Concerned that a 2.7 THP pump for a 600lb sand filter would be too weak for a commercial pool, thoughts? Thank you.

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PoolGuiverTheChemist

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Jun 1, 2023
10
Texas
TRC 100C, 600lb total media required

JVS270S THP 2.7

Total setup involves 2 TRC 100C's and 2 pumps that each have a 3.95 THP.

***
Follow up question, does anyone have a recommendation for a single or variable speed with a THP closer to 3.95?

Thank you. !!
 
How many gallons is the pool?

What is the filter pressure?

What is the required turnover time?

What is the required flow rate?

What do you have now?

What is wrong with the current setup?

What suction does the pool have?

Number of Skimmers?

Number of Main Drains?

Pool surface area?

Why do you think that the total HP needs to be 3.95?

Do you want just 1 pump or 2 pumps?

If two pumps, why two pumps?
 
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JamesW said:
Why do you think that the total HP needs to be 3.95?
Click to expand...
This information illustrates current equipment THP.
I'm unsure of how many brand new pumps you've installed in the field, you do seem experienced, however most installers seek to at least match the previous equipment's specs.
.
We are bidding this large apartment to replace 1 of their 2 pumps.
.
Pool's Suction? Two $1,500 18" x 18" drains... replaced by myself with scuba gear last December. Yes, calculated sledge-hammering was required.
.
JamesW, I can understand why you seek to know this specific pool's GPM calculations, that's the only question you've asked that makes any sense. I've no idea how much commercial experience you actually have, and therefore, providing all of this information only to find that your simply a home owner with 1 pool would be ... a waste of both of our time.
.
I have Leslie's district manager contact who can connect me with their commercial team, I think I'm going to follow up with him after this onslaught of questions. Even the commercial technician's who answer the phone's for Pentair did not ask 80% of the questions you've posited.
 
MrRouteof8Apartments said:
Follow up question, does anyone have a recommendation for a single or variable speed with a THP closer to 3.95?
Click to expand...
1690164049620.png

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MrRouteof8Apartments said:
TRC 100C, 600lb total media required

JVS270S THP 2.7

Total setup involves 2 TRC 100C's and 2 pumps that each have a 3.95 THP.

***
Follow up question, does anyone have a recommendation for a single or variable speed with a THP closer to 3.95?

Thank you. !!
Click to expand...
That pump, a rebranded Hayward TriStar, is more than capable of backwashing a TR100 at its highest speed. That's the only reason to be concerned about the horsepower rating of a pump with a large sand filter. You could filter with one rated at 1/2hp, but it would likely never be able to "liquify" that much sand during a backwash.

Your biggest issue might be approval by whatever government agency oversees commercial pools. Here in my area, that pump wouldn't fly because it isn't listed with them, but its identical counterpart, the TriStar is, so it would be approved.
 
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Commercial sand filters are usually limited to 15 GPM per square foot of surface area.

The TR100C is approved to 20 GPM per square foot of surface area.

Ideal backwash is about 15 GPM per square foot of surface area, which is 74 GPM.

This means that the pump only needs to provide a maximum of 74 GPM for the filter.

However, you still need to know the required system flow and turnover since it is a commercial pool and commercial pools are regulated to meet certain minimum flow rates and turnover rates.

You do not size a pump by the HP.

You graph the system curve onto the pump performance curve to find the operating point, which is the intersection of the system curve and the pump performance curve.

How to Read Pump & System Curves

If you find yourself somewhat mystified by pump curves and performance charts, or if you need to train someone about hydraulic efficiency, here’s a brief primer to get you started.
www.aquamagazine.com www.aquamagazine.com


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For example, if the pool is 1 million gallons and the required turnover is 8 hours, then your minimum flow rate is 125,000 gallons per hour or 2,085 GPM.

Each skimmer is rated for maximum flow and the main drains are also rated for maximum flow, so you have to know these numbers as well.

Sizing commercial equipment is complicated and you have to do all of the calculations correctly.

You can’t just use “Rule-of-Thumb” to guess if a certain horsepower will be right for a certain weight of sand.

So, you can’t ask if a 2.7 HP pump is right for a 600 lb sand filter because it does not work like that.

This shows the performance of the SP32950VSP which is the 2.7 HP Tristar VS pump.

It can exceed 175 GPM, but only at low head loss.

If we graph 3 possible system curves on the pump performance curve, we can estimate the flow at any speed.

To develop a system curve, you need to know the total head loss and flow at different speeds.

However, we need to know the pool volume and required turnover to calculate the required flow rate.






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JamesW said:
Commercial sand filters are usually limited to 15 GPM per square foot of surface area.

The TR100C is approved to 20 GPM per square foot of surface area.

Ideal backwash is about 15 GPM per square foot of surface area, which is 74 GPM.

This means that the pump only needs to provide a maximum of 74 GPM for the filter.

However, you still need to know the required system flow and turnover since it is a commercial pool and commercial pools are regulated to meet certain minimum flow rates and turnover rates.

You do not size a pump by the HP.

You graph the system curve onto the pump performance curve to find the operating point, which is the intersection of the system curve and the pump performance curve.

How to Read Pump & System Curves

If you find yourself somewhat mystified by pump curves and performance charts, or if you need to train someone about hydraulic efficiency, here’s a brief primer to get you started.
www.aquamagazine.com www.aquamagazine.com


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View attachment 516502

Click to expand...

This helps me tremendously. I thank you for taking a moment to share this information. I am someone who wants to do things by the book, and it appears to be glaringly clear to us both now, I have a bit more to learn. Thank you.
 
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1poolman1 said:
That pump, a rebranded Hayward TriStar, is more than capable of backwashing a TR100 at its highest speed. That's the only reason to be concerned about the horsepower rating of a pump with a large sand filter. You could filter with one rated at 1/2hp, but it would likely never be able to "liquify" that much sand during a backwash.

Your biggest issue might be approval by whatever government agency oversees commercial pools. Here in my area, that pump wouldn't fly because it isn't listed with them, but its identical counterpart, the TriStar is, so it would be approved.
Click to expand...
This helps me! Thank you.
 
Your local authority having jurisdiction should provide the necessary specifications for commercial pools including things like turnover requirements etc.

There are also rules for water velocity, which are usually 6 feet per second for suction and 8 feet per second for return.

So, you have to consider the pipe sizes as well when setting the speed for the system.

For example, if the line from the main drains is 3", then the flow is limited to 138 GPM regardless of the rating of the main drains themselves.

Size.......6 ft/sec......8 ft/sec.
1.5"...........38...............51 gpm
2"..............63...............84 gpm
2.5............90.............119 gpm
3.0".........138.............184 gpm

Commercial pools usually require a permit to operate and periodic inspections are usually required.

Inspections make sure that all codes are being complied with including filtration, flow rates, occupancy, chemical levels, signage etc.
 

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JamesW said:
For example, if the pool is 1 million gallons and the required turnover is 8 hours, then your minimum flow rate is 125,000 gallons per hour or 2,085 GPM.

Each skimmer is rated for maximum flow and the main drains are also rated for maximum flow, so you have to know these numbers as well.

Sizing commercial equipment is complicated and you have to do all of the calculations correctly.

You can’t just use “Rule-of-Thumb” to guess if a certain horsepower will be right for a certain weight of sand.

So, you can’t ask if a 2.7 HP pump is right for a 600 lb sand filter because it does not work like that.

This shows the performance of the SP32950VSP which is the 2.7 HP Tristar VS pump.

It can exceed 175 GPM, but only at low head loss.

If we graph 3 possible system curves on the pump performance curve, we can estimate the flow at any speed.

To develop a system curve, you need to know the total head loss and flow at different speeds.

However, we need to know the pool volume and required turnover to calculate the required flow rate.






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Click to expand...

This video certainly helped me to grasp your responses. Thank you again.
 
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