Northstar impeller noise

mg_gti · May 5, 2013

I just replaced the bearings & shaft seal in my Hayward Northstar pump. Put it back together and the pump was making a noise like this:

[youtube:2tsah87d]flY03WsMxsE[/youtube:2tsah87d]

(this isn't my video, but the pump was making the exact same noise)

Removed the impeller ring and the noise went away. Seems to pump fine without it; does anyone know what the purpose of the ring is? Is it supposed to help with self-priming?

mas985 · May 5, 2013

The impeller ring helps in priming and efficiency. It prevents re-circulation loss. But the reason it may be making that noise is that the motor shaft may be bent and probably the reason you needed to replace the bearings and seal.

mg_gti · May 31, 2013

Took a closer look and it does seem like the pump output is reduced without the impeller ring. I guess I must have bent the shaft somehow during the bearing change (the impeller was really stuck and required a great deal of force to remove).

So I guess I'm in the market for a new motor or pump. The current one is 1/2 hp and I run it 24/7 during the summer; I'd like to go with a 2-speed or VRS to save some energy. I noticed that you did a 2-speed conversion on your 1/2 hp Northstar; would you recommend that route, or am I better off spending the extra money and getting a new VRS? I have an Aqualogic PS-4 for control.

mas985 · May 31, 2013

I put a 1 HP Superpump 2 speed motor on my Northstar wet end. The motor is just slightly oversized for the 1/2 HP Northstar so it works pretty well. The diameter is slightly smaller so I just used a shim underneath the motor body for support at the back.

http://www.amazon.com/1725rpm-Frame-Vol ... B0009XF2IS

But before doing that, I know I have had some alignment issues when taking apart the Northstar so you might try taking it apart again and just checking to make sure the diffuser is put on correctly. Did you run the motor while disassembled? Did the impeller wobble?

mg_gti · May 31, 2013

The diffuser is on correctly; I've had the pump apart about a dozen times trying different things. I did run the motor when disassembled and did not notice any wobble, but perhaps I should check again. I'd be really surprised if I actually managed to bend the shaft; perhaps the impeller is unbalanced. I tried replacing the ring to no avail. It doesn't actually start making noise until it reaches full prime; that's when the ring starts vibrating.

Do you know how many watts the 1 HP draws at low speed?

mas985 · May 31, 2013

It depends on the plumbing but mine is around 260 watts.

chrisexv6 · May 31, 2013

Not trying to steal the thread, but I was curious (mas985): do you see any electrical savings going from the 0.5HP single speed to low speed on the 2 speed SuperPump motor?

Knock on wood my 1/2HP Northstar is running just fine but was curious if I could justify going to a 2 speed motor with the same pump and impeller based on electricity savings alone. Also wondering if you had a thread on here about your conversion, if there is anything other than just the new motor required, etc.

Thanks in advance.

-Chris

mas985 · May 31, 2013

Yes! Doesn't matter the size of the pump, low speed is always around 1/4th the power as high speed while only 1/2 the flow rate. So for the same turnover, you always save about 1/2 the energy.