Low water pressure

[tworley]

I replaced an interior water ball valve which feeds my vacuum breaker for the sprinkler system. Replacing the ball valve required me to turn off the main water supply and drain the entire house system. Replaced with a new ball valve, turned the water back on but now have low water pressure throughout the entire house. Hot/Cold work just fine, but the pressure is nowhere where it used to be. Pulled strainers on sinks/showers. They are clean. What are my next steps?

 

[LukesfirstJeep]

Two thoughts. I'm assuming the new ball valve is the same nominal size as the old. When open, is the "hole in the ball" the same or larger as the old valve? Is the vacuum breaker operating correctly?

 

[tworley]

Two thoughts. I'm assuming the new ball valve is the same nominal size as the old. When open, is the "hole in the ball" the same or larger as the old valve? Is the vacuum breaker operating correctly?

Yes, replaced 3/4" ball valve with a new 3/4" ball valve.

Yes, vacuum breaker is operating as it should.

 

[sab]

If the ball valve you replaced only supplies the sprinklers (not the rest of the house), the only thing I can think of that could cause the overall pressure to drop is a leak in the sprinkler system. Was the old ball valve turned off, and the new one is on? If so, maybe you have a leak you didn't know about. You can turn off the new ball valve and see if the pressure returns. If so, then you likely have a leak somewhere.

Just "spit-ballin'" here...

 

[N757KF]

What type of valve did you shut off?
Was it a globe valve, gate valve or ball valve?
Also, are you on a private or public water system?

 

[tworley]

If the ball valve you replaced only supplies the sprinklers (not the rest of the house), the only thing I can think of that could cause the overall pressure to drop is a leak in the sprinkler system. Was the old ball valve turned off, and the new one is on? If so, maybe you have a leak you didn't know about. You can turn off the new ball valve and see if the pressure returns. If so, then you likely have a leak somewhere.

Just "spit-ballin'" here...

Good thought. The sprinkler system hasn't ran in 20+ years. There are 100% leaks. I've got the VB turned off until I can trench new lines. However, still low pressure in the house.

 

[tworley]

What type of valve did you shut off?
Was it a globe valve, gate valve or ball valve?
Also, are you on a private or public water system?

Main line to the house is a gate valve I think. Its located in thecrawlspace. I'll have to look again. Public water, that valve is located adjacent to my sidewalk outside

 

[N757KF]

It's unlikely that the sprinkler system is the problem. Shut off the ball valve to the sprinkler system, that'll isolate it.
The only thing you touched was the gate valve to the house, that's most likely where your problem is.
It's not unusual for the stem in the gate valve to break and the "gate" portion of he valve to hang up in the partially open position.
Most likely the gate valve will have to be replaced.

 

[tworley]

It's unlikely that the sprinkler system is the problem. Shut off the ball valve to the sprinkler system, that'll isolate it.
The only thing you touched was the gate valve to the house, that's most likely where your problem is.
It's not unusual for the stem in the gate valve to break and the "gate" portion of he valve to hang up in the partially open position.
Most likely the gate valve will have to be replaced.

Agree on sprinkler not being the problem.

I worked the main valve. It turns the water off, and can hear the rush of water when I turn it back on, but it is possible it's not opening fully.

I've got everything in the house on right now seeing it it would eventually build pressure. Upstairs sinks won't even run, bathtubs are a trickle. The sinks downstairs and spigots outside are a smidgen more than a trickle .

I could probably replace the valve to the house, I just dislike soldering copper

 

[TJ4Jim]

Did you break the union next to the valve on the PRV and clean the screen, may have slugged some crap. Also when operating the gate valve does it feel like the valve is functioning properly.

 

[tworley]

Did you break the union on the PRV and clean the screen, may have slugged some crap.

No. Honestly didn't even notice that union that could be worth a shot though. I'll give it a try tomorrow

 

[TJ4Jim]

Agree on sprinkler not being the problem.

I worked the main valve. It turns the water off, and can hear the rush of water when I turn it back on, but it is possible it's not opening fully.
View attachment 423490

I've got everything in the house on right now seeing it it would eventually build pressure. Upstairs sinks won't even run, bathtubs are a trickle. The sinks downstairs and spigots outside are a smidgen more than a trickle .

I could probably replace the valve to the house, I just dislike soldering copper

No. Honestly didn't even notice that union that could be worth a shot though. I'll give it a try tomorrow

Should be a cone shaped screen in the union.

 

[N757KF]

The device above the valve is a pressure regulator (which can also fail in a low flow rate)
Undo the lock nut at the tag and turn the screw clockwise with a large screwdriver and see what happens.
It may help alleviate the problem. There also may be debris in that too.
Try the union too as @TJ4Jim suggested. You'll probably need to disconnect it fully to check the volume. Be aware, though water will come out with "great enthusiasm".
So, there are 3 potential problems:
1. Valve may have failed (it's not a gate valve)
2. Debris in the screen at the union (as @TJ4Jim suggested)
3. The pressure regulator has failed.
Crossing my fingers for debris in the screen.
Good luck

 

[tworley]

Tried bleeding the system a few times tonight by opening all faucets with the main supply closed, then turning the water back on. No change. This weekend I'll undo the union and go from there. I'd be lying if I said I wasn't hesitant to undo the union. It's probably the one installed from 1985

 

[TJ4Jim]

Tried bleeding the system a few times tonight by opening all faucets with the main supply closed, then turning the water back on. No change. This weekend I'll undo the union and go from there. I'd be lying if I said I wasn't hesitant to undo the union. It's probably the one installed from 1985

Generally the unions on the Watts Prv's are of a good quality brass and the corrosion isn't to bad, should not be a to much of a bugger to take apart.

 

[N757KF]

Unlikely to have a corrosion problem.
If it's that original, there's a fibre washer that may come apart.
Have some pipe dope ("Rectorseal" or equivalent) and teflon tape available. You might need it.

The good news is that if you have to replace the pressure regulator is its threaded on both sides.

 

[tworley]

Unlikely to have a corrosion problem.
If it's that original, there's a fibre washer that may come apart.
Have some pipe dope ("Rectorseal" or equivalent) and teflon tape available. You might need it.

The good news is that if you have to replace the pressure regulator is its threaded on both sides.

Have plenty on hand

How does one bench test a PRV?

I am suspecting its clogged though. After bleeding my pressure feels back to normal for a split second before dropping dramatically

 

[N757KF]

It's really volume you're looking for (yes, I know everybody calls it pressure but it isn't).
There reason it's high for a split second is that the pressure regulator has time to equalize pressure, so that when you open the faucet full pressure is there for a brief instant.
Realistically, the only way to test is to completely disconnect the piping and open the valve (ball valves are better for this).
Yes you'll dump a lot of water on the floor, but it's the only way to really know (experience helps here too!!).
You could also take out the regulator and put in a straight pipe (nipple) to see what happens. If you get good flow then the regulator is the problem.

Edit: You can get a couple 1/2" nipples, two 1/2" couplings and a 1/2" union to make a temporary connection. It doesn't;t matter if they are iron (steel) pipe for diagnostic purposes.

 

[TJ4Jim]

Have plenty on hand

How does one bench test a PRV?

I am suspecting its clogged though. After bleeding my pressure feels back to normal for a split second before dropping dramatically

The strainer inside the union is there to protect the prv so look at that first, if it's plugged then that's most likely the issue but you can also back off on the adjuster and that should increase the downstream pressure.

 

[tworley]

Got the old prv off. Nothing looked out of the ordinary. Screen was fairly clean. Damaged in a few spots which I thought was odd

Started to feel inside the passage ways and something was wedged inside, I could barely move it with my finger. So I took it all apart and found this (more fell out too as I took it apart

The diaphragm was also in pretty rough shape. I went to go get a rebuild kit but couldn't find any locally. So, I wound up with a new Zurn prv for $130. Plumbed it in and could immediately hear a strong flow of water. Every faucet and spigot ran when opened. Set the presure to 68-70. So, problem solved.