Pressure/PRV Issue

[utilengr]

I work for a utility and we have been having a long term issue associated with a customer's pressure. The customer has had some leaks, one of which resulted in the loss of a significant amount of water. There are a number of issues, including the customer's internal piping which is a mixture of materials including Qest. We've notified the customer of this and have been working with him - initially trying to provide the information to him to allow him to install and maintain his own PRV properly. Other issues have come up and we've gotten more involved as we are being accused of being the source of the issues. The customer is served by a small diameter line (likely a 1" galvanized line) that we intend to replace as part of our ongoing line replacement program. In the meantime, I have been unable to make sense out of what is happening at this customer location. There 3 other customers on this line, this customer is at the end of the line and is the only one having issues (that we know of).

The description of the set up at this location is as follows:
System (105-110 ave. press.)-->Customer Meter-->PRV1 (Wilkins)-->Tee for Press. Recorder 1-->Check valve (inline ball check)-->Lateral to house-->PRV2 (Watts)-->House plumbing-->Press. Recorder 2

The customer watches his internal gauges constantly and calls whenever the pressure is above 70 psi. We have several charts showing something that I am not able to explain. I have attached one. The pressure routinely climbs above the setpoint of the PRVs. Initially it appears that is could be thermal expansion and we added a check valve to the line in the anticipation that this would provide the data needed to demonstrate this or that something internal to the home is adding energy to the system. However, the data following the installation of the check valve (between the 2 PRVs) shows that they both increased in pressure and continued to track along with each other. The check valve is new and I guess there is a chance that it may not be working properly but it didn't seem probable. We have adjusted the PRVs and they continue to allow pressure to go above the setpoint. As a result, we continued to receive calls. The PRVs are direct acting 3/4" valves - both are relatively new.

To try to keep the pressure from being seen on customer side we also installed a pressure relief valve after the first PRV that would keep the pressure at 65 psi. This worked for a few weeks but we are now seeing that the PRV upstream from the blow off will no longer maintain a pressure setpoint - we make adjustments (while flowing a small volume of water) but as soon as we stop the flow, the pressure climbs over the setpoint and up to the relief valve setpoint (10 psi higher than the PRV setpoint), which will then run/drip almost continuously.

Any thoughts/suggestions on this would be appreciated.

 

[bimr]

Wilkins has a video to understand whether it is PRV failure or thermal expansion is the issue:

https://www.youtube.com/watch?v=9TsBMqj9NZM&list=UUCYIwLvVA5TPfhv6dbo_BMg&index=1

Is this a residence? If so, what size and what is the water usage?

Regarding: The customer is served by a small diameter line (likely a 1" galvanized line) that we intend to replace as part of our ongoing line replacement program.

Are you sure that this a 1-Inch pipe and is it buried?

What type of water heater is it? Tank or instantaneous?

Is there a water filter on this house?

It doesn't appear likely that the PRV is over sized, but PRV's tend to leak through when over sized for the application and are operating at low flows.

 

[coloeng]

itsmoked,

While I agree that the majority of the pressure spikes are due to a malfunctioning pressure tank, the spike at 11:53 PM that doesn't drop down until 3:00 AM can't be attributed solely to a malfunctioning pressure tank. With the amount of usage that is shown in that same time period, there has to be something else going on. Most likely it is the PRV getting something stuck that prevents the PRV from fully closing.

 

[itsmoked]

Hi coloeng.

I would attribute that to the before bed shower water-heater recovery followed by no water use, what-so-ever, except a dripping leak somewhere.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[coloeng]

Except that the usage chart shows the customer used 65 gallons in that 3 hour period.

 

[utilengr]

Thanks for all of the replies/suggestions. This has been helpful as we continue to work through this. I have some updates and believe we may be honing in on the issue.

We spent about 2 hours at the house a week ago in an attempt to slow the constant drip from the relief valve. What we discovered is that adjusting the relief valve set-point up didn't slow the flow - even as we approached system pressure. This indicated to me that the PRV was no longer working. Coincidently, the owner left while were there so we were also able to remove the meter and check for any pressure building from the customer side - this was eliminated as a variable.

The customer has a whole house filter on the incoming line (after his PRV located in the house). We schedule a time to remove the filter cartridge. The owner had replaced the cartridge about a week prior. What we obtained in the sample is shown in the attached. These particles would have travelled through both PRVs prior to ending up in the cartridge housing (at the bottom). They settle quickly, some are magnetic. If this is getting to this the filter, I would suspect that some larger particles are staying in the PRVs.

While there to look at the water filter, the owner's plumber just happened to be there. I suggested that he have his plumber check his expansion tank to make sure it still has air in it (he has a standard tank hot water heater). He called me the next day and said that he decided to just have his plumber replace it. Not what I was looking for but this variable should also be removed. (The check valve in the line should have also prevented the pressure from getting back to the first logger near our meter, so I've had a hard time with pointing to this as the problem.)

We're ordering a repair kit for the Wilkins PRV to give us a chance to confirm our suspicions. I understand that the Model 70 Wilkins has a 40 mesh screen in it but I don't think that's going to be good enough based on what we're seeing (evidence was in the filter). I must say that I was surprised the customer never pointed out or complained about what he was seeing in the filter. This would have tipped us off a little sooner.

@coloeng, We are working on a replacement plan for the service line as well. I believe that the configuration of his connection is also detrimental given what we are now seeing - I think his connection, which is at the end and downhill from the larger main, is right off the end of the line. This isn't how we typically make a service connection. Typically, we put the corp. stop above the spring line angled up at about 20 degrees. This would help keep some sediment/debris from moving through the service connection. We need to fix this.

 

[utilengr]

@bimr, Thanks for the YouTube links. This was also helpful. We believe that the line is a 1" galvanized based on an estimated install date (we have no records for this line) and a 1" valve near the larger main. I considered cutting a coupon out of it to see what it looks like but I may put this off now that I've seen what's in the filter housing - I'd hate to do anything else to the line at this point that might cause more debris to be shaken loose and end up at the customer's house.

 

[coloeng]

utilengr,

Thanks for the update and good luck.