Smallest Allowable Distance between Pump and Open Water, underground pool.

[Olle]

Hi Team!
Here is another poorly designed swimming pool. As the title suggests, I wonder what the smallest distance between pump and pool should be.
Background: Our pool equipment is located 5' above the pool surface due to the slope of the lot, visible in the lot survey below. The pool surface is 87' above sea level, you can relate all other elevation marks to this. The 5' negative head has created the following problems:

• Several extra check valves increase power consumption.
• Sensitivity to vacuum leaks. The slightest dirt or tiny pine needle in the the lid o-rings introduce air and massively increases power consumption. I regularly see over 300W @ 25 gpm according to the Pentair Intellifow VSF display. We installed new pumps, no improvement.
• Very hard to prime. We have the pumps running 24/7 for this reason.

For these reasons, we are considering relocating the pumps closer to the water level. Pumps would push through downstream (upstream elevation wise ) suction lines (future return lines) to existing equipment site and keep filer and heater there. The image below shows some proposed locations.

• 'A' benefits from existing suction lines already surface at 'A' for check valves, minimum re plumbing would be required. A is only 2' horizontal from the water surface. I have never seen a pump this close to open water and wonder of there is a reason. I read NEC Section 680 and found the following:
  • "The maintenance disconnecting means must be readily accessible and located within sight" OK, checks out.
  • "at least 5 ft from the permanently installed pool": OK
  • "Underground wiring isn’t permitted under permanently installed pools or within 5 ft horizontally from the inside wall of the pool unless necessary to supply the permanently installed pool or storable pool equipment. If space limitations prevent underground wiring from being at least 5 ft away, wiring must be installed in complete raceway systems of rigid metal conduit, intermediate metal conduit, or PVC conduit." OK
• 'B' would be my second choice because relatively modest re-plumbings requires only lawn digging.
• 'C' is 6' below pool surface. Requires removing a deck as well as hand digging under the pool to re route suction lines. My least favorite option for that reason. There is no room to run pipes over due to trough and tall concrete columns.

Questions for the forum:

• Would location A with its proposed shut off be code compliant?
• Do you see any other reasons not to opt for location 'A'?
• What are your opinions on B and C?
• Do you have any other solutions for solving this pump problem?

Thanks in advance to anybody who can give some insight to this.

 

[Olle]

Bump

 

[mas985]

I would contact your local building department to get a read on that. Local codes will sometimes trump NEC. I know ours are more restrictive.

Personally, I would be more inclined to choose B so the pump is some distance from the pool for noise issues plus seems like an easier install.

But are you just relocating the pump or all of the equipment? I would be more inclined to keep it all together which is another vote for B.

 

[SJPoe]

Given some of the signed-off installations I've seen lately, pretty sure you could locate the shutoff on a floating platform in the middle of the pool and someone would sign-off on it.

I don't see a huge issue with A as far as wiring is concerned, properly contained (raceway/RMC) and GFCId, but the equipment would concern me being that close. Pretty sure there is a 6ft rule, but I can't find it.
I would imagine that at a minimum it would have to be contained in an enclosure of some sort, its well within spillage/reaching distance. If the casing of the pump was live and you reach to get that ball...blammo. -

So, I agree with mas985 - contact the local inspector and have them 'rule' on it ahead of time, but B would seem like the beter choice.

 

[Olle]

I would contact your local building department to get a read on that. Local codes will sometimes trump NEC. I know ours are more restrictive.

Personally, I would be more inclined to choose B so the pump is some distance from the pool for noise issues plus seems like an easier install.

But are you just relocating the pump or all of the equipment? I would be more inclined to keep it all together which is another vote for B.

Thank you for that good advice. Normally I’d agree to move all equipment. Because B is conspicuous, I was only planning on moving the pumps to B. Could put a little shrub in front of it. Pool heater and filter are nicely hidden behind some trees now.

 

[mas985]

Rethinking your issues, I wonder if changing the pump location will be worth it.

The check valve on the inlet to the pump isn't really that bad in terms of head loss. Typically it would add only about 5% to the total head loss so removing it isn't really going to change much from an energy usage perspective.

However, do you have a bypass for the heat pump? They have LOT of head loss and typically require a bypass to keep the head loss in check. This could be the major cause of excess energy use. When running what is the filter pressure when the filter is clean?

While 5' is a pretty high lift and can cause priming issues, I wouldn't expect it to be that bad. There are plenty of folks on the forum with that much lift which do not have that much trouble. When you fill up the pump basket with water, it should fill to the top since you have a check valve. Is the water draining out? Perhaps there is an issue with the check valve.

 

[Olle]

Rethinking your issues, I wonder if changing the pump location will be worth it.

The check valve on the inlet to the pump isn't really that bad in terms of head loss. Typically it would add only about 5% to the total head loss so removing it isn't really going to change much from an energy usage perspective.

However, do you have a bypass for the heat pump? They have LOT of head loss and typically require a bypass to keep the head loss in check. This could be the major cause of excess energy use. When running what is the filter pressure when the filter is clean?

While 5' is a pretty high lift and can cause priming issues, I wouldn't expect it to be that bad. There are plenty of folks on the forum with that much lift which do not have that much trouble. When you fill up the pump basket with water, it should fill to the top since you have a check valve. Is the water draining out? Perhaps there is an issue with the check valve.

Good thoughts. No I don't have a heater bypass, but have been thinking about adding one.

Also, a third option occurred to me. Digging a pit for the pumps at their existing location. What do you all think about that?

 

[mas985]

That would make accessing the pump very difficult unless the hole was very wide so you could stand in the hole.

If the objective is to reduce energy use, I think the bypass will solve that.

The priming issues and air leaks should be solvable without having to move the pump but it will take a bit more effort to prevent them from happening. But what about my previous question:

When you fill up the pump basket with water, it should fill to the top since you have a check valve. Is the water draining out? Perhaps there is an issue with the check valve.

 

[Olle]

That would make accessing the pump very difficult unless the hole was very wide so you could stand in the hole.

If the objective is to reduce energy use, I think the bypass will solve that.

The priming issues and air leaks should be solvable without having to move the pump but it will take a bit more effort to prevent them from happening. But what about my previous question:

Yes I do fill to the top of the baskets and it stays unless there is debris in the check valves. Even with perfect priming it sometimes fails, once air from beyond check valves reach the pumps.

 

[mas985]

When you first turn on the pump, the water will exit the pump basket and air from the elevated lines will enter the pump basket, that is normal. However, after a few minutes it should prime. Are you just saying it takes a little while because that is normal for an elevated pump? Or are you saying it never primes?

After the fully primes and the pump shuts off, does the pump basket remain full or does it empty?

 

[ajw22]

What model number Pentair pumps do you have?

How long have you given the pumps to prime?