new max-e-pro sta-rite pump & operating questions

[mas985]

Tenax,

The problem is pipe length is not equivalent to head loss although they are related. There are rules of thumb but I would not recommend calculating head loss from the plumbing design as this is very difficult to do and not always very accurate. The easiest and most accurate method is to calculate it from your existing filter pressure.

Based upon your filter pressure of 16 PSI, you are currently at about 50 feet of head which is fairly typical.

Is the new pump a full rated or up rated 1 HP? A 1 HP uprated pump is the same as a 3/4 HP full rate pump so the one you got may be ok or close enough.

Also, you will have more GPM with your valves open than you will with them closed. You mention closing valves to control GPM but why would you want to do that? Filter limits? If so, I would not try to adjust GPM on the suction side as this usually causes cavitation or air leaks. It is best to control GPM on the return side if possible. Pumps perform better this way.

[tenax]

the current 3/4 hp is actually a 1/2 hp uprated..the new one will be a 3/4 hp uprated to 1 hp.

maybe i'm not explaining myself properly on the valves thing..here's what i know...when i have both ball valves open on the 2 lines labelled skimmer and main (lines that come in from the ground as 2 separate lines into 2 separate valves, then into a T and then into the pump intake i guess you'd call it) i get less pressure in my filter when i have one or the other closed..but note that if i have the skimmer valve open but the main drain line closed, there is more velocity in the skimmer..if i reach my hand in, there is definitely more suction in the skimmer.

so, back to the original question about the new vacuum and should i have enough gpm flow. or maybe i'm making an assumption that extra suction is higher flow rate..my brain hurts now

it sounds like i wont' have a concern otherwise relative to to much pressure for the filter (which is rated for 62 gpm max) with the new pump!

[mas985]

The reason you get less pressure in your filter when you close one of the two suction valves, is that you are increasing the suction head and thus reducing flow in the system. Less GPM on the return side means less PSI on your filter guage. If you had a vacuum guage on the suction side, you would see this rise when shutting off the valve. This is why to get an accurate head reading, you need both the filter PSI and suction inches mercury. Calculating total head from just the PSI reading is a very rough estimate and can lead to errors for this type of special situation.

Increasing the head on the return side has a similar effect on the suction (less suction).

The vacuum cleaner should not be an issue as you are going to a stronger pump. You may need to balance the valves so you do not have too much suction on the cleaner.

At 50 feet of head, the new pump will be at about 60 GPM so you will probably be ok. My guess is that your head loss will increase to maybe 55 feet of head because the pump is stronger so you should be under 60 GPM and not need to restrict the flow at all for the filter.

[tenax]

cool mark...i get what you're talking about now..thanks a bunch! good education! ps- that makes good sense re: the vacuum..don't want to suck the liner right off the pool