Combining suction lines....worth doing?

[aceman67]

Folks -

I have 3 pumps on my pool, 2 for water features, 1 for main filtration.

All 3 pumps have their own 2 inch suction lines in the deep end of the pool. I recently upgraded my main filter pump to a 2.5HP variable speed pump, and per my flow valve, I'm pushing 80 gal/minute. I rarely use the 2 waterfeature pumps so was thinking if it would be worth feeding the main filter pump with an additional set of drains. Would this increase my efficiency any?

Appreciate any thoughts -

thx

Aceman

 

[ajw22]

Welcome to TFP.

No.

 

[rlab]

To expand on that, it depends, but probably no. Most of the system pressure is likely on the return side rather than the suction side. So reducing suction side pressure won't help that much.

But there is a way to tell for sure, you would need to put a vacuum pressure gauge on the suction side of the pump (in the drain port), and that will let you compare the suction side pressure to the return side pressure (from the filter pressure gauge).

 

[aceman67]

Rlab -

Thanks for the info. I will do try that today. Is the goal for them to be equal? I have multiple return lines (3 - 1 deep end, 1 shallow end, 1 spa)

 

[rlab]

There is no goal per se, just that the system tdh is the suction side pressure plus the return side pressure. The filter gauge gives you (approximately) the return side pressure, the vacuum gauge on the pump suction side gives you the suction side pressure.

Once you have these 2 values you can estimate system tdh (feet) = 1.13 * suction pressure (in Hg) + 2.31 * return pressure (in psi).

Then to estimate the effect of adding another suction line you can subtract, say 20%, from your suction pressure. This is because whatever flow was going through the main drain is now split between 2 lines, but your skimmer still needs the same flow it had before.

But long story short, your suction pressure is likely already low versus return pressure, so you will only be saving 20% of not very much.

 

[duraleigh]

How many gallons is your pool? If you are running that VS to produce 80 gpm, you likely can save some money by slowing down.....unless you pool is around 30-40k.

 

[aceman67]

Sorry for the late reply Dave....my pool is 37K....