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This is why you should test the water pressure


Scottpat

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This was on this mornings inspection. Water flow inside the home was fair to good. The static pressure at the rear hose bib was over 160 psi. The flow pressure dropped to 25 psi!

Hose bib was at the main line as it came into the home.

Home was on a municipal water supply.

Any takers on what might cause this large of a drop in the flow?

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I'm not sure, but the first thing I would look at is the way it is piped.

What size pipe supplied the valve? 1/2"? What size was the valve? 3/4"?

1/2" copper fits INTO 3/4" threaded valves and can be sweated together. It is faster and uses less fittings than using a felame adapter. I don't know if internally a 3/4" valve is larger than a 1/2" valve... but it probably is. If so, there would be a bigger drop in pressure. What was the flow like?

I would also be concerned about the 160lb. pressure.

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Originally posted by Scottpat

This was on this mornings inspection. Water flow inside the home was fair to good. The static pressure at the rear hose bib was over 160 psi. The flow pressure dropped to 25 psi!

Hose bib was at the main line as it came into the home.

Home was on a municipal water supply.

Any takers on what might cause this large of a drop in the flow?

If it were really 160 psi, then water would have been coming out of the TPR valve at the water heater. Was it?

Could this bib be tapped off of the street side of a pressure regulator? So that water pressure on the street side is 160? Did you measure the pressure drop at this same bib or a different one?

Was the water service valve partially closed?

- Jim Katen, Oregon

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Ah grasshopper! The main supply line is 3/4" and the hose bib is on a 3/4" line and is tapped right off the supply line as it enters the crawl space. Right after the hose bib the line is reduced to a 1/2" CPVC line. Then the house is plumbed out with 1/2" CPVC! Then for the fixtures we have the famous 3/8" PB risers.

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Originally posted by Jim Katen

Originally posted by Scottpat

This was on this mornings inspection. Water flow inside the home was fair to good. The static pressure at the rear hose bib was over 160 psi. The flow pressure dropped to 25 psi!

Hose bib was at the main line as it came into the home.

Home was on a municipal water supply.

Any takers on what might cause this large of a drop in the flow?

If it were really 160 psi, then water would have been coming out of the TPR valve at the water heater. Was it?

Could this bib be tapped off of the street side of a pressure regulator? So that water pressure on the street side is 160? Did you measure the pressure drop at this same bib or a different one?

Was the water service valve partially closed?

- Jim Katen, Oregon

The water heater had a pressure regulator at the tank. So the hose bib was on the street side and the high pressure. Water valve was open all the way at the meter.

That was the only hose bib at the house.

I have just never seen a pressure drop that much.

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Water flow inside the home was fair to good. The static pressure at the rear hose bib was over 160 psi. The flow pressure dropped to 25 psi!

Water valve was open all the way at the meter.

Just a guess of course, but I (make that someone else) might be looking for a crimp in the buried supply line.(?)

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Originally posted by chicago

How did you recommend correction?

I told them that I had no idea what was causing this or really what needed to be done. My first recommendation will not cost them anything. I told them to contact the local water provider. They have an engineering department and they will decide if it is on the city side or the house side. Then I told them if it is on their side that they will need to have a plumber to take a look at it.

One of those times that you just say, I don't know!

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Originally posted by Scottpat

The water heater had a pressure regulator at the tank. So the hose bib was on the street side and the high pressure. Water valve was open all the way at the meter.

That was the only hose bib at the house.

I have just never seen a pressure drop that much.

So, if I'm understanding this correctly, you measured the pressure at 160 psi. Then you ran water in the house, came back outside and saw that the pressure was 25 psi?

If that's the case, there's a wicked-bad obstruction somewhere upstream of the spot where you made the measurement.

- Jim Katen, Oregon

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Originally posted by Jim Katen

Originally posted by Scottpat

The water heater had a pressure regulator at the tank. So the hose bib was on the street side and the high pressure. Water valve was open all the way at the meter.

That was the only hose bib at the house.

I have just never seen a pressure drop that much.

So, if I'm understanding this correctly, you measured the pressure at 160 psi. Then you ran water in the house, came back outside and saw that the pressure was 25 psi?

If that's the case, there's a wicked-bad obstruction somewhere upstream of the spot where you made the measurement.

- Jim Katen, Oregon

That is what I'm thinking as well.

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