Pool plumbing pressure test and pressure drop

Jan 6, 2019
7
0
Tucson/arizona
#1
My pool builder is pressure testing the plumbing with water. Pressured it up to 30 psi, went up to 31 psi later in the day, then dropped to 29 psi the next day. Stayed around 29/28 for 3 days. Pressure gauge is still on after 3 weeks and reading has dropped to 12 psi. We have had temps from 80 to 24 here in Tucson during this time. Is this pressure drop to be expected after this amount of time or do i have a small leak?
 
Jan 6, 2019
7
0
Tucson/arizona
#3
He really doesn't give me an answer. He thinks since it held for 3 days everything is Ok and there is no leak. I just wonder why it dropped from 30 to 12 in 3 weeks if the system is a sealed system. From what I have seen they usually don't pressure test for more than 24 hours and it was fine in that time period from 30 to 28 psi fluctuating with temperature.
 

duraleigh

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#4
I think he does the pressure test for the governing authority to pass him or not. Do you think he failed? can you get him to give you an answer?? Seems like it is pretty cut and dried.
 

setsailsoon

LifeTime Supporter
Oct 25, 2015
562
1
Stuart/FL
#5
Paj,

Nobody I know pressure tests for more than a couple of days. Most likely somebody opened a valve then heard a hiss and closed it. That said, if you're concerned ask the PB to repeat the test. If he balks tell him it's in both your interest to check it now unless he's certain why it dropped and can prove it. If he doen't agree to retest then document your concern plus the situation.

I hope this helps.

Chris
 

sktn77a

Gold Supporter
May 16, 2010
762
0
Chapel Hill, NC
#6
We have had temps from 80 to 24 here in Tucson during this time.
Do you mean the temperature dropped from 80 to 20 over the 3 weeks in question, which would cause a drop in pressure (but not 18psi) or was this the day night range?

Have him repeat the test for 3 days (something might have happened to the plumbing during those 3 weeks) - if it stays up you should be fine.
 

quantase

Active member
Jun 19, 2018
40
0
Central Virginia
#7
Interesting. I had a similar issue. My PB pressured tested with air at 25 PSI, it held for 3-4 weeks with slow decline of 3 PSI each day. Then they were putting in some trenches and cracked one of the plumbing pipes. They fixed it and pressured it back to 25 PSI and it lasted for only 6 days until it was at 2 PSI. I told the PB that I was concerned and it said that the industry norm is usually no leaks for the 30 minutes and that the leaks could come from around fittings on the heat pump, SWG, and water filter pump that may have small leaks (which is okay?) and allow some air to leak. The PB said that you can't ever get a complete sealed system. Before the deck is laid, I plan to ask him to pressure test it again. I understand that the environmental temperature may play some affect, but what do others think about how long should the PSI stay stable (or what average interval of PSI decline per day should be seen) for water or air pressure testing?
 
Jan 6, 2019
7
0
Tucson/arizona
#8
Thanks, he is going to pressure it up again and watch it for 3 days. Hopefully it will stay near 30 with slight flucuation for temp, 68 day and 40 at night. We did go from 78 to 26 temp in span of 3 days, welcome to the desert southwest! I am hoping it is just some small air leaks as suggested since it did hold pretty steady for 3 days before slowly dropping. At a 24 he test i am guessing it looked pretty good
 

riley00dog

Gold Supporter
Nov 14, 2017
2,207
0
Brisbane, Qld, Australia
#10
I'd have to disagree with this - if it leaks air, it will leak water!
Yep. Do not mess around with this. Our pool supposedly passed its leak test. Obviously it didn’t or we wouldn’t be left with a brand new pool with leak that is completely inaccessible. It may be an inconvenience now, but I can tell you that it can quite easily turn into your worst nightmare.
 
Jan 6, 2019
7
0
Tucson/arizona
#11
So he pressured it up to 30 psi at 7:30am and 12 hrs later it is still at 30 psi. I am guessing this is good. We will drop 30 degrees tonight so I am hoping when I check it in the morning it will be 30 or 29 so there would be no change in 24 hrs, which from what I have seen would indicate a good pressure test?
 
Jan 6, 2019
7
0
Tucson/arizona
#12
Did some more research and Arizona code says 25 psi for 30 minutes is the requirement for pool pressure testing and pressure should be maintained while decking is poured (we are using flagstone for deck so no pouring occuring). So I guess if the pressure holds for 24 hrs I am good to go?
 

setsailsoon

LifeTime Supporter
Oct 25, 2015
562
1
Stuart/FL
#13
Paj,

You can estimate the temperature impact to the pressure by using the ratio the temps in degree K. Degree K = Deg F+460.

I hope this helps.

Chris
 

JamesW

TFP Expert
Mar 3, 2011
12,669
3
#14
(°f − 32) × 5/9 + 273.15 = k

P[sub]1[/sub]/T[sub]1[/sub] = P[sub]2[/sub]/T[sub]2[/sub]

P[sub]1[/sub] = 30 +14.7 =44.7 psi.
T[sub]1[/sub] = (80°f − 32) × 5/9 + 273.15 = 299.817k
T[sub]2[/sub] = (24°f − 32) × 5/9 + 273.15 = 268.706k

44.7/299.817 = P[sub]2[/sub]/268.706
P[sub]2[/sub] = 40.062.

Final gauge pressure = 40.062 - 14.7 = 25.36 psi.
 

setsailsoon

LifeTime Supporter
Oct 25, 2015
562
1
Stuart/FL
#15
(°f − 32) × 5/9 + 273.15 = k

P[SUB]1[/SUB]/T[SUB]1[/SUB] = P[SUB]2[/SUB]/T[SUB]2[/SUB]

P[SUB]1[/SUB] = 30 +14.7 =44.7 psi.
T[SUB]1[/SUB] = (80°f − 32) × 5/9 + 273.15 = 299.817k
T[SUB]2[/SUB] = (24°f − 32) × 5/9 + 273.15 = 268.706k

44.7/299.817 = P[SUB]2[/SUB]/268.706
P[SUB]2[/SUB] = 40.062.

Final gauge pressure = 40.062 - 14.7 = 25.36 psi.
Whoops... what James said. I had deg absolute. Thanks James.
 
Jan 6, 2019
7
0
Tucson/arizona
#16
Thanks for all the input. According to the pressure/temperature calculations we should be fine. It dropped from 30 psi to 27 psi over a 36 hr period and a temperature swing from 70 to 38 and back up to over 70. Also discovered a very small leak in one fitting to the whisperflo pump and another one from the pump cover (all other equipment fittings were completely dry). I feel pretty comfortable when the pool builder says there is no leak in the plumbing under the shotcrete. So hopefully we can move forward.
 

JamesW

TFP Expert
Mar 3, 2011
12,669
3
#17
Paj,

You can estimate the temperature impact to the pressure by using the ratio the temps in degree K. Degree K = Deg F+460.

I hope this helps.

Chris
This converts the temperature to the Rankine scale, which also works because it is an absolute scale.

44.7/539.67 = P2/483.67.

P2 = 40.062.

For a 10 degree temperature change in Fahrenheit, you get about a 1 psi change in pressure.
 

quantase

Active member
Jun 19, 2018
40
0
Central Virginia
#19
I just had my pool plumbing pressurized again, and we could hear the air escaping from around the lid of the pump filter. Even after adjusting it, replacing the gasket and lid, air seems to still be coming pass it. It is a slow leak, maybe 1 PSI every 2 hours. Do anyone think that this is a concern or should I request for a whole new pump?