Pool Filter Exploded - pressure to high?

Pool pumps, pool filters and the plumbing of
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My Pool: 20' x 40', inground, sand filter, 1.5HP pump
Location: Montreal

Pool Filter Exploded - pressure to high?

Postby Benm » Wed 19 Aug, 2009 11:32

I have an inground pool, about 20' x 40' with a 1.5HP Jacuzzi pump and a Jacuzzi ST24 filter. Part of the system is an electric pool heater that gets used occasionally when the water gets too chilly (we live in Montreal, Canada).
Sunday I found the filter cracked in 2 almost along the horizontal seam with spider cracks radiating up and down right trough the plastic. Also water and sand everywhere! Very scary!

I had the filter replaced with a Hayward Pro 200 by our local pool guys and they tell me they see this kind of filter "blowouts" all the time?!?!?!
On the other hand the insurance guy (adjuster) tells me that in his 22 years of pool maintenence experience he's only seen this twice?!??
Confusing, or what?

Anyways, I do all the regular maintenance on the pool and normally my pressure gage is at 25psi and it goes up to 30 psi when I run the heater (bigger loop?).
Is this normal? How can I properly calculate what the pressure should be considering my pipe diameter and length, pump hp and other equipment I have?
Also, is there a safety device that can be installed that will either shut down the pump or release the extra pressure? I can't believe this is not mandatory, since a filter blowout can really hurt somebody!!!

Cheers and thanks for any opinion in advance, Ben


Pool Filter Exploded - pressure to high?

Postby tothee » Sun 23 Aug, 2009 22:14

this probably wont be that much help but i had a filter split vertically top to bottom once. de filter came with the house we bought and was fairly old. when we opened the pool for the 1st time it was horrific. ran filter backwashed and took it apart and cleaned numerous times. with so much cleaning required, and the pressure differences throughout the process i attributed the blow out to to much pressure. the last time i looked at the pressure gauge before it went was the highest i had seen it to that point.
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My Pool: 26x13, inground, 1.5 hp pool pump, hayward pump, filter, and propane gas heater
Location: Montreal

Pool Filter Exploded - pressure to high?

Postby lmcancu » Tue 01 Sep, 2009 18:44

On my hayward filter (s244t) the drain cap is made of a weaker plastic so that if the pressure gets too high, the cap will break apart instead of the filter walls. Filters generally are rated to take about 50 PSI, so it seems the pressure inside your filter got too high. Either the pump is oversized (which I doubt), or something in your filter got blocked causing the pressure to go too high. Recommend you backwash at least once a week to relieve any abnormal pressure build up. Watch your pressure gauge carefully to see how much it rises throughout the week. Hayward recommends you backwash after the pressure rises 8-10 PSI ...
How big are your pipes? 1.5" or 2"

There is an article here that may help to see if your equipment is sized right.

http://www.poolspa.com/publications/sin ... /pumps.htm
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Pool Filter Exploded - pressure to high?

Postby mas985 » Tue 08 Sep, 2009 11:26

Most filters should be able to handle up to 40 PSI. If the filter was old and exposed to UV, it was likely it's time to fail. Filters undergo quite a bit of flexing on start up and shut down of the pump so it is a matter of time before the plastic will fail.

As to what is normal. A 1.5 HP pump will produce quite a bit of pressure if you dealing with 1.5" pipe so 30 PSI is not out of the question.
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18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, Solar Panels, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater
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Pool Filter Exploded - pressure to high?

Postby czechmate » Tue 08 Sep, 2009 17:13

Well built system SHOULD NOT have more start up back pressure than 15-16 PSI.
Ideal is around 12-13PSI.
The 25PSI than should be close to a backwash pressure area.
The more force the pump has to generate results in more electrical current draw, meaning higher bill and more strain on the elements in case of poor coating with DE resulting in possible element damage.
Further higher pressure in the filter directly indicates slower flow and longer turnover or so called turnover.
Running 9 hrs daily instead of 5hrs or 6 hrs present lot higher electrical bill and shorter lifespan of the pump motor.
I have seen heater manifold hooked up backwards with starting back pressure of 20PSI. That later resulted in freeze over in the winter under 13Ftemperature and with the pump running.
I do not see ANY justification nor need to accept filter pressures in excess of 30PSI.
Such a case indicates poor design and execution of a pool contract. Period.
For something that cost as much as a new car and it's bulk built mostly by hired help, there is no excuse.

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