Dometic RM5310 fridge problem

[blackrose]

Is that silver tube actually a tube and should I try to remove it from the aluminium block and blow it out?

[WotEver]

27 minutes ago, blackrose said:

Is that silver tube actually a tube and should I try to remove it from the aluminium block and blow it out?

No. 

It is, as I said earlier, the temp sensor for the stat and we already know that it works (because it's ok on mains). 

[Tony Brooks]

If this was mine on a holiday boat. It looks like its going to cost £138 to get a new thermostat so even if I totally buggered the existing one up I would have lost nothing.

The brass gas valve looks like it is secured to the plate on the thermostat housing by 4 screws fitted from the back of the plate. The plate is fitted to the housing by what looks to be 6 bent over tabs.

If the gas pipes were disconnected and the tabs straitened I think the gas valve will just lift off. I bet the valve itself is only bearing on a piston or diaphragm with nothing to secure it. That MIGHT allow you to see if the valve itself is free to move and if any bypass slots etc are blocked up.

I think the alloy bit with the red seal on it maybe the gas thermocouple so don't mess with that.

[WotEver]

5 minutes ago, Tony Brooks said:

If this was mine on a holiday boat. It looks like its going to cost £138 to get a new thermostat so even if I totally buggered the existing one up I would have lost nothing.

Me too. Blackrose, are you a tinkerer?

[blackrose]

2 hours ago, WotEver said:

Me too. Blackrose, are you a tinkerer?

Yes, I'll isolate the gas and have a go.

I am a tinkerer and I fix most things myself, but I always find it easier if I know how it works first. Of course I usually work that out afterwards!

I've got the fridge working on mains now and that's all I need for the moment. If I take the brass fitting off am going to disturb the mains thermostat? It's the same temperature adjustment knob for mains, gas and 12v.

I need a working fridge.

Edited July 24, 2017 by blackrose

[blackrose]

I can't get the brass valve off without dismantling the box it was connected to. The adjustment spindle goes straight through it.

Edited July 24, 2017 by blackrose

[philjw]

Logically, if they sell the part as a spare there will be a way to remove the old unit. Maybe you will have to dismantle it some more.

[blackrose]

1 minute ago, philjw said:

Logically, if they sell the part as a spare there will be a way to remove the old unit. Maybe you will have to dismantle it some more.

Yes, but at the moment I don't want to stop it working on mains.

[philjw]

Good point.

[blackrose]

That's how the part is sold. I don't think you're supposed to take it apart.

[WotEver]

31 minutes ago, blackrose said:

I don't think you're supposed to take it apart.

I have a small handheld Bosch rechargeable shrub trimmer and the internal battery failed just outside warranty. Bosch assured me that it was unrepairable but if I returned it to them they'd give me a voucher for 10% off a new one. After much experimentation I got it apart and found a Hitachi battery inside. A bit of Googling found a Chinese supplier and I got a new battery for a couple of quid. That was about 4 years ago and I still use it regularly. 

Moral of the story - just because it's not supposed to be serviceable doesn't mean it can't be

[blackrose]

27 minutes ago, WotEver said:

I have a small handheld Bosch rechargeable shrub trimmer and the internal battery failed just outside warranty. Bosch assured me that it was unrepairable but if I returned it to them they'd give me a voucher for 10% off a new one. After much experimentation I got it apart and found a Hitachi battery inside. A bit of Googling found a Chinese supplier and I got a new battery for a couple of quid. That was about 4 years ago and I still use it regularly. 

Moral of the story - just because it's not supposed to be serviceable doesn't mean it can't be

I didn't say the fridge wasn't serviceable? The difference is that you took an appliance apart, whereas I've been trying to take apart a component that's sold as a unit.

Edited July 24, 2017 by blackrose

[WotEver]

10 hours ago, blackrose said:

I didn't say the fridge wasn't serviceable? The difference is that you took an appliance apart, whereas I've been trying to take apart a component that's sold as a unit.

But the similarity is that neither are 'supposed' to be taken apart. In my case I had to peel off hand grips, unsolder metal tape and prise off hot glue melt. In your case you have to unbend tabs and remove screws but the difference is the same - what do you have to lose?

[blackrose]

2 hours ago, WotEver said:

But the similarity is that neither are 'supposed' to be taken apart. In my case I had to peel off hand grips, unsolder metal tape and prise off hot glue melt. In your case you have to unbend tabs and remove screws but the difference is the same - what do you have to lose?

You've obviously misunderstood or didn't see my pictures? I've already removed the screws and unbent the metal tabs and discovered that it doesn't come apart because the adjustment spindle goes through the entire component. It's like a factory sealed component.

I don't mean to be ungrateful but if it was as easy as you've suggested I'd have taken it apart last night, and what I have to lose is that if I break the part the fridge won't even work on mains and I'll have no fridge at all because the adjustment knob/spindle operates gas, 12v and mains.

Edited July 25, 2017 by blackrose

[blackrose]

Anyway, I think taking this valve apart may be barking up the wrong tree. I've just spoken to this guy who seems to be the most knowledgeable person I've been in contact with so far and he says it could be a weak thermocouple. Or that the magnet inside where the thermocouple connects to the brass valve may be faulty. It's accessible by unscrewing the thermocouple from the valve. The other possibility is that there is an electrical fault in the thermocouple wiring.

http://www.motorhometech.co.uk/fridge_repairs_11

[WotEver]

2 hours ago, blackrose said:

Anyway, I think taking this valve apart may be barking up the wrong tree. I've just spoken to this guy who seems to be the most knowledgeable person I've been in contact with so far and he says it could be a weak thermocouple. Or that the magnet inside where the thermocouple connects to the brass valve may be faulty. It's accessible by unscrewing the thermocouple from the valve. The other possibility is that there is an electrical fault in the thermocouple wiring.

http://www.motorhometech.co.uk/fridge_repairs_11

Fair enough.

The fact that you stated that the flame goes instantly from full to off I don't see how it could be in any way thermocouple related. If the thermocouple was completely bust then the flame would never stay alight. If the thermocouple was 'weak' then the flame would drop small for a second or two and then go out. If the magnet where the thermocouple connects was faulty then you'd see one of the above two symptoms. 

It is purely based on your report that the flame went from full to off with no intermediate 'low' flame that Tony B suspected the valve body. 

(That link doesn't work btw - 404 error)

[blackrose]

2 hours ago, WotEver said:

Fair enough.

The fact that you stated that the flame goes instantly from full to off I don't see how it could be in any way thermocouple related. If the thermocouple was completely bust then the flame would never stay alight. If the thermocouple was 'weak' then the flame would drop small for a second or two and then go out. If the magnet where the thermocouple connects was faulty then you'd see one of the above two symptoms. 

It is purely based on your report that the flame went from full to off with no intermediate 'low' flame that Tony B suspected the valve body. 

(That link doesn't work btw - 404 error)

Well my report on the flame was accurate and I reported the same thing to the guy from Motorhome Tech, but his diagnosis is different and he does think it could be thermocouple related.

Here's his link again.

http://www.motorhometech.co.uk/fridge_repairs_11.html

 

Edited July 25, 2017 by blackrose

[WotEver]

25 minutes ago, blackrose said:

Well my report on the flame was accurate and I reported the same thing to the guy from Motorhome Tech, but his diagnosis is different and he does think it could be thermocouple related.

Well, for a couple of quid and 5 minutes to fit one it's easily checked, as I said way back in this thread. 

[blackrose]

2 hours ago, WotEver said:

Well, for a couple of quid and 5 minutes to fit one it's easily checked, as I said way back in this thread. 

Unfortunately it's not a couple of quid - a generic thermocouple won't fit in to the brass valve, you have to fit the Dometic/Electrolux one with the correct fitting. I don't think it's horrendously expensive, but I don't want to be buying parts for the sake of it.

[WotEver]

1 hour ago, blackrose said:

you have to fit the Dometic/Electrolux one with the correct fitting

Well ain't that just typical of them. 

[Tony Brooks]

10 hours ago, blackrose said:

Unfortunately it's not a couple of quid - a generic thermocouple won't fit in to the brass valve, you have to fit the Dometic/Electrolux one with the correct fitting. I don't think it's horrendously expensive, but I don't want to be buying parts for the sake of it.

I am sure a few months ago I saw a generic thermocouple that came with a set of different "screws" for that end. They were slotted so you could put them over the pipe.

Have you had the inlet union off the valve yet? If there is one that's where the filter I mentioned might be.

[WotEver]

1 hour ago, Tony Brooks said:

I am sure a few months ago I saw a generic thermocouple that came with a set of different "screws" for that end. They were slotted so you could put them over the pipe.

When ever I have bought one (and I've bought a few) that has always been the case. I assumed from OP's description though that the end was totally unique to Dometic. 

[blackrose]

I've just received this email from Leisure Spares Direct. Looks like the parts are horrendously expensive after all!

The mag valve comes as part of the gas valve and the thermocouple comes with the burner and electrode, details as follows

Part no 2412798312 (gas valve)                  Cost £84.64  - delivery is up to 4 weeks as the manufacturer does not have stock

Part No 2412802825 (burner complete)  Cost £49.49 – delivery is 2 to 3 working days

PP £4.99 + VAT

 

[blackrose]

3 hours ago, Tony Brooks said:

I am sure a few months ago I saw a generic thermocouple that came with a set of different "screws" for that end. They were slotted so you could put them over the pipe.

Have you had the inlet union off the valve yet? If there is one that's where the filter I mentioned might be.

Yes I've taken the gas inlet off the brass valve but couldn't see a filter.

Do you know where I could get a generic thermocouple of the type you mention? Would it need to be the same spec or rating as the Dometic one?

Thanks

[blackrose]

3 hours ago, WotEver said:

When ever I have bought one (and I've bought a few) that has always been the case. I assumed from OP's description though that the end was totally unique to Dometic. 

I have no idea, but that's what the guy from Motorhome Tech told me on the phone.