Dometic 'Fridge on Autogas

[Usinmyknaus]

Basil - 2007-08-15 9:56 AM

 

Usinmyknaus - 2007-08-13 2:09 PM

 

I've received a definitive answer from Dometic, who were commendably quick in responding to my request.

 

They say the problem with using autogas is that the flue central tube (chimney) will soot up in a short period of time. Autogas contains oily substances which give rise to combustion problems i.e. sooting when burning. This is the reason they do not recommend its use, although the performance of the fridge itself should not be affected. They add that if Autogas is used the burner and central flue will need to be cleaned regularly when in use.

 

Bob

 

Bob

 

I can only repeat my previous post that we have used Autogas with our Gaslows for three years now and there has been absolutely no change to our use or service regime, there has been no difference whatsoever in the performance of any appliance or the need for any more regular servicing to be carried out, when I service it annually there has been no change to the condition of any of the appliances including the fridge.

IMHO their reply, to use one of Brians sayings, is Bovine Excrement for whatever reason to discourage the use of Autogas.

 

Bas

 

Bas,

 

Thanks that's very encouraging. Based on all the information I have received I reckon it's a reasonable risk to install refillables. Derek has given me some good tips on fridge servicing and I'll buy a copy of the Haynes manual he recommended.

 

Bob

[Nobby]

I am a long time Autogas user and have no intention of going back to an exchangeable bottle system.

 

However, I have experienced occasional unusual sooting of my fridge flue accompanied by high stench levels (the exhaust, not me!). On the basis of what I had found out, I had put this down to accumulations of impurities and stenching agent in my cylinders after numerous refills where the cylinder had not been totally emptied. I have experienced this with Calor cylinders also on a couple of occasions.

 

I would be interested to hear what flicka (above), or indeed anybody else with first hand knowledge, who works at a refinery where autogas and LPG is produced, has to say regarding the revelation that some kind of oily substance (for lubrication purposes) is added to autogas. I am not prepared to dismiss this possibility out of hand as, on the face of it, it would make some kind of logical sense to do so to lubricate fuel pumps etc in a liquid take off fuel system. Much the same thing is necessary for a diesel pump to prevent premature failure.

 

If such an 'oily substance' is added to autogas, then it may indeed be necessary for users to pay attention to more regular flue servicing especially when the cylinder is not completely emptied and this is allowed to accumulate over several refills. The suspicion that this is 'bovine excrement' may be well founded but there exists the possibility that it may not be. I await with interest.

 

Nobby

[Clive]

My suggestion of bovine excrement is based on four basic facts :-

1 Dometic fridges are designed to run from Propane

2 Dometic fridges are designed to run from Butane.

3 The standardised regulator pressure is now the same for both.

4 Any oil residue that may reside in the bulk tank will not turn to gas - even at ambient pressure so should remain in the tank.

 

The only possibility of any thread of credibility is if any oil residue gets into the gas outlet pipe and through the regulator. But as the regulators are (or blooming well should be!) mounted above the tank this should not happen. However this risk applies equally well with any of the exchange bottle companies. Do they "wash them out" between fills? I very much doubt it!

 

 

[Nobby]

I have to say that I agree with you and say that I doubt that commercially filled bottles are purged between each fill, although I am quite prepared to be corrected by somebody in the know.

 

Not sure I agree with you entirely on point no. 4 though Clive. The stenching agent is added as a liquid and manages to escape in molecular form (at least) with the gas (otherwise it wouldn't smell) so there is every chance that any number of other substances could also do so and cause sooting during combustion.

 

As I say, I have experienced occasional bad sooting with accompanying stench and this has been attributed to a single bottle (or fill) of gas rather than my appliance which has been found to be in good order when checked. Other people have had similar experiences - 'vile smell'.

 

The bottom line is simple for me - I would like to know categorically what it is that causes this occasional sooting/stench in a bottle or fill of gas. The accompanying stench of the exhaust AND also of the gas left in the bottle has led me for some time to suspect that it may be an accumulation of the stenching agent which can have taken place in my own or the suppliers bottle or holding tank (before delivery). I am hoping that flicka or somebody with trade knowledge can enlighten us on this.

 

Nobby

[breakaleg]

could it be that those who are having problems, are using a bottle until it runs empty? where as those who don't are refilling before they are empty?

i have had two gas low cylinders with a auto change valve, since november 06, but only refilled once and that was after only using approx one cylinders worth of gas.

pete

[robin]

As one who has experienced both stench and sooting:

1. My regulator is properly situated above the gas bottles.

2. I always refill after number 1 bottle has emptied and changed over to number 2, although I managed to misjudge it and empty both cyclinders in France about 18 months ago - IIRC, I have been running on French autogas most of the time over the past twelve months.

3. I don't understand why it is only the 'fridge that is affected. I have had no problem from the truma boiler or the Smev oven or Dometic hob. Anyone know why that could be?

[Nobby]

Hi Robin,

 

I have wondered the very same thing and have come to the conclusion that it may be related to the size of the flame in the burner i.e - small as it is in the fridge.

 

We use a double skillet to cook with and this often operates with a very low flame. When the 'smelly gas' situation manifests itself, I have noticed that there can be a smell from the hob burner under the skillet on a low flame. Maybe a bigger stronger flame is hotter and normally manages to burn off whatever is carried in the gas that makes the stench.

 

The stench agent (ethyl mercaptan) used in LPG is often described as the smelliest thing on earth so I guess it might only need a slight over-accumulation to make a difference to the combustion process.

 

On those occasions when I have been unfortunate enough to have a particularly smelly fill of gas, it only really causes smelly fridge exhaust when you get to lower levels in the cylinder. Many people who habitually refill before reaching a low cylinder level may not notice anything until such day they eventually run low before refilling.

Perhaps those users with a horizontal tank may never notice the problem as the orientation of the tank will mean that sloshing around during motion (free surface effect) will be more likely to keep things suspended in the liquid gas and therefore more likely to gas off than in an upright cylinder where impurities may more easily settle towards the bottom.

 

All hypothesis of course - I don't know the answers!

 

Nobby

8-)

[trigrem]

Nobbys theory about the liquid sloshing around in a horizontal tank may explain why Clive has not experienced any problems, as I believe his tank is horizontally mounted. Although reading the thread others with vertical cylinders have not had problems either so I will shut up.

[Basil]

Hi All,

 

Been thinking about this. Those that are experiencing this problem are they all using the Truma/ Gok 30mb Regulator, or at least a new standard 30mb reg anyway?

If they are (I am using a Propane dedicated 37mb regulator) perhaps it is the fridges inability to burn propane correctly at the lower 30mb pressure that is causing the problem, that seems a more likely cause to me as the burner is a compramise to allow the use of both Butane and Propane gas at the same pressure despite the fact they have a different CV!

It would be interesting, to me anyway, to know which pressure and regulator people are using that has given no problem compared to those that have had a problem.

 

Bas

[flicka]

Nobby - 2007-08-15 11:28 AM

 

 

I would be interested to hear what flicka (above), or indeed anybody else with first hand knowledge, who works at a refinery where autogas and LPG is produced, has to say regarding the revelation that some kind of oily substance (for lubrication purposes) is added to autogas. I am not prepared to dismiss this possibility out of hand as, on the face of it, it would make some kind of logical sense to do so to lubricate fuel pumps etc in a liquid take off fuel system. Much the same thing is necessary for a diesel pump to prevent premature failure.

 

If such an 'oily substance' is added to autogas, then it may indeed be necessary for users to pay attention to more regular flue servicing especially when the cylinder is not completely emptied and this is allowed to accumulate over several refills. The suspicion that this is 'bovine excrement' may be well founded but there exists the possibility that it may not be. I await with interest.

 

Nobby

 

Nobby - 2007-08-15 8:03 PM

 

I have to say that I agree with you and say that I doubt that commercially filled bottles are purged between each fill, although I am quite prepared to be corrected by somebody in the know.

 

Not sure I agree with you entirely on point no. 4 though Clive. The stenching agent is added as a liquid and manages to escape in molecular form (at least) with the gas (otherwise it wouldn't smell) so there is every chance that any number of other substances could also do so and cause sooting during combustion.

 

As I say, I have experienced occasional bad sooting with accompanying stench and this has been attributed to a single bottle (or fill) of gas rather than my appliance which has been found to be in good order when checked. Other people have had similar experiences - 'vile smell'.

 

The bottom line is simple for me - I would like to know categorically what it is that causes this occasional sooting/stench in a bottle or fill of gas. The accompanying stench of the exhaust AND also of the gas left in the bottle has led me for some time to suspect that it may be an accumulation of the stenching agent which can have taken place in my own or the suppliers bottle or holding tank (before delivery). I am hoping that flicka or somebody with trade knowledge can enlighten us on this.

 

Nobby

 

Nobby

Firstly we have to remember that LPG in it's various forms is a product refined from Crude Oil, so you can't fully discount the possibility of some "oily" residues 100%. However the product spec eliminates this, so should not occur. Having said that look what happened with the Petrol fiasco causing fuel pump failures, not so long ago.

Regarding the stenching agent, checking the product data sheet shows that it would gas at a lower ambient than the LPG, so I think we can discount that one.

I would suspect if there is any possiblity of "oily" deposits. it could be a possibility where the LPG changes it's consistency repeatedly, i.e. if say you have a Tank that is feeling the benefits in sunlight during the day causing some Liquid to evaporate to gas internally then cooling at night back to liquid. This can also be applicable if the tank is sited near the van exhaust.

Having said all of that though, I agree with Clive, in what I take to be regarding the possibilities of the plasticiser leaching out of the connection hose, finding it's way through the system.

There has been a high volume of reported problems with Regulators associated with this. Any of that substance being burnt would certainly be sooty, oily and pungent.

Also to my knowledge, (but this is not a operation carried out at the Refineries) LPG cylinders are not washed between fills and I am not even sure they are cleaned internally for their periodic mandatory inspections.

I don't know the position regarding this for fixed LPG Tanks but assume they are also subject the periodic mandatory inspections.

 

[scotchjock]

Hi

I have a thread posted on my recent 'near death' experience with a dometic fridge running on gas. Fumes and incorrect combustion were caused by a baffle plate fitted above the 'lazy T' ( flue terminal)restricting the exhaust. This was out of sight behind the ventilation grill. Fumes were spilling into the living area. The local Dometic engineer condemned the installation as 'immediately dangerous' and a danger to life. Hope this helps somebody survive a similar situation.

[handyman]

would a sensor alarm not be a good idea? I got one in bnq for £25

[scotchjock]

Absolutely spot on Handyman. It should be mandatory for all motorhomes and caravans to be fitted with a CO monitor. But a monitor does not cure a faulty installation or substitute regular sevicing of all gas appliances.

[handyman]

at least I'm doing something right (lol)

[scramblers]

robin - 2007-07-23 12:40 PM

 

Greetings All,

After complaining about a vile smell from the fumes on our 'fridge, I was informed by the Dometic engineer that the burner had sooted up due to using Autogas and that Dometic now frown on such uasge.

He changed the burner and all seems o.k. after a 10 day trip.

The fridge is about 8 months old and had been used mostly on gas (autogas) for about 6 weeks away.

The documentation with the 'fridge refers only to use with LPG with no mention of any autogas restriction, so as far as I am concerned this is Dometic's problem, should it re-occur. (as Autogas is LPG).

The reason for this post is:

1) to suggest that prospective purchasers of new 'vans check the Dometic documentation for any restrictions if planning to use Autogas; and

2) to wonder if anyone else has come across this?

Cheers,

Robin

:-)

 

I have just purchased a preloved 2008 motorhome that has a Dometic RMT7655L fridge fitted and gaslow refillable gas cylinders. I have also noticed the vile smell from fumes from the top external fridge vent.

 

On searching the internet I found this forum and hoped it might answer all my queries. However, the last post was some time ago with no apparent resolution.

 

Can anybody update me to a possible remedy to the problem?

 

Kind regards,

 

scramblers

 

 

[tonyishuk]

 

 

We had a very similar problem with cylinder gas (Not Autogas refilled) used on a mobile home in France. The smell made me think that we had a gas leak,

 

I was told that it was not uncommon as the amount of "Smell" was overmeasured and or stayed in the bottom of the cylinder. The effect being that when filled again, the residual remained and was added to.

 

If you smelt gas, the cylinder was about to run out, (Correct as it happened !)

 

(Although I thought that cylinders were presure tested, before refilling and reuse, but it was France!)

 

Rgds

[747]

This year, I came across a few caravanners (pardon my French) who had smelly fridge syndrome. They only use bottled gas.

 

I would not be surprised if there had been design changes to fridges which is causing this problem. Something like the new Fiat gearbox saga. They will of course deny any liability if this was proved to be the case.

 

At the same time, there have been numerous cases of regulators failing. I had this problem myself but mine stopped working abruptly. In some cases, they could fail slowly and the fridge shows this up first.

 

Quite mystifying.

[Derek Uzzell]

This was posted on the forum recently:

 

HTTP://www.outandaboutlive.co.uk/forums/forums/thread-view.asp?tid=21392&posts=2

 

GOOGLE-ing suggests that the stenching agent added to LPG does not burn and can separate from the liquified gas. So the advice that stenching agent can build up within a gas container is persuasive.

 

My 2005 Hobby has a Dometic RM-7605L refrigerator that has always been run on 'autogas'. Although the fridge has not been problem-free, having gone through phases of failing to auto-relight on gas, I've never noticed any unusual smells from the ventilation grilles.

 

If scramblers's 'vile smell' problem is indeed down to stenching agent concentrating in the Gaslow bottles, then matters can only get worse with time. All I can suggest is that the bottles be removed from the motorhome (preferably when there's little gas left within them) so that all the remaining liquid contents can be emptied through the bottles' outlet-valves. This task has very obvious inherent risks, but I can't see any viable alternatives. It should at least identify whether or not the gas itself is to blame. If the smell from the upper ventilation grille persists even after the bottles have been completely emptied and refilled, then it's likely that the gas/air mixture at the fridge-burner is incorrect.

[Derek Uzzell]

tonyishuk - 2010-10-29 6:35 PM

 

 

 

We had a very similar problem with cylinder gas (Not Autogas refilled) used on a mobile home in France. The smell made me think that we had a gas leak,

 

I was told that it was not uncommon as the amount of "Smell" was overmeasured and or stayed in the bottom of the cylinder. The effect being that when filled again, the residual remained and was added to.

 

If you smelt gas, the cylinder was about to run out, (Correct as it happened !)

 

(Although I thought that cylinders were presure tested, before refilling and reuse, but it was France!)

 

Rgds

 

I've found a 2003 article by John Wickersham relating to Calor gas cylinders. This suggests that steam-cleaning of the bottle's interior, pressure-testing, etc. normally only takes place if the bottle is to be refurbished. Otherwise, Calor bottles are just refilled. Having said that, I would have thought exchanged cylinders in any country would have any liquid left inside them emptied out before being 'officially' refilled.

[scramblers]

When I purchased the new(er) motorhome it had been fitted with a single gas cylinder gaslow system, so I arranged to have the dual cylinder gaslow system from the old motorhome swopped to the new motorhome.

 

I had been using my dual gaslow system with a Dometic fridge for many years in the old motorhome without any problem. Only on the new motorhome did the problem arise. This I have put down to the 2 year old Dometic RMT7655L fridge, as my gaslow system did not cause any ‘vile’ smells from the top external fridge vent of the old motorhome.

 

The old fridge was the small Dometic fridge with the internal freezing compartment and installed under a work surface; the Dometic RMT7655L fridge is the tower unit with separate fridge and freezer and a gas cooker on top.

 

Does any forum member know if Dometic have developed a ‘fix’ for the problem ie maybe a replacement burner assembly or gas jet for the burner(?)

 

Cheers,

 

scramblers

[Keithl]

Scramblers,

 

Does the fridge only smell when used on gas or does it smell on 230v?

 

If so I would suggest checking the small condensation drain vessel located at the back of the fridge just before the heaters. You will need to remove the lower vent to see it.

There was a post on here recently where this was smelling badly because it was part full of rancid water!

 

I have fitted a drain pipe to ours leading out through the gas drop vent so that it cannot sit part full of water!

 

Worth checking.

 

HTH,

Keith.

[scramblers]

Hi Keith,

 

I only have the problem when on gas.

 

I will however install the drain as you suggest.

 

Cheers,

 

scramblers

[Brian Kirby]

scramblers - 2010-10-29 5:32 PM ...........I have just purchased a preloved 2008 motorhome that has a Dometic RMT7655L fridge fitted and gaslow refillable gas cylinders. I have also noticed the vile smell from fumes from the top external fridge vent. On searching the internet I found this forum and hoped it might answer all my queries. However, the last post was some time ago with no apparent resolution. Can anybody update me to a possible remedy to the problem? Kind regards, scramblers

There was a Dometic recall on these tower fridges, though not, I think, for smells.  Irrespective of the smell issue, it might be worth checking if the recall work has been carried out on yours.

The top vent of the tower unit being quite high, have you checked for the smell regularly?  I just wonder if the previous owner had not used the fridge on gas, so your use is the first instance.  Dometic do warn of odd smells on first use.  Possibility?

If the smell were due the autogas stench agent it would surely have been commented on quite frequently.  Most folk who have refillables tend not to use sites and hook-up so, logically, will regularly run their fridges on gas.

Have you tried the fridge on gas with the grilles removed, to see if the increased airflow clears the pong?

Final thought.  Might the gas flue itself be the source, especially if it has had little use?  Might cleaning the flue clear the source of the smell?

[Derek Uzzell]

I would have expected a Dometic RMT-7655L appliance in a 2008 motorhome to be beyond the date-range of the 2007 recall that involved adding an extra support-bracket at the fridge's rear.

 

I'm not totally convinced by the stenching-agent theory, as I would have thought the smell at the upper fridge ventilation-grille should also be evident at the heater's exhaust and at the hob and oven gas-burners.

 

I'd be surprised if the small amount of water that collects in the fridge's 'drain cup', even if well polluted, would be sufficient to produce a really bad smell. Even if it were able to do this, I can't see why it would happen only when the appliance was running on gas.

 

As scramblers is evidently able to reach the drain-cup through the lower grille, it should also (hopefully) be possible to remove the gas-burner's shielding to check what the flame looks like. Unfortunately it's not possible to clean the gas-flue from below and, looking at the photo of scramblers's motorhome, I'm pretty sure that the fridge will need to be moved backwards (or even removed completely from its enclosure) to reach the top of the flue.

 

There has been one instance on this forum where a Hymer owner complained that the installation of his Dometic Tec-Tower (fridge/freezer + oven) had been badly carried out, with inadequate clearance being left between the top of the gas flue and flammable material above it. It may simply be the case that the hot gasses emerging from the flue of scramblers's fridge are overheating something above or close to the flue, or that there is something potentially smelly (like a big blob of sealant, of a spare piece of plastic-covered wire) in contact with the flue itself. Once again, it may not be practicable to check this without first moving the fridge.

[lennyhb]

When we picked up our van from our Belgium dealer he made a point of telling us not to fill up with French Autogas as it causes problems with the fridge. Also we have met other people on our travels who have had to have the fridge jets & chimney cleaned after running on French gas.

 

In our user manual (76 series) Dometic say the fridge must not be run on Autogas, however we have been running on Autogas for over 2 years without problems. We always try to fill up in the UK mainly because UK supplies are 100% propane all year round.