Frost Valve Power Supply

[Jack TGA]

Does my truma boiler frost safety valve require the 12v leisure power master switch to be turned on?
(Or does the frost valve run off the engine battery?)

 

[ivorantony]

Nope it’s only a piece of wax in a valve, when the temperature drops the wax shrinks and the spring loaded valve opens dumping your water,

 

[David and Sally]

Our Truma frost valve is not supplied with 12v. It is purely mechanical.

Are there wires going to yours? If so, try switching on and off the hab power whilst checking the voltage across the valve. My guess it is always live to the hab battery. But I'm no expert on the 12v ones.

 

[Lenny HB]

If your valve is a black one with a red knob it will be fed with 12v from the hab battery.
Newer ones with a blue knob & button are mechanical so no electrical connection.

 

[Jack TGA]

If your valve is a black one with a red knob it will be fed with 12v from the hab battery.
Newer ones with a blue knob & button are mechanical so no electrical connection.

Mine is a black one with a red knob. If it's fed from the hab battery does that mean the 12v switch in the hab area needs to be ON for the frost valve to function? (I mean the 12v kill switch on the control panel with remaining battery powers and water levels)

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[Lenny HB]

Mine is a black one with a red knob. If it's fed from the hab battery does that mean the 12v switch in the hab area needs to be ON for the frost valve to function? (I mean the 12v kill switch on the control panel with remaining battery powers and water levels)

Normally they are wired to a permently live output on the distribution unit so you can turn the panel off and they will still work.

 

[NicM]

If you have a 12v one if it looses power it will open anyway so you will know.

 

[Sandyt]

There is an optional heater for the valve itself. This is to permit the valve to close if your van has been in storage with the system drained down. If it's freezing, the valve wouldn't normally be able to remain closed whilst you fill the tank. The little heater is activated when the Truma system is active ie "ON" - neither gas not EHU is required to power this unit, so just switch the system on, and by the time you've arrived at your destination, the frost valve can be shut, and the system filled. The power is taken from the ECU on the Truma heater itself.