Pump/Flow Issues

[themilkman]

So pool is installed and running finally. Now I am trying to learn the quirks of my new system.

Here is my equipment breakdown along with a picture of my pump set up to help.

Intelliflo VS-3050 Pump
Hayward Sand Filter
Aqua-Rite TC-Cell-9 (Not turned on currently)
2" PVC Piping and Valves Throughout

Ok here are a few issues I would like some help with.

1. Flow - So I bought the Intelliflo to be able to vary the flow for cost savings and a water feature. Due to start up I have been running the pump in the the Speed 3/Speed 4 range due to cleaning etc. Now that the pool is clean and the concrete in I switched the speed down to Speed 1 (1/2 horsepower) for day to day cleaning. When I did this the pressure gauge on my Sand Filter went from this:

And it went to zero, no pressure. Now the pump is flowing and the returns has pressure, I assume this is just because of the upsized 2" piping that there is just no back pressure in the system. Is this an issue with filtering or anything?

2. Air in the pump glass - Normally the pump glass is solid with maybe just the tiniest bubbles. But when I go through the backwash cycle, rinse cycle I end up with a lot of air in the pump and line to the point it actually blows out of the returns. I am pretty sure I have a small leak right on top of my pump as I have found some water there between the pump and the sand filter. Is this the cause or is it just that backwashing sucks some air into the system?

 

[duraleigh]

1. As the pump speed slows, of course so does the flow of water. The slower water going through your system encounters much less "resistance" to it's movement (particularly in the filter) so your pressure goes down. That guage they provided you looks pretty clunky and you may be getting 5 or so psi when it reads zero. There are some pricier guages that are a little more accurate but what you are seeing sounds perfectly normal.

2. Anytime air gets in the system, it is a suction side leak....it won't be coming from the top of the pump as that is on the pressure side of the system. I am puzzled in that it is only occurring in backwash mode. Others may be able to get that figured out and I'll think about it some more but right now I'm stumped. I don't see it as immediately harmful but somthing that will eventually need to be fixed.

 

[Bama Rambler]

Don't worry about the filter pressure going to zero. It's probably not really zero but the accuracy of those gauges is not good so anything out of the middle of the range isn't going to be close to the actual pressure.

If you're getting that much air in the pump basket there's a suction leak somewhere. It could be the pump basket lid. Have you cleaned and lubed it yet? The backwash line usually has a lot less head loss than the return line so the pump actually moves more water thereby creating more negative suction pressure and exploiting any small leak on the suction side.

 

[themilkman]

Thanks for the quick replies as usual.

Ok I am going to see what we have at work for pressure gauges, I seem to remember having a 0-30 psi around that should be perfect and give me a more accurate reading.

I will check the pump lid as I know it hasn't been lubed. I also remember an issue we had with the Hayward Sand filter during start up. There was some plastic flashing left on the valve after he pulled it apart that he had to cut off since we couldn't get it to backwash. My guess is even though we removed this flashing that air is still leaking there which would be causing the massive amount of air through the returns that i am seeing. The issue with air in the pump glass is a seperate issue I will tackle.

 

[geekgranny]

Don't worry about the filter pressure going to zero.

Ditto. I have the VF. When my big filter is really clean and I run on my usual low speed, 19 gpm, which is probably pretty close to speed 1 on your pump, my filter psi is about 3. I have 1.5" pipes (more resistance) going from pumping station to pool and 2" only on all the plumbing at the pad. On my gauge the mark from 0-2 is very tiny. Starting at 3 the increments are larger between each. As I speed the pump up the psi increases.

gg=alice