# 12v timer for Truma



## wazandnic (Nov 21, 2005)

Bought a 12v programmable thermostat to use as a timer switch for the truma c boiler. The idea being to leave the hot water switched on permanently and rely on the timer for switching. 
Connected to 12v supply between dump valve and boiler pcb. When the timer switches on the truma lights come on but the red failure light also comes on. If I then switch on and off at the truma control all is ok and it shuts down when the timer switches off. Can anybody advise why I get the red failure light, please.
Thanks


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## Jezport (Jun 19, 2008)

Maybe there are more than one 12V line that supplies the Truma. What type of 12v Thermostat did you get?


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## wilse (Aug 10, 2007)

Not 100% if this is correct, but I'm sure I recall reading somewhere that if you bodge a non Truma timer in this fashion... that is has to be zero voltage??

Perhaps some-one more knowledgeable could advise.

I'd also be interested in what timer/programmer you are using.


w


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## wazandnic (Nov 21, 2005)

Its a ECO ET2 programmable room thermostat and is battery powered.

A renewable energy website had an article describing how to use this thermostat as a timer. I think it is zero voltage but I will have to check.
Thanks


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## artona (Jan 19, 2006)

Is it this one? Is the supply you have used to the truma from your 12 volt system or 240v.

Will this item work with with 12v if it is a 12v supply? 

stew


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## wazandnic (Nov 21, 2005)

If you google 'Use Thermostat as 12 Volt Timer' you will get very good articles on options for 12v timers. 
5.30 work alarm call just to get up and flick the water on would be so much sweeter if it were 6.00 and getting up to hot water.


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## wilse (Aug 10, 2007)

Just shooting out ideas here.

Would it be a fair assumption to say that even when the truck is connected via EHU, that the voltage to the timer is 12v?

IF so, could you use something like this?

=uk_insert&cookie_v[1]=8V&cookie_d[1]=&cookie_p[1]=%2f&cookie_e[1]=Thu%2c+01-Apr-2010+10%3a38%3a10+GMT&scrwidth=1440]12v timer

Also another thought.... it hurt!
Could your problem be the fact you are using a timer/thermostat as opposed to just a timer. Would the Truma's thermostat conflict with your 'add-on'?

I'd like to find a solution to this, but don't want to pay Truma's £150+!

w


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## ICDSUN (Oct 10, 2006)

wazandnic said:


> Bought a 12v programmable thermostat to use as a timer switch for the truma c boiler. The idea being to leave the hot water switched on permanently and rely on the timer for switching.
> Connected to 12v supply between dump valve and boiler pcb. When the timer switches on the truma lights come on but the red failure light also comes on. If I then switch on and off at the truma control all is ok and it shuts down when the timer switches off. Can anybody advise why I get the red failure light, please.
> Thanks


Very likely to have a holding circuit for safety, resetting at the control knob resets the circuit,hardly worth messing with as the extra costs amount to a few pennies use of gas/electric

Chris


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