Mertik Maxitrol GV60: 

Gas-fired, remote controlled stove

This is a quick page to mention a gas-fired imitation solid-fuel stove I’ve been engaged to fix. It’s not that complicated but finding diagnosis info about it has been remarkably difficult even from the manufacturer so I thought I’d write a brief web page about it. It might help others wrestling with diagnosing one! 

This particular stove is a WoodWarm Phoenix 3 but lots of makes of stove seem to have this Mertik Maxitrol system. There is a remote control handset rather like a TV remote. You have to use this remote controller to light the stove and turn it off, or turn it up and down. The user cannot do it with controls on the stove. This is what makes this stove difficult to diagnose when it stops working. The radio receiver makes it work in a different way from the average stove or gas fire without the remote. There are two Maxitrol systems, the GV36 and the GV60. The GV60 is the more complex system with more features etc. but both are similar, comprising a user handset/remote controller, a receiver module, a power supply or batteries, a gas control valve, an Oxypilot assembly and a main burner.

There are no user controls in the gas fire itself. Everything to control the gas fire is done from a distance, using the remote handset. 

The problem they all seem to suffer from is the pilot light igniting and burning briefly, then turning itself OFF for no apparent reason as though the thermocouple has failed, but fitting a new thermocouple (or complete pilot assembly) does not fix the fault.

The ignition sequence (initiated from the handset) appears to be as follows:

    1.    Receiver module receives a radio signal from the remote controller to light the pilot flame

    2.    Receiver module sends a strong electrical pulse to the gas valve to open the pilot gas solenoid

    3.    Receiver holds the pilot gas valve solenoid open with a weak current

    4.    Receiver module starts a stream of ignition sparks for 30 seconds to ignite the pilot flame

    5.    Gas valve pilot solenoid is latched ON next, using current from the now-hot thermocouple via a switch in the receiver 

    6.    Receiver monitors the flame by sensing current through the pilot thermocouple interrupter circuit.

    7.    Once the spark stream stops, the receiver module sends voltage to gas valve main valve actuator motor to open the main burner valve

    8.    To turn the pilot off from the headset, I suspect the receiver module disconnects the interrupter circuit.

The above might still be wrong in detail but is the best I can determine so far from reading about the Mertik Maxitrol GV60 and examining and testing this one I’ve been engaged to fix.

References:

Valor GV60 troubleshooting guide here:

https://www.valorfireplaces.com/media/training/Basic-Troubleshooting-Maxitrol-GV60.pdf

Diagnostic tests/information:

There is a row of five unused pins on the receiver. Farthest pin from the gas valve Molex plug is battery voltage and must be 5.8Vdc or higher, or replace batteries.

Thermocouple. Must be 8mV to 13mV between Earth and the red terminal (core signal conductor) on receiver. The thermocouple core conductor is -ve and connects to the red wire. and the earth/body is +ve and connects to the yellow interruptor wire.

Receiver module. Expect between 2mV and 4mV across the red and yellow terminals. Over 4mV, replace receiver. This is just a switch, I think! 

Yellow terminal to earth should be 12mV with hot thermocouple, dropping to 2mV as solenoid clunks out after flame extinguished.

So today, it looks as though the receiver unit on this particular stove is failing as I am getting 12mV across the red and yellow terminals. So a new receiver has just arrived in the post (29/9/26) and I’ll fit it soon and update this page with the result.