MasterTemp 400 not getting over 100F

[Pesh]

Brand new MasterTemp 400 connected to IntelliCenter utilizing Fireman's Switch + J2 connection for Automation. Max temps set on heater as follows:

Pool Max Temp : 104F
Spa Max Temp : 104F

When 104F selected as set-temp for Spa, I cannot get the spa to exceed 99F/100F??? It can run for tens-of-minutes at 99F/100F but wont increase over 100F.

Any tips?

 

[ajw22]

It can run for tens-of-minutes at 99F/100F but wont increase over 100F.

Is warm water coming out of the spa return?

Put a cooking thermometer in to spa and measure actual water temperature.

 

[Pesh]

Yes, the water is warm, even hot. Just not sure why the temp sensor is reading 99F / 100F and with a set temp of 104F, why the heater wont keep heating?

 

[ajw22]

Yes, the water is warm, even hot. Just not sure why the temp sensor is reading 99F / 100F and with a set temp of 104F, why the heater wont keep heating?

You are getting hot water and it is heating.

What has been your air temperature?

When you heat an inground pool/spa for the first time you need to heat the surrounding ground. The ground around the spa can be a large thermal sink drawing heat from the water for a while.

 

[Pesh]

Air temp has been in the 70-80s here in Austin, TX.

 

[ajw22]

Air temp has been in the 70-80s here in Austin, TX.

At night?

 

[Pesh]

70's at night and 80's during day.

 

[ajw22]

Measure the temperature 3 to 4 feet into the ground. You may be surprised.

 

[Pesh]

Actually, about 50%+ of the hottub is exposed to air.

 

[ajw22]

Actually, about 50%+ of the hottub is exposed to air.

That is worse. Your tub does not have the insulation the ground provides and thermal mass once you warm up the ground.

The plaster, gunite, and stone lose the 100f heat to the 20 to 30 degree temperature differential with the air.

 

[Pesh]

My testing was done yesterday around 3pm in the afternoon when outdoor air temp was 85F+

 

[ajw22]

Just let the heater run. It will get there eventually.

 

[Pesh]

Just to update the thread with feedback from Pentair support that actually did end up helping...

When IntelliCenter is telling the heater to run, go to the heater keypad on the heater itself, there the heater is set to be on (on either pool mode or spa mode it doesn't matter which) the set point there is set to 104? If not, press up arrow repeatedly to set that to 104. Heater must be left in this state for the the IntelliCenter to have control. ​

In my case, both pool and Spa set points are 104F.​

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The current water temp will also show on the heater keypad on the heater itself. Does the heater and the IntelliCenter both agree on what current water temp is? If not:​

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From IntelliCenter outdoor panel, main screen: Settings > General > Temperature Sensor Calibration > Water Sensor. Then click the up or down arrows so our two temp sensors are in agreement with each other.​

In my case, the "True Read Out" and "Adjusted Water Temp" did not match. There were about 3 degrees different, so I changed them to match and voila, i'm getting spa water temp to 103/104F. I've ordered a pool thermometer to measure actual and see whether i'm really getting what I think i'm getting. That will be the final test.​

 

[ajw22]

Put a cooking thermometer in to spa and measure actual water temperature.

J I've ordered a pool thermometer to measure actual and see whether i'm really getting what I think i'm getting. That will be the final test.

 

[Pesh]

One would presume I have a cooking thermometer (which I dont)

I'll get something in a few days from Amazon and confirm everything is behaving as it should