Copyright ©2016 Paul F Greig

Caravan Hot Water System Activation LED.
On a recent trip we were surprised to find that one of our 9kg gas bottles became empty long before it should have, fearing a gas leak I checked all connections and lines closely, (using soapy water in a spray bottle, not a cigarette lighter!) found nothing and simply decided we had used the gas up. It wasn’t until a week later that I realized what happened.
We were in an isolated campground out on the Warrego Highway in western Queensland when, during the wee hours, I was awoken  by the sound of what I thought was our neighbours gas hot water system heating up.
When heating these systems sound a little like a hot air balloon passing overhead...I thought little more of it until the morning when I realized that we actually didn’t have any nearby neighbours!, and on discussing it we now recalled hearing this before a few times on this trip, we had been hearing our own gas being used up!

And I knew why...right away I knew had happened!!....after a bit of thought I knew what I had to do to fix it, anyone with a little low voltage wiring experience can do it too...click  below for an explanation.
This is the Hot Water System (HWS) control panel as installed in our Jayco Outback caravan. There are probably different panels around but this one is quite common across the Jayco (and others)  range. In this photo the system is activated, the switch is in the 'on' position and the indicator light glows, when the gas ignites (about 5 secs) this indicator lights goes out, however the switch is still on of course and the system is still active, if left in this position the gas will re-ignite automatically as soon as water cools.
Now it dawned on us just why our gas was all used up, we had forgotten to turn the system off, there being no indicator to warn us it was still on, the system is not particularly noisy on start up, we may not have heard it.. Obviously I needed to do something. The panel is easily removed, just two screws.
I popped into Jaycar and brought a small LED indicator light. It cost all of $3.45!! I used green but they are available in blue, amber and red.
At the rear of the panel there are four connectors...on the left hand side there is a blue wire (12v pos) at the bottom, on the right hand side there is a terminal with two white wires (ground) at the top. It is between these two terminals that you will connect your LED, the LED has two wires, red (12 vdc pos) and black (ground).
I cheated a little here, I found I was able to insert the tiny LED wires into the existing push-on connectors behind the switch panel, you may prefer a more 'professional' approach but I doubt that they will be able to drop out, they are a very tight fit.
Using a 5 mm drill I put a hole in the plastic panel. One thing to be careful of here, when you disconnect the wires from behind the switch as you will do in order to easily and accurately drill the hole, be very careful that they don't drop back through the hole on the wall, I think they would be a 'bitch' to retrieve.
In this photo the system has been activated and it is sending a spark to the HWS awaiting gas ignition, this takes around 5 seconds or so, once fired up the amber main light will go out.....
...but now the newly installed LED remains lit after the main indicator goes out, the green LED will stay lit while the switch is in the on position, once the gas has heated the switch is moved to the off position and all lights go out.. the LED is quite bright and gives excellent warning . ..I really have no idea why the HWS manufacturers didn't do this in the first place.
Warning...ensure you disconnect your mains voltage connection before proceeding
The Website of Paul and Pam Greig - Queensland Australia
Calliope River Camp -  Central Qld - 2017
The Website of Paul and Pam -
Queensland, Australia.
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