Do not use Autogas - Dometic says

Gromit wrote:I would suggest sending it to one of the bosses rather than to Mark. With no detriment to him at all, it goes above his pay scale . . . . and from what I gather they wouldn't listen to him anyway.

And what do you hope to gain from this?

Simple things like this end up ruining the situation for everyone.

So you go back to AS and say you shouldn't be using Autogas.  AS say there's nothing they can do as that's the only supply they can fit to the underslung tank and it's accepted that Autogas is used in those tanks, but they'll cover the fridge in the warranty period anyway.  They get people pushing blame their way if the fridge fails outside of warranty period, blaming the use of autogas and they end up having to pay out.  All new vans then come without underslung tanks and back to the inconvenience of gas bottles so that AS protect themselves from compensation claims and everyone loses out.

Either that or they put an underslung tank in a specify in the manual if you don't fill with only propane or butane it's your fault.  Then everyone puts autogas in anyway and goes back to not worrying about it.

I used to own a VW T25 that was 25 years old and had been running the fridge off an underslung tank with autogas since day 1.  After 25 years it was still with the original fridge, still working fine.

I would suggest you simply continue to fill the tanks as the rest of us and go out and enjoy the MH instead :)

Hi  

Paulmold wrote:Response just received, very interesting content...blame the converter..... invalidate warranty.... anyway read yourselves..

As Autogas is a unspecified mixture of both butane and propane. Both these gases burn at different temperatures and can cause fluctuations in the flame temperature, plus more carbon can be produced, lining the inside of the exhaust creating a thermal barrier and thus causing issues with cooling. ]

Really?

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Brod

After some advice from the forum I changed our 2005 Exec from butane to propane but the original 30mb bulkhead regulator had been replaced with a 28mbar butane reg which I just changed for a 37mbar propane regulator with no issues.
From what I could gather from the interweb (various sources) the 30mbar regulator is a "compromise " to allow either 100% butane , 100% propane or any mixture of the two (as in autogas). 
I may be wrong but to me the biggest compromise would be using propane with a 30mbar regulator as burners would not function at there full rated capacity. 

The Dometic fridge in our van is marked inside the fridge  I3+  28-30/37    and  I3 B/P  28-30  and  I3P 37 which I have taken to mean 100% Butane  ok at  28mbar, 100% Propane ok at 37mbar  and if using a 30mbar regulator any % mix of propane/butane is fine.

(apologies if this has all been said before)

Hi Brod

A difference of 3 degrees Celsius in almost 2000 between butane and propane, and a mixture of the two being exactly the same as butane. Gosh - now you have me worried!!   

Where does the "more carbon" come from - just for interest?

And the next question, "More compared to what and/or when?"

And what "issues with cooling" does it cause if it lines the exhaust, and how?

Full service required every six months, when the van may well have been used for only a week during the winter!!

The whole statement is a failed attempt to justify a thoughtless and ill informed warning in the handbook, written by someone without the slightest clue about LPG or how motorhomes utilise it.

To reply to Greyhound. Hopefully someone with sufficient authority at A/S might have replied to Paul, refuting the warnings with some verifiable data, logic and common sense - thus setting to rest the minds of any novice members who read the handbook and worry, believing (naturally enough) the so-called experts who wrote the Dometic handbook or sent that response.

Every one of us with the benefit of experience knows it's a load of rubbish, but newcomers are faced with a steep learning curve, and they know the one thing you don't mess with is gas!!


Thanks for the edit Paul. A senior moment! 

Gromit wrote:Hi Brod

A difference of 3 degrees Celsius in almost 2000 between butane and propane, and a mixture of the two being exactly the same as butane. Gosh - now you have me worried!!   

Where does the "more carbon" come from - just for interest?

And the next question, "More compared to what and/or when?"

And what "issues with cooling" does it cause if it lines the exhaust, and how?

Full service required every six months, when the van may well have been used for only a week during the winter!!

The whole statement is a failed attempt to justify a thoughtless and ill informed warning in the handbook, written by someone without the slightest clue about LPG or how motorhomes utilise it.

To reply to Greyhound. Hopefully someone with sufficient authority at A/S might have replied to Paul, refuting the warnings with some verifiable data, logic and common sense - thus setting to rest the minds of any novice members who read the handbook and worry, believing (naturally enough) the so-called experts who wrote the Dometic handbook or sent that response.

Every one of us with the benefit of experience knows it's a load of rubbish, but newcomers are faced with a steep learning curve, and they know the one thing you don't mess with is gas!!

Agreed , lots of misinformation about. After reading some posts on other forums one reply from the Dometic "technical " department states.  


Dometic said:
"Technical comments regarding the use of LPG gas (Autogas) for the 
operation of the fridge burner 

Compared to the use of standard camping gas, i.e. propane or butane filled in gas cylinders, there are some factors that have to be considered, when using LPG-gas, which is also referred to as Autogas and which can be purchased at gas stations. In particular cases, these factors can 
be the cause of malfunctions of gas-fuelled devices installed in an RV, such as the heating system, the cooker; the refrigerator etc. : 

-A large variance in the technical composition of Autogas, i.e. x % of propane and y % of butane whereas x and y vary from 20% to 80%. 
-The amount of residual evaporation gas, such as nitrogen (N2), carbon dioxide (CO2) etc., which remain in the gas tanks and pipes after emptying and refilling, is double compared to standard gas cylinders. 

These factors have an influence on the quality of the combustion process, resulting in an increased emission of carbon monoxide (CO) and the increased formation of soot particles carried along by the flue gases, thus possibly leading to a defilement of the vehicles’ ventilation grill and veneer, as well as to a possible blockage of the gas circulation. 
-Due to inadequate cleaning of the gas tanks and pipes sedimentations of residual paraffin or oil can circulate inside the Autogas distribution system. 

Not all of these distribution systems are equipped with adequate filters for removing the paraffin and oil residues, or the filters are not regularly and sufficiently cleaned. Thus a deterioration of the regulating gas valve’s membranes by using Autogas can not be totally excluded.

Taking all the described factors, i.e. the random composition and quality of Autogas and the quality of gas distribution and filtering systems, and the possible implications into account, DOMETIC strongly recommends not to use Autogas for the operation of the fridge burner and other gas-fuelled appliances."




I can see the logic of the contamination argument and lots of the posts on this subject seem to be clustered around 2007/2008 so perhaps contaminantes could be the problem but I if the gas is uncontaminated I think the ratio of butane to propane is a spurious argument.


I suspect there is lots more to be said!        

Mrgeoffrey wrote:I suspect there is lots more to be said!        

You can bet on that Mr Geoff. 

That is a far more erudite response from Dometic, but nowhere does anyone suggest a practically viable alternative to autogas when using Gaslow and its variants, or an underslung tank.

There are no practical alternatives, and many years of experience shared by multitudes of motorhomers (and some caravanners - using Safefill or Gaslow bottle for example) suggests beyond all reasonable doubt that "reports of the early demise of any appliance due to the use of autogas is greatly exaggerated."

I would hope that any newcomers reading this thread (and thanks to Paul for raising the issue) are reassured that there's nothing to worry about.

Ipad must be playing up as can't get this post to work.

Reading

I notice there is no mention of the gas boiler/heater in the above feeds.

Does the type of gas also apply to Truma when running off gas?

Just wondering,

Richard

rgermain wrote:I notice there is no mention of the gas boiler/heater in the above feeds.

Does the type of gas also apply to Truma when running off gas?

Just wondering,

Richard

Boilers/heaters/cookers use much bigger jets and are only used for short periods but the fridge has to burn with a much smaller flame for hours on end so any contaminante issues are likely to cause problems here first.
It has been suggested to run the fridge separately on its own non autogas supply ,ridiculously impractical and also not always a solution as some have experienced problems on the continent with super market supplied bottled gas.

Just doing a bit of a calculation: our fridge has been running for approximately 1600 hours on autogas and it's still a happy bunny so I reckon the best idea is don't worry about it and 'carry on camping' 

The response from Dometic above is a touch flawed: The composition of the autogas does not change between fills. Whatever the ratio used to fill can't change. When refilling, the ratio is unlikely to be wildly different and when mixed with the remains still in the tank will bring it even closer to the same ratio. Any residue of other gases which remains in the tank or pipe cannot affect the burn, as it is still in the pipe/tank. Whilst it is a fact that propane and butane have different calorific values that doesn't appear to be a concern to Dometic.
As already stated if the appliance can work happily on either gas without modification a blend of the 2 must be ok.: 99%p 1%b. 50% of each 1%p 99%b. How can the ratio matter?

Perhaps they're saying that one of the gasses doesn't burn properly when mixed with the other at certain ratios, thus producing unwanted combustion products and soot?

Jaytee wrote:Just doing a bit of a calculation: our fridge has been running for approximately 1600 hours on autogas and it's still a happy bunny so I reckon the best idea is don't worry about it and 'carry on camping' 

John,
I think you have hit the nail on the head - there must be by now a lot of A/S motorhomes that have been using Autogas over the last 5+ years (1600X ???? = is a lot of hours) since the under-slung gas tanks were fitted as standard and I don't recall a significant rise in Fridge issues on this forum.  
I don't think I shall worry too much about it - if it ain't broke don't fix it.

Liam wrote:

Jaytee wrote:Just doing a bit of a calculation: our fridge has been running for approximately 1600 hours on autogas and it's still a happy bunny so I reckon the best idea is don't worry about it and 'carry on camping' 

John,
I think you have hit the nail on the head - there must be by now a lot of A/S motorhomes that have been using Autogas over the last 5+ years (1600X ???? = is a lot of hours) since the under-slung gas tanks were fitted as standard and I don't recall a significant rise in Fridge issues on this forum.  
I don't think I shall worry too much about it - if it ain't broke don't fix it.

The 1600 was a bit of a guess. We have spent 160 nights in the van and at 'least' half of those were off grid plus 'lots' of days out with fridge on gas so worked on 80 x 12 plus 90x 6 hrs. Oops 1500