Remotoring Whisperflo 1.5 hp to 0.5hp

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cschmelz

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May 13, 2009
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I recently bought a beautiful house in Washington State with a 45,000 or so gallon monster pool. It is fairly old but it good shape with fairly small plumbing (1.5 inch) and a single skimmer feeding a TR-60 Triton sand filter

The motor died right before we moved in and the previous owner spec'ed out a nice Whisperflo but at 1.5hp (and no timer!) so clearly it is sucking a lot more power than necessary.

My previous pool was a combined spa/pool at about 20,000 gallons in Tucson which was being driven by a 2hp pump. That system clearly needed a 2 speed to power the spa jets and so I installed a 1.5hp 2 speed pump and pretty much let it run at low speed silently 24/7 with the SWC.

This system in Washington I see no reason to go 2 speed as there isn't ever a need for high flow (not using the heater, no need for jets and am going to use a electronic robotic cleaner vs suction or pressure side).

Is it pretty simple to just pull the 1.5hp motor, pull the 1.5hp impeller and then just swap in the 0.5hp motor and impeller setup along with new seals?

I price that out at about $225 vs almost $450 for a new 0.5hp Whisperflo, though that would also allow me to sell my almost new 1.5hp to someone who thought they needed that much horsepower.
 
If your pool is 45,000 gallons, you do need a pump in that size range to get the circulation you need for sanitation. If you put a smaller motor on the existing impeller, the smaller motor will try to do the work of the bigger one. It actually will move the water the same as the bigger motor, but it will overheat from the work.
 
If you switch both the motor and the impeller the pump will work, though it may not be a good fit for your pool. But a better idea is to replace just the motor with a two speed motor of the same HP. That way you can run on low speed most of the time and save electricity, but still have high speed available if you really need it.
 
Sorry to glom on but I would think that filter is not nearly large enough for a pool you size. I have the TR-140 for my 43,000 gallon pool and, while it's a little large, it's not by much.

A TR-100 would certainly help your entire system.
 
Just to add some numbers to what others are saying, here are some turnover times assuming 1 1/2" plumbing, 2 suction pipes, 1 return pipe, 30' of pipe length, typical fittings, filter and heater.

All Whisperflo Full Rate Pumps

1/2 HP, 57 GPM, 49' head, 13.2 hour turnover
3/4 HP, 62 GPM, 58' head, 12.2 hour turnover
1.0 HP, 66 GPM, 67' head, 11.3 hour turnover
1.5 HP, 71 GPM, 77' head, 10.6 hour turnover
2.0 HP, 73 GPM, 81' head, 10.3 hour turnover

If you look at these numbers, the first thing you will notice is that there isn't a lot of difference between 1/2 HP and 1 1/2 HP in terms of turnover and flow rates. Flow rates decrease by only 20% by going with a 1/2 HP and turnover only increase by 25%.

The main problem with the 1/2 HP is that you will only be able to get 1.8 turns per day maximum. However, even with the 1.5 HP, you still will only get 2.3 turns per day. Better but not by much.

Given that you already have a 1.5 HP pump, you might be better off sticking with that. Another option you should consider is to swap the motor with a 1.5 HP 2 speed. If you stick with the same braking HP, you won't need a new impeller but you will have 1/2 speed most of the time but full speed when you really need it.
 
Well it actually is a Superflo with a fairly cheap motor. 1.5hp with a service factor of just 1.1 so total functional HP of 1.65.

Can I just remotor with a Whisperflo energy efficient 2 speed pump? They have much higher service factors, so it looks like I could get a 1 hp full rate dual speed pump. At high flow it should have the same effective HP as the Superflo pump (1hp x SF1.65 still equals 1.65)

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