truma heater issue

[martin n]

Hi there



I'm newbie to the forum, and hoping that someone can help to shed some light on an intermittent problem with my truma gas heater s3002 in our 2005 Ci motorhome.



It worked really well over the last cold snap, then about 10 days ago (possibly due to the gales with horizontal rain?) it has developed an intermittent fault:



At times it is completely dead with the exception of a once only click when you turn the gas control button on 1-10



And at times it works normally, about half the time. It will always restart if turned back on soon after turning off, but may not if it is left for say over an hour, even if it has been left on for 24 hours.



A few times it clicks irregularly as you try to start it whilst the gas button is suppressed and before the button is released the gas supply dies before the thermocoupke has heated up, but then when retrying to start a second or third time it starts fine. (faulty gas supply valve?)



When it works I have left it running three or four times over a 24 period (just in case damp is affecting it) mainly on low setting but turning up and down to check it works. and it always stays on fine, it never goes out once on, and there is no clicking when it is on.



Flue down to the heater seems completely dry

Intake under bodywork is clear

Control run rotates and supresses fine

When it is not working, the ignition box still works when tested by shorting the two power connections (and a new battery fitted). If the sparking wire is disconnected the ignitor clicks regularly when the gas control knob (1-10) is turned on but when the sparking wire is connected then the ignitor stops working (ignition box stops clicking)



It seem to be worse in the wet and windy weather but I cannot see why so maybe is a coincidence?



And something else a little strange but not necessarily connected, when it first stopped working the fan would turn on and off but now it is dead and I have a fuse light on on the control panel but cannot find a fuse that is broken, all the fuses in the box in the cab are fine, maybe I shorted the fan connectors when putting it back during testing but buggered if I can find the fuse! The fan does not affcect the gas heaters operation so I guess it must be a separate issue?



I am thinking that the issue is with the gas valve but just wanted to ask for advice from anyone who may know (a lot) more than me in case it is something else.



I think that that is all of the relevant info, hope so...



Thanks for reading, any feedback much appreciated!

 

[Itsmcb]

I was going to suggest a new battery in the ignition but I see you have done that. It definitely sounds like an ignition fault, the gas will need very little spark to ignite if the heater is still hot but more if it's cold. Sounds like something is preventing the ignition box from sparking. Are you sure the battery you fitted is good?

 

[martin n]

Hi - no, the battery is fine I have checked (twice and used a meter). I'm fairly sure it is not the ignition box as the box works every time when I disconnect the spark wire that runs to the gas valve, and also when I disconnect the power leads to the box and short it as explained in the original thread.

I think that it is gas flow not ignition, maybe it always restarts immediately after use as the gas flows when the valve/thermocouple is still open when it is hot in the same way that it needs little spark when hot, as you suggest.

Thanks anyway!