Pressure Leak During New Pool Build

[Cerealbars]

Hello All,

We have begun construction on the pool. The iron and plumbing have gone in and now the PB is waiting on me to allow him to spray gunite. The day the plumbers left, there was a leak in the main drain, it was coming out really bad. The PB had the crew come back out and fix it. Should the pressure gauge stay the same for 24hrs or is it normal for the pressure guage to fall. Even after the crew came back out to fix the issue, the pressure guage continues to fall. The PB assured me this is normal, but my Spidey sense has me asking this forum if it's normal.

Thank you for your responses!

 

[jimmythegreek]

It will vary with temperature but should maintain pressure. Unless his guage rig leaks or the pipes leak

 

[Cerealbars]

It will vary with temperature but should maintain pressure. Unless his guage rig leaks or the pipes leak

OK thank you. The pressure on the plumbers first run went from 30+PSI to 9 PSI. This time it was a drop of 7PSI sitting at 24 now from around 32 (in three days). I’m just a little worried because my neighbor has a leak in his plumbing and it’s going to cost him an arm and leg to get it fixed.

 

[x Wild Bill x]

As Jimmy said, they pressure in the pipes will change with temperature, also you can expect to see a drop in pressure right after the pipes are first filled with air. When the air is compressed in the compressor it is heated due to friction, once in the pipes it cools and will drop some pressure. However, after the first day (once the air charge has cooled) you should not see any more pressure "loss", the pressure should only vary depending on air temperature and sun exposure of the pipes. If you can, I would hold the PB off from gunite for a few days to make sure there is no more pressure lost.

 

[Cerealbars]

As Jimmy said, they pressure in the pipes will change with temperature, also you can expect to see a drop in pressure right after the pipes are first filled with air. When the air is compressed in the compressor it is heated due to friction, once in the pipes it cools and will drop some pressure. However, after the first day (once the air charge has cooled) you should not see any more pressure "loss", the pressure should only vary depending on air temperature and sun exposure of the pipes. If you can, I would hold the PB off from gunite for a few days to make sure there is no more pressure lost.

Thank you. The plumbing was water pressured but I’m sure there is some air in there. The PB is coming back tomorrow and he is going to rerun the test while we are waiting on the city to give us a green light on the iron and copper. I got a quote today for 300 bucks for an independent pressure test. Okay end up doing that for peace of mind.

 

[x Wild Bill x]

Hmm, okay, so you are saying they filled the lines with water up to 32psi or so and then you had some pressure loss after that? That makes it a little trickier to validate, as waters volume and therefor pressure also changes with temperature. However it changes less and I would assume the water put into the pipes was the same temperature or maybe even colder than the ground / surrounding air of the pipes. If this was the case then there should not have been much of a pressure change. If you knew the size and total length of piping, plus the temperature the water was when it went into the pipes and the ambient temperature when the pressure dropped you could calculate the pressure increase or decrease. A super quick back of the napkin calculation assuming 30 gallons of water in your piping - 200ft of 2" pipe, would need the temperature of the water to drop 20 degrees Fahrenheit to have your pressure loss.

So, basically what I'm suggesting is your plumbing could be fine and leak free, or there may be a leak. If it were my build, I would spend the $300 for the peace of mind plus a second chance to check the plumbing especially since you already had one leak. I hope all goes well and it passes the independent pressure test and you can get on with your build.