Eberspächer – poor heat output

Eberspächer – poor heat output

Eberspächer – poor heat output

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Pete Riley’s problem, and how he solved it.

The initial post on the chat group:

We have a 16 year old Morello. A fine specimen that we love dearly.

However we have never had any success getting the heater to work properly. It gives a pathetic output. Yesterday I removed the heat exchanger to examine it properly.

System spec:

  • Eberspacher D5 WSC Hydronic unit in the engine compartment, which was fitted 11/05 by Cumbria Autos – rated at 5kW

which feeds the:

  • Helios 2kW fan matrix (combined heat exchanger and fan) The dimensions of the square formed by the heating fins is about 5″ x 5″ (Fitted under the wardrobe towards the rear of the van).
  • The output to the fan feeds directly into a sealed wooden box with 2 outlets at either side. The 2 circular duct holes from the box feed directly: into the bathroom; and via a 1m corrugated, foil lined pipe to a vent under the ‘chez longue’ part of the van seating. The box merely serves the purpose of ‘collecting’ all the heated air, and providing a union with the 2 outlets.

My actions / observations:

  1. The D5 appears to be working well. From cold it quickly provides very hot water to both the hot water heater, and the Helios. Within only perhaps 15 minutes or so, the exposed metal unions on both the water tank and the Helios are far too hot to touch.
  2. The Helios is clean from dust which could potentially block the heat vanes.
  3. The Helios fins / vanes are completely undamaged.
  4. There are no blockages in the 2 pipe circuits in the Helios. Connecting to a hose to flush out showed no sludge or any other deposits of any kind.
  5. The Helios had been fitted upside down, with the bleed screw at the lowest point in the unit instead of the highest point. It had been fitted this way so that the warm air exiting from the combined unit is directed towards the van interior and not to the inside of the cupboard. Mounting it in any other way would cause a convoluted engineering problem to get the warm air going in the right direction. I don’t know if there had been any air pockets in the Helios, however I did refit after 4. above and ensured it was bled properly. The results were still unimpressive and possibly no different to before – suggesting that there was probably no airlock originally.
  6. The fan on the Helios works well. No accumulated dust or impediment to air flow.
  7. The wooden box and ducting arrangement is crude, however removing the box and ducting from the system and leaving the Helios unit to operate free standing still produced unimpressive results.

Whilst I know I’m not comparing like for like, a free standing 2kW electric fan heater heats the van space up very effectively on a cold day – in less than 30 minutes. We have a number of van friends who have very effective heating, who don’t have to resort to hook-up power.

The question then: Does anyone else have such poor heating? Does anyone else have a similar set-up that works well? Am I missing something in my diagnosis?

Thanks, and apologies for such a long and technical query!

and after a number of suggestions:

Well…..over 3 months after pure exasperation drove me to start looking for a solution to the dire heating system in our 2000 Morello, I finally completed the engineered update today. 3 months of thinking and talking to unreliable suppliers / heating engineers. Less than 2 hours to do the work!

I said I would post the outcome as many of you not only kindly offered your thoughts, but a number of old Murvi owners reported the same problem.

  • I replaced the 2kW Webasto Helios heat exchanger with a 4.6kW Webasto Madera 4   – £260
  • Required 2 x adaptor outlets for the unit                                                                    – £24
  • 1m radiator hose off EBay                                                                                       – £8
  • 1.5m 55mm heater ducting off EBay                                                                        – £16
  • Scraps of copper pipe and plumbing unions                                                              – garage
  • Extra air outlet valve                                                              recycled from existing fitment
  • Some DIY skills
  • ie just over £300 for the conversion.


  1. Now 2 outlets instead of 1
  2. Far greater air flow to the cab
  3. Noticably good flow of warmer air.
  4. Bit noisy

Whist this update does not compare with many up to date heating systems it will now allow us to extend our acceptable season. This evening the outdoor temperature was 7 deg. After 30 mins of running the cab temperature (with no screen cover or blinds drawn) the cab temperature was quite tolerable. This solution genuinely improves our off-season scope for wild camping.

Thanks again to all who took an interest.


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