MasterTemp400 No Power to Membrane Pad

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Navy Davie

Member
Apr 11, 2025
6
United States
Hi TFP,

New to the site and new to pool ownership. I attempted to heat up my spa for the first time yesterday and surprise, surprise... no heat.

My Master Temp Heater is connected to an Easy Touch System and a Clean and Clear Plus Filter and Intellichlor chlorine generator (IC 40). I don't know the age of the system. I do know that the heater was assessed as part of the move-in inspection and at the time the unit powered up (i.e. membrane pad and LEDs working), but they didn't assess whether it was actually generating heat.

Anyway, I want to get the heater working, but as a first step would be happy to get back to square 1 with the membrane pad and LED working. Open to any suggestions!
 
Welcome to TFP.

Do you have a multimeter and know hwo to test voltages?

You need to do some diagnostics and first determine if your heater fails to power up because of a problem in the EasyTouch or a problem in the heater.

The EasyTouch uses the Fireman's switch through a 2-wire connection to power the heater on and off. The first thing is to restore local control of the heater control panel. You need to disconnect the control wire in the heater and connect the two wires in teh ehater together with a wire nut.

Pentair_MasterTemp_Firemans_Switch.jpg

Lots more information in Pentair MasterTemp Heaters - Further Reading
 
Hi AWJ, Yes I have a meter and can test voltages, but a novice at reading schematics. I did open the panel and have identified the Fireman's Switch from your image and connected the yellow wires as suggested. However, after powering on the pump via the Easy Touch control panel, I still get no activity on the heater (i.e. no lights on the membrane panel).
 

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This picture does not show the correct wiring.

There are yellow and green control wires, but only the yellow wire is connected, and the green wire is hanging down. The green wire should be connected to the terminal with the fuse.

Show me a picture of the two sides of the fireman's switch properly connected together.

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After turning the pump on from ET Panel and waiting for about 5 min. I attempted to turn on the heater via the "Pool On" button. Nothing happens. No lights (LEDs), temp display, and no response from any of the 5 buttons (Spa on, Pool on, Heater Off, Temp. Up, or Temp. Down)
 

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Your EasyTouch thinks your pool temperature is 105F and the HEATER is not enabled.

You have a problem with the water temperature sensor.

And you need to check the Heater Menu settings (page 25).

The water temperature sensor can be checked using your multimeter. Read Temperature Sensors - Further Reading

Review the manual and Wiki and let's discuss what you find in your system.

pxl_20250412_015856489-mp-jpg.637576



1744424965069.png
 
Navy Davie said:
. I attempted to turn on the heater via the "Pool On" button. Nothing happens. No lights (LEDs), temp display, and no response from any of the 5 buttons (Spa on, Pool on, Heater Off, Temp. Up, or Temp. Down)
Click to expand...

The EasyTouch controls the 24V AC power to the heater through the Firemans Switch. Nothing will power up on the heater until the EasyTouch calls for heat.

Your EasyTouch is not calling for heat since it thinks the pool is 105F.
 
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You can confirm that your heater works by disconnecting the two wire nuts and wires. Then, jumper the two contacts, as shown by the purple line, to connect the 24V AC control line.

The heater should then work with its local control panel when the pump is running.

1744425728897.png
 
Navy Davie said:
AJW, you are the man! It worked just as you predicted once I jumpered the two yellow wires. Now I just need to troubleshoot the temp sensor.View attachment 637595View attachment 637596
Click to expand...
If you get this kit, you can replace both the air and water temp sensors for about $20.00. Sensors go bad often, boards not so much. Good quality product.
 
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