Gas heating/Fridge

[george23]

Evening all, My gas heating and fridge will not ignite automatically it will only light with a lighter, There is a spark, A motorhome repair man looked at it and said i would need a new fridge, At the time i did not know the heating was not working, would anyone know if there is a part i can locate and replace, Thanks

[Keithl]

George,

 

What make, model and year is your MH and what make and model are the fridge and heating system?

 

Keith.

[george23]

Burstner T615 2005, I don't know the make/model of the fridge, No markings i can see

[george23]

Thank you for you're reply,I will check the heating system and booklet to see if there is a name on it

[Derek Uzzell]

george23 - 2020-09-01 10:42 PM

 

Burstner T615 2005, I don't know the make/model of the fridge, No markings i can see

 

On-line photos of RHD 2005 Burstner T615 motorhomes all show the vehicle as having a large fridge/freezer with a gas-oven above it. The fridge freezer seems to be manually-operated OR ‘automatic selection’ but the make is (I’m 99.9% certain) Dometic.

 

Dometic appliances will normally have a paper label inside the fridge that identifies the model. (The image below is of a Dometic 7-series fridge/freezer).

[Keithl]

George,

 

A possible cause of both failing to ignite could be low leisure battery voltage. What is your leisure battery voltage and could you try connecting to EHU and trying again (assuming you where not initially)?

 

Keith.

[george23]

Keith,

 

You're right it's the one in the photo Dometic model no RM7505, The heating is truma Trumatic C, The manual says the heat exchangers should be replaced after 10 years could that be the problem, my leisure battery is quite new, The fridge works ok on EHU, The heating is gas only, It's the ignition spark that wont work

 

George

[BruceM]

george23 - 2020-09-02 10:01 AM

 

Keith,

 

The fridge works ok on EHU, The heating is gas only, It's the ignition spark that wont work

 

George

 

Following up on Keith’s point and to clarify what you stated, when your van is connected to EHU does the fridge work ok on gas or does it still fail to ignite?

[george23]

The fridge works on EHU, If I disconnect the EHU the fridge will automatically start clicking looking to run on gas but wont ignite unless i light it manually from the access panel, The heating is the same when i switch it on it keeps clicking but wont light,

Hope this makes sense, The fridge works ok on leisure battery while travelling to and from camp sites, I leave it on the lowest setting 1,

 

George,

[george23]

My main problem is having the gas heating in the cold weather,

George

[BruceM]

george23 - 2020-09-02 12:22 PM

 

The fridge works on EHU, If I disconnect the EHU the fridge will automatically start clicking looking to run on gas but wont ignite unless i light it manually from the access panel, The heating is the same when i switch it on it keeps clicking but wont light,

Hope this makes sense, The fridge works ok on leisure battery while travelling to and from camp sites, I leave it on the lowest setting 1,

 

George,

What I take from this is:

There is a gas supply as the fridge lights manually

There is a visible spark when on automatic

The spark does not ignite the gas.

 

As an experiment, turn the gas thermostat up to its highest setting and see if it ignites automatically.

 

If still nothing it sounds as if the ignition spark is not aligned correctly to the gas jet. That’s something I’d have expected your engineer to spot though. Were they a Dometic approved engineer?

[BruceM]

george23 - 2020-09-02 12:26 PM

 

My main problem is having the gas heating in the cold weather,

George

 

This may be a separate issue entirely. Have you checked all your fuses and are you confident that the heater has a gas supply?

[george23]

The gas supply is fine i can light it with a lighter,

 

George

[george23]

The engineer who had a look at the fridge was doing a habitation check on a caravan while i was on a camp site, I gave him a few pound to have a look, I have tried all settings it wont light automatically, Should i replace the ignition part ?

 

George

 

 

[BruceM]

george23 - 2020-09-02 1:22 PM

 

The gas supply is fine i can light it with a lighter,

 

George

1/ How do you light your gas heater with a lighter? It’s a sealed unit? Bear in mind you may have gas supply to the fridge/hob but not the heater.

 

2/ If when on automatic your fridge is producing a visible spark but not lighting the fridge gas and yet at the same time you can ignite the gas manually then it doesn’t sound like there’s anything wrong with the igniter other than alignment. Did you try the experiment I suggested (turn fridge up to maximum)?

[Derek Uzzell]

george23 - 2020-09-02 10:01 AM

 

...The heating is truma Trumatic C, The manual says the heat exchangers should be replaced after 10 years could that be the problem...

 

George

 

Replacing heat-exchangers every 10 years was a German regulation that did not apply outside Germany. This Truma webpage refers

 

https://www.truma.com/uk/en/faq/replace-heat-exchanger-of-truma-lpg-heater

 

Anyway, it’s highly unlikely that your Trumatic C’s heat-exchanger has anything to do with the heater failing to start up.

 

Operating Instructions for Trumatic C appliances can be downloaded from here

 

https://www.truma.com/uk/en/service/self-service/product-family/truma-c-heaters

 

and gas-operation trouble-shooting is descibed on the 1st file attached below.

 

.....................................................................................................................................

 

The Dometic RM7505 fridge/freezer (Manual here)

 

https://manualscollection.com/?fid=94403a0b97a001bfc2e4460f9ce5697b&read=online

 

was an automatic-energy-selection model (AES II) but - unlike some other ’smart’ 3-way fridges (including alternative Dometic models) apparently there was no means to manually ‘force’ an RM7505 to select 230V, 12V or gas - you switch an RM7505 on and the AES system takes full control.

 

So, if George connects his motorhome to an EHU, the RM7505 will automatically choose to operate on 230V (which it does) and when George then disconnects from the EHU, the RM7505 will automatically switch to gas operation (but the gas igniter fails to light the gas). What George cannot do is get his RM7505 to select gas-operation while the motorhome is connected to an EHU, as the fridge’s AES system won’t allow this to happen,

 

Evidently the RM7505 selects 12V and operates OK when George’s motorhome’s engine is running.

 

The Dometic Manual has two sections that may be relevant (2nd and 3rd files attached below).

 

It may be simple coincidence that the RM7505 fridge/freezer’s gas-burner won’t light automatically and that the gas-only Trumatic C combination air/water heater also refuses to start up, as (presumably) both appliances are at least 15 years old.

 

George has said that sparks are being produced at the fridge’s gas-burner, and that the gas-burner can be lit manually with a lighter. BruceM has suggested that the problem may lie with the electrode that produces the spark, so cleaning and adjusting the ‘spark gap’ to optimise the spark’s intensity may be all that’s needed.

 

(I notice that a lot of ‘critical’ spare parts for the RM7505 model no longer seem to be available, which might explain the repair man’s advice.)

 

 

[Keithl]

George,

 

Your problem just may be low gas pressure.

 

Do you use exchange cylinder, like Calor, or refillable, like Gaslow ?

 

Try using a new cylinder and see if the problem persists, but do note it may take a couple of minutes of trying before the gas gets through to appliances if they are far from the cylinder.

 

Keith.

[george23]

Thank's for all you're suggestions and help with the gas info very interesting, The gas is Calor, There is an access panel/ air vent to light the gas manually i removed a small metal cover to light with a gas cooker lighter, i will try the things suggested and let you know the outcome,

 

George,

[Derek Uzzell]

The simplest general check for adequate gas-pressure will be to light all of the motorhome's hob's gas burners, turn all the burners to their maximum output and see what the result is. If all the hob burners will operate continuously at maximum 'flame', the pressure of the gas (which should be 30mbar) downstream of the gas regulator must be considered OK.

 

Gas is clearly present at the fridge's burner as George can light it. As he has owned this motorhome for some time, I assume he knows how the fridge normally behaved when the gas was lighting automatically and what the burner sounded like. Certainly, on my 2005 Hobby motorhome - that had a Dometic non-AES fridge/freezer - it was easy to hear the burner roaring away after the gas had lit.

 

When was the Dometic fridge last serviced? There might be debris in the gas-burner assembly affecting spark ignition of the gas, or a new jet is required. If George wants this sorted out soon, a Dometic-literate technician should be able to accurately diagnose the cause of the problem pretty quickly.

[747]

george23 - 2020-09-02 12:22 PM

 

The fridge works on EHU, If I disconnect the EHU the fridge will automatically start clicking looking to run on gas but wont ignite unless i light it manually from the access panel, The heating is the same when i switch it on it keeps clicking but wont light,

Hope this makes sense, The fridge works ok on leisure battery while travelling to and from camp sites, I leave it on the lowest setting 1,

 

George,

 

The Fridge problem may be a faulty Printed Circuit Board. Instead of leaving your Fridge on the 'Auto' setting, turn the knob to Gas and see if it ignites. This fault is not uncommon, I have had it with the same model of Fridge.

[Derek Uzzell]

747 - 2020-09-02 7:33 PM

 

The Fridge problem may be a faulty Printed Circuit Board. Instead of leaving your Fridge on the 'Auto' setting, turn the knob to Gas and see if it ignites. This fault is not uncommon, I have had it with the same model of Fridge.

 

"Instead of leaving your Fridge on the 'Auto' setting, turn the knob to Gas and see if it ignites.”

 

How does George do this, please?

 

In my posting of 2 September 2020 2:44 PM above I mentioned that the Dometic documentation for the RM 7505 AES II fridge/freezer model suggests that there is no manual override for 'energy selection’.

 

The two photos attached below show the control-panel of a Dometic fridge/freezer and were taken from on-line adverts for 2005 Burstner T615 motorhomes.

 

The 1st photo is of a Dometic RM 7505 AES II appliance that seems to have been what was normally fitted to 2005 T615 motorhomes (and what George has said his T615 has).

 

The 2nd photo shows a Dometic fridge/freezer with a control-panel that has two knobs on it. This is one of the RM76xxL appliances and will either be a RM 7601L ( manual energy selection) or a RM 7605L (automatic OR manual energy selection). The Dometic Manual for these appliances can be viewed here

 

https://www.manualslib.com/manual/1656377/Dometic-Rm-7605-L.html#manual

 

The left knob of a RM 7605L appliance allows the user to choose automatic energy selection via an ‘Auto’ switch position, or to overiride automatic energy selection and to manually select gas, AC mains power or 12V DC operation. The left knob in the attached photo seems to have 4 ‘selection’ positions and, if that’s so, the photo is of a RM 7605L appliance that has an AES/manual capability. (But Geoge has a ‘knob-less’ Dometic fridge/freezer.)

 

It is, of course, possible that the problem George has with his Dometic RM 7505 fridge/freezer may be due to a faulty PCB, but (as I said above) ‘electronic’ spares for 15-year-old Dometic appliances are not easy to come by (and are expensive even when they can be obtained).

 

As gas gets to the burner, ’sparking’ takes place and the gas can be manually ignited, the logical approach would be to follow BruceM’s advice in his posting of 2 September 2020 12:34 PM above. George may be able to take on that task himself, though he’d be wiser not to play about attempting a gas appliance DIY ‘fix’ when it’s plain he lacks the necessary expertise. Even manually lighting the fridge through its exteror ventilation grille carries substantial risks...

 

If the fridge fault is ‘electronic’ George won’t be able to confirm this himself, so if simple basic DIY checks prove unsuccessful, he’s going to need a competent Dometic engineer to inspect the fridge and advise on the best way forward.

[747]

Oh well, he's stuffed then Derek. 8-)

 

What he really needs is a Gas Fitter capable of examining the Fridge properly ... rather than one who just says he needs a new Fridge. The replacement Fridge will cost around £2000+ with fitting costs.

 

My local Dealer (who I bought my current van from) said exactly the same thing. I brought it home and with minimal cost (for a new Burner assembly) wiring checks and Flue cleaning I have an excellent Fridge/ Freezer again. Luckily for me I can manually switch to Gas.

 

George will not be able to source a PCB 'off the shelf' but if he needs one of them repaired, then there are companies that can do this.

[BruceM]

I concur that in principal this sounds to me like a fridge that does not require replacement.

 

By the very nature of diagnosing via the forum it’s likely that we have made assumptions based on our interpretations of George's feedback.

 

I’m particularly concerned that we’ve assumed that there’s a visible spark when it’s possible that George can only ‘hear’ the spark.

 

So George, I suggest that if you have the tools and feel competent to do so and have not done so already that you;

 

1. With everything turned off remove the lower fridge vent.

2. Remove the gas burner cover – two screws I think.

3. Wipe around the gas burner to remove any debris and carbon deposits, then with the gas burner covered by a bit of paper, eg kitchen towel, to prevent anything falling into its jet, clean the spark electrode ideally with contact cleaner and a bit of emery paper.

4. Contact cleaner is inflammable so best if you apply it to the emery paper rather than squirt is all over the place. In the absence of contact cleaner just use water and emery paper.

5. Try the fridge on automatic with the burner cover still off to observe what happens – you should see the electrode sparking and ideally the gas ignite. Have a cup of water ready in case excess contact cleaner ignites and needs to be put out.

6. If all good then turn off and reassemble. If not then let us know what happened.

[Derek Uzzell]

BruceM - 2020-09-03 12:22 PM

...

 

1. With everything turned off remove the lower fridge vent.

2. Remove the gas burner cover – two screws I think.

...

 

 

George has done this to allow him to manually light the gas

 

His posting of 2 September 2020 4:03 PM said:

 

There is an access panel/ air vent to light the gas manually i removed a small metal cover to light with a gas cooker lighter...

 

When George heard a clicking noise as his Dometic fridge tried to light up the gas-burner, it’s certainly to be hoped that he subsequently did the obvious thing and - once he had removed the burner’s metal shield - that he confirmed that the ciicking noise was accompanied by the production of a spark at the burner. (In his original posting George did say "My gas heating....will not ignite automatically it will only light with a lighter, There is a spark...”, so it’s reasonable that George has made that confirmatory check.)

 

My 2005 Hobby motorhome had a Dometic RM 7651L MES fridge/freezer that could be cantankerous regarding gas-burner auto-ignition. I regularly used to clean the gas-flue and burner and in 2014 commented on that procedure in this forum thread.

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Sooty-exhaust-when-fridge-on-gas/36533/

 

How easy it will be to ‘sweep’ the flue of an Electrolux/Dometic fridge will depend on the model of fridge and how it has been installed.

 

Before sweeping can take place the baffle that hangs inside the flue will need to be removed and, before the baffle can be removed, the top section of the flue will need to be removed. Removing the flue’s top section may be possible wth the fridge remaining in situ if there’s an upper ventilation-grille in the right place. Similarly, cleaning the burner will be possible if there’s a lower ventilation-grille in the right place.

 

With my Hobby’s 7-Series Dometic fridge/freezer I used to sweep the flue using a variant of the method described by Billggski. In my case, after removing the flue’s top section, the baffle and the burner assembly (the Hobby had BIG ventilation-grilles) I used a home-made ‘brush’ made up from a length of multi-strand galvanised wire with a spiky ball of wire part-way along its length. I used to pull the wire up and down through the flue from the top and bottom, finishing off by pulling a rag through the flue (a bit like using a ‘pull-through’ on a .303 rifle).

 

To allow me to sweep the flue I needed to disconnect the complete gas-burner assembly and move it from below the flue’s inlet. This then allowed me to clean the burner properly (and carefully!) and any debris this produced was removed from the burner with a vacuum cleaner.

 

A generic Dometic video on burner cleaning can be found here

 

 

(Regarding PCBs, the symptoms of the fridge fault suggest that the Dometic fridge’s PCB is not a prime suspect. On the other hand, Truma Trumatic C heaters gained an unhappy reputation for PCB problems and the cost of a new replacement PCB is likely to exceed £300.)

[george23]

A big thank you to everyone for all the information provided, Some very helpful and knowledgeable people out there, Good news my fridge is working on gas again, My gas hob has always had one faulty ring the flame only stays on if i hold the knob down, I lit the other two one full flame the other half power , I tried another gas bottle still the same, That's a job for another day, I removed and cleaned spark electrode and all other bits, After a few attempts the gas lit, I done this a few times it seems fine now, I also tried the gas heating it works as well, Thanks again,

 

George