Pentair PSL4 Communication Issues


New member
May 9, 2020
West Central Maryland
My wife and I can't seem to... Oh, not those type of communication issues! Hi everyone- I'm brand new to the Forum and a first-time pool owner so please excuse any ignorance I have of these systems in figuring this all out!
A little background info: we just got our pool/spa combo and it contains a Pentair PSL4 Control System, a Pentair IntelliFlo VS pump, and a Pentair MasterTemp 400 Heater (converted to LP). These are running off of the Pentair Screenlogic Interface for remote/iOS app control.
The PSL4 is on AUTO Mode and I can only control it from the app- select pool or spa, change temperatures, pump speed, etc., unless I switch modes. The MasterTemp heater should be setup to be controlled similarly.
Here is an example of my issue given the Pool/Spa temp is at 70 degrees, and I want it to go to 80 degrees. If I activate the respective valve and set the temperature to 80, via the app, everything kicks on and heating begins. These settings are displayed on the PSL4 display screen. After some time, I look at the app and it shows the heater is still running and the temp is currently at 74. I go outside and notice the heater is not running. I notice the display on the heater shows 74 degrees. If I then manually increase the temp to 80 on the Heater, it kicks on again and will heat to 80. The stumper is although the PSL4 display shows it is set for 80, the heater was apparently only set to 74, and would not go past that, eventhough it was set for that on the PSL4 and on the app.
That's where it seems the communication issue lies... am I on the right track here, or am I missing something obvious?
Thanks for any assistance!!

Rocket J Squirrel

Silver Supporter
Bronze Supporter
Jun 7, 2018
Alamo, CA
The EasyTouch doesn't "communicate" with the heater. All it does is turn the heater on and off. You need to manually set the temperature on the heater to be as high as you'll ever want the spa, say 100°F. Then the EasyTouch will use its own water temperature reading to turn the heater on and off as needed.


Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
Bedford, TX

Do you know how your heater is being controlled? I think your heater can be controlled by either an RS-485 cable, like your pump, I just looked at the manual and it appears to me your heater can only be externally controlled by the heater's firemans switch. This means the Heater has to be set to full hot before the EasyTouch can control the heater.

Just like RJS says above...


Jim R.
Last edited:


New member
May 9, 2020
West Central Maryland
Thanks Jim and Rocket Squirrel... that was the issue! It now works as it's supposed to!
I wish they would've mentioned this in the setup manual!!
This forum is great and thanks again for solving my issue.
Stay safe...