One-speed to two-speed motor swap

[svenpup]

I have seen a few topics about replacing an old one-speed pump motor with a two-speed motor to improve efficiency (here and here for example).

I came across this website that said the following:

One of the main purposes of a volute casing is to help balance the hydraulic pressure on the shaft of the pump. However, this occurs best at the manufacturer's recommended capacity. Running volute-style pumps at a lower capacity than the manufacturer recommends can put lateral stress on the shaft of the pump, increasing wear-and-tear on the seals and bearings, and on the shaft itself.

I was going to replace the motor on my max-e-glas with a two-speed, and I wonder if this is an issue. I did a quick search, and there are two-speed max-e-glas type pumps out there.

 

[PoolGuyNJ]

Only if you go from a 1.5 HP single to a 2HP Two speed. The 1.5HP two speed is the same,

Scott

 

[svenpup]

It is actually a 3/4 hp now and going to a 3/4-1/8 hp two-speed.

 

[JasonLion]

You will be fine. All you need is for the high speed HP to match.

 

[svenpup]

Thanks for the help Scott & Jason. A.O. Smith B2980 and Tightwatt2 ordered and on the way.

 

[no-mas]

...A.O. Smith B2980 and Tightwatt2 ordered and on the way.

Me too! Well, different motor for my whisperflow...

Anyway, is it possible to run a single additional wire in the conduit for the high/low speeds, or does my existing 14/2 copper need to be replaced with 14/3?

 

[Bama Rambler]

You can run single conductors as long as you're running it in conduit.

 

[PoolGuyNJ]

If it's on a 20 amp breaker, it should be 12 gauge wire. I realize you're not pulling that many amps and 14 gauge will probably be fine, assuming it's under 150' and no other loads are attached. I seem to recall it's near the house and likely to be nearer than that to the breaker or timer.

Scott

 

[no-mas]

Thanks guys

 

[svenpup]

How much pressure should I expect on low speed. Everthing is together, but on low I get no pressure. Is this normal?

 

[JasonLion]

Yes, that is normal. The pressure on low speed will be dramatically lower than on high speed. Often it reads as zero, even though it isn't really zero. The gauges common in the pool industry are not all that good at measuring low pressures.

 

[svenpup]

My new energy efficient two-speed pump is in and working. The Tightwatt2 didn't show up yet, so I can't change speeds without rewiring, but now biggie.

It is amazing how quiet it is on low...basically silent.

I had a hard time finding a definitive answer, so for anyone looking in the future here it is: replacing a 48y square flange frame with a 56y square flange frame works fine.