How to measure water pressure


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Old 09-20-06, 05:48 AM
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How to measure water pressure

First off, thanks for all the help in the past.

I had my water heater replaced and the guy doing the job said I had high water pressure (110 psi). He said I should have my PRV replaced before he installs a thermal expansion tank because the tank can't handle that kind of pressure. I went out and bought a watts water pressure gauge. I screwed it on the laundry faucet and the black needle reads between 70 and 75 psi and it dips down when someone turns another faucet on. What is the red needle for? It is frozen at 82 PSI. Do you think my PRV is really bad? It is a Watts 25AUB.

Thanks.
 
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Old 09-20-06, 09:16 AM
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I'm not a plumber so better advice is likely to follow. I think I own the same pressure gauge. The red arrow indicated the highest pressure read while it was hooked up. 24 hr reading gives the best info.

You can lower your incoming water pressure by adjusting the pressure reducer valve. If it won't lower the pressure it would need to be replaced.
 
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Old 09-20-06, 10:01 AM
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Wink

the guy doing the job said I had high water pressure (110 psi). He said I should have my PRV replaced before he installs a thermal expansion tank because the tank can't handle that kind of pressure.
What did he use to read that PSI and was it right????
Put you gauge on a outside hose shutoff see what you read there.Most work at 60 to 80 all the time. If you dont have a tank now and he turned the heater on yes you could have hit a 110 psi when the tank got hot water in it
The red hand on the gauge is set to anything you want. You can set it to anything . Its like a sign not to go over.

ED
 
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Old 09-20-06, 10:24 AM
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I don't know what pressure he was referring to.......I wasn't home and my wife only relays info to me.

I understand that the pressure in my hot water tank would increase since I have a closed system AND I'm going to get the expansion tank as he recommended. I just don't want to replace the PRV if I don't have to.

He told my wife that our water pressure was high at 110 psi. My wife called me and I told her to have him adjust the PRV. He said that our PRV has settings from 25 to 75 and that if it read 110 that the PRV was just not working.

I figured he was right but I decided to put a gauge on it anyway. It reads between 65 and 75 at both the laundry room (cold tap) and outside spigot.

Is it possible that water pressure can vary that much from the street or is this guy feeding me a line?
 
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Old 09-20-06, 10:37 AM
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Out of the box here. If he put the new water tank in and filled it with the cold water . Then turned it on and the water got hot as it should. Sure the psi can go up the water has no place to expand. Yes you do need the tank there for sure.

I screwed it on the laundry faucet and the black needle reads between 70 and 75 psi and it dips down when someone turns another faucet on.
You see now the water is hot in the tank.

ED
 
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Old 09-20-06, 11:02 AM
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I'm OK with the Thermal expansion tank....I plan to have one installed as soon as I can.

I'm more concerned now about the cold water pressure coming in from the public service. When he told me I had water pressure of 110 psi, I was assuming he was taling about pressure from the street, not hot water tank pressure.
 
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Old 09-20-06, 11:34 AM
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When the water heats up cold water all the water in the home PSI will go up . You had a 70 to 75 when the water was hot Id say yourPRV is good.

ED
 
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Old 09-20-06, 12:27 PM
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Thanks evertyone!
 
 

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