When is a 2 stage pressure reducing valve required?

[Rileydog123]

Hello,

I have a house with a PRV that Im told is the cause of recent low pressure. The PRV was installed shortly after I purchased the house in 2010.

I am also told that I have to install a 2 stage prv instead of a single stage. At a higher cost of course.

I already have an expansion tank on the water heater, if at all relavent.

I am not finding much info on when a 2 stage is required. Any info on this?

Thanks

 

[Terry]

What is the street pressure?
Normally a PRV is all you need. Is there irrigation involved?

 

[Sponsor]

 

[Jadnashua]

Different designs have a maximum pressure across them. When you exceed that, they don't work, or will limit how much they drop the pressure. In that case, you may need to reduce the pressure in stages.

To know if you need to do that, you must first know what your peak pressure is, then what you want the outlet to be, then, examine the specs of the valve(s) you select. Some can handle a larger drop than others. No idea if that high pressure will affect their overall life.

 

[Valveman]

Usually over 100 PSI of differential pressure needs to be stair stepped down with two PRVs. Like incoming is say 200 PSI, the first prv reduces it to 125 PSI and the second takes it from 125 to the 50 the house needs.

 

[Rileydog123]

I had the water company measure the pressure they are delivering at the box. Its 48 PSI. Which is higher than the 30 PSI they said they are required to deliver. Both of those numbers seem low to me. What is “normal”?

 

[Reach4]

What is “normal”?

30 to 80. No PRV needed for you. Who said you need one? 48psi is nearly ideal. Maybe you can disable the PRV without having to take it out.

 

[Rileydog123]

Well the water pressure in the house seemed lower than usual. A plumber came out and told me the PRV is bad. And that it needs to be a 2 stage. The 2 stage seemed odd to me, (plus more $$$) so I didnt agree to have it replaced that day.

 

[Reach4]

Do get a garden hose thread (GHT) pressure gauge. Under $20 and sometimes under $10. Then you will know, and will not have to use fuzzy terms like low.

 

[Jadnashua]

When I lived in the middle east for awhile, we had water delivered to a tank on the roof. The pressure in the house was entirely via gravity (about 0.43# of pressure increase per foot it had to fall. That's what I call low pressure. But, it worked. Filled the toilets, ran the sinks, the showers were a bit anemic, but you could get the soap out of your hair, but it took awhile. IMHO, more is nice, but not necessary. 48psi is not bad.