So I've been having some strange water pressure in my house for some time now. We have city water. Sometimes we just notice it coming out of the sink extra fast. And then I found the pressure relief valve on my water heater opened a few times. Lastly I have a water pressure guage installed a few feet from where the water comes into our house. It's been all over over place.

First thing I did was replace the Guage to confirm there is an issue with the pressure coming in.

Here's a picture. is this something an intermediate DIYer can replace or is this a plumbers job. As I'm writing this I'm thinking professional job, basically the water outside the house must need to be shut off first?

 

How did you change the pressure gauge if the water supply shut off valve is faulty?

 

Great question beezlebob. I also just learned that it can also be the hot water expansion tank, which I had installed about 10 yrs ago. So with that and your point maybe it's not the reducing valve.

So I installed another pressuee Guage onto the water heater. This one has a current and a high point marker on it. Black and red needles. So I'll watch and see.

 

The pictures are showing the pressure reducing valve/PRV. Is that what you think is faulty? Or the one behind it that appears to be a ball valve in the OFF position? Where is the meter in relation to the PRV? To the left unseen, or outside the wall beyond the ball valve?

Adding a pressure gauge at the water heater will not show any different than the original gauge unless you can isolate the hot water system from the cold (and how would it get pressure?). You should check the HW expansion tank to make sure it is not waterlogged.

 

You can usually tell whether it's a faulty PRV or faulty pressure tank by determining when the pressure increase happens.

A bad PRV will exhibit high pressure randomly throughout the day regardless of your water usage.

A bad pressure tank will show normal pressure as you're using the water. When the water isn't used for a few hours (in the morning, or a few hours after a shower), then you'll get the splash of high pressure, which will then relax back to normal.

 

How does the title fit in ?
Faulty water main shut off doesn't affect water pressure.
If your gauge is all over the place the PRV in the picture is defective.
It is an easy job to replace.

Watts LF25AUB prv

 

OK thank you this helps alot. I wasnt sure what the part was called but, yes, its the PRV that I was talking about.

I placed the pressure gauge on the faucet in my laundry tub earlier tonight, while we were all home and using water. 3 people showered as well. And now I'm seeing it with a steady reading of @50PSI with a high reading of 140PSI. Wow. Had no idea it was this bad.

So based on what you've all said it sounds like this means I have a bad PRV and should be easy to replace. Been watching videos and seems straightforward.

Will tackle this one tomorrow and post updates!

 

Some PRVs have kits to refurbish them including new filter screens (at the bottom). Even if you have to replace yours (due to cost of a kit vs.new PRV) you have the correct fittings (union, etc.) to do it easily.

However Zorfdt's hot water comments may apply and the PRV may be fine as is.

The PRV will reduce the incoming pressure but it does not affect pressure created on its load side (i.e. pressure created by heating the water.) The safety valve on the hot water heater will open to relieve that excess pressure if above its limit.

If you are using a gauge that records the highest pressure, it may be seeing an instantaneous water hammer event caused by closing a valve quickly (washing machine, dishwasher).

 

Interesting. The one thing I'll call out is that it was at a constant 120 or 140 (cant remember) for awhile last night. At least 20-30 mins, Could that be when the HW heater was heating up all the water after 3 showers?
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Could be.

A HW T&P valve is usually set for 150 psi (and 210 degrees). Any pressure that builds up in the pipes from the water heating will be relieved when any (hot or cold) faucet is opened. If the pressure goes above 150 the T&P valve will open and relieve the pressure.

The pressure builds up because the PRV prevents it from going back into the municipal system. A pressure tank or device before the inlet of the hot water heater provides an air buffer to accommodate the pressure build-up. If that buffer is waterlogged the pressure will show up in the pipes.

 

Hmmm ok. How can I determine if the pressure tank is water logged?


BTW this is what I have when I say I have an expansion tank for my HW heater (not an actual picture just one from the web)

 

No image. You posted some before so I know you know how to do it. Maybe something went wrong in Edit mode. Use "Go Advanced-Manage Attachments" if necessary.

 

Darn. I can see it in my post from my computer. heres a link to the image

https://homeinspectioninsider.com/wp...vice%2Frscb2-2

Tank Image

 

Relax.... your image is there and quite visible.

Shut the water main off. Shut the water heater off..... put in pilot only if gas.
Drain water out of hot and cold at any faucet.
Check for air pressure at Schrader fitting on pressure tank using gauge like what is used for tires.

 

ok great. thanks! I'll try this tonight

 

Ok so I just followed the steps above. Water main off, water heater on pilot only, all hot and water drained from house.

I used a reliable tire Guage and it's reading zero psi. Tried a few times. I did shake the tank a bit and heard water sloshing.

does this mean it's water logged? Will do some searching online.

 

Recommended pressure is between 50 and 60 psi. Since your PRV is marked 55 psi you could pressurize the tank to that. Use a bicycle pump or compressor.

PS. The image problem is with Safari on my computer. I can see the images on an iPad and in Firefox.

 

Ok so I was doing some reading and watching videos. Some say these new air bladder tanks (mine is a Watts DET-12 btw) can't be recharged and must be replaced.

On the tank it says the pre charge should be 40 psi.

 

The description of the DET-12 tank says that it can be charged in the field. Try it. If water comes out of the Schrader valve (tire valve) then the bladder is broken and the tank will have to be replaced.

 

Oh great! I didnt see that. I'll give that a try when I get home tonight. thanks a bunch!

 

Ok really learning alot of stuff here. So it looks like it's not the expansion tank. I recharged it to 40 psi and restarted everything. At first things looked good and the house pressure stayed 60 or below (even though main Guage at water line on basement initially said 55. But after awhile and throughout the night and this am it reached back up to 120-140 at times.

So...I believe this means it's the PRV where the water comes into the house. And thanks for the link and feedback above I'll head out later and get and new one.

Will post results.

As always thank you so very much

 

This indicates to me that the bladder inside is broken. It's like a flat car tire, you might be able to add air and get it re-pressurized, but there's definitely a hole and it's going to leak air, tomorrow it'll be flat again.

Since it's happening overnight, I would lean towards the expansion tank rather than the PRV. But, it's quite possible both have an issue.

 

Oh, didnt think about that. Well, I will say the tank still measured 40PSI when I repeated the process this morning. So it didnt seem to lose any pressure yet the house PSI fluctuated wildly in between measurements.

I read in some places people said these things need to be maintained/recharged where others said maintenance free. Hmmm?

 

If your tank measured 40# after water was shut off, faucets opened, etc. then it sounds OK. The bladder is allowing the pressure to hold. If it was broken the pressure would be lower or zero under those conditions.

Are you seeing the high pressure readings when they occur or are they telltales? Have you checked for water hammer noises when dish- or clothes- washers are operating. (Quickly closing a faucet or valve against a high water flow could also cause water hammer.) Typical noises are clunks, bangs or buzzing vibrations. Some piping has dead end pipes to provide an air buffer at faucets and if waterlogged they can be emptied by draining the system. There are water hammer arrestors that can be installed near washers if that is the problem.

 

So I'm not seeing anything like hammering, bumping, etc at all (sidebar: except when I keep turning off the water main and draining everything out - in addition to the multiple times I've done that with this project, I just completed a separate plumbing project this week) so the family LOVES coming home to all of the pipes pushing their air out. Lots of scared screams when the toilet sounds like its going to eat you).

Back on track, the only telltale signs I've seen are:
1) I have a permament water gauge installed next to the main water inlet (and after PRV) I frequently check to see if its at 55ish randomly goes through the roof
2) Opening sinks (kitchen, bathrooms) we notice a strong gush of water often
3) Hot water tank pressure valve has opened up multiple times and drained water onto my floor (I never kept a bucket or anything beneath it)

Let me know if you think the above points to something else, otherwise I think I'll install a new PRV today before permanent damage is done to fixtures and appliances (if it hasnt already).

 

Have you ever measured the pressure on the inlet side of the PRV? It would need to be high for the PRV to pass high pressure. The PRV cannot make a low pressure higher. If no high pressure before the PRV, then the problem is within the house system. Probably the HW expansion tank. You may need a larger tank. (If your existing tank is good then a second one in parallel can also work.) The PRV is not so expensive to replace but may not solve the problem.

Items 2 & 3 are indications of the high pressure being released.

If you have drained the system several times then any air chambers/hammer arrestors should have emptied.

 

good question. I dont have a way to measure since there's no gauge and its city water. ok well I'll try installing a new one today and see what happens. thanks again!!

 

Update: well that seems to do it! Installed new PRV about 24 hrs ago and no spikes in pressure. Gauge shows a peak of 60psi or so. Thank you!!! However.....now my water meter is making strange noises. I'll may post this in a new thread but sometimes when I run the house water, a few seconds later the water meter makes a loud mechanical noise. I don't think it's pipes rumbling. It just started happening this AM. And it's about 12-16" down from the PRV. It's loud enough that I can hear it from the 3rd floor after flushing the toilet. Runs about 30 secs and then stops.

 

Are you sure it is the meter and not a vibration in the piping? Does it only happen when flushing a (that?) toilet?

One of my toilets has a worn fill valve that will sometimes set off a loud vibration (water hammer) as it nears its closing limit. Opening a faucet will get it to stop.

I do not have an expansion tank in my system but I do have air chambers at most faucets.

 

Ok after spending today listening to the water humming noise I can't figure it out. I'll start a new thread. But to your question above I don't think it has anything to do with the water meter. It was making that noise when the vibration/humming started bc the plastic cover over the meter rattled. Ugh.

 

I'm happy to say the water pressure surges have stopped completely! Still monitoring the humming which also hasnt occurred in the last 24 hrs. But the pressure gauge I have on my laundry room sink spigot hasnt gone above 55 at all since replacing the PRV. thank you all!!!!!