New pump or motor replacement: decision time

[frbruno64]

As mentioned in my previous thread, I'm planning to upgrade to a two speed pump.

Replacing the motor with a two speed Century B2983 and keeping the wet end was the original thought. However, it occurred that an analysis of purchasing a new pump is in order, especially if my current equipment is oversized.

Determining if my current SFHP 2.2 pump is oversized is beyond me, but I'm inclined to consider it's oversized after reading posts on this forum. Thus, I'm asking the folks on this site to chime in.

Attached is a diagram showing pool piping and equipment.

• Pipe routing is a logical guess
• Location of splices is purely to keep the diagram neat
• At the pad, there are two 1.5" suction lines into the pump and one 1.5" return out of the filter
• Pump is a Challenger CF-NI-2A High Flow pump

For an estimate of pipe length, I measured horizontal distances along the pool perimeter from the pump to skimmers, return ports and drain. I added 9" for the drain vertical drop
Total length of 1.5" suction piping:75'
Total length of 1.5" return piping: 85'
Piping between pump and filter is 3' of 2" PVC with two 90 degree elbows.

• 33,000 gallons
• Pool only, no features or spa
• FNS+ 48 filter
• Equipment pad on level with coping
• Existing pump wired 220 volts.
• Multiport valve is Purex Triton with 2" ports
• No heater
• 1" eyeballs
• Skimmers are Baker Hydro from 1971
• Drain not routed through skimmer
• Electricity is 15 cents/kw

The questions on the table are:

1. Determine the appropriate pump capacity required for this pool
2. Determine if current pump is oversized
3. If oversized, identify a suitable two speed replacement pump
4. Recommendation on replacing motor or installing a new pump

I'm looking for the right option for the long term, not just the cheapest option. Other considerations are:

• the age of the current wet end
• optimal filter performance
• operating cost inefficiency if the current pump is oversized

Thanks in advance for any help.

 

[mas985]

The pump is probably oversized for the pool if you run at full speed most of the time. But if you are running on low speed most if not all the time, then not so much.

Since you have two skimmers, you might want a slightly larger pump for them to work properly on low speed.

The third skimmer in the middle of the pool is actually a main drain correct?

A VS would allow more fine tuning of flow rate to get the skimmers to work at a minimum flow rate.

 

[frbruno64]

Yes, the main drain is in the middle and was incorrectly labeled. I corrected the diagram with the proper label. Thanks for noticing my error.

Note that the current motor is single speed. All we have is full blast!

 

[mas985]

My comments were based on IF you chose to replace the motor with a two speed.

 

[weird_tolkienish_f]

It's up to you. I don't find anything beneficial to them personally, at least not worth the price. You don't even need to run the pump that much. Just follow the BBB method.

When my motor was on the fritz I bought a new one on Amazon for $150 and haven't regretted it one bit.

 

[frbruno64]

Now I understand your point.

 

[mas985]

It's up to you. I don't find anything beneficial to them personally, at least not worth the price. You don't even need to run the pump that much. Just follow the BBB method.

When my motor was on the fritz I bought a new one on Amazon for $150 and haven't regretted it one bit.

So saving over 75% in energy costs is not beneficial? You can easily make up the extra cost of the two speed motor in a fairly short period of time.

 

[weird_tolkienish_f]

So saving over 75% in energy costs is not beneficial? You can easily make up the extra cost of the two speed motor in a fairly short period of time.

No it definitely is beneficial. For somewhere where they run the filter 12 months a year it probably makes more sense. Here in the Northeast it's basically 3 months a year.