Flow rates lower than I thought

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S

Sk8Surfr

Well-known member
May 28, 2016
98
South Florida
New pool - was going off the spec chart for the plans that shows 54gpm at 1,500 RPM for the Pentair Intelliflow VS. Noticed my Jandy JXI heater says 'check flow' when I activate the bypass valve and send water through the heater.

I have to increase the speed to about 2,000 rpm to get the Heater to have sufficient flow (the manual says 30 gpm minimum)

The interesting thing is at 1,000 rpms - the Intellichlor says it has sufficient flow - and that manual says 25 gpm +/- 5.

My main and returns are 3" (reduced to 2.5 inch for all the valves at the equipment)

The heater is 2" in

Maybe the heater is just more restrictive to flow? I can 'hear' the water in the heater if that makes sense

Really just trying to figure out a good amount of run time for the pool on a daily basis.
 
S,

Just from reading here, it seems to me that most people with heaters need about 1800 RPM just to turn on their SWCG.. When your SWCG was working was the heater in the circuit or was it by-passed?? I guess my point it that it sounds normal to me.

Let's see if one of our flow experts can chime in..

Thanks,

Jim R.
 
Jimrahbe said:
S,

Just from reading here, it seems to me that most people with heaters need about 1800 RPM just to turn on their SWCG.. When your SWCG was working was the heater in the circuit or was it by-passed?? I guess my point it that it sounds normal to me.

Let's see if one of our flow experts can chime in..

Thanks,

Jim R.
Click to expand...

SWG was working regardless of the heater bypass or not - the question wasnt the SWG but the flow the heater needs.

The SWG was green good flow at 1,000 rpms
The Heater needed 2,000 rpms to kick on.

If that all sounds about normal - well then GOOD!
 
S,

Well, compared to most people, your SWCG is coming on at a pretty low RPM since you have a heater.. And your heater is coming on at a slightly higher RPM than most people.

But.. "most people" don't really mean much, it all depends on your plumbing and your pool..

Let's see if @mas985 has any input to your situation...

Thanks,

Jim R.
 
Sk8Surfr said:
New pool - was going off the spec chart for the plans that shows 54gpm at 1,500 RPM for the Pentair Intelliflow VS.
Click to expand...
That would be for very low head loss plumbing.

Is all your plumbing, suction and return side underground, 3"?

What kind of filter do you have (make/model)?

What is the distance pool to equipment?

How many returns are in the pool and what size are the eyeballs?

What is the filter pressure at full speed?
 
mas985 said:
That would be for very low head loss plumbing.

Is all your plumbing, suction and return side underground, 3"?

What kind of filter do you have (make/model)?

What is the distance pool to equipment?

How many returns are in the pool and what size are the eyeballs?

What is the filter pressure at full speed?
Click to expand...

Yes, all underground is 3"

Pentair Clean and Clear 200 (using the 2.5 inch)

The distance is far... roughly 100' (it's a lot of pipe)!

5x 1.5 inch returns in the pool that all come off the 3" return

Pressure is 18psi at 3,400 rpms
 
So at 3400 RPM, the flow rate should be about 138 GPM and at 1500 RPM, about 61 GPM. So basically, you do have very low head loss.

But heaters do not work on GPM, they actually use a pressure switch to detect flow rate. Because you have such low head loss, the problem is likely that the pressure is not high enough to trigger the pressure switch in the heater at 1500 RPM. However, you should be able to adjust the pressure switch so that it turns on at 1500 RPM.
 
I did do one thing with the plumbing I should probably change - I'm not sure why I did it this way - everything like I mentioned is 2.5 around the equipment (minus the 2" fittings in and out of the pump). But I used 2" fitting in/out of the salt cell. Should I re-do this and make these 2.5 or it it really not going to gain me much or anything?

IMG_7914.jpg
 

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Sk8Surfr said:
Is 'very low head loss' a good thing or bad thing?

I'm trying to read about it - but it's a bit confusing!
Click to expand...
It is generally a good thing but does have some consequences (i.e. low pressure). So if you adjust the pressure switch, the heater should work fine.
 
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