Three way fridge issues

[IdealStandard]

My STRONG RECOMMENDATION is not to. As I said earlier the flane failure device is different and in my opinion it would be dangerouse to convert to piezo push click ignition.

Did you miss my earlier post?

 

Unless of course you changed the FFD too but that would be more expensive than just getting the right think. Why not go to a caravan breakers and get the part? Not sure where you are but Newhaven. caravans in Newhaven might help.

 

I skimmed over your earlier post as I had already set about trying to figure out the problem.

 

I'm in Bristol, will look around for my nearest. Or I'll just fork out for the bit.

[alan_fincher]

These fridges were really designed for gas - they're woefully inefficient on electric and indeed the 12V never does much at all.

 

I think the original purpose of the 12V was to try and retain some cooling between camp sites for a caravan being towed. At best it'll partially retain its cool - what it'll never do is make anything more chilled than it was before you switched to the 12V supply.

This actually isn't the case for some of them, although it has often been stated on the forum.

 

Perhaps not all are the same, but what will happen with some models on 12 volts, (if you can "find" enough of it!), is it will actually get very cold indeed, and start to freeze things you don't want it to.

 

What it does do though is absolutely drain batteries (about 8 amps continuous, I think from memory), and that's what makes 12 volt use on a boat fairly silly, unless the alternator is actually running when you are doing it.

 

I'm not saying there have not been models that will not get cool enough on 12 volts, but some that draw continuous current with no regulation will possibly get far too cool!

 

Just a random thought - maybe the ones that fail to cool on 12 volts, (particular in camping use), are using inadequate supply cabling, and that is getting hot at the expense of the relevant part of the fridge not getting hot as it should, because of the volts drop in the supply cable?

[simon&jan]

[Keeping Up]

Ok, so I took the flue off, cleaned the twirler and the burner housing, held down the bypass for the thermocoupler and it lit and stayed lit. There was a bit of crackling and smoke (hopefully just loose dirt which I knocked loose) but the flue got hot and the rest got cold. So far so good.

 

I tried wiring the ignition to a battery as reccomended and still nothing so I removed the little white bit of plastic which makes the sparks. I tried holding this directly onto a 12v supply and still nothing.

 

Now to find a replacement and wire it all in.

 

I honestly don't know what I'd do without the help of people on here. Greatly appreciated as ever.

 

Many thanks

Tim

 

 

If I read this (and your other thread) correctly, you connected 12v directly to the electrode and didn't get a spark, so you assumed the electrode is faulty? The electrode needs several thousand volts to make a spark, so the replacement will not work either.

[alan_fincher]

If I read this (and your other thread) correctly, you connected 12v directly to the electrode and didn't get a spark, so you assumed the electrode is faulty? The electrode needs several thousand volts to make a spark, so the replacement will not work either.

Yes,

 

Am I not the only one thinking they may be soucing the wrong part?

 

I would have thought, as you say, what is pictured (in the other threa?) is just a bit of metal through a bit of ceramic, and not much can go wrong with that bit.

 

The problem is surely at the end that is meant to produce thousands of volts.....

 

(Unless I have totally misunderstood!....)

Edited January 8, 2013 by alan_fincher

[IdealStandard]

*sigh*

 

Ok, school me.

[Keeping Up]

*sigh*

 

Ok, school me.

 

 

The electrode makes a spark if you feed it with several thousand volts. The gap from the end of the electrode to any other bit of metal, is what the spark jumps across. If there is a mixture of gas and air in that gap, the spark ignites it. The size of the gap depends how much voltage you need - too big a gap and you get no spark, too small a gap and the spark isn't big enough to light the gas. I believe you need about 25000 volts per inch - or if you're metric, that's about 1000 volts per mm.

 

The high voltage comes from one of two sources. Either a piezo-electric crystal, which basically gives out a big pulse of voltage if you thump it, or an electrically-driven system that steps up the 12v to a high voltage by switching the current in a coil. In either case the unit has a wire that takes the high voltage to the electrode, and the electrode is placed so that the spark jumps to earth (eg to the metalwork of the fridge) in the path of the gas jet.

 

Does that help?

 

 

Edited for tryping errrrs, and also to add that the high-voltage genrator itself needs to be connected to earth at the appropriate point to complete the circuit. 12v igniter units can rely on the 12v negative upply for this, piezo units will generally have a small tag that touches the metalwork when they are in place.

Edited January 8, 2013 by Keeping Up

[IdealStandard]

The electrode makes a spark if you feed it with several thousand volts. The gap from the end of the electrode to any other bit of metal, is what the spark jumps across. If there is a mixture of gas and air in that gap, the spark ignites it. The size of the gap depends how much voltage you need - too big a gap and you get no spark, too small a gap and the spark isn't big enough to light the gas. I believe you need about 25000 volts per inch - or if you're metric, that's about 1000 volts per mm.

 

The high voltage comes from one of two sources. Either a piezo-electric crystal, which basically gives out a big pulse of voltage if you thump it, or an electrically-driven system that steps up the 12v to a high voltage by switching the current in a coil. In either case the unit has a wire that takes the high voltage to the electrode, and the electrode is placed so that the spark jumps to earth (eg to the metalwork of the fridge) in the path of the gas jet.

 

Does that help?

 

 

Edited for tryping errrrs, and also to add that the high-voltage genrator itself needs to be connected to earth at the appropriate point to complete the circuit. 12v igniter units can rely on the 12v negative upply for this, piezo units will generally have a small tag that touches the metalwork when they are in place.

 

That helps plenty. The idea of 12 volts jumping across an air gap is pretty ridiculous. Sometimes you just believe what you want to!

 

So if the unit does not work as is, and I have bypassed the switch mechanism, the issue probably lies with the system which steps up the voltage.

[sociable_hermit]

This actually isn't the case for some of them, although it has often been stated on the forum.

 

Perhaps not all are the same, but what will happen with some models on 12 volts, (if you can "find" enough of it!), is it will actually get very cold indeed, and start to freeze things you don't want it to.

 

What it does do though is absolutely drain batteries (about 8 amps continuous, I think from memory), and that's what makes 12 volt use on a boat fairly silly, unless the alternator is actually running when you are doing it.

 

I'm not saying there have not been models that will not get cool enough on 12 volts, but some that draw continuous current with no regulation will possibly get far too cool!

 

Just a random thought - maybe the ones that fail to cool on 12 volts, (particular in camping use), are using inadequate supply cabling, and that is getting hot at the expense of the relevant part of the fridge not getting hot as it should, because of the volts drop in the supply cable?

 

Ok, I stand corrected then!

 

I've never met anyone on a boat who has had any luck using the 12V on a 3-way fridge.

 

Mind you, from what you've said, that's probably because they've killed their batteries in the first day of trying?

 

Given that most boats with these fridges are being purchased second hand, I'm sure under-sized cables are very often an issue, but who would bother taking the interior to bits to tackle it? Especially when there's two alternatives.... I guess these problems just tend to get passed on from one owner to the next.

[Keeping Up]

That helps plenty. The idea of 12 volts jumping across an air gap is pretty ridiculous. Sometimes you just believe what you want to!

 

So if the unit does not work as is, and I have bypassed the switch mechanism, the issue probably lies with the system which steps up the voltage.

 

 

Indeed - although you just might still prove us all wrong because spark electrode assemblies can fail by the insulation breaking down and effectively shorting out the spark. However that is rare unless either the ceramic has cracked, or there is a surface track and that is usually clearly visible.

[IdealStandard]

Sourced a new igniter, wired it all up and it works a treat. Ignites fine and seems to burn happily.

 

I also installed a new cooker and hobs and took the opportunity to get a gas safety certificate done.

 

The last question I have is regarding the opening to outside the boat. There is a flue hole to the outside which is currently not directly linked to the flue. As it is currently, the flue is just aimed at the hole. Is that normal or is there normally a connecting pipe?

 

Thanks for all the help.

[Grace and Favour]

Sourced a new igniter, wired it all up and it works a treat. Ignites fine and seems to burn happily.

 

I also installed a new cooker and hobs and took the opportunity to get a gas safety certificate done.

 

The last question I have is regarding the opening to outside the boat. There is a flue hole to the outside which is currently not directly linked to the flue. As it is currently, the flue is just aimed at the hole. Is that normal or is there normally a connecting pipe?

 

Thanks for all the help.

 

I am fairly confident that there should be a 'gas-tight' flue connection to the exterior. I wouldn't run it without

[IdealStandard]

Just found this

 

http://www.canalworld.net/forums/index.php?showtopic=39583&st=20

[Teadaemon]

You could fit a piezo igniter, or a battery igniter off an electric cooker, but both are likely to fall foul of a vigilant BSS examiner as being modifications which have not been approved by the manufacturer. Keep your ears open for a S/H one with a duff cooling coil- they rust out frequently - and talk to any local caravan places to see if they can find you one/have one already. In the meantime light it with a match.

 

Clean the burner and flue again about every 3 months or so.

 

N

 

2013 BSS Checks

 

There's nothing in the above document that would prevent fitting a replacement igniter of a different type to that originally fitted.

 

Edited to add: Providing of course that the flame failure device is still functional.

 

With regard to the flue, I quote from check 8.10.2:

 

"LPG and paraffin fridges in non-petrol-engined boats may be installed without comment, to open-vent into the boat’s interior providing no flue components are added to the appliance’s integral flue stack."

Edited January 11, 2013 by Teadaemon