Pressure Reducing Valve reduced pressure fall offs????

[Jasesun23]

Hi Guys, with the forums help I installed a Watts lf25aub-z3 pressure reducing valve and an expansion tank. Reduced my house pressure from 95-100 (city) to ~55. My question is about "normal" pressure fall offs? In my original post someone included a Watts chart, but i'm not sure if I'm understanding it. I just want to know if the pressure drops I'm seeing with water running is okay or if this valve is faulty and I need to return it for another?

Static pressure is set to around 55 psi. If I turn both the hot and cold sink faucets on in the 1st floor bathroom the pressure drops to around 45 psi. Its a new faucet so I know it has a 1.5 gpm max flow. If I turn on the shower, which has a max 2.0 gpm, it drops to around 43. If I use the tub spout, which I believe is unrestricted, it drops down to 38 psi.

http://www.watts.com/pages/learnAbout/reducingValves.asp?catId=64
If i'm reading this chart in the link above correctly a 1.5 gpm flow should have barely any pressure fall off
Do these drops register as normal or do I need to return this?

thanks Jay

 

[Reach4]

If the pressure gauge is right at the output of the PRV, I would think you could if you have a 1 inch PRV or even a 3/4 inch PRV. However the Watts LF25AUB-Z3 PRV seems to have more restriction than some of their other PRVs.

If the pressure gauge is much farther down the line, there may be a restriction between the PRV and the gauge that adds to the pressure drop from the PRV.

Do you have symptoms beyond the pressure gauge indication? If so, you could crank up the PRV to maybe 65 PSI. The pressure PSI drop will be pretty constant, so the percentage drop would be less.

Snip from http://media.wattswater.com/ES-LF25AUB.pdf

 

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[Jasesun23]

Thanks for the reply Reach4. A little more info from my side. Its a 3/4 inch PRV. There is no pressure gauge next to the PRV, in retrospect probably should have installed one. I'm just using a screw on pressure gauge. Have tested it at the hose bib in the garage, and at the drain valve on the bottom of the hot water heater.

Besides the indication on the PRV I can see/tell there is a reduction in flow if taking a shower and someone is running a sink. Its not massive but you can feel a reduce in flow which correlates to that reduction in pressure.

I could always increase the PRV pressure , but I'm more interested in knowing if there is an issue with this brand new PRV? Should I buy a new PRV to test? With everything soldered in it would be a pain to try it to only find out this is normal.

 

[Reach4]

I can see/tell there is a reduction in flow if taking a shower and someone is running a sink. Its not massive but you can feel a reduce in flow which correlates to that reduction in pressure.

I presume you had no such symptom with the old PRV, or were you running the 100 PSI through the pipes previously so that pressure drop in the pipes would be relatively small?

How about having the pressure gauge on a hot line at the laundry area or the drain on the water heater. Then do your flow test by running cold water. The theory is that the cold line to the water heater probably splits off early in the path from the PRV. Or maybe you have a hose bib that tees off close to the PRV and you switch to measuring the pressure at that one.

If the water heater was cool enough to not cause the mixing valve to mix in cold, or you don't have a mixing valve, you could monitor a cold line pressure while doing your test flow by running only hot. That way any drop after the PRV would only be between where the line to the water heater splits off.

Maybe crank your PRV to even 75 and re-test for symptoms before you go to the trouble of replacing the PRV. I would raise the air precharge (with the water pressure = zero) for the expansion tank to between 0 and 5 PSI higher than the PRV pressure setting. Many/most expansion tanks specifications limit the precharge pressure to 80 PSI.

If you are in an experimental mood, you could compare the pressure at different places in your plumbing. Draw the same load for each test, such as bathtub cold full on. Any differences would be due to plumbing between the different measuring points.

One nice feature, IMO, your PRV has the bypass feature. So if there is no check valve in your incoming water line, the inside pressure would be limited to a little more than the incoming water pressure. In that case, you might never even notice an expansion tank failure.

 

[Jasesun23]

Prior to installing this PRV there was nothing . That house was getting 95-100 psi city pressure. If I turned on a faucet it would drop 2-3 psi.

The hose bib in the garage is about 25 ft of 3/4 inch pipe away from the PRV. The hot water heater (drain valve) is even further.

The PRV does have a bypass valve. When I installed it, to test if it worked, I turn off the valve going to the expansion tank. When the hot water heater kicked on the max pressure it got to was 95-100 psi which is the same as the city's psi.

So if I installed a pressure gauge right after the PRV and it dropped 10 psi when a 2.0 gpm faucet was running at full force, would that indicate a bad PRV? Is it possible that a 10 psi drop is normalish? Anyone out there with a PRV that drops from 50 psi to 40 psi when then turn on a 2.0 gpm faucet or shower head?

thanks
Jay

 

[Reach4]

So if I installed a pressure gauge right after the PRV and it dropped 10 psi when a 2.0 gpm faucet was running at full force, would that indicate a bad PRV?

I would think so, but you should contact Watts if that happens.

It looks to me as if there is an access port for the stainless steel strainer. I might try removing the strainer. Inspect the strainer for debris. Some people leave it out, and restore the plug to not have a strainer.

 

[Jadnashua]

What kind of piping is in the house? Without knowing that, and how it was run, it could be the branch size is inadequate for the volume you're trying to pull. Also keep in mind that you lose about 0.43#/foot of elevation change, so if the piping has to go up 10' from the basement to the second story, that's 4.3# right there.

 

[Jasesun23]

The majority of the pipe is 3/4 inch brass threaded pipe. At least thats what I see in the basement. Some of the branches are 1/2 inch like the shower on the first floor, but it is only 5 or 6 feet. The pipe going to the second floor bathroom is 3/4 which supplies the shower and faucet. The pipe going to the basement slop sink is all 3/4 and there is no elevation change to it. When that sink is turned on there is a drop of 10 psi.

 

[Reach4]

The majority of the pipe is 3/4 inch brass threaded pipe.

That would be unusual. Try taking a magnet to a long pipe.

Elevation plays no part in pressure changes for house plumbing.

 

[Jasesun23]

The whole house is brass pipe (drinking water), 3/4 inch is most of the pipe. Some short branch offs are 1/2 inch. The hot water heating system is all galvanized pipe. Original owner built the house himself in 1957 and used that best products available at the time. The floor joists are even 2x10.

Wanted to be positive I didn't have a defective PRV so I went to Home Depot early this morning. Installed the new one and it works the same. Seeing a 10 psi drop when I open the faucets or shower. So its something inherent to my system. Maybe its the whole house water filter I put in. It has 3/4 inch threaded inputs but the actual ID inside looks much smaller. Maybe its just the way the pipes are set up. But at least I know its not the PRV.

And a slight upside, even though I had to do some work to put the new one in, it was on sale so I got it for 25 dollars less than the original.

 

[Reach4]

Maybe its the whole house water filter I put in.

Ding ding ding....
I suspect we have a winner. Tell us about that filter.

Some filters will let you take the element out and let water flow through the empty housing, which you could do for testing.

 

[Jasesun23]

The filter has a bypass feature that allows it to completely eliminate the filter medium. Also the filter medium is 50 micros and its a week old so its not clogged. When I put it in bypass mode I still get the 10 psi drop so its not the filter medium. But there is a chance it could be the filters ID inner tube size.

 

[Reach4]

What is the brand and model of the filter?

 

[Jadnashua]

Water pressure IS affected by elevation, especially when it flowing. That's the reason we have water towers, and on taller buildings, they pump the water to the top, store it there, and let it come down to maintain good water pressure. It's why if you live on the top of a hill, your pressure is lower than your neighbor down in the hollow. Now, in the typical elevation of a home, maybe not, but it is measurable and real.

As said, brass pipe is unusual in a home. Water filters tend to have a fair amount of pressure drop across them. If you're lucky, yours has a bypass valve and it would be easy to check, or remove the cartridge, but the openings may play into it.

 

[Jadnashua]

Water pressure IS affected by elevation, especially when it flowing. That's the reason we have water towers, and on taller buildings, they pump the water to the top, store it there, and let it come down to maintain good water pressure. It's why if you live on the top of a hill, your pressure is lower than your neighbor down in the hollow. Now, in the typical elevation of a home, maybe not, but it is measurable and real.

As said, brass pipe is unusual in a home. Water filters tend to have a fair amount of pressure drop across them. If you're lucky, yours has a bypass valve and it would be easy to check, or remove the cartridge, but the openings may play into it.

 

[Jasesun23]

Its a Watts Whole House Filter Model is either 500222 or 500223 (list both on the filter)

Watts WH-LD Premier Whole House Filter System

Those models are not listed on Watts site, the closest to it would be
http://www.watts.com/pages/_products_details.asp?pid=7389

Reach4 I appreciate your time in trouble shooting this with me.

 

[Reach4]

VIH34APC appears to be another name for this filter. While I don't find an applicable spec, other than 20 PSI minimum water pressure, I don't see complaints about a pressure drop.

You usually try to not plumb filtered water to your outside spigots. I understand that this would be hard for retrofits.

Have you tried monitoring the hot water pressure while using cold?

So anyway, it would have been nice to add a water pressure gauge after the PRV.

To work around the pressure drops, which are not horrible, I would crank the PRV up to 75 PSI and raise the precharge in your expansion tank.

 

[Jasesun23]

Sounds good, thanks for you help