Truma combi not working on elec (1 Viewer)

[Gazza333]

works fine on gas but for heating and hot water flashes twice yellow when switched on (indicating low or no power ). The flashes on the unit itself also mirror that fault diagnosis.

Theres 240 v at the cable going to the boiler (it then disappears under the boiler and I don't really want to take it out ). The fuse in the boiler is ok. Any other checks I can do before getting an engineer out?

I have all the tools I need and know how to use them i.e. Multimeter etc.

Gary

 

[Pausim]

If your boiler is anything like mine, the fuse you can reach easily to check is the 12v one. Further down under the lower cover is a 240v 10amp slow acring fuse. I have had this one blow 3 times. It is a pain to reach because I can only get my hand in squashed flat. I now lower the fuse on a slip knot of cotton, push it into place with my flattened hand and then pull on one end of the cotton to remove it. I got my replacement slow acting fuses from Maplin. My control panel gives an error code indicating a mains failure, if your panel is different there may be other differences in your system too but I would be surprised if there wasn't a second fuse somewhere.

 

[Gazza333]

If your boiler is anything like mine, the fuse you can reach easily to check is the 12v one. Further down under the lower cover is a 240v 10amp slow acring fuse. I have had this one blow 3 times. It is a pain to reach because I can only get my hand in squashed flat. I now lower the fuse on a slip knot of cotton, push it into place with my flattened hand and then pull on one end of the cotton to remove it. I got my replacement slow acting fuses from Maplin. My control panel gives an error code indicating a mains failure, if your panel is different there may be other differences in your system too but I would be surprised if there wasn't a second fuse somewhere.

Ooh oooh. There's a lower cover ? Ok thanks I'll take it apart and have a look tomorrow I only saw one fuse. I hope it's that as it'll be an easy fix

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[Pausim]

Good luck. Your unit may have a different layout and be hiding a fuse elsewhere but I would be surprised if there wasn't an internal 240v fuse somewhere in there.

 

[Ingwe]

We had a similar problem but took the van to the dealer who found that a switch had melted. Neither of the fuses had 'blown' which concerned us. However, the faulty, melted switch was replaced and cost about £12.00 fitted.
If it is the fuses, I'd be a little concerned as to why they are blowing. But you are definitely more technically inclined than me. So good luck.

 

[wp1234]

I'm in deepest France at the moment and my Trauma 6 is indication no 240 v but is working on gas ok.I've had reset and checked the 12 volt fuse and next job is to locate the 230 v fuse . I'm assuming it's on top of the boiler somewhere . Thank good I fitted Gazit tanks before this trip so no worries .

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[Ingwe]

@Pausim above indicates that there is another fuse underneath the Truma. Not the top. Good luck. We're also in rural France.

 

[Gazza333]

I've not looked yet as been away all weekend. I'll hopefully have chance to look tomorrow

 

[MikeD]

It took me about eight hours to strip the boiler out, removing most of the furniture around the boiler. The fuse costs about 30p to memory.

Make sure you get a slow burn type.

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[Scotties]

You don't mention the age of the unit, but another likely problem is the heater element. Fingers crossed for you

 

[Gazza333]

It's a 2013 motorhome. Fingers crossed I'll find another fuse tonight when I get in from work

 

[Pausim]

I can get to the fuse without removing furniture etc. which probably varies between mh models. I have to unplug the wiring, loosen the lower cover and squeeze my hand in from above, hence my tip of lowering the replacement fuse on a cotton thread so I just have to push it into place.

Not sure what causes the fuse to go, I suspect power fluctuations or surges but it does not happen so often that I think the element is at fault. Fixed one for a neighbouring caravan last year where access was easy.

Helpful pics from MikeD.

Good luck GA.

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[Gazza333]

Ooh ooh. I found the other fuse and it's blown. I'm off to marlin now to go fetch a few . Fingers crossed it's not the element taking out the fuse . Great pictures Very helpfull

 

[Gazza333]

Yes I love you all

Fixed for the princely sum of £3.50 ish . Many thanks to you all I thought that was going to cost me £600 to get fixed . For anyone else once you get the easy pull off cover off on a combi 4000e you need a torx bit to remove the top two screws then the whole panel comes off to reveal the other sneakily hidden fuse

Ps the £3.50 was for 10 fuses

 

[wp1234]

Just replaced my 230 v fuse and luckily for me with some sore knuckles and fingers I could get at the torx screws and get the fuse changed without taking the van apart ... thanks for thinking about it Rapido .
Im sure it was one particular site in France that caused this blow so am thinking about how best to protect myself against this in the future with an easier to replace inline fuse .

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[pixer]

I know this is a late post to this thread but I add it possibly for the benefit of others. This fuse fault appears to be common on Truma combi units especially on continental campsites. My Combi 4 was working fine on gas and electric in France until about the end of September then no electric (water or heating). Contacted Truma by email (fault code two quick yellow flashes then five seconds delay repeat). They gave out the same information as in the boiler handbook, try reset button and check fuse. The boiler is totally inaccessible under the rear travelling seats in my Brevio so they finally suggest taking to dealer on return.
Had it fixed by the dealer and on collection managed to talk to an engineer about the problem, who had recently been on a Truma course. It had taken them nearly a day to dismantle seats and access boiler and they had found that the 10amp 230 volt slow blow fuse situated under the boiler had blown. This fuse evidently is a safety requirement for boilers installed in vehicles! It is not supposed to blow and it is made difficult for untrained personnel to access as it is mains voltage and not meant for replacement by the consumer. The vehicles electrical trip suppling the boiler should blow first as it should not allow excessive current caused by short circuit. But if you start up your Heating/water at 1800w on a site that has an unstable or lower voltage supply (+or- 10% allowance, say 200v rather than 230v) then the current demand for the boiler would be at least 9 amps. This is close to the fuse limit. This is not helped by increased resistance caused by dirty/loose fuse terminals and cold heating elements. Hence the start-up current required is greater than the fuse value and it blows. The suggestions given were on arrival at a site, start your heating/hot water on gas then when required water temp/heat reached, changeover to electric as the electric heating element will then be warm also.
The reset switch on the combi is evidently a mechanical overheat cut-out set at 90C. There is also an electrical auto reset control set at 80C so the reset button should not be required. I believe the fuse on the customer accessible panel (not accessible on mine!!) is a 12v fuse to protect the circuit board. It was very sensibly suggested that all 12v and 240v should be disconnected if any attempts to access anything on the boiler as there is live voltages present under the covers. Another tip offered is that do not leave your heating on in the MH if storing over winter because the boiler is estimated to last about 10 years of MH use. That is intermittent use so you could be shortening the life of the boiler. Either drain the water off or if like us you use the MH in winter at times, buy an electric low wattage thermostatically controlled heater and leave that on instead.
I hope this may be of help to anybody who has a similar problem. Must also add excellent service from the dealers service department.

 

[Pausim]

Thanks @pixer, interesting. Not too impressed by Truma’s reasoning or their suggestion that we need to warm up the system on gas in cold weather. I would have thought that power/voltage fluctuations and cold elements were to be expected for this type of use. I would describe it as engineering naievity not to design such problems out of their product. A heating element that does not function properly in cold weather would be laughable if it were not such a pain in the butt to change the fuse.

 

[pixer]

Hi Pausim
I must agree with you. A terrible design flaw. Applicable both to Truma and Burstner regarding accessability. Burstner could have put a flap in the seat base for access and Truma could have put in an electronic auto resetting trip for current protection before the 10amp 230 volt fuse. I wonder what size the protection fuse is for the Truma Combi six version, which has much larger wattage heating elements? It was not Truma directly who suggested the gas warm up period but the dealers engineer and I must confess I have seen this suggested elsewhere on other forums. Have also seen many large MHs on French sites, that have only 5 amp hook ups continually blowing the hook up trips as soon as they turn on their heating! So presume they only use gas.

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[Michael Davies]

What is the diameter of the elements on the combi 4e

 

[pandas]

We thought there was an issue staying at Stellplatze in Germany. Our conclusion was that the power supply on these locations is not sufficient. Now in Italy on an ACCI site no issues - although it is 16c warmer than it was in Germany!

 

[PennyBenimar]

I also need to replace the 230v fuse due to the same fault. Unlike others the boiler is accessible, and I can see how to remove the panel held with torx screws. We're in isolation from Covid in the MH, so not likely to get any expert help anytime soon. Anyone know what we need to do to safely replace the fuse i.e. what power connections, or gas connections, need to be unplugged and re-plugged?

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[Pausim]

The important thing is to make sure the mains is completely disconnected, I would unplug at source. The fuse is a special slow acting 10A one, or at least it was on my last motorhome and I could only get the replacement in by dangling it on the end of a length of cotton.

 

[MikeD]

I had to remove the bed, disconnect everything - Gas, electric and water - to get at the 240v fuse on mine.

The 240v fuse is on the bottom of the panel and you need to take the lower section of the cover off.

It's a slow burn fuse. Make sure you buy the correct type.

 

[PennyBenimar]

Thanks Pausim and David for the advice. On Ebay I see "Slow Acting Glass Fuse Tube Electrical Blow 0.25A-15A Amp 5mm x 20mm 250V" and "6mm x 30mm 250V Slow Acting Glass Fuses Tube Blow". Anyone know which is right?

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[Pausim]

I bought some from Maplin but sadly they are now gone. A 10A 250V slow blow fuse is what is needed, this came up on a search https://www.componentshop.co.uk/10a-32mm-fuse-slow-blow.html
I don’t recall the length and I am not in a position to get to my stored motorhome to check.

 

[MikeD]

When the 240v fuse went on mine Truma - I posted this thread and there was quite a bit of chat regarding fuses. I hope it helps

Truma Combi E blown 240v 10a fuse

Well I hope I have found out why the 240v heating is inoperative on the Truma heating. A blown 10amp fuse buried behind a panel on the boiler, that was jammed in by the converter between the side of the van and the bed mounts/base. I had to dismantle the entire bed, ducting, gas and water...

www.motorhomefun.co.uk

 

[PennyBenimar]

Pausim and Mike. I'm struggling with figuring out what size the fuse is without actually trying to take it out and measure it! Is it '6 x 32mm' as in Pausim's post, or 5x 20mm or "6x 30mm" from Ebay?

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[MikeD]

Pausim and Mike. I'm struggling with figuring out what size the fuse is without actually trying to take it out and measure it! Is it '6 x 32mm' as in Pausim's post, or 5x 20mm or "6x 30mm" from Ebay?

I will measure the ones I have left tomorrow and repost

 

[MikeD]

The fuse size on my Truma is 20mm x 5mm - 10amp

 

[PennyBenimar]

Thanks I've gone for 10 'Fuse 5x20mm Slow Blow CERAMIC BODY Multi-Variation Listings' from eBay with type 'T10AH250V' for princely sum of £3.31. So not too costly a mistake if not right.

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