Diesel Heater Discussions in Dunedin

Eberspacher diesel heaterThis is a little discussion about diesel heaters. A motorhome without a good heater is not good any time. And in winter it is bad. Suzi motorhome had a diesel heater installed when she was built back in 2008. In recent times the heater started stopping occasionally – which was not good. We have had various chats with motorhome servicing places and finally got it sorted out last week in Dunedin.

Diesel heaters are good for motorhomes. They are very efficient, using a litre of diesel in 10 hours on low and 4 hours on high. Plus most motorhomes already have a diesel tank (for the engine). Plus they can be used when driving (whereas gas heaters shouldn’t). Plus they are a small unit which can be installed just about anywhere.

The negatives with diesel heaters include a higher purchase price than gas heaters, more minutes before the warm air starts to flow, a lot noisier on start-up and more noise when cruising, and a big hit on the batteries on start-up (peaking at 14-16 Amps – 12V).

Our heater is an Eberspacher Airtronic D2 which can produce 2 Kw of heat.

Eberspacher diesel heater

Eberspacher Airtronic D2 diesel heater

We like our diesel heater but for the last year it had taken to noisily shutting down and off. It would restart by switching it off and after a short while switching it back on. Someone in Blenheim thought it might need servicing. They said they removed them and sent them down to Dunedin for servicing. This wasn’t a good option when we were living in it in autumn so they put us onto someone else in Blenheim.

He thought we needed an extra fuel filter so we got one installed. This seemed to help but did not eliminate the shutting down problem completely. A few more noisy heater bail-outs as we were heading south gave us the impetus to visit the motorhome guys at Dunedin Motorhomes. They seemed to know what they were talking about and we’ve always had good dealings with them. We were happy to book Suzi in for a heater check and service and they did the work last week.

They found an internal fuel filter somewhat clogged and a fair bit of dust and not a lot else. They were able to interrogate the heater electronically and it was mostly happy with life and with itself which is good. It turns out that Dunedin Motorhomes is somewhere other motorhome places send diesel heaters for servicing and fixing – and we can see why. They are knowledgeable and efficient.

Now our little diesel heater goes like it did when it was new. It starts when it should, idles like it should, and only shuts down when we say so. Which is jolly good.

Over the last few years we’ve learnt and been told a few useful things about diesel heaters that are worth sharing.

  1. When turning the heater on, run it at full for 15-20 minutes before adjusting the thermostat lower.
  2. Don’t turn it on for a couple of minutes and then turn it off again.
  3. To avoid the voltage dip when the heater fires up run the motorhome engine so the battery is charging.
  4. Even better, if you’re going to be needing the heater when you arrive somewhere, turn it on 20 minutes before your get there.
  5. A diesel heater can only usefully have 4 metres of ducting (maybe that’s a 2 Kw unit?). And for each 90 degree bend reduce that figure by 1 metre!
  6. Install a fuel line out of the main tank and about 25% above the bottom. This avoids having a separate tank and means no risk of the heater emptying the main tank.

Any comments, contradictions and suggestions welcome.

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9 Responses to Diesel Heater Discussions in Dunedin

  1. Keith Hallam says:

    Good info there on the D2. We have a 10 year old Autosleeper Duetto 2.4 diesel automatic and the D2 is giving problems. If we’ve been parked all day it starts up on the button but shuts off after a couple of minutes. If I run the engine it starts up and runs fine and keeps running after I stop the engine. The repair shop said the leisure battery was duff so I spent good money and had a new one fitted. Off we went on a trek and the same problem came up. The fitter had told me that a D2 should start up even if the battery was down to 11 volts. My tester showed the voltage at 12.4 before pressing the start button, immediately dropping to 12.28, then the D2 stopped. I started the engine, battery charging at 14.2 volts and the D2 ran ok and carried on running after stopping the engine. I’ve since been told that some D2’s need the battery to be at least 12.5 volts!
    I could probably live with this situation for some time except for one thing. The layout of the Duetto motorhome is such that the drivers seat has to be fully forward to make the beds up. This means that if you want to put the heater on in the morning, being an automatic, the brake pedal has to be depressed to start the engine. With the seat fully forward you can’t reach the pedal. You have to get dressed and go round to the drivers door and reach in to start the engine. Believe me, that’s easier than disturbing the wife to move the bed!!
    I’ve now got to find out if the voltage sensor in the control unit can be adjusted to accept a lower starting voltage….

    • Ross says:

      Sounds like a very circular problem Keith. I’m guessing she-who-won’t-be-moved doesn’t want to get out of bed until the cabin is warmer. Which isn’t easy without moving her. Maybe this is Catch D2? 🙂
      I’ve heard that the D2 and maybe any diesel heater is sensitive to voltage. The initial start-up process is a big draw of 10-15 Amps – glow plugs or something. That’s going to knock the stuffing out of a low battery, and 12.2 is low by some measures. I’m no expert but I’m not sure it should start at 11 volts. I’d have thought most sensible appliances should have shut down by then as a battery at 11 volts is definitely flat by any measure I’ve seen.
      Apparently the D2 can be interrogated to get error codes. If like ours you have the knob/dial control it has to come out but those with the right stuff can find out what the heater thinks is wrong.
      Somebody I’d recommend for advice on D2s is Brian the boss at Dunedin Motorhomes. I know he gets heaters sent to him from around the country to fix. A bit of a D2 Whisperer? (And how I wish the D2 would whisper sometimes …)
      I would suggest regardless of heater issues you might need to address your power set-up. As in generation, storage, and consumption. Maybe the heater problem is just a symptom of a power shortage?
      My understanding is that the heaters have a circuitboard that governs it, and I’d have thought all have the same cut-out voltage. I’d be interested to hear how you get on – we’ve got on-going issues with ours as well 🙁

      • Keith Hallam says:

        Finally, after 5 visits to a certified Eberspacher installation, repair and maintence facility my D2 is working as it should. It would appear that I didn’t need a new leisure battery but of course I can’t prove it. This last visit a different technician, a young geeky looking kid, listened to what I had to say, tried to start the D2 and it failed. He then connected his laptop. He’d already checked the battery was at 12.5 volts. The D2 was only seeing 9.75 volts. No wonder it wouldn’t run! He wriggled the bunch of wires and there was then 12.5 volts. Another wriggle and there was 10 volts….
        I walked away. When I came back later he had a short length of wire with a loose bullet type push-in connector that he’d cut away. He’d also removed some unnecessary plug connectors and wires and told me he’d run a feed wire straight to the D2. Job done. We’ve been away all this last week and the Eberspacher D2 heater has performed well. A couple of nights it ran all night, just purring away with a gentle low output. Now if only Eberspacher did a decent control thermostat….

        • Ross says:

          Good result, even if it took a while. It should have been possible to test your house battery in place to determine its health. I was amazed to see the battery man at Gulf Harbour test ours in a partly discharged state first thing in the morning and get a machine printout of the % health (storage %) of each – around 40%. Which meant the survived a bit longer, but not much. Those battery test machines must be magic considering the complexity of the task. Did your’s test needing replacement or was that just a guest/estimate?

          • Keith Hallam says:

            “Did your’s test needing replacement or was that just a guest/estimate?”

            I’m guessing they were guessing! I didn’t witness any battery test or readout, not allowed into the workshop area. It’s all on trust. That was the third visit.
            The fourth visit was installing the new battery that had taken a week to arrive due to the size and terminal layout. All tested and correct I was told. It worked ok that night. Next morning 150 miles away, the heater started for 2 minutes then stopped and I had to run the engine to get it going.
            Who can you trust?

  2. Ross says:

    Time for an update.
    The blimmin’ heater started playing up again last year. All nicely serviced and it started stopping again. That’s going through it’s shut-down routine. We tried a place in Christchurch who were not much good. Helpful but not good at getting it sorted. They had a diagnostic box which said there were no error codes. Which defied belief. We ultimately had a discussion with them and they refunded the bill and said they were planning on getting better diagnostic tools.
    Luckily we were orbiting back through Dunedin over the summer so we headed straight to Dunedin Motorhomes. It took Bryan about 2 and a half minutes to get the list of error codes and about half of that was taken up with going away to get his gear. It was overheating and shutting down.
    Given the recent service that was a bit of a mystery and there was some head-scratching and testing required. Bryan didn’t like the look of the 180 deg bend on the air intake hose, it was crinked. He thought that might be enough to upset the heater. So he took the hose off completely to test it and it seemed OK after that. In fact, it hasn’t faltered since. The inlet hose is still off as we’re waiting for a bit of a rejig of the ducting arrangements – that’ll happen next month.
    It was a simple-enough problem finally sorted out by someone with the right diagnostic gear who knows how to use it.
    This reminds me that I must get back to Dunedin Motorhomes to tell them how right they were and how brilliant they are.

  3. Emm says:

    Are you able to advise on places to have diesel heating installed in Auckland?

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