Pentair Master Temp Spa Problems

Krisher

Well-known member
Aug 28, 2013
58
Huntington Beach, CA
I have a Pentair Master Temp that runs normally when heating the pool, but when we run it in spa mode the heater will heat for approximately one minute, then shut off for a minute and reignite for a minute repeating the process indefinitely. The pipes do shake briefly, but I have checked my chemical levels and confirmed with local pool store...everything is in ideal range. The thing I'm confused about is why it runs perfectly when in pool mode and not Spa. I checked the flow rate and they were operating at the same rate. I decided to lower the flow rate for the spa mode from 2900 to 2250 and it would only fire for about 10 seconds (maybe less). I then tried it at 3200 and extended the time to about 1:30.

Does anyone have an idea why it's not working in Spa mode?

Thanks for any help.

17,000 gal pool
Pentair Intellitouch
Pentair IC40 Chlorinator
Pentair Master Temp

Southern California Location
 

danpik

TFP Guide
Jun 4, 2012
1,709
western NY
By the sounds of the test you ran it needs more flow. Too little and the heat won't be pulled away as fast and it may shut down on overtemp. Can you increase the flow over 2900?
 

Krisher

Well-known member
Aug 28, 2013
58
Huntington Beach, CA
I currently have Spa mode running at 3200.

Pool mode is set at 2900 and runs fine. Is there a difference in temp depending on what it's set at? I assume it just heats water at relatively the same temp/rate until it reaches the desired temp. Is that correct? Or does it heat hotter when set at higher temp?
 

ps0303

TFP Expert
In The Industry
Jul 6, 2011
4,001
FL
Are you sure you have all valves set correctly for spa mode? What you described is that there is a water flow issue and the heater isn't getting enough flow.

A heater heats water period. It has not idea where the water is coming from or going to. It doesn't output water any hotter if the thermostat is set high or low. It just needs the correct amount of flow to operate.
 

OldPoolMan

In The Industry
Jun 2, 2015
423
Wildomar, California
Definitely sounds like a flow rate The shaking pipes are due to low water flow which causes boiling water in the manifold, which causes the high limit switch to shut down the heater. Increase the flow rate.
 

danpik

TFP Guide
Jun 4, 2012
1,709
western NY
Has it worked properly before this. Did something get changed recently downstream of the heated? (between the heater and spa) when you say the pump is set at 3200, is this just a setting on the controller or is there flow meter actually measuring the flow output? Do you maybe have an automatic valve that is not opening properly.
 

ps0303

TFP Expert
In The Industry
Jul 6, 2011
4,001
FL
Since it works to heat the pool but won't when you switch the valves to spa, it has to be something in the valve settings or as others have said, something preventing the heater from getting water flow.

Can you post a picture or two of your valves and also include how they are set for pool mode and then for spa mode.
 

Krisher

Well-known member
Aug 28, 2013
58
Huntington Beach, CA
Sorry for the late response, we were out of town. Anyway, here are a few pictures of the valves as they are set.
/Users/Krish/Desktop/IMG_1991.JPG

This is the valves set for Pool.
/Users/Krish/Desktop/IMG_1992.jpg

This is the valves set for Spa
/Users/Krish/Desktop/IMG_1993.jpg

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I'm having trouble uploading photos,no matter how small I make them?