New Spa - Spa Mode Heater RPM Recommendations

JMPool99

Member
Jul 31, 2021
23
So Cal
We just got our new in-ground spa going. We have a separate booseter pump, so we use that when we want jets on. So, really our filter pump in spa mode is just used for the heater.

The default RPMs was 3350, but that's because it generates bubbles at that RPM from the jets that do the heating.

What RPMs does everyone recommend for just heat and no bubbles? I set it to 2950 and no bubbles, but would prefer to set even lower if I can (E.g., 2650). Is there a minmum RPM required to ensure a good flow rate through the heater? Circ pump is an Pentair VSP IntelliFlo.

Thanks!

Sorry - I realize this should be in the SPA forum. APOLOGIES.
 

ajw22

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TFP Guide
Jul 21, 2013
29,152
Northern NJ
Pool Size
35000
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Pentair Intellichlor IC-60
What model heater are we discussing?

As long as you have the minimum flow rate required for your heater the flow rate does not effect heater efficiency. My gas heater works fine at 1,800 rpm on my pool and spa.

See discussion on Water Flow Rate and Heater Output Temperature Rise in Heater Maintenance - Further Reading
 

JMPool99

Member
Jul 31, 2021
23
So Cal
Heater is a 400K Pentair MasterTemp (only six months old). Manual for my heater says MIN 40GPM and MAX flow 120GPM .

I read through the Pentair Intelliflo Pump manual and it talks about RPM but I don't know what that equates to for GPM. The RANGE for my pump is 20GPM to 140GPM. Manual only states the defaults for RPM and RPM relationship: That 40GPM is 1000RPM. So if I assum the relationship is linear (probably not?) then that would mean 4GALLONS FLOW PER 100 RPM.

That means running my pump at 2650RPM would be 106GPM and 2950RPM would be 118GPM. Both are well within the range, but since I don't need bubbles produced by my circ pump and it would save power, sounds like 2650 is plenty of RPM!

Thanks for your help!
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
14,735
Pleasanton, CA
Pool Size
20000
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Plaster
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1000 RPM for 40 GPM would be extremely unlikely. For most spas, full speed (3450 RPM) would be between 70-100 GPM. So 40 GPM, would probably be close to half speed (1725 RPM)+-. Plumbing design has a big impact on the flow at a particular RPM so every spa in going to be unique.

Also, GPM and RPM are proportional. A 10% change in one is a 10% change in the other. So half speed (1725 RPM) is half flow of full speed (3450 RPM).
 
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