Slowing down a spa Blower

[markayash]

I have a 220V spa blower that is too strong, bubbles blow above the top of the spa..I know I can buy a smaller blower but wondering what would happen is I ran it on 110V vs 220V. Would it run slower?

 

[JamesW]

Changing the voltage won’t make any difference; it’s the same power either way.

Also, you can only change the voltage if the motor accepts either voltage, and you have to configure the motor voltage setting to the correct input voltage.

You could use a valve to restrict the air, but that would probably cause the blower to overheat.

Probably the best thing to do is to install a valve on a T to use as a vent to control air at the jets.

 

[jblizzle]

I did not think there was a danger of hurting the blower unless you cut off all the outlet flow, even then I am not sure it would overheat. Easy enough to add a valve on the air pipe.

 

[JamesW]

http://www.jandy.com/~/media/zodiac/global/downloads/tl/tl500.pdf

Blower motors are cooled by air flowing over the motor. The
amount of air required to prevent overheating is determined by
the blower horsepower (HP), the system back pressure and the
number and size of the air holes/jets in the spa. Airflow is meas-
ured in cubic feet per minute (CFM).
Different horsepower blowers require different levels of air flow
to keep the motor cool. A higher HP motor requires more flow.
System back pressure, measured in inches of water, is the sum
of the forces restricting air flow over the blower motor and
through the spa plumbing. These limiting forces include:
• Pipe diameter • Number and type of elbows
• Length of run • Check valves
• Number of spa jets • Size of spa jets
As back pressure increases, air flow decreases, reducing the
ability of the motor to stay within normal operating temperatures.

 

[jblizzle]

Well that certainly seems counter to what I have previously read around here. Seems like a 3 way valve to vent out would be the best solution. Or actually just a teed off valve to vent air.

 

[JamesW]

Excessive back pressure can definitely cause a blower to overheat. A valve can be used as long as the backpressure is not excessive.

A valve to vent air will allow the best control while keeping the motor cool. However, in some cases, the vent can get noisy, so the design might need to be adjusted if it's too loud (sometimes a whistling sound).

 

[markayash]

thanks I did add a t and a small bleed off but wasn't enough but I didn't add a valve below to restrict it..Will try that next

 

[jblizzle]

I think you want a larger bleed off to ensure you do not have heat issues

 

[mas985]

They don't really say how much you can reduce the air flow before overheating but I would guess that it is at least 50% and perhaps as much as 75%. You don't really need much air flow to remove the heat with convection. Plus when the air flow is restricted, current draw is reduced in the motor (much like a pump motor) so there is actually less heat to dissipate.

 

[markayash]

Thanks, we rarely use it..I do have a follow up question..
Mine is a 1.5HP 220V and air supply ( same company ) makes a 1hp model..How much real difference would switching make..I see the flow curve is less but hard to relate to real life.

 

[mas985]

Have you tried removing the blower from the air pipe and seeing if you get enough bubbles without it? A well designed spa should not require a blower. Many PBs install them out of habit and to compensate for their poor designs.

 

[markayash]

Ha, with no pump it's perfect for me but not my wife

 

[mas985]

I said no blower, not pump. But I don't mean just shutting it off, you have to completely remove it from the air pipe otherwise it will restrict the air.

 

[markayash]

Meant with pump and no blower its good enough for me

 

[Seanhan]

Have you adjusted the jets any ? Mine was blowing out on the deck and i turned the offending jet 180deg
And problem solved ..
You might be able to install a variable resister to throttle it back a little..