Water Pressure

I have a water softener, and was told that 80psi was too high and that it was causing my tank to crack, if I want to install a water pressure regulator, where should we put it?

I depends on your layout; most do not want to regulate their irrigation/outside spigots, so the regulator would go just upstream of the softener.

In many locales, 80# is the threshold of where a PRV is required. But, most any components should be fine with that pressure, and are generally tested to a higher value than that. But, also keep in mind that a daytime pressure of 80# might turn into one of #130 at night when fewer people are using water and they may be refilling the water towers (if you have those around). You can purchase a screw on pressure gauge that has a tattle tale hand (i.e., a peak reading pointer) for about $10 or so at a big box store. Screw it onto a hose bib and open the valve (or elsewhere with the proper adapter). Pick one up, leave it attached for a day or two and see if you have peaks that are higher. If you do, then yes, you should install a PRV and an expansion tank. Adding the PRV makes a water system in the house a 'closed' system, and when you heat the water in the heater, it expands. This needs somewhere to go otherwise that, all by itself, could raise the pressure over 150# where the relief valve on the WH will open, and drip some water out.

jadnashua said:

In many locales, 80# is the threshold of where a PRV is required.

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You make a valid point about a pressure relief valve. While the OP was talking about a pressure regulator, once installed, an expansion tank and a PRV might also be required.

LLigetfa said:

You make a valid point about a pressure relief valve. While the OP was talking about a pressure regulator, once installed, an expansion tank and a PRV might also be required.

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I'm pretty sure there is a PRV of some sort on the hot water tank already...

WH are required to have a T&P safety valve on them, this is not the same thing as a pressure relief valve. The T&P valve is to prevent the tank from splitting if the pressure gets too high, caused either by excess temperature or pressure. A WH is tested to 300#, which would really mess up house fixtures, they chose 150# to give it some margin of error. The temperature part of the equation is in case the acquastat goes bonkers, and keeps heating the water...it will release water to relieve pressure in that case too. A common occurance on a WH with a PRV and no expansion tank is that when it runs, the pressure exceeds the safety limit, and the valve weeps or discharges a little bit (since water doesn't effectively compress, any expansion causes stress on everything, and the pressure will rise radically once expansion starts, so it doesn't take much expansion to increase pressure a lot).

With the water softener, there may be a check valve in the system, and even without the PRV, he may need an expansion tank to prevent the WH from raising the pressure when it runs. He may not need a PRV. Only monitoring it during a normal day or two would tell that.

dlarrivee said:

I'm pretty sure there is a PRV of some sort on the hot water tank already...

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I chose my flame retardant words carefully when I said "might also be required" as codes vary and I make no claim WRT to code in the OP's jurisdiction. All I know is the introduction of a pressure regulator can turn an open system into a closed system where thermal expansion "could" become an issue.

I also wanted to add the distinction between a pressure regulator and a PRV.

Even if the pressure does not exceed 80 psi, that really more pressure than you need. Higher pressure puts strain on valves such as toilets and washers. Pressure from 40 to 60 psi is usually plenty. A pressure gauge is necessary to set and adjust a PRV anyway, so if you set the pressure at 40 psi and felt that you wanted more, it would be easy to adjust the PRV and thermal expansion tank to a higher level.