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truma combi 6e elements blown


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hi.i have a 2018 swift exclusive 4eb model fitted with the truma combi 6e boiler,the heating/hot water stopped working on electric and after several checks i figured it must be the heating elements in the boiler that had blown.not feeling very competant at attempting the job of replacing the elements myself i got a quote from a dealership which was for over £600 .after a bit of digging round i managed to get the job done for £400 from a caravan service engineer who did jobs on the side,still expensive though for a 4 year old van.i figured the van had been away for a maximum of 300 nights during the 4 years.so the elements hadnt lasted long at all.i always used the water heater/blown heating on electric as i figured we always were on hook up so why use gas when the electric is included in the price.my question is have i been unlucky or do these elements only last this amount of time,if so its an expense every few years i could do without,or should i use gas or mix1 or mix2 to hopefully preserve the life expectancy of the elements.thanks in advance

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3 hours ago, mozza 1952 said:

hi.i have a 2018 swift exclusive 4eb model fitted with the truma combi 6e boiler,the heating/hot water stopped working on electric and after several checks i figured it must be the heating elements in the boiler that had blown.not feeling very competant at attempting the job of replacing the elements myself i got a quote from a dealership which was for over £600 .after a bit of digging round i managed to get the job done for £400 from a caravan service engineer who did jobs on the side,still expensive though for a 4 year old van.i figured the van had been away for a maximum of 300 nights during the 4 years.so the elements hadnt lasted long at all.i always used the water heater/blown heating on electric as i figured we always were on hook up so why use gas when the electric is included in the price.my question is have i been unlucky or do these elements only last this amount of time,if so its an expense every few years i could do without,or should i use gas or mix1 or mix2 to hopefully preserve the life expectancy of the elements.thanks in advance

Mix 2 is recommended by Truma

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I have the 4e. Please tell me, what is mix1 and mix2

thank you. 

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mix is gas and electric  on together and 1&2 are the temperature.  If you use the higher temp. be careful of tripping the electric as some sites only have 6 or 10 amp on the ehu. 

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When you consider the elements are about £340 + around 3 hours labour, I think you got a cheap job, assuming whoever did the job re crimped the fins down onto the elements…..,otherwise you will get hot spots and they will blow again!

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On 05/02/2022 at 18:52, mozza 1952 said:

hi.i have a 2018 swift exclusive 4eb model fitted with the truma combi 6e boiler,the heating/hot water stopped working on electric and after several checks i figured it must be the heating elements in the boiler that had blown.not feeling very competant at attempting the job of replacing the elements myself i got a quote from a dealership which was for over £600 .after a bit of digging round i managed to get the job done for £400 from a caravan service engineer who did jobs on the side,still expensive though for a 4 year old van.i figured the van had been away for a maximum of 300 nights during the 4 years.so the elements hadnt lasted long at all.i always used the water heater/blown heating on electric as i figured we always were on hook up so why use gas when the electric is included in the price.my question is have i been unlucky or do these elements only last this amount of time,if so its an expense every few years i could do without,or should i use gas or mix1 or mix2 to hopefully preserve the life expectancy of the elements.thanks in advance

 

I'm sure I once read a post by a caravan service guy that stated the design life for the Truma and Alde systems.  I think it might have been the fans in the case of the Truma though. At that point, we had Combi 6 system and I seem to recall thinking we might expect to get ten years use. We are typically away 35 nights in a year, so maybe 350 nights

 

Sorry that's all so vague.  My main recollection is that it completely persuaded me that running your caravan heating system over the winter as frost protection is crazy on so many levels.

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Just saw on a MH forum, someone quoting 10,000 hours but then revising downwards to 2,000 hours for design life of the heating elements.  

 

Even assuming only 2 hours use a day (maybe mostly summer use and low hot water use), that's only getting you 1000 - 5000 days.  

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thank you for the info scarab,much appreciated

mutley.i hope that  the job was done properly!!.the guy in question works at a large dealership so heres hoping------ !!

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Replacing mine cost £495 last year, carried out by the mobile guy I use. My van is a 2018 but to be honest I think it was my stupidity that blew the original one (I switched on the heating with the vents covered by the storage cover - doh!). An expensive lesson.

Edited by BM Bairn

Towing: 2018 Swift Sprite Quattro EB

Tow Car: 2020 BMW X3 M40i

 

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I've seen the elements advertised to £160 on eBay, but I know there's a lot of labour involved in the swap.

Nissan X-Trail Tekna + Coachman Festival 450

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Our guy removed the boiler, took it away, repaired it, brought it back and installed it again, so I can understand the high labour content

Towing: 2018 Swift Sprite Quattro EB

Tow Car: 2020 BMW X3 M40i

 

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1 hour ago, BM Bairn said:

Our guy removed the boiler, took it away, repaired it, brought it back and installed it again, so I can understand the high labour content

Truma quote 3 hours, but depending on van/vehicle it can be much longer, as in getting the heater out to start with!!

 

Parts as quoted in my earlier post, unless someone has old stock, this would have been elements only, the new kits come with everything.,.nuts bolts gaskets eg

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I have just had exactly the same experience as the OP with my 2018 Knaus.  It cost me £700 - but that included over £200 for transport charges to and from the dealer in Cumbria - so about the going rate.  I noticed that they had charged me over £300 for the 'element' - and I, too, have seen them on the net for about £165 and when I queried this, they had actually replaced both elements and used the kit with all the gaskets etc and they are, indeed, over £300.

According to the Service Manager - failed Truma elements are common and they have had more problems with the Combi 6 than the Alde system.  Looks as if I'm going to have to live with it. I also queried whether or not it was possible to burn the elements out through not having any water in the boiler (we had experienced a glitch with the float switch in the inboard tank which allowed it to run dry whilst the water heater was on) and he assured me it was not.  There are two fail-safe devices in the Truma system - a temperature sensor and a thermal fuse to prevent this happening (can't say I was entirely convinced, though).

Since getting the van, we have been away for about 270 nights (so about the same as the OP) but I have the heating on at home on a regular basis during winter - so I suppose it's had a fair bit of use. 

I'm a bit confused by Scarab's suggestion that heating the van has an impact on the water heating elements? I thought the two heating systems (van and water) were separate - hence the ability to have the van heating on without any water in the boiler?

VW Touareg Escape towing a 2018 Knaus Starclass 695

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Yes, I've always understood that the hot water and warm air were separate.  This video shows the internals of the Truma Combi and at about 3.47 you can see that the heater elements are outside the hot water jacket. 

Incidentally,  I can't find an authoritative description of how it all works, but  I believe that although each heater element is rated at 1800W, they only ever operate at half that power.  Controlled by relays, on Heat 1 they are in series so produce only 900W in total.  On Heat 2 they are in parallel, but a diode is inserted in series with each element to provide half wave rectification and hence only half the power (900W).  The diodes oppose each other so one element provides the top half of the AC sine wave and the other element the bottom half to produce the full 1800W.

Edited by Crannoghome
wrong time in video

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2 hours ago, Crannoghome said:

Yes, I've always understood that the hot water and warm air were separate.  This video shows the internals of the Truma Combi and at about 3.47 you can see that the heater elements are outside the hot water jacket. 

And that would explain why - with mine - although the water was only getting lukewarm - the heating was operating normally.

VW Touareg Escape towing a 2018 Knaus Starclass 695

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  • 3 months later...

Took my van in yesterday with similar problems as above. Service manager explained to me that the two elements (900w each) are mounted outside the water tank and the heat is transfered somehow through the tank wall to heat the water. Hence the space heating can be used safely without any water in the tank.

He phoned me this morning to say one of the elements had blown and quoted me £520 to replace both as they come in a kit. After picking myself up off the floor I gave him the go ahead to do the job. After reading the above it seems I was quoted a reasonable price.

This is the second time this has happened. The other occasion was in 2019 when the van was 2 years old and covered by the warranty so I was not interested in how much it cost.

 

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26 minutes ago, Philept said:

Hence the space heating can be used safely without any water in the tank.

He phoned me this morning to say one of the elements had blown......... 

 

These two statements contradict each other. 

Graham

Unless otherwise stated all posts are my personal opinion 

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No they don't. The element blowing was nothing to do with whether there was water in or not. In fact there was water inthe tank when it happened.

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OK. Tks. 

Graham

Unless otherwise stated all posts are my personal opinion 

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On 13/02/2022 at 04:38, richardandros said:

I'm a bit confused by Scarab's suggestion that heating the van has an impact on the water heating elements? I thought the two heating systems (van and water) were separate - hence the ability to have the van heating on without any water in the boiler?

 

My answer - I'm not sure!

 

You certainly can run the heating without water. The video also says that there are no elements in the tank. I assumed they were the same elements but there was a mechanism to allow them to be optimized for water heating

 

I'd be interested to know even though our current van has the Alde system as I always liked the Combi and would have few qualms about going back to it (the fluid changes on Alde soon add up!)

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Well now I am totally confused.  We have another problem with our Truma Combi 6 and as I write, I'm waiting for the driver to come and collect the van and take it back to the dealer in Cumbria.

This time - when I switch the heating onto High - with the boiler cold - what little heat comes out just does so with a trickle.  However, if I heat the water up first - and get the boiler hot - the heating works normally if switched on thereafter. The other weird thing is that both the heating and water heater are pulling about half of the current that they should be. It's pointing to the fact that, possibly, one of the newly installed heating elements has already failed.  The Senior 'Tech" at ALV tells me that the same elements are used for both water and space heating - but I really don't understand how this works but it would explain the weird way in which the Combi is now working. We will wait and see what their diagnosis is.  I did ask if there could be a fault with the PCB - but his response was that they either work or they don't but I'm not sure I go along with that.

VW Touareg Escape towing a 2018 Knaus Starclass 695

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Posted (edited)

Bit of a back story first......

For many years, we had a Truma C6002EH in our Swift motorhome, the 6E is the uopdated version IIRC.

After a few years solid use, one element blew, had it replaced by a mobile service guy and then the second original went. So with two new elements fitted, off we went but after three months, both elements failed again. Serrvice guy changed them under warranty but 6 months later, both blew again.

So we booked into Truma HQ for them to look at the issues. Truma said they see so many new elements fail due to incorrect installation whereby the elements are "pinched" against the heat exchanged when inserted. This reduces their lifespan considerably. After Truma fitted new elements (no charge even though it wasn't their problem), we had four years of no issues until we sold the MH.

So it could be the fact that the replacement elements haven't been fitted correctly thus leading to premature failures.  JMO ;)

Edited by Pebble

2019 Adria Adora Thames

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Sounds like a design flaw to me  , using elements that burn out in air, even mounted to a metal plate ie water boiler,  is not good design.

We used to use Incoloy elements in  our laboratory ovens and they could reach surface temperatures  of 400 Degrees C lasting for many years with 8 hours/day duty.

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richardandros - there's a lot of posts over on Motorhome Fun and Motorhome Facts about the 6E elements getting half power and the reasons why :).

2019 Adria Adora Thames

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13 minutes ago, Pebble said:

richardandros - there's a lot of posts over on Motorhome Fun and Motorhome Facts about the 6E elements getting half power and the reasons why :).

Thanks for that - had a look and can't find anything.  Would you be kind enough to provide a link?

VW Touareg Escape towing a 2018 Knaus Starclass 695

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