Truma heater unpleasant smell

I recall being puzzled by a periodic “off” smell in our first van and eventually traced it to the grey waste tank. Regular tank freshener solved the problem.

Tim

The trouble with smells is that they are different so what the OP is smelling may not be what others have smelt.  We have had stale smells in our van.  I attributed it at first to lingering cooking smells but then I discovered that the rubber backed mats that we have used to replace some of the fitted carpets were trapping water under them between the rubber and the vinyl floor.  A good clean and dry out of the carpets and the interior in general solved it.

We have had grey water smells but have largely cured that by flushing all the plug holes with a mains water hose after every trip, with the grey water tank drain open.  I also refit all the plugs when the van is out of use.  

We have encountered a heat smell from the Truma but it hasn't bothered us greatly.  That said, in the early days large flakes of brown paint were blown out of the heating ducts.  I reported it to Truma and A-S who expressed disbelief making me feel that they thought I was making it up or that the paint had come from somewhere else.  I didn't get to the bottom of it until last year when we were having our electrical heating elements replaced.  For a time Truma had been painting their heat exchanger and that is where the paint had come from.  Some of the flakes were still there which the technician cleaned out.

Ready to go wrote:..
Had thought about trying to remove the entire front panel of the locker to look further but this doesn't seem to be an easy option.
...

I haven't personally removed the front panel but I know it is easy to remove.  Mine has been removed 2 or 3 times when it's been in for repair.

I'm looking forward to hearing what's causing the smell  

Ready to go wrote:The mystery about the smell has been resolved!
A fellow motorhome owner came around last week to give my vehicle a "sniff".  After going through the obvious views about the toilet and something dead, he thought it was gas.  So, I shut off all of the gas taps in the vehicle and in a short time the smell completely disappeared.  I then turned each of the three internal taps on in turn - having a sniff each time - and then concluding that the problem was associated with the boiler.
Took the vehicle to a local independent expert this morning who fixed it.  There was a split in the pipe going to the boiler.
I've really learnt something by this experience - I didn't know that the mix of gas is set to give off an unpleasant smell.  If this happens again, I'll know straight away.  Could have ended badly as when we were recently away my wife insisted on lighting a candle to get rid of the smell.  The flame might have got rid of us too - if it ignited the gas!

I'm pleased its been sorted and no one here guessed it was the gas.  We've all learnt something.  What a good job it didn't ignite.  Most of the gas should have gone down a drop hole beneath the Combi.  This is something that should have been picked up on the annual habitation service.