Truma heater unpleasant smell

We've had a 2021 Broadway for 18 months and have only recently noticed an unpleasant smell in the vehicle.  My wife has a sensitive nose and she believes it is coming from the cupboard housing the Truma heater. The vehicle has been used daily over the last two weeks, with the heating on (electric) daily.  The smell is present even when the heating isn't on. Initially we thought the toilet needed emptying, but it wasn't that, but its that sort of smell.  Have used a torch with my phone to try and see if someone has left a little gift which has gone off, but can see no sign.    
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.
Any thoughts?

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

Thanks Tim
I think i've ruled that out as I have treated the fresh and waste water tanks and flushed them all through thoroughly a good few weeks ago.

The Truma smell is well documented on various forums. It's normal and will eventually disappear but can take a long time to do so.
Examples ..

https://www.caravanclub.co.uk/club-together/discussions/information-technical-tips-advice/caravans/truma-combi-hot-plastic-smell-venting-into-caravan/

https://www.autosleeper-ownersforum.com/t14088-scorching-smell-from-electric-water-heater

We had that smell too in our Warwick. I believe it was caused by the pipe insulation getting hot.

Eventually, we could sniff the air and say "the heating's kicked in again". 

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.

Caraman wrote:
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.

Nearly 9 years on and we still get "the smell", mainly when the water heater is on rather than the space heating. Removing the front panel is relatively simple if you are reasonably competent and dextrous. After ensuring everything is switched off, If you remove the the large front inlet vent it will give you access to the drawer runners which may need to be removed to get the drawer out. This is not as difficult as it sounds. There are two retaining screws behind the panel, one on each of the hoses holding them  onto the front vents. These need to be removed to pull the hoses off. With the plastic screw covers removed from front panel the retaining screws will be evident, they are screwed in to the floor and sides at an angle. There may also be a couple if small brackets inside at the top of the panel. The panel is a tight fit so a bit of grunt is needed to pull it out. It sounds a lot but I was able to do all this in about 20 minutes.

Thank you everyone for your thoughts which are always appreciated.  Haven't cracked it yet as the smell is definately getting worse  - which may be linked to the warmer weather.  Really does seem like something is dead or decaying!  I am continuing to investigate and I've managed to book it in at a local independent specialist on monday next - so fingers crossed they can sniff the air and sort out the problem.

Are you sure it isn't? !  A visitor with whiskers?

Cymro

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

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!

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.

It is disappointing that this was the first trip out AFTER the Habitation Service was done by AS in Broadway - and there were no matters raised by AS on the habitation report  

I am also glad you got a resolution and many thanks for coming back to let us know the outcome