Water Pressure Question

[SAS]

I have reasonable water pressure throughout most of the house, but the master bath, particularly the shower, varies between very low and mediocre pressure. I have changed shower heads, but that clearly isn't the issue. I suspect that when the previous owner had that bath completely renovated, something in the plumbing has caused an issue. I also have noticed that when I am showering, any use of the water elsewhere in the house immediately lowers the water pressure in the shower quite a bit.

So I though that maybe the simplest answer would be a slight increas to the pressure reducing valve. And then I remembered that there is a pressure gauge on the input side of the water softener. Here's what that looks like:

That would seem to indicate that the pressure is already higher than it should be. Or am I misunderstanding something (or do I need a new gauge)?

 

[John Gayewski]

Your pressure is too high. Turn it down and see how the gauge reacts. Generally if the gauge is moving the gauge is OK.

 

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[SAS]

I've ordered a second gauge that I can attach to the outdoor hosecock. I also noticed that when just one toilet is filling the pressure drops down to 34. Is that an excessive drop?

 

[GReynolds929]

If the gauge is after your PRV it has most likely failed.

 

[John Gayewski]

I've ordered a second gauge that I can attach to the outdoor hosecock. I also noticed that when just one toilet is filling the pressure drops down to 34. Is that an excessive drop?

Yes that drop would be excessive.

 

[EdwardGab]

Pleased to read this! Excellent facts and the caliber of fine detail provided is awesome!
Have a great day!

 

[Jeff H Young]

if the entire house is cpvc we could eliminate possibilty of a kinked line like soft copper. could be rocks or something plugged in the pipes Ive had to back flush befor. is it the hot or cold ? on showers it might be both if pressure ballaced valve is used try putting guages at the lav on cold and hot and see the diferential but you gotta figure out which side is bad so you know where to look. Also you need to eliminate if the cause is at the valve

 

[SAS]

I've received the second gauge and hooked it up to the outside hosecock. It's the first branch off of the main. I get a different reading on this gauge, but it is still quite high at 80 psi. I also tried adjusting the Zurn NR3XL pressure reducing valve to lower the pressure, but the adjustment did not affect the reading on either of the gauges. I'm not sure if the difference between the gauges is due to the fact that the new one is installed before any significant pipe runs, but I'm pretty sure that the PRV is not working properly. I've ordered a repair kit for it and I'll see if that does the trick. I saw a YouTube video where someone had the same issues (high pressure readings on the gauge but very steep drop off as soon as any valve was opened) and replacing the innards of his NR3XL solved the problem. Wish me luck!

 

[Reach4]

Are you sure the sillcock is downstream of the PRV? When adjusting the PRV, you should be trickling water.

 

[Jeff H Young]

rebuild or replace the Regulator, add x tank Actually I got your issue confused with another posting but if your regulator isnt working proper get that kit or replace it . probebly should add the x tank even though thats not your problem.
very true a regulator can produce high pressure but low volume but again not sure this applys to your case

 

[SAS]

Are you sure the sillcock is downstream of the PRV? When adjusting the PRV, you should be trickling water.

Yes, the sillcock is definitely downstream of the PRV. In fact, even the meter is downstream of the PRV. There is a shutoff valve before the PRV, then the meter, then another shut off valve. My plan is to turn off the first valve, open a faucet to relieve the pressure and then turn of the second valve before I start working on repairing the PRV.

I tried adjusting the PRV another quarter turn while trickling some water, but it has not affected the pressure readings.

 

[SAS]

So I've replaced the innards of the PRV and the everything seems to be working fine now. I do have one dilemma, however. The new gauge that I installed on the sillcock shows a pressure of 76 while the old gauge that is installed just before the water softener shows 83. Other than mechancical incaccuracy, is there any reason to expect this discrepancy? Would the pressure increase after several dozen feet of pipe run? The outside sillcock is the very first branch after the PRV and water meter while the inside gauge is at least a 30 foot run of pipe farther downstream. Also, if the inside gauge is correct, do I need to lower the pressure? How critical is it to stay below 80 psi?

 

[Jeff H Young]

I dont think its critical at all. But I dont think that higher pressure outside of what is recomended by any authority is better than keeping it at normal pressure. its not going to cause a blow out but you might get a blow out years sooner everything fails you just make it happen sooner

 

[John Gayewski]

You will lose about 1/2 psi as the elevation climbs. So how much higher in elevation is the hose bib?

 

[SAS]

You will lose about 1/2 psi as the elevation climbs. So how much higher in elevation is the hose bib?

I'm guessing that's 1/2 psi/foot? It's about 4 feet, so that would account for about 2 psi of the 7 psi difference. For now, I've set the PRV so that the gauge on the hose bib reads 70 psi and the indoor gauge reads 77 psi. At that level the water pressure in the house seems to be fine and at somewhere between 70 and 77 psi I'm at a safe level.

 

[Reach4]

Do both gauges indicate zero when the water pressure is zero?

A 100 psi gauge will normally be easier to read than a 200 psi gauge,

See if you can compare to a third gauge.

 

[SAS]

Do both gauges indicate zero when the water pressure is zero?

A 100 psi gauge will normally be easier to read than a 200 psi gauge,

See if you can compare to a third gauge.

I was going to get another gauge, but I now have a more pressing issue. I just checked the gauges and they were both around 100 psi! I can't imagine what caused the spike, but I ran some water to lower the pressure and adjusted the PRV quite a bit. I'm not sure how long you need to wait after adjusting the valve before you can accurately judge the pressure. If I keep getting these spikes I'll have to either figure out what's causing it or call in a plumber.

 

[Reach4]

Maybe your thermal expansion tank is not working. Set the air precharge to whatever the PRV is set to. Air precharge is measured and set when the water pressure is zero.

 

[SAS]

Maybe your thermal expansion tank is not working. Set the air precharge to whatever the PRV is set to. Air precharge is measured and set when the water pressure is zero.

I think that may be the issue. I've lowered the pressure to about 50 psi and I'm going to buy a gauge with a lazy hand to see if that spike is a recurring problem. Examining the expansion tank is going to be a challenge. It's installed horizonatlly above the water heater with only 1-2 inches between the valve end and the wall. I think there's a plastic cover over the valve but it's angled so that I can only see it with a mirror or with my phone camera.

 

[SAS]

What is the best/simplest way to depressurize the system so that I can check the pressure in the expansion tank? Just turn off the water main and open a faucet until the system pressure goes to zero? Or shut off the valve that feeds the hot water heater and drain some (how much?) water from the bottom of the heater?