Water Pressure Reading next steps

Users who are viewing this thread

AlGreen

Member
Messages
135
Reaction score
6
Points
18
Location
New Jersey
Due to an ongoing issue with water hammer when running my washing machine, I picked up a Watts model IWTG pressure gauge and installed it where the machine's cold water hose would hook up. The static pressure hovered right around 60 psi, dipping a little when running water in the house. What concerns me is that I found the red needle pegged at max once and then after resetting it, I found it at 120 psi.

Other information:

- I don't see a regulator anywhere near where the water main comes in.
- I had put a Sioux Chief Mini Rester on the hot and cold lines to the washer a few months back, which seemed to address the water hammer until a few days ago when I heard it again. That prompted me to buy the test gauge.
- My water heater does have an expansion tank, fwiw.

Suggestions?
 

Reach4

Well-Known Member
Messages
38,798
Reaction score
4,412
Points
113
Location
IL
1. That red needle might have moved up due to vibrations, and the pressure was never that high.
2. The pressure may have climbed that high because the thermal expansion tank has failed. Turn off the water. Measure the air pressure. The air precharge pressure, while the water pressure is zero, should be maybe 60 or 70 PSI. If there is water in there, you need to replace the thermal expansion tank. You may be able to tell by knocking on the tank while it is in service. The tank should normally be empty of water.

Some come new with 40 PSI and others 50 PSI of precharge. If you don't raise the air precharge to the actual water pressure or a little more, that puts more strain on the pressure tank. So for better life, adjust the precharge.

pressure-gauge-winters-2.jpg
 
Last edited by a moderator:

AlGreen

Member
Messages
135
Reaction score
6
Points
18
Location
New Jersey
1. That red needle might have moved up due to vibrations, and the pressure was never that high.
2. The pressure may have climbed that high because the thermal expansion tank has failed. Turn off the water. Measure the air pressure. The air precharge pressure, while the water pressure is zero, should be maybe 60 or 70 PSI. If there is water in there, you need to replace the thermal expansion tank. You may be able to tell by knocking on the tank while it is in service. The tank should normally be empty of water.

Some come new with 40 PSI and others 50 PSI of precharge. If you don't raise the air precharge to the actual water pressure or a little more, that puts more strain on the pressure tank. So for better life, adjust the precharge.

Thanks. I just disconnected the gauge in order to do some laundry, but I'll reconnect it after and check the air pressure.

Regarding the water expansion tank, I can't really hear anything when I knock on it. The precharge is 40 psi.

2016-11-10 09.50.11.jpg
 

Reach4

Well-Known Member
Messages
38,798
Reaction score
4,412
Points
113
Location
IL
Regarding the water expansion tank, I can't really hear anything when I knock on it. The precharge is 40 psi.
I hope you don't mean that literally. Maybe somebody else could try it, and could tell from the sound if the tank was empty or full of water. Either way, you should hear something... dull thud if full of water or higher pitched knock sound on an empty tank.

There should be a Shrader (tire) valve that allows you to read or change the pressure. That number, even though it is prominently printed, is only what the tank is shipped with. Like a tire, you want to set it yourself.

If it actually measures 40 PSI, that would be OK with your 60 PSI water, but it would not be as good as setting the air pressure to 60 PSI or a little more.

You measure the air precharge pressure with an air pressure gauge. You do need to have the water turned off and the water pressure down to zero. You could use a water pressure gauge to see when the pressure is down to zero, but you could just tell because the faucet that you open to relieve the pressure stops flowing.
 
Last edited:

AlGreen

Member
Messages
135
Reaction score
6
Points
18
Location
New Jersey
Poor choice of words: I couldn't hear anything that sounded like water in there. Maybe I expected to hear the ocean? :)
But if I had to choose, I'd say it sounded more like a dull thud.

I have a quality dial type air pressure gauge that I'll use to check the precharge air pressure.
 

AlGreen

Member
Messages
135
Reaction score
6
Points
18
Location
New Jersey
Ok, I turned off the water and let the faucet run dry. When I attach the air pressure gauge to the valve on the tank, I get no reading. Was there a step I missed?
 

hj

Master Plumber
Messages
33,602
Reaction score
1,041
Points
113
Location
Cave Creek, Arizona
Website
www.terrylove.com
Unless your tire gauge is broken, you do not have any air in the tank. If so, you have to leave a faucet open and use an air compressor to force air into the tank, which will push the water out of the tank to make room for the air.
 

Reach4

Well-Known Member
Messages
38,798
Reaction score
4,412
Points
113
Location
IL
Also, while the tank is empty of air, knock on it. You will then know what an empty tank sounds like. A good tank should usually be empty of water in service.

You can try setting the precharge on the existing tank as hj suggests. When/if you find you cannot and the air just blows out the open faucet, you will replace the tank. You can set the air to 63 psi (approx) before or after you install it. It may be handy to do that at a gas station on the way home with it.

http://www.amtrol.com/support/therm_res_sizing.html is one of the sizing calculators if you want to select a big-enough tank.
 

AlGreen

Member
Messages
135
Reaction score
6
Points
18
Location
New Jersey
Unless your tire gauge is broken, you do not have any air in the tank. If so, you have to leave a faucet open and use an air compressor to force air into the tank, which will push the water out of the tank to make room for the air.

I double checked the gauge, and it's working properly. Would a small portable air compressor used for tires work here?
 

AlGreen

Member
Messages
135
Reaction score
6
Points
18
Location
New Jersey
I'm going to replace the tank. It seems relatively straightforward, but I'd like to hear any pointers that a first timer should know.
 

Reach4

Well-Known Member
Messages
38,798
Reaction score
4,412
Points
113
Location
IL
Turn WH off, or put in vacation mode. Water will be turned off before the thermal pressure tank , and you will relieve the pressure: let some water out of the WH drain, or at least open a lower hot water faucet to let water drain below the tee.

Use at least 3 wraps of very good teflon tape or 8 wraps of cheap teflon tape. Using tape and pipe dope both may be worthwhile.
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,770
Reaction score
1,190
Points
113
Location
New England
If you have a valve on the outlet of the WH and one before the ET (there should not be one between the WH and the ET), if you shut both of those, there will be very little water in the line so if you relieve the pressure first (close the inlet valve, open a hot water valve somewhere), then close the outlet valve, you can just unscrew the old tank without a lot of water coming out. What can get dangerous for a WH is if you expose the element in an electric one, or aren't covering the area where the burner is on a gas on...make sure to open all of the valves and purge any air as soon as you're done. Safest is to disable it from running and make sure it is full before you enable it again, but depending on the situation, it is not really necessary.

FWIW, Dupont owns the trade name Teflon(R) and says that they never make plumbing tape. It's PTFE (the chemical name). While most people know what you're talking about, it's like calling all tissues Kleenex(Tm) or all cellophane tape Scotch(Tm)...and in this case, it certainly isn't Teflon(R) tape, since they do not make any!
 

AlGreen

Member
Messages
135
Reaction score
6
Points
18
Location
New Jersey
Turn WH off, or put in vacation mode. Water will be turned off before the thermal pressure tank , and you will relieve the pressure: let some water out of the WH drain, or at least open a lower hot water faucet to let water drain below the tee.

Use at least 3 wraps of very good teflon tape or 8 wraps of cheap teflon tape. Using tape and pipe dope both may be worthwhile.

Yep, this is the kind of info I was looking for. Thanks. I have an Amtrol ST-5 en route.
 

AlGreen

Member
Messages
135
Reaction score
6
Points
18
Location
New Jersey
If you have a valve on the outlet of the WH and one before the ET (there should not be one between the WH and the ET), if you shut both of those, there will be very little water in the line so if you relieve the pressure first (close the inlet valve, open a hot water valve somewhere), then close the outlet valve, you can just unscrew the old tank without a lot of water coming out. What can get dangerous for a WH is if you expose the element in an electric one, or aren't covering the area where the burner is on a gas on...make sure to open all of the valves and purge any air as soon as you're done. Safest is to disable it from running and make sure it is full before you enable it again, but depending on the situation, it is not really necessary.

FWIW, Dupont owns the trade name Teflon(R) and says that they never make plumbing tape. It's PTFE (the chemical name). While most people know what you're talking about, it's like calling all tissues Kleenex(Tm) or all cellophane tape Scotch(Tm)...and in this case, it certainly isn't Teflon(R) tape, since they do not make any!

Thanks. Regarding the part about the burner on a gas WH, you're recommending to turn it off while doing the install and then let it fill up again with water before restarting, right?
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,770
Reaction score
1,190
Points
113
Location
New England
Yes, you can put it to vacation mode (if it has one) as was already said as that will prevent the burner from turning on. ou really do want to ensure that the WH is full before it's heat source turns on. Off works too. But, it won't likely come on unless it has set for a long time or was running when you started, but best to be safe.
 

Reach4

Well-Known Member
Messages
38,798
Reaction score
4,412
Points
113
Location
IL
Thanks. Regarding the part about the burner on a gas WH, you're recommending to turn it off while doing the install and then let it fill up again with water before restarting, right?
He is. I am not. Vacation mode if you have one, and only partial drain for me.
 

AlGreen

Member
Messages
135
Reaction score
6
Points
18
Location
New Jersey
Installed. Thanks for the guidance.

And Reach4: Now I know what the expansion tank with air vs. water sounds like.
 

AlGreen

Member
Messages
135
Reaction score
6
Points
18
Location
New Jersey
I thought my original problem of water pressure surges was solved after installing the expansion tank. Today, however, I've seen the gauge spike to 120 twice. I'm not positive, but I think the spikes came after using the washing machine (hot water cycle) and dishwasher, both of which have mini arresters.
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks