Hot Topics: What Is the Correct Water Pressure for a House?
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Hi, All! I have posted before about the water hammer noise in our home (started with one toilet, then both, then the clothes washer), and the noise has been getting progressively worse. Thought about just buying a water hammer arrestor, but since the sound is getting progressively louder, and after some good advice here, I am looking at the pressure regulator (PRV) at the front of the house. Incidentally, we don't have an expansion tank in our Southern California home built in 2002, but the inside plumbing is all a PEX system.
I put a gate water pressure gauge on the water spigot, which is just before the 3/4 inch pipe goes into the house. Here is where I am a bit confused: what exactly should the water pressure be at? Some say 30 to 50 PSI, some say 40 to 60 PSI. A few YouTube videos made by plumbers say 70 or even 80 PSI is OK. So, which is it?
In our case, I am getting a base pressure of 70 PSI (black needle), and the red needle (MAX pressure) shows 100 PSI. My understanding is that the black needle shows the static pressure, and the red needle shows the most the water pressure PSI has been since it was last reset. Is that correct? If so, does the fact that the max pressure is 100 PSI, even if only for a short time, mean there is a problem with the water pressure? Or is it normal to have pressure spikes and that I should only care about the base pressure?
Finally, if the consensus here is to adjust and, if need be, to rebuild or replace the valve (Watts LFN45B), how do I do that? I know how to adjust the pressure (by screwing in/out the screw), but how do I open up the valve to rebuild it? The rep at Watts gave me the part number (0006960), which doesn't include the diaphragm or big spring—just a black plastic thing with a screen on it, along with two o-rings. However, I don't know if there is a rebuild kit that replaces all the guts inside. Does anyone know if there is one?
Thanks in advance to all who offer help or advice.
Pilot Dane Group Moderator
There is no "right" water pressure. I generally go for a max of 60-80 PSI.
There is no standard for pressure gauges. You will have to look at what you purchased and determine what each color needle is indicating. But, you shouldn't be seeing spikes above your set pressure. Have you spent some time watching the gauge to determine when and why it's spiking?
marksr Forum Topic Moderator
I'd have to dig up my pressure gauge to see which needle is what color, but the gauge will read the current pressure as soon as it's screwed in and the valve is opened. The other needle records the highest pressure while it's in operation.
I live on top of a hill and don't have a pressure reducer valve. My pressure averages between 20 and 40 PSI with nightly spikes up to 60 PSI. It sounds to me like your PRV isn't working correctly. While I've adjusted them, I've never repaired one—only replaced defective ones. They can last decades or crap out in just a few years.
Do you have an expansion tank in your water system, usually mounted near the water heater? If not, or if such a tank is worn out, then you can get unusually high pressure in your water system.
From the instructions on the water pressure gauge package, the black needle is the base/constant water pressure, and it goes to 70 PSI right when I put it on the front spigot and turn on the water. The red needle shows the highest water pressure and it sits at 100 PSI. We don't have an expansion tank and I have not been out there to see what goes on/off that drives the red needle to 100 PSI. I guess my question is if a PRV should ever let the water pressure jump to 100, even for a short time? If not, then the PRV is defective.
marksr Forum Topic Moderator
You did reset the red needle to zero before you hooked up the gauge, right? It doesn't automatically go to zero like the black needle does.