Spa Jet & Pump questions

jsjamesOctober 17, 2011

Hi -

I have a pool/spa that was built in early 1990's. It has a separate Spa pump to power the Jets. The jets plumbing is 2" PVC and the pump is located ~50ft away from the spa. There is a separate drain for this pump and it is not connected in anyway through the filter or heater. I don't have any special "jets" in the spa, they just look like 1" i.d. PVC pipe that are exposed throught the gunite. The original pump was a Challenger Pac Fab 2HP - and I was getting good jet action with this pump.

The original pump broke down and I plumbed in a Whisper Flo (WFE-4) which I had in the garage. In looking at the pump performance curves, the Whisper Flow has a little less flow (10-15 gpm, depending on TDH) and so I expected a little less jet power, however, the flow seems considerably less which surprised me.

see performanc curves here:


Question: Would a total 10-15 fpm flow rate (1-2 gpm per nozzle) make that big of a difference on the jets?

To increase the flow rate, I've read that I can change out the WhisperFlo motor and impellor. I'm thinking about changing those out to get to 2HP (WFE-8). I've read you need 1/4 HP per jet, however the distance from my spa->pump seem long.

Question: Any issues in just changing the motor/impeller on the Whisper Flo to get the increased flow?

Question: Does 2HP WhisperFlo seem like the right choice?

Question: Is a larger pump required given my distance from spa->pump?

Many thanks for your help!!


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6 or 8 jets?

You went from a 2 HP pump to a 1 HP pump. You're going to lose more than 10 to 15 GPM with that change. More like 20 and yes, that will make a significant difference in performance.

Swapping with a full rated 2 HP motor, changing the impeller and seal set will return your performance. You might consider though, a two speed motor so the power used in normal circulation is reduced.


    Bookmark   October 17, 2011 at 9:35PM
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Hi Scott - Thanks for the reply.

I have 8 jets.

Regarding getting a 2 speed motor, I don't quite understand why I would use a lower speed for circulation. The "primary" pump motor (which is variable speed) is the one that circulates the water through the filter & heater.

Thanks again,

    Bookmark   October 18, 2011 at 10:10AM
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I missed that this was the spa booster. Then the 2 HP is what you should be using. Especially since there are 8 jets, likely basic Waterway jets.

A 1HP pump trying to push through a loop is going to meet a substantial head loss.

If you have ever seen a pool with attached spa that uses the circulation pump for the spa, you would see the pressure in the filter increase, often by as much as 10 PSI, indicating a significant resistance was being met.


    Bookmark   October 18, 2011 at 12:33PM
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