Filter too small & Pump too big??

[Hey_Dad]

This forum is awesome. I want to start by saying thanks to all for the questions and the answers... I've learned a ton. However, I do have a question. Last August we had a 17K - gal Fiberglass ig 15 X 34. We have a 1.5HP Hayward Tristar with a Hayward Perflex DE EC40AC. Plumbing is 2" from a single skimmer to the pump,thru the filter, heater, SWG and then into a manifold where it goes down to 1.5" to a total of 6 returns. I've noticed that the pump always sounds like it's working hard and the flow out of the returns isn't very strong. After cleaning the DE fingers per the "Stickey" about cleaning a DE filter, and adding DE, the starting pressure is about 14lbs. Still not much flow. Does this sound like my pump is too big and/or the filter is too small? How can I calculate what I need so that I can validate the equipment I have? It seems odd to me that the pump requires a min of 2" pipe, but the first thing it does is get reduced to 1.5" at the base of the filter and out of the filter it goes from 1.4" back up to 2". It seems to me you would want to remove the restrictions....

[Watermom]

Hey Dad! Welcome to the forum. I can't help you with your question unfortunately, but the plumbing part of pools is not my thing. Hopefully someone else will be along shortly who can. Just wanted to say hi. And, you are right ----- this forum IS awesome thanks to all the great people here! Hope you enjoy being a part of our group.

[aylad]

Bumping this back up.....

Janet

[Hey_Dad]

Maybe I need to clarify this a bit...I'll start with H2O intake....

Question Part 1 - The skimmer on my pool Leisure Morroccan 15x34 (fiberglass ig) says the max GPM is 75 (it's stamped into the lid of the skimmer cover) . I know the pool builder connected 2" flexible pipe from the skimmer to about 4' in front of the pump, at which point he converted to 2" Schedule 40 hard pvc into the pump. This is about A 17' straight run. There is only 1 skimmer and is the only source of water for input into the pump. The pump is a Hayward Tristar sp3210X15 and is at about the same height as the top of the skimmer. So it's not pulling water straight up 17 feet or anything crazy like that. There is a chart on page five of the manual that says Maximum system flow rate by pipe size for a 2" pipe is 80 GPM. The sales pamphlet shows a chart with a curve between 78GPM & 130GPM depending on total head. (I have no idea how to calculate total head, so I don't know where on that line I fall)

However, based on these readings, I think I am capable of pulling in about 75GPM to this pump. Is this correct? (or at least close??)


Question part 2: Assuming I am correct about the above.... next up is my filter. It's a Hayward EC40AC. From the Hayward site the "Design flow Rate" for this filter is 40 - GPM. If I am reading this all correctly, it looks like the filter is about 1/2 the size it should be to handle what I think the pump is sending it. If this is true then which filter should I replace it with? I want to stick with DE. It looks like the Hayward EC75A is what I would need (~$500 on Amazon).

If I can get a validation on Q1, I think everything else will fall into line....

The reason for the questions are two fold

1) My pump is running hot. It is wired 220. It was 56 outside early this AM, and when I went out to check the filter the pump was hot to the touch. I am concerned about premature wear and tear on the pump.

2) My return jets have weak flow. I have a total of 6 spots where the water goes back into the pool. The closest one is strong, all the others are weak..I'd like to increase the flow. The weak 5 jets all point at the skimmer...the theory being... .push the dirt towards the filter skimmer.

Any input would be appreciated... .
Thanks

[madwil]

when you say pump is hot, do you mean the pump housing, or the motor?
the water flow should cool the pump part- it should be roughly same temp as water
The electric motor hot to touch could be an issue, but motor issue not pump (not trying to confuse you, just making sure which part is hot). If it is hot when outside temp is 56, I'd get an electrician to check it...

I'll let the real equipment experts address your flow rates- but it sounds like you're right about to much pump!

[CarlD]

That is one powerful pump! At 40' of head it flows over 100gpm! To get it down to 40gpm you have to have over 70' of Total Head.

Can you bypass the filter so the pump runs from skimmer to returns? If you can do that, does the flow improve drastically? Does the pump cool down?

You have a small, little filter with a super-powerful pump designed to roof solar panels, fountains and waterfalls. I'm no pump expert but you have 'WAY too much pump!

I wonder what the installer was thinking, with only one skimmer and no low drain. It's clear: Your pump is over-heating because it can't flow enough water--too restrictive.

What to do? Here I'm just making WAGs...Wild A-- Guess. IF it works OK when you bypass the filter and the pump cools down it could be as simple as just getting a bigger filter--one that handles over 100 to 120 gpm. If you like DE, they make them that big and bigger.

If it doesn't then down-sizing the pump is probably better. Something like a 3/4-1 hp uprated pump or a 3/4 full-rated might do it, but sizing has to be done correctly.

There's a very good chance your DE filter has been damaged. It should be opened and examined if you are going to keep it.

These are just starting ideas. The real pump guys can guide you better than I can.

There are ways to calculate and to estimate total feet of head, but I don't really understand them.

Carl

[mas985]

Based upon your description, I estimate that you should have about 82 GPM @ 49' of head. However, because you only have one suction line and it is only 2", the suction is likely to be quite high which could draw in some air into the pump basket. Do you see any air in the pump basket?

If you are trying to equalize the flow between returns, one way to do that is to downsize the eyeball diameter in the closest return, assuming that is even possible for your returns.

[Hey_Dad]

Madwil - "when you say pump is hot, do you mean the pump housing, or the motor?" Answer: The metal part so the motor is what seems to be getting hot.

Carl - I can not bypass the filter without replumbing it. As for the WAG, since I can't easily bypass the filter I was thinking about increasing the size of the filter to handle the load, I was thinking something that would handle at least 75GPM since that is what is stamped on the skimmer,.... I did take the filter apart and did the acid wash etc this spring. Everything looked ok. It's in service now and working just fine as far as I can tell. The pressure in the tank when it's totally clean, NO DE, is 13 LBS pressure. After adding the DE it goes to about 15ish.... I don't let the pressure get above 22. So maybe there is a flow restrictor in the input of the filter. The manual says one is supplied but since I didn't plumb the filter I don't know whats in there.... Bottom line, I think the pressure in the filter is low enough that it's not going to blow up or anything. (If I'm wrong yell at me.... ) However, the more I read, the more I believe the filter size needs to be increased.

Mark - The only time I get air in the pump basket is when I vacuum. When I attach the vac hose the pump couldn't draw enough H2O and just struggled. It had a high pitch whine and then the basket lost prime. To solve this problem I drilled a 1/8 " hole in the vacuum plate. Started the pump, and attached the hose. I repeated this, each time making the hole larger, until the H2O flow could keep up with the pump.

Yes I am trying to equalize the flow. I have "massage" jets that the water just trickles out of. Not much of a massage. :-) I have also been playing around with 2 valves in the pipe manifold (returns) I am able to increase the flow to the massage jets, but that causes the pressure in the filter to go up about 4lbs. So I keep that valve open 100%.

Anyway, the more I think about it.. the more I believe that I need to reduce the size of that pump and increase the size of the filter.... I'd rather spend that money on beer with the neighbors, but....

[Hey_Dad]

Can I just swap the motor out on my pump? Could I swap it out for a two speed motor? If so, how do I know which motor will fit?

I was thinking that this might be the cheapest/fastest way to fix the issues above.

[PoolDoc]

To reduce delivered HP / wattage consumed you need to swap out the impeller and diffuser, not the motor. A motor will draw current according to the load placed on it -- it's just that if you put a 2HP load on a 1HP motor, it will burn up. However, if you put a 1 HP load on a 2 HP motor, everything will be fine.

Ben