and you need to replace the tank. If no water then you need to first ascertain the incoming water pressure at the moment and then close off the feed to the water heater and drain off the pressure by opening a hot tap at any sink. Then using a small air compressor or a hand tire pump add air to the expansion tank until it is at, or slightly above the incoming water pressure. This will allow for the maximum expansion room. Open the cold water feed to the water heater.

The expansion comes from when the water heater has to heat a significant amount of water from cold and in that process the water will expand. The PRV prevents the increasing pressure from "backing up" into the municipal water main and often the water meter itself will have a check valve that prevents back flow. Since water is all but incompressible the expansion causes the water pressure to rise, often dramatically. The expansion tank, with its air cushion gives the expanding water a place to go and limit the pressure rise to only a few psi.

It is probably not the 1/2 inch lines going to to the upstairs as much as the length of the 3/4 inch main lines that is causing the low flow. Unfortunately, unless you are willing to replace the piping all the way back to the meter it is something you will probably have to live with. If your pressure at the house was below 40 psi I might recommend a booster pump but wait until you remove the PRV and see if conditions improve.
 
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Old 07-20-14, 07:53 PM
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IMO from reading this thread you have a faulty PRV...

Its there for a reason and you probably have high pressure...

Replace the PRV and adjust it to aroung 70 psi...( Reinstall in an accessible location as stated...)

As furd stated have the expansion tank serviced also...
 
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Old 07-20-14, 09:11 PM
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I agree the PRV is probably faulty but he also states a maximum reading pressure gauge connected BEFORE the PRV never exceeded 60 psi over a 72 hour period. That alone tells me that no PRV is needed.
 
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Old 07-20-14, 10:09 PM
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but he also states a maximum reading pressure gauge connected BEFORE the PRV never exceeded 60 psi over a 72 hour period.
Faulty gauge??? Could be... need to rule it out IMO..

But i agree... Low street pressure no prv needed... Again its there for a reason
 
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Old 07-21-14, 01:36 AM
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Mike, with the street pressure (at the house) being what the poster states, the only reason for the PRV is that it is likely a tract home and the builder/plumbing subcontractor installs PRVs in EVERY home whether or not it is needed. Or, it could be that the LOCAL code requires a PRV regardless of the static pressure at the house.

I personally see no reason for a PRV when the static pressure at the house is 80 psi or less. I have seen several residential installations where the static pressure is well over 100 psi with no ill effect PROVIDED the piping was done properly.
 
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Old 11-29-14, 05:57 PM
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quick update to the thread, it has been awhile.

Got back after vacation and i flipped on the water, came out for a second, and cut out, thought i forgot to pay the water bill! But then went out to the hose that is on the other side of the PRV and it worked fine....

sooo, off to home depot i go, got a $50 sharkbit crimper tool and some PEX, etc, plucked the PRV out and we are so happy, water and everything back to normal.

The weird thing is that the failed PRV had normal pressure for a second or two, and then couldn't keep up and dropped flow substantially, dunno if that is how they normally fail. Looked into it and it looked like it was about 50% clogged with buildup around the brass fittings, dunno what that is about? Even though i have no PRV now, the pressure is a very reasonable 40PSI throughout now and water is flowing well to upstairs.

The only thing i am still thinking about is running some 1" instead of the 3/4". 1" enters the house and then immediately goes down to 3/4". I'm thinking that if i run 1" to the point where it splits between hot and cold (that are both 3/4"), we'll be able to have 2-3 items running water simultaneously. Right now there is a small but still noticable reduction in the amount of water flowing with 2 items running open, like a shower upstairs and downstairs at the same time.

Wife thinks i'm crazy and it won't work, should i do the re-piping?
 
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Old 11-30-14, 09:58 AM
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If you do a little math you will find that the volume of a 1" pipe is almost double for a 3/4" pipe. Running 1" pipe to the split would increase the volume to that point.
 
 

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