3/4 meter to 1.5" main line - where to install PRV and Backflow preventer?

[PeterT]

Existing meter is 3/4". The house main line (250' long) should be 1.50" based on fixture # and run length. Pressure and flow are fine presently from the 3/4" meter via a 1" a pvc main line.

As the yard is torn up, I'm going to install a new 1.5" main line in case there's a need to upgrade the water meter in the future. Presently, there's a 1" PRV reducing pressure from 80psi to 60psi.

Question: can I install a 1" PRV and a 1" backflow valve just after the 3/4" meter and on a 1" pipe but before the transition to the 1.5" main line? Any reason why this isn't advisable other than a future meter upgrade would require them to be upsized? Does it make a difference installing the PRV so far from the house presuming I just run the pressure a bit higher to compensate for the long run?

1.5" PRV's and 1.5" backflow prevention valves get very expensive and may actually never be needed. But I don't know if their 1" size will somehow limit flow even though the meter is only 3/4".

thanks.

 

[Reach4]

Calculating Thermal Expansion & Contraction in Plastic Pipes

Learn how to calculate and accommodate thermal expansion and contraction when designing plumbing systems with plastic pipes like PVC and CPVC.

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Question: can I install a 1" PRV and a 1" backflow valve just after the 3/4" meter and on a 1" pipe but before the transition to the 1.5" main line? Any reason why this isn't advisable other than a future meter upgrade would require them to be upsized? Does it make a difference installing the PRV so far from the house presuming I just run the pressure a bit higher to compensate for the long run?

Installing the PRV at the house is better for regulation.

 

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[PeterT]

Calculating Thermal Expansion & Contraction in Plastic Pipes

Learn how to calculate and accommodate thermal expansion and contraction when designing plumbing systems with plastic pipes like PVC and CPVC.

www.charlottepipe.com

Installing the PRV at the house is better for regulation.

agreed, can I install a 1" PRV where the 1.5" transitions back to 1" pex in the garage or does the PRV need to be 1.5"?

Also, I'm thinking it may be better to have the sprinkler system unregulated (meaning the PRV can go in the garage vs outdoors) since sprinklers don't have the same high pressure risk factors as an indoor pipe.

 

[wwhitney]

agreed, can I install a 1" PRV where the 1.5" transitions back to 1" pex in the garage

Sure.

PRVs are sized based on the expected flow and the acceptable pressure loss through the PRV at that flow. That is, if your PRV sees 80 psi static (= no flow) on its inlet, it will keep the outlet pressure at 60 psi. But if you draw 10 gpm, say, through the PRV, the outlet pressure of the PRV will drop a little, maybe a few psi? If you use a large PRV, you can get more flow through the PRV with less pressure drop.

So if a 1" PRV is adequately sized for your flow, and you need to install it in a 1.5" line that was upsized due to distance, there's no harm in just downsizing to 1" for a foot or two so that you can connect a 1" PRV.

Cheers, Wayne

 

[PeterT]

Sure.

PRVs are sized based on the expected flow and the acceptable pressure loss through the PRV at that flow. That is, if your PRV sees 80 psi static (= no flow) on its inlet, it will keep the outlet pressure at 60 psi. But if you draw 10 gpm, say, through the PRV, the outlet pressure of the PRV will drop a little, maybe a few psi? If you use a large PRV, you can get more flow through the PRV with less pressure drop.

So if a 1" PRV is adequately sized for your flow, and you need to install it in a 1.5" line that was upsized due to distance, there's no harm in just downsizing to 1" for a foot or two so that you can connect a 1" PRV.

Cheers, Wayne

thanks Wayne.

Ditto for the back flow prevention valve at the meter? Can I use a 1" backflow prevention valve before upsizing to 1.5" pipe for the long run? I need to keep the BFP near the meter as its the highest point in the yard.

 

[Fitter30]

Both in the house in case there is any problems with either devise.