Erberspacher , Shower .

2003 Topaz 

bought last year after 10+ years with the first of the T4  Petrol (Autoholmes Koncord)

its been brilliant ,  this one has the Erberspacher heating and the P.O. said it had just had a new leisure battery fitted , but heater would work if used shortly after stopping but if left for a while was reluctant to complete its cycle , fan would start , cycle through then stop.

battery would show 12.9 at terminals but not start .

I have a couple of these on other vehicles and had a little bit of experiance of the faults , so ran a substantial  wire( one half of a jumper lead ) from the battery to the brown feed to the heater , started up no problem but left to its own devices it wouldn't .

so, I ran an extra wire from the live ( battery under the cooker ) through the wall towards the shower then into the gap where the rear doors slide , luckily there is a hole already there and I used this to get underneath the van , under the van I meandered across to a spare grommet close to the erberspacher combustion inlet and connected to the brown feed. 

it never fails to start now, even with everything  on .

Shower , part of the reason for buying a Topaz was the shower , when we bought it there was a little spirit level handily placed on the dash
wasn't sure what it was for until several showers later with flooding and general overflowing blamed on block drains I realised it was to get the van VERY level indeed .... small price to pay I thought ,until I sorted the Erberspacher , whilst under the van I saw the drain hoses for the shower were fixed to whatever was handy and little thought to the restricted fall for the shower into the waste tank 

I undone most of the fixings which were way higher than they should be and using cable ties adjust the fall correctly . 

result , happy showering at an incline, ok not talking Eddie Edwards practise slope but the sort where if you would be staying overnight you might employ the ramps  on the first notch .

The build quality of the Topaz is superb , and seeing the quality of the rest of the build I found it out of character for Autosleeper to use 
such under sized wire for this application, I think this was the first year of Erberspacher ? could be wrong? but for anyone else thinking of putting the right size wire in ( and thus saving on un needed leisure battery replacement ) its quite a bit longer than you think! by the time you wind your way around it adds to 4+ metres , where its only 1m from the batt to the heater direct.

The Toapz looks like a lovely van, I saw one close up when allowed pre lockdown....nice...but sounds like the 'build quality' under the van isn't so good?
with the kitchen and washroom/shower being at the rear, shouldn't this be where the grey tank is so that the waste pipes are short and dropping directly into the tank?
If it's not there, it possible to relocate it so that Gravity has an easy job?
If the tank is forward or central, then any 'nose up' attitude will cause the exit flow to stall and lead to poor (or no) decent drainage, even back flowing.
A useful 'mod', once moved, could be to have more than one entry spigot into the tank, say one for the kitchen and one for the washroom, so that they don't have to be joined and routed unnecessarily into a single pipe run.
You could then use short runs of wide bore flexible pipe to connect to the relevant input spigot.
Our own van has central washroom and kitchen and the waste tank is directly underneath with multiple entry spigots for the kitchen sink, washroom sink and for the two shower plug holes, meaning the pipe work is really short running with flexible wide bore pipes dropping from their particular waste outlet to their particular tank input.
You could do it with two such pipe runs.
Obviously this depends on how easy/difficult it might be to move the tank or even source a new one. I guess we aren't looking at something massive on a Topaz?
Someone like Cak Tanks would be able to help...
We use our shower regularly and, as you say, you've changed vans to get a decent shower and poor plumbing and draining doesn't cut it.
Good luck

The feed wire is 2.8mm  across the bare multi stranded wires.

I did try to follow the original feed to see if there was any corroded connections etc but it meanders everywhere , it could conceivably be quite long as you say , by going to the fusebox and back , but either way it drops voltage on startup and would suggest the leisure battery was not up to the job when clearly it is with the additional feed.
With LED lights and occasional use of the water pump the leisure battery doesn't get much heavy use.


The waste tank is under the side door , so middle of van and I would guess the drop 
is around 50-60mm in practise , the shower drain is the same side as the tank and around 4ft  long ( metric and imperial measurements in same reply , would give Sherlock Holmes a clue to my age ) . There was very little to play with as the run went
and if it was on a ramp and level when installed it would work fine, it was secured well  given the limited room but to maintain the fall it required fixing where there was no natural fixing and that's were I made the changes. it really has made a big differance
to the use of the shower .

The build quality under the van not so good ?  the routing "problem"  aside, it really is very well built , sealed,  fixed and secured very well indeed.

for what its worth I also fitted a seperate tank for the Erberspacher, two reasons , so I could get a better idea of fuel consumption of the van and to use heating oil in the Heater , ( along with my other Erberspachers on other vehicles)

2.8mm diameter equates to 6mm sq csa which is certainly big enough so look for poor connections or as you suggest battery

Sorry, I didn't mean to suggest the van wasn't well built (not a good phrase perhaps, 'lacking in early design thought' might be better) merely to highlight that components like tanks, heater systems, plumbing etc need to be designed in as part of the conversion concept not, as is often the case, tacked on afterwards.
Rear washroom vans need the waste tank to be somewhere rearward, front washroom vans need the tank to be up front somewhere as waste isn't pumped like fresh water is and relies on gravity, so long runs on gentle slopes via narrow gauge pipes don't make this an easy job.
I'm glad your mod of changing the height of the pipe run has helped and that you can enjoy the shower as you should have been able.

the tool that Roopert has said about can only be used on heaters that get fitted as an extra and not from new by the vehicle manufacture as they don't have the test point plug to connect the tool to

The Eberspacher diesel heater consumes a lot of power, only really met if you're camping on a site connected to EHU, which seemed like you've discovered. We owned a Duetto a while back and had A-S increase the thickness of the wire supplying current to the Eberspacher. We found it to be a good heater but only if on EHU. Even then it could be a bit temperamental, sometimes needing a second startup, and time to settle down before the heat kicked in.