Sunday, January 10, 2010

Installing a Pressure Reducing Valve

A typical situation that develops in growing areas is a gradual increase in water pressure as the water utility adjusts to serve the greater population density. New homes come with PRVs installed. Older homes don't, and so experience greater faucet and appliance valve wear, increased stresses on pipe fittings, and higher water/electricity bills than when they were first constructed.

We currently have 80psi from the street, and I'd like to try something more reasonable, like 50-60 psi. I recently installed a new water heater with expansion tank which rectified the thermal expansion problem we had. The PRV I chose is a $28 unit from Lowes. It can regulate 25-75 psi, and comes preset at 50 psi.

I bought two 3/4" male adapters to attach it to the feed pipe. If you notice the PRV has a union on one side. This is because you have to solder the male adapters before you attach PRV. There would be no way to spin it to attach both sides without the union.

Here is the cutoff valve for the house. I will be installing the PRV above this on the vertical section. First I start by turning off the valve. I then open all the faucets in the house so i can quickly drain the residual water.

Next I measure and cut the pipe section out to make room for the PRV. About two gallons came out. I have a plastic pail below this to collect it. Water was still sitting in the lower pipe, so I siphoned it out with a piece of vinyl hose from an aquarium store - you cannot solder a pipe full of water.

I clean the pipe ends and fittings with emory cloth and wire brushes, to get to bright, bare copper. Successful soldering depends on this step. The fittings and the pipe ends are then coated with flux, and heated with a MAPP torch. Solder is sweated into the joint and then wiped with a clean rag while still hot.

PTFE Pipe dope is applied to the male threads and the unit is attached on the non-union side first, making sure the flow direction arrow is pointed the right way :) The union is then tightened to complete the connection.

Water turned back on, it works great! The lower pressure should save us about 30% on water bills, and probably 15% on electricity. After a few days of "trials", I will need to adjust the expansion tank charge pressure to whatever value we decide on.


benthomasson said...

The saving of electricity comes from less use of heated water right?

Digital Twilight said...


Digital Twilight said...

Ended up staying with 50 psi, so I adjusted the pressure on the expansion tank to match.

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