We just moved into a 2 year old house. At the time of home inspection we found the water heater leaking and asked the seller to get it fixed. Apparently they called a plumber and found that it was a bad expansion tank. I verified that it was replaced. For the past few weeks the water heater has been leaking from the relief valve. Knowing that the expansion tank had be replaced I started looking else where for the problem. I got a pressure gauge from the hardware store and am a little confused about what I found:

Outside spigot pressure is around 70 psi. Inside on the washing machine line the water pressure is at 120 psi. It is also 120 PSI on the spigot of the water heater.

I found my pressure relief valve and tried to adjust the pressure. No matter which way I turned it It didn't seem to make a difference.

So, Two questions:

1. why is the pressure lower on the outside spigots and higher on the water heater and washing machine line?

2. Is my pressure regulator bad?

Thanks in advance for the help!

 

What "pressure relief valve" is this? Where is it located? Did you mean pressure regulating valve?

Perhaps there are two pressure regulators or perhaps you are not properly measuring the pressure inside. IF you measure the pressure inside AFTER a significant amount of hot water has been used and the water heater has recovered BUT you have not used any water (hot or cold) during the time then it could easily be from thermal expansion. When you read this high pressure inside run some water (anywhere) and not what happens to the inside pressure.

Possibly, we have not established that you even have a pressure regulator. You might just have a faulty expansion tank on the water heater or maybe no expansion tank at all.

 

Thanks for the reply Furd

I was wrong... I was referring to a pressure reducing valve. The pressure reducing valve is located under my house, in the craw space, and from what I can tell it is connected to the main inlet water supply for the house. I have verified from google searches and how to that this is indeed a pressure reducing valve. It has a brass body and a dome like feature on the top with a lock washer and a bolt used for adjusting the water pressure. It does not seem to work. Adjusted the pressure reducing valve does not change the pressure at all.

I searched and have only found ONE pressure reducing valve. I could have been checking the pressure wrong. I left the gauge on the water line all night o see if there was nay thermal expansion. The meter stayed at 120 psi. If I run some water anywhere in the house the meter only drops to maybe 110 psi, just a little. The outside spigots are never affected and stay at around 70 psi.

Hopefully this new info will help. Thank You!

 

Ok, here is an update:

It appears that the pressure reducing valve only controls the outside spigots, and it works. I can adjust the pressure with the control valve to the outside spigots. So it appears there is two different lines ran into the home. One for the house and one for the spigots. I can not find another pressure reducing valve to the home.

Does this mean the city is pumping too much pressure into the home?


Thanks everyone.

 

Yes that is too much pressure. The pressure reducing valve should be installed for the whole house.. Joints can burst as well as water heaters split and burst from this constant high pressure...

Why only for the hose bibs? I would say possibly there is an irrigation system?

 

Thanks for the reply Lawrosa.

There is no irrigation system on the how or any type of connections.

It looks like: One line coming in from the street. Then, It appears to split off somewhere(I guess). I have two shutoff valves in the pantry. I found those two lines under the house. One goes to the pressure reducing valve and then to the spigots and the other line looks like It goes to the kitchen sink. its a red like and the rest are PVC white.

Seems like, for whatever reason they only put and pressure reducing valve on the line for the spigots but not the rest of the house. Not sure why... I have look all over for another presses valve but can not find it!

Guess I will need to get a pressure valve put in for the whole house.

 

do you need a expansion tank for sprinkler system if you are just using pump for it only ?

 

There is no irrigation/sprinkler system on the house. There is an expansion tank installed about the water heater.

 

While it is rather odd to have your only PRV attached to your outside faucets, the results you're measuring seem to support that. You seem to have 110-120psi coming in from the street, then reduced to 70psi for the outside faucets but not reduced for your inside plumbing. That 110psi is what's causing your relief valve to drip since it's much too high. The expansion tank that was added is necessary, but unfortunately isn't helping enough since you have such a high incoming pressure.

I can see having two separate PRVs, having a higher pressure outside is sometimes nice. But you'll either need to find the inside PRV (which may not even exist) or install one.

 

Thanks zorfdt, my thoughts exactly.

I will continue to look for another PRV. Its a Centex home built only 2 years ago. Maybe I can get some sort of blueprints that can tell me where to look for a second PRV.

Another question: IF there is only the one RPV, under the hose on a separate line for the spigots, Should I install the other RPV under the hose on the "hose" lines? OR would it be best to install it by the water main?

 

Sorry in being so late in returning...
You have stated several things that are troubling. You state the piping to the outside hose faucets is PVC and then you state that the rest of the piping is "red like" which I at first thought would be copper but in a follow-up yous call them "hose" lines. I suspect what you have is PEX (cross-linked polyethylene) flexible plastic piping.

In my area the plumbing codes require that ALL piping, both inside and outside be served through the pressure reducing valve if the pressure is too high for the system. Previously outside faucets were often fed with full pressure while the interior was fed through a pressure reducing valve but that is no longer allowed in new construction.

How many soldered or threaded joints as well as water heaters have you seen in your career that definitely split from a water pressure of 120 psi? I have NEVER seen this although I have seen (more than once) a copper tube supply to a sink held with only slip washers pop out of the fitting. This was in a house with 103 psi water pressure. I have also worked in two different facilities where the normal water pressure was 125-130 psi and we NEVER had any fittings or water heater tanks burst. One of these is still using the same water heater as when I worked there in the early 1970s and the water heater was old back then.

Water heaters are designed to work at 150 psi and THAT is why they are required to have safety valves set at 150 psi. If they could not handle any more than 75 psi they would have 75 psi safety valves.


No, it isn't. If the safety valve is leaking at 110 psi then it is defective. The expansion tank may have lost its air charge or was never properly charged in the first place. The air pressure on the bladder MUST be equal to, or very slightly higher, than the nominal water pressure. If the expansion tank has only a 40 psi air charge then the bladder will be fully collapsed when the water is turned on, leaving no room for expansion. You can ONLY check the air charge when there is no pressure on the water side.

Adam, you only need ONE pressure reducing valve and it should be piped so that ALL the water goes through it.