Hot water

Caravan Hot Water – Ignition Issues

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Our caravan hot water system in our Jayco like many caravans, is a Suburban brand gas/electric hot water heater. In general we don’t have any issues with it. However it’s always been reluctant to start first time.

Our heater usually takes at least three restarts before it actually runs as expected. At first, We just thought “oh the wind has blowing the flame out” so I never really looked into it any more. As time goes by it finally annoyed me enough that I thought I’d take a look into what the actual cause was.

The symptoms

  • Flick the switch on to ignite the flame and heat your water up
  • You can hear the ignitor sparking and the flame start
  • It then goes out and tries to auto re ignite shortly after
  • Again it ignites but almost immediately goes out
  • It then goes into a failed state and no longer tries to start on it’s own
  • Flick the switch off then back on again and ta da… the gas ignites , flame continues running and soon you have hot water… all’s good

Sound familiar ?

So whats actually happening here ?

Suburban Heater thermocoupler
Photo: Thermocouple and ignitor assembly

When you turn on your water heater, the Suburban heater directs a flow of gas down a pipe which comes into contact with a spark from a ignitor like your BBQ does. When the flame starts, it heats up a thermocouple electrode which then sends a very small voltage reading back to a electronic module on the heater. The voltage tells the heater that ” I have a flame and I’m running”. Knowing that… the heater now continues to supply gas to the flame. Without this signal the heater says ” ok I have no flame therefore I have no need to waste gas and so I’m shutting the gas off”.

Keeping the above in mind, there are 4 common things can cause the issue in my thoughts. ( there is more but lets stick to 4 for now)

  1. The thermocouple has a build up of carbon on the end of it which means it makes it harder to heat up and therefore slower to send a low voltage signal back to the module so that the gas keeps flowing.
  2. The Thermocouple is not in the direct flame and therefore takes a while to get hot and send the signal back to the module
  3. The module receives the signal but is faulty so does nothing with the signal.
  4. Some insect/animal has made a nest in your discharge tube which is restricting the flow of gas.

How we fixed our caravan hot water issues

Working on a gas hot water system is best done by a certified technician. However in this case it’s a simple mechanical repair and is not dealing with gas regulators etc so all is good.

Suggest shutting off the gas bottles just for good practise before proceeding.

  1. Open the caravan hot water heater door and you should see something similar to this above photo.
  2. Remove the three screws that attach the burner cover to the heater body.
  3. Remove the electrical connection from the thermocouple
  4. Unbolt the discharge tube so that you have the whole unit in your hand.
  5. Inspect and clean the tube from insect nests etc.
  6. Look at the two pins on the end of the tube. There should be a air gap between the two so that the spark can jump between both rods
  7. Both the rods should also be in direct flow of the flame. If not ( like ours wasn’t) bend both rods so they are over the discharge pipe outlet and therefore in direct line of the flame.
  8. With light sandpaper give both these rods a light sanding to remove any excess carbon build up.
  9. Reassemble and test.

You should now have a caravan hot water heater that starts up on first attempt. If not then you may have extra issues where you’re probably best to get it checked out by a technician. Modules can have their faults and are quite expensive so best to have someone test it first. Thermocouples aren’t too badly priced but like in our case it was really a case of making sure it was in direct path of the flame.

Hope that helps someone one day

Check out our other helpful tips and tricks in these posts.

Questions and answers

Re syncing a Jayco slide out

Our list of other help articles

Cheers

Larry

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