Pressure Reducing Valve (Regulator) Questions

[skikt22]

I have a question on PRV (pressure reducing valve, not relief ) performance and set-up

My situation: From Street to water heater


Street water pressure 160 to 180 psi

Wilkins 1 inch strainer- Put in as we used to have lots of rust,etc in the system. Street mains have since been replaced and this is probably no longer needed.

First PRV - Wilkins 1 inch BR4 set to 100psi
- This one supplies several outside taps and landscaping and then feeds the inside.

Second PRV - Wilkins 1 inch 600 set to 65 psi which feeds the inside of the house.

Watts expansion tank 4.6 gallon in front of water heater.

All internal plumbing is 3/4 inch - two hot and cold lines servicing different parts of the house. off the 1 inch and water heater.

My first question is how long the PRV should be expected to last. I do fairly regular maintenance of cleaning the screens but it seems that I end up with a failure about every three years on the Wilkins 600. My water heater relief valve blew again this weekend because the reducing valve has failed again, the last time it failed was just over three years ago. The spring was slightly corroded and the cap that goes on top of the spring had a lot of accumulated deposit on it that I was unable to get off. The diaphram looks ok, but I'm not sure what a bad one would look like. It seems three years is very short. Should I be replacing this PRV with a different brand like watts? Or did I just get a lemon on the first one. I know there are rebuild kits but they seem to be almost the price of a new valve and not readily available, and replacing the whole valve takes a lot less time.

The second question is about the amount of pressure drop I should get on the PRV's. When I run a faucet (2.5 gpm) the Wilkins 600 shows a drop of 5-10 psi (after I replaced it) which seems reasonable, but the BR4 shows a drop all the way to 40-50psi from 100. We have pressure drop off at times and I believe this is the cause. Is this an indication that it needs to be replaced or overhauled as well?

I also noticed one instance of street pressure after the first PRV which may just have been because I was fiddling with the system and could have had some momentary debris or it could be a early warning sign.

 

[Jadnashua]

Next time you do work on them, you might want to install a few pressure gauges. If the pressure creeps, the regulator is shot, or there's crud on the diaphram. One before, between, and after. Make sure the expansion tank isn't shot and it's precharge is proper.

 

[Sponsor]

 

[Furd]

Depending on the quality of your water and the amount you use three years may not be unreasonable. You may also benefit from simply cleaning the valves rather than a full rebuild although if the valve seat or disc is damaged it will likely require replacement.

I am not that familiar with the different brands of pressure regulators used in residential service so I cannot comment on the Watts vs. Wilkens issue. I will state that a 10 psi pressure drop with a 2-1/2 GPM flow on a one-inch PRV sounds excessive. Your primary PRV showing a pressure drop of 50+ psi with only a 2-1/2 GPM flow is definitely wrong.

 

[Valveman]

There are only two kinds of valves ever made. Those that leak, and those that will leak. The velocity of the water flowing across the valve seat can be 200 feet per second or more. This is going to wear the valve seat and allow leakage, it is just a matter of time. Actually, the lower the flow you use, the quicker the wear happens. A 1" valve isn’t open very much at 2.5 GPM, and the differential pressure is greater, so the water is jetting across the seat and wearing it faster than if you were using 10 GPM. This is one reason you don’t want to oversize control valves.

If you use low flow a lot of the time with a 1" valve, three years is probably about right. Larger systems use two different size valves in parallel, to handle wide ranges of flow.

No matter the size or brand of valve, even a brand new valve can have some pressure creep. This will eventually allow the pressure on both sides of the valve to equalize. The expansion tank just makes it take longer, and the pressure relief is needed for when the tank is no longer enough.

The 50 PSI pressure loss is not correct. The largest of the two o-rings is probably bad or out of place. You also should not have moisture in the spring cage. It is usually the diaphragm nut that has worked loose.

 

[hj]

Prv

I use the Honeywell-Braukmann valves, but even if your secondary valve failed, the primary one should not have allowed the pressure to increase beyond 100 psi, so if it did, then you have a problem other than the one you think you do.