Pool Mechanicals 15 feet above pool level

[Dennis3]

Hi,

I have a question. We're building a pool in a FEMA zone. They are allowing us to install the pool on the ground level, but all the pool mechanicals (pump, filter, etc) have to be about 15 feet high.

From our pool, we would go about 50 feet horizontal, and 15 feet vertical to reach our pool mechanical area.

Is this something that is doable? I am curious if there are any drawbacks or problems we would run into by doing this.

 

[JamesW]

Why does the equipment need to be that high?

Most pumps specify that you shouldn't put the pump more than 10 feet above the water level.

You can do 15 feet, but you're going to have difficulty priming the pump. You can use a check valve on the suction and push water into the lines at the skimmer to fill the lines.

You can put the check valve at the output of the pump then push water into the lines to prime. This will avoid the check valve head loss on the suction side.

You can prime the pump by continuously refilling the basket and trapping the water in the pipe with the check valve or a Jandy NeverLube valve. The water will lift about 6" each time, so you need to do it about 30 times.

Or, you might be able to use a vacuum pump to pull water into the lines. Just use a fitting and valve.

You could put check valves at ground level and then prime as normal, but the check valves would need to be accessible for service. Maybe put them in an access box.

The other issue is risk of cavitation if your suction vacuum gets excessive.

You're starting with a 15 foot static lift. You would want to minimize dynamic head loss by oversizing the suction plumbing. Probably 3" would be good.

If you’re going to have multiple skimmers and if you’re going to keep the flow down, you can probably run 2.5” PVC from each skimmer to a 3” manifold at the pump.

In any case, I don’t think that you would be able to exceed 3,000 rpm on the pump, but you shouldn’t need to anyway.

I would recommend the IntelliFloXF pump with a 2.5" x 3" Jandy check valve and suction plumbed with 3" pipe.

If you get a heater, you would need to install a flow switch and remove the pressure switch.

 

[cfherrman]

Go with a 3 hp vsp, your efficiency is going to be very bad as pumps cannot suck water, really only push.

I would recommend against a 3" suction line as that is a lot of fluid to pull and prime.

It should be doable, but your 3 hp pump will probably be a 1 hp.

 

[Dennis3]

James and cfherrman, thank you very much for the replies.

To answer your question james, we're building a 50 room hotel, and the site is in a Fema zone which has a minimum elevation structures need to be off of the ground. The grade where the pool will be installed in-ground is currently about 3 feet above sea level. Our base flood elevation is 13 feet. I exaggerated a bit regarding 15 feet, but I believe the the location of the pool mechanicals will be roughly 12 to 13 feet above pool water level after the first floor system gets installed.

Thank you very much for the tips. James, by any chance would you be interested in helping design the pool system? I'm really looking to work with someone to ensure we don't have any issues for the pool.

Imagine a building similar to this: https://i.imgur.com/ApW2zS3.jpg

Our pool would actually be in front, the plumbing for the pool would run up with one of the columns, into a storage room.

We were originally going to have the pool on the roof but it added additional building costs due to additional load on the roof as well as increased foundational load for the piers.

 

[LI poolguy]

Why does the equipment need to be that high?

As someone who lives on the water, my guess of the OP's mention of "FEMA zone", means they are in a flood zone. The minimum electrical & dwelling requirements for a flood zone are 2 feet above flood. That means he/she is on the map of a 100 year flood occurrence, 13' foot flood zone. After hurricane Sandy, and battling the insurance company, FEMA and local authorities, the new rules/codes are pretty strict on the new FEMA maps. My suggestion would be to elevate the pool. After Sandy, some in our neighborhood had elevated "in ground" pools installed. The concrete shell is built above ground, with concrete piers supporting an elevated deck around the pool. While the pool is technically below the flood plain, the equipment is above, but much closer in elevation in relation to the skimmer and returns.

 

[Dennis3]

As someone who lives on the water, my guess of the OP's mention of "FEMA zone", means they are in a flood zone. The minimum electrical & dwelling requirements for a flood zone are 2 feet above flood. That means he/she is on the map of a 100 year flood occurrence, 13' foot flood zone. After hurricane Sandy, and battling the insurance company, FEMA and local authorities, the new rules/codes are pretty strict on the new FEMA maps. My suggestion would be to elevate the pool. After Sandy, some in our neighborhood had elevated "in ground" pools installed. The concrete shell is built above ground, with concrete piers supporting an elevated deck around the pool. While the pool is technically below the flood plain, the equipment is above, but much closer in elevation in relation to the skimmer and returns.

bingo.

We thought of elevating the pool 13 feet, similar to how you described, but the floodplain manager for our city is requesting it to be certified that it won't divert potential waves to other buildings. And this would also cost more for the building to build piers to support the pool. A in ground pool is our best option. There's a bunch of properties nearby that have inground pools, but they are all grandfathered in, so they got to keep mechanicals at the same level as the pool. The recent changes make it much harder.

Since we're working with a tight budget for this project, it makes most sense to have the pool in ground, and have the mechanicals at the BFE.

I am looking for some kind of clarification as to if it's doable, and the best system to use. The tips above were great.

 

[LI poolguy]

bingo.

We thought of elevating the pool 13 feet, similar to how you described, but the floodplain manager for our city is requesting it to be certified that it won't divert potential waves to other buildings. And this would also cost more for the building to build piers to support the pool. A in ground pool is our best option. There's a bunch of properties nearby that have inground pools, but they are all grandfathered in, so they got to keep mechanicals at the same level as the pool. The recent changes make it much harder.

Since we're working with a tight budget for this project, it makes most sense to have the pool in ground, and have the mechanicals at the BFE.

I am looking for some kind of clarification as to if it's doable, and the best system to use. The tips above were great.

Make sure you are at a minimum of 2' above BFE to be in compliance. The last thing you want to have an inspector deny a CO because of a few inches. I do sympathize with you, the new codes, while well intentioned, are an extreme hindrous to anyone who wants to build something. If you look into helical piles as opposed to concrete piers, you'll be surprised at the difference in costs, at least here in NY. The thought of a 13' storm surge wave crashing into the structure and being diverted into another structure is insane. Water from storms does not rush in like that, it piles up from repeated high tides over the course of hours, and the waves on TOP of the surge is what causes major/smashing damage. The wave height of flood is still only 3-4 feet like a regular beach day.With the cost of helical piles, and an engineer to certify that it won't affect any other dwelling, it may be cheaper than a standard pool because the insurance costs over a prolonged period of time.

 

[JamesW]

Go with a 3 hp vsp, your efficiency is going to be very bad as pumps cannot suck water, really only push.

I would recommend against a 3" suction line as that is a lot of fluid to pull and prime.

It should be doable, but your 3 hp pump will probably be a 1 hp.

The diameter of the suction line is irrelevant as far as the amount of water that has to be lifted.

The line could be 1,000 feet in diameter and it wouldn't make any difference.

The only thing that matters is the elevation difference.

Priming will be a challenge in any case, so there won't be any significant difference between 2" or 3" plumbing.

A bigger line reduces dynamic head loss. So, the bigger, the better, up to a point.

The efficiency is not really going to suffer because the system is closed loop and the return head loss decrease will offset the suction head loss increase.

 

[LI poolguy]

The diameter of the suction line is irrelevant as far as the amount of water that has to be lifted.

The line could be 1,000 feet in diameter and it wouldn't make any difference.

The only thing that matters is the elevation difference.

A bigger line reduces dynamic head loss. So, the bigger, the better, up to a point.

The efficiency is not really going to suffer because the system is closed loop and the return head loss decrease will offset the suction head loss increase.

Once the pump is elevated 15', and with the back pitch to the pool, is it really still considered closed loop? Even with a check valve, there is still loss of water in the suction pipe. Depending on how long the pump is not running, it may lose it's prime. What if a "trap" is installed between the pool and pump. Kind of like a drain on a sink. It may prevent water loss at the pump intake.

 

[JamesW]

As long as the system is airtight, it's closed loop.

The pump will lose prime periodically. That's why you need to have a method for priming that's reliable.

If you know what to do, you can minimize the number of times that you need to prime.

 

[LI poolguy]

As long as the system is airtight, it's closed loop.

The pump will lose prime periodically. That's why you need to have a method for priming that's reliable.

A 15' rise in elevation from water level to the pump seems drastic. The water will eventually seek its own level and flow back to the pool, even with a check valve. A check valve only holds under pressure. If that happens, there will be air in the suction line. However, I'm not an expert in this particular situation, so my posts are only based on thoughts and open for discussion and for being proven wrong. Sometimes being wrong is a good thing, it's a called learning a lesson.

 

[JamesW]

A 15' suction lift is not ideal. I would avoid it if at all possible. However, if it's the only choice, it can be done.

The 2.5" x 3" check valve is designed to have less than 3 feet of head loss.

There are several ways to design the system that will work.

The entire pool and equipment should be designed by a professional engineer with relevant experience.

 

[cfherrman]

The diameter of the suction line is irrelevant as far as the amount of water that has to be lifted.

The line could be 1,000 feet in diameter and it wouldn't make any difference.

The only thing that matters is the elevation difference.

Priming will be a challenge in any case, so there won't be any significant difference between 2" or 3" plumbing.

A bigger line reduces dynamic head loss. So, the bigger, the better, up to a point.

The efficiency is not really going to suffer because the system is closed loop and the return head loss decrease will offset the suction head loss increase.

I'm talking about time to prime, not the lifting portion. It will take longer to prime a 3" than a 2" and the pump running dry for longer periods than necessary is not good.

 

[JamesW]

The problem is that you're starting with a 15' suction lift. If the dynamic head loss gets too high, the pump will cavitate.

We need to know the design flow rate before calculating the dynamic head loss for different pipe sizes.

This is a situation where you can't just fill the pump strainer and turn the pump on and expect it to prime.

You're going to have to do something to fill the line other than having the pump pull the water 15'.

Therefore, using a 2" pipe has no benefit over a 3" line.

However, a 2" line might well create enough head loss to cause cavitation.

Can the OP provide some pool specifications?

 

[needsajet]

One handy thing for your situation is to have a spigot from your fresh water system with a short length of hose handy to the pump. That way it won't be much effort to fill the suction line. A garden hose from somewhere else is also fine, but I think it would be handy to have something nearby.

As JamesW mentioned, you don't need to worry about emptying if everything is installed properly. If air can't get in, the water can't drain, and no extra energy is consumed while it's running (other than the small amount of friction loss caused by distance). Losing prime due to an air leak might be more likely I suppose. You could run at a low wattage 24/7 to eliminate that risk.

If there's a twig or leaf stuck in the check valve the day you open and clean out the pump strainer, that hose will come in handy, rather than trying to do it with a bucket! I would definitely put the check valve close to the skimmer (but just above the pool water level) in a service box. The other thing I'd do is make sure there's no ups and down in the suction line... just straight out and then down, with no high spots that would trap air while you're filling.

 

[Dennis3]

One handy thing for your situation is to have a spigot from your fresh water system with a short length of hose handy to the pump. That way it won't be much effort to fill the suction line. A garden hose from somewhere else is also fine, but I think it would be handy to have something nearby.

As JamesW mentioned, you don't need to worry about emptying if everything is installed properly. If air can't get in, the water can't drain, and no extra energy is consumed while it's running (other than the small amount of friction loss caused by distance). Losing prime due to an air leak might be more likely I suppose. You could run at a low wattage 24/7 to eliminate that risk.

If there's a twig or leaf stuck in the check valve the day you open and clean out the pump strainer, that hose will come in handy, rather than trying to do it with a bucket! I would definitely put the check valve close to the skimmer (but just above the pool water level) in a service box. The other thing I'd do is make sure there's no ups and down in the suction line... just straight out and then down, with no high spots that would trap air while you're filling.

Yes, there will definitely be a spiget near the pool area to allow people to rinse off before/after pool use.

 

[PoolGate]

How about a sump pump to start the prime of the main pump located at the water line? Or is that also not allowed and considered part of the equipment?

 

[LI poolguy]

How about a sump pump to start the prime of the main pump located at the water line? Or is that also not allowed and considered part of the equipment?

It may not meet code because it would require an electrical device below the flood elevation. Wonder if it's possible to install a water feed into the drain plug of the pump basket, powered by a float switch of some sort. It would detect low water and just fill the pump basket and shut down once filled.

 

[JamesW]

One way to do it would be to run 2.5" pipe from each skimmer and main drains to a 3" manifold at ground level.

Each pipe would have a valve to control the flow from each skimmer or main drains.

Just past the manifold, put a 3" valve then a water feed line.

At the pump, put a 3" valve on the suction and a 3" check valve on the discharge.

When you want to prime, close the 3" ground level valve and turn on the feed line.

Water will fill the line, the pump strainer pot and past the check valve.

Then, turn off the feed line and open the 3" ground level valve.

The water will stay due to the check valve.

Then, turn on the pump.

When you need to empty the pump basket, close the 3" valve at the pump suction to keep prime.

Note that this is an example assuming that the total flow will not exceed about 130 gpm and the flow in the 2.5" lines won't exceed about 80 gpm.

If you need to exceed 130 gpm, go to 4" pipe, which is good to about 235 gpm.

In any case, a professional engineer with relevant experience should design the system to meet local code and operate efficiently.

Assuming that you're at sea level, you should design the system such that the total suction head loss does not exceed 25'.

Since you're starting with a 15' static head loss, the dynamic head loss should be kept to less than 10 feet, which is not easy.

 

[swimcmp]

What about a vault of some type that could be at ground level? Could it have access through the roof with it being 15' to keep water out.