2 speed pump wiring

[highendman2]

I recently replaced my spa pump 56 Frame Executive by Waterway (AO Smith 3721621-PD).  It is the same pump that came with the spa - size, specs, looks.  The original was made by GE (same part number) and accepted all 4 wires from the power cord (white, black, red and green).

The new motor says "Do NOT wire both speeds to run simultaneously."  It has a two diagrams: Low - showing the lines going to common and low, High - showing the lines going from high to common.

I assume the white is wired to the common.  The red line went to the low spot on my previous motor, and the black to the high spot.

Because of the direction to NOT wire both speeds, I assume that I must choose either low or high and not wire one of the wires. The diagram shows only 2 wires being wired, aside from ground.   https://www.google.ca/search?q=ao+smith+pump+2+speed+wiring&source=lnms&tbm=isch&sa=X&ved=0ahUKEwja34f7uczSAhWB7IMKHXpIBUYQ_AUICCgB&biw=1536&bih=755#imgrc=dxId6ZflH2XjeM:

Should I wire just the black and white and leave the red dangling (insulate the connection) ?  There is a spot for all three wires, but the instructions insist to only connect 2.

Please forgive the simplicity of this question, but i want to make sure I get it right. I could not find this situation in the search.

Thank you.


I had made a previous post about the new pump being a good 1/4 shorter and my plumbing not reaching. I followed the good advice on here and ended up cutting the line and gluing in an extension.  That worked out fine. Thank you!

[bud16415]

I’m just taking a guess here but wouldn’t the spa control make the selection of speed and isolate the other connection. I would think the warning is if you were direct wiring it to a power source you wouldn’t want both modes energized at the same time. In your case the control panel is making that routing based on what you select at the touch pad.

That’s just my guess. Did it run with two speeds before?

[highendman2]

Hi Bud,

Thanks for the reply.  I had the same thought about the two speeds. I wired it like it was wired before (connecting red white and black) and it blew my main circuit breaker immediately.

It did run at two speeds before - controlled by the controller panel.

[bud16415]

Hi Bud,

Thanks for the reply.  I had the same thought about the two speeds. I wired it like it was wired before (connecting red white and black) and it blew my main circuit breaker immediately.

It did run at two speeds before - controlled by the controller panel.

You could try some voltage testing of the wires without the motor connected selecting high and low speed at your controller and see what wires come hot.

When you bought the motor was it sold as a direct replacment?

There is always the chance the control is messed up also.

If it was us we could live with just the high speed as we never hardly use the low. 

[highendman2]

The replacement pump has the same part number as the original.  It has the same specs, looks identical and is the same size, but the wet end is a 1/4 inch shorter.

The wiring end has a slightly different piece inside.  The old unit has more slots to attach wires.

That's a good idea to test the voltages out of my controller.

Thanks again.

[highendman2]

I got it!

I had wired the new pump the same as the old, which seemed like an obvious move.  The old wiring had the white at the top, black in the center and red at the bottom.  Upon re-examination, I noticed that the new pump wants the common in the center, so it's black, white, red at the bottom.  Thankfully, I was able to reach the pump wiring without moving the hot tub out from the wall and taking the motor out, and swapped the black and the white wiring and gave it a try.

So far so good. Circuit breaker did not blow, pump worked spitting out the little water there was in the line. I immediately shut it off and now have to wait for the hose to thaw in order to refill.

Thanks again.

[Tman122]

I got it!

I had wired the new pump the same as the old, which seemed like an obvious move.  The old wiring had the white at the top, black in the center and red at the bottom.  Upon re-examination, I noticed that the new pump wants the common in the center, so it's black, white, red at the bottom.  Thankfully, I was able to reach the pump wiring without moving the hot tub out from the wall and taking the motor out, and swapped the black and the white wiring and gave it a try.

So far so good. Circuit breaker did not blow, pump worked spitting out the little water there was in the line. I immediately shut it off and now have to wait for the hose to thaw in order to refill.

Thanks again.

I heard no mention of the green connected to housing?

[highendman2]

Naturally, the green was connected all along.

[bud16415]

All well that ends well. Now get her filled up and enjoy.

I have a really short hose i made to fill the tub about 10' long and it drains out. Got tired of bringing a 50' hose in the house to melt.