Pentair MasterTemp Fireman Switch


Gold Supporter
Sep 19, 2016
My learning continues....I think that this is a pretty easy question for anyone that has this heater. :)

If the heater has power, but the fireman's switch is open (no call for heat from the automation system), does the display panel light up, or does the display only illuminate when the fireman's switch is closed (calling for heat)?


Bronze Supporter
Oct 17, 2016
Dallas, TX
I only get lights on the panel when I'm heating. I've got an Easytouch panel that does the controlling. On when heat is needed otherwise no lights or direct control at the panel at all.

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TFP Expert
In The Industry
Jul 6, 2011
When hooked into a control system like an Easytouch, if installed correctly, the heater does not power on the system board until the ET system tells it to.


Gold Supporter
Sep 19, 2016
Perfect - exactly what I wanted to know. My gas line is buried but not connected yet (Tuesday is the plan). My IntelliChem and IntelliChlor are on the same relay as the heater. I pulled the connection for the heater from the back of the EasyTouch (to the heater's fireman's switch) hoping that it'll prevent the heater from turning on, and would still allow me to turn on the other equipment. Sounds like it'll work exactly as I'd like it to.



Well-known member
May 19, 2009
Just did a bunch of wire testing on the Mastertemp. The Heater has it own power wire at 115v. The fireman switch is basically a jumper wire that can be use as a switch. Its an open or close circuit depending if the jumper wire is there or not. Fireman switch operates at 24v.

So if you use a jumper wire the heater will work manually with the heater control panel.

If you wire the fireman switch's 2 wire to the easy touch Heater connector. The easytouch will open and close the circuit to switch the power on an off according to your temperature setting. You still need to manually set your heater to 104 degrees on the panel so the water can go up to that high for a spa. Easytouch will use the water temp sensor to dictate the heater on and off time.

However if you want to keep the water below 80 for a pool. Manually set the heater temp to 80 and it will never to above that temperature. At this setting your spa will never get above 80 degree either. consider it a second level of water temp control.