Hot Topics: Proper Water Pressure for Pressure Reducing Valve

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What's a good psi for a standard home? As always, the forum has the answer to that question, and many more!

Original Post: Proper Water Pressure for Pressure Reducing Valve

klawman213 Member

I am wondering what is appropriate water pressure for a 2,400 square foot, two-story house with a kitchen sink, dishwasher, half-bath downstairs with a toilet and sink, downstairs laundry room with washing machine faucets, and two full upstairs baths each of which has double sinks. A plumber, through a meter on the bib coming from the 1-inch feed for the house, said it read a little less than 70, but that was with a slab leak. He estimated that pressure may be more like 80 when the leak is corrected.

One reason I ask is we have to install expansion tanks when replacing the hot water heater and which one I get depends on whether the pressure is 80 or greater. Also, it seems that a new reducer is a good idea as mine is 27 years old. As I understand it, less pressure is better for the pipes, but I don't want it set too low.

PJmax Group Moderator

I would consider 50 psi to be a good setting for an average home (60 psi the maximum).

klawman213 Member

Thanks. I will replace the 27-year-old pressure reducer valve. I noticed about 6 months ago that the water pressure seemed a lot higher at a sink that used to have low pressure. That should reduce some wear and tear on my pipes. I will go ahead and pick up one of these Watts. It looks simple enough to install. I inviting trouble if I just adjust the pressure down on this 27-year-old reducer valve (assuming it will adjust)?

chandler Forum Topic Moderator

I would have a replacement on hand. Replacing it will ensure another decade or two of good regulation of the water pressure.

klawman213 Member

Thanks, Chandler. I will pick one up at the same time I get a pressure gauge, in case the old one goes bad when I try to adjust the pressure. The replacement looks simple enough if I can get one to match up with the original.

I went to the Home Depot to get a reducer valve and a water pressure gauge. They are all sealed up, but to me it was unclear if any will slip in without some cutting of the main. I think what I have is a double union 1-inch, brand unknown. Without undoing the unions, I can't tell just what the gap in the main is, but I suspect it may be about 4 inches. With the unions on, the space is just about 3.5".

Does anyone have an idea as to what to buy for a slip-in replacement? The pressure reading peaks just over 80 when the bib is turned on and immediately drops to about 68 psi measured with the hot water shut off at the hot water tank. Leaving the bib on, I then opened the ball valve for the tank and got no change in psi. (Perhaps a drop of 1 pound that came back to 68 after the hot line may have tightened up a pinhole leak at a joint that opened up while I was working on isolating a 1/2" line of copper.)

I have a suspicion that there is no way to tell if the gap has increased or decreased until the couplings are backed off and pulled back.

chandler Forum Topic Moderator

You should be good to go with this one Zurn-Wilkins 3/4 in. x 3/4 in. Brass Water Pressure Reducing Valve-34-70XLDU - The Home Depot

klawman213 Member

I was looking at the box holding a Zurn-Wilkins at my Home Depot, but I thought I needed a 1-inceh. The o.d. of the pipes to which the reducer couples on each side is 1.16," including the beautiful paint. The pipe coming up out of the mudsill behind the water heater is a 1" that immediately reduces to 3/4.

Meanwhile, I loosened the lock nut and backed the adjusting screw out pretty far, about 1/2," while monitoring the psi. It didn't budge. Does that sound like the prv is frozen/no good?

...I have left the psi. gauge on that bib for a couple of hours now and then opened up four hot water taps. Pressure dropped by about six pounds and returned to 67 when I closed the taps.