Electric Water Heater Issues

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Lindside, WV
Hey Jeff...
A second unit would be for added security/protection, and at the time I didn’t know much about how this small-town utility worked. But they did make it yesterday. The young man was pretty good at his job and explained some details to us about our area. As I said, we are in a rural area, basically up in a “holler” about two miles. We have some neighbors fairly close and all are on this fairly new line, which runs through some mountain territory, so it presents some challenges. Our meter is alongside the single-lane road with our line running uphill about 500 feet into the house... The fellow didn’t know what normal pressure on their side should be at our exact location, but he added that having an inside PRV would be good idea, as so many others here have done so. Also, their supplied units tend to only last 2-4 years. In fact, when he showed up, he immediately brought out a new one and installed—said that usually fixed many of the problems in our area...
And yes, I had called them back on the second day just to me sure we weren’t missed. Turns out the one fellow had been swamped and got to us as quickly as he could. (Second PRV would have helped calm my fears while waiting lol)
Plus...I’m still learning all the little ins and outs of the plumbing system here—lots of “odd” ways of doing things to me, so I’m learning as I go on thinking like the late husband-installer did. After all, this place is spread out in a lot of square footage now, having started only as a single-wide trailer, and being added-on to over about 20 years or so. He had tried to explain some things as he realized his time was short but his memory gave out too...

Jeff H Young

In the Trades
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normally a "second PRV for added security" would be total waste I've never seen 2 installed for that reason.
but a 500 foot run "up hill" who knows how many feet isn't normal either , so I guess you could run 1oo psi and then drop down to 50 or so at the house.
What ever the case the existing PRV is junk needing service or replacement. if that didn't happen then the second one in the house is doing all the work and the other one is doing nothing or little as we know its bad.


Well-Known Member
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And, I had installed the Expansion tank last night so that’s all good. I do question one thing about that—it’s factory set with 40 psi...do I need to add more to it to equalize something?
Yes. Set it to the pressure the PRV delivers when you run water at a very slow trickle.

Tire pump. The air precharge is always measured and changed when the water pressure is zero.

Under normal conditions, the expansion tank is empty of water. Knock on the side of the empty tank, and remember that sound. If that tank ever gets full of water, the tank has probably failed.


Retired Defense Industry Engineer xxx
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New England
The distance from the road to the house can make a difference for two reasons:
- water running through a pipe has some friction, so when water is flowing, depending on the volume, speed, and diameter of the pipe will all affect what pressure losses you may have
- water pressure will change with elevation at about 0.43#/foot of elevation change. So, if you're actually downhill a bit, that water coming down the hill will have more pressure at your outlet simply because of gravity. Conversely, if it has to go up to your house, the pressure will drop accordingly (so it wouldn't be uncommon to have different pressures at the supply by the road and at the house). To ensure water gets to all of the homes up and over hills, the utility may need some fairly high pressures, and a PRV is then required per code (must be >=80psi in the home).

A PRV will have a maximum range over which it can work. If you have REALLY high pressure, depending on the PRV you select, you MIGHT need two in series to drop the pressure sequentially to a safe value, otherwise, having a secondary one isn't really much of a benefit. Exceed the range of one, and you may cause it to fail. Most people won't have that issue as their pressure isn't that high.

An ET won't last forever - eventually, the bladder will leak. They don't hold their pressure forever, either, so you should probably check it maybe annually and top it off if necessary. FWIW, the cap, if it has a good gasket in it, is the better seal than the Schrader valve in the tank. IOW, don't omit the cap and make sure it's tight.

A PRV creates a closed system. That means that when expansion occurs, it needs a place to go or it will leak out the weakest location. In a well maintained system without leaks, that generally (at least should be) is the safety T&P valve on the WH, but it could just as easily leak from a worn valve. Common ones are toilet fill valves, but any valve with a leak under high pressure can potentially relieve it before the T&P valve opens (which SHOULD be at 150psi...your gauge may not be well calibrated, or the valve might be a little weak).

To comply with federal guidelines, if your utility doesn't already have a check valve on your supply, they may be installing them, so that could then make your system closed, when it didn't beforehand, and require an ET.
Hey, wait a minute.

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