Our caravan fridge has a piezo igniter that is a bit temperamental. Is it possible to just replace the sparking unit with a generic 12v electronic igniter (if such a thing exists)? Electrolux kits seem to be on the expensive side.
I'm not fussed about flame sensing or anything fancy as the fridge already has a thermocouple and I'm happy to turn the igniter on and off manually once I see the flame is alight.
Tim
This sort of thing?
IME piezo igniters are very sensitive to damp/humidity. I have a couple of hand-held ones and they give a perfectly good spark when stored in the house, but keep them out in a shed where I have a gas-fired pottery kiln and where they're needed, and they're useless. Fortunately the kiln also has a built-in battery operated spark igniter, runs off a single D-cell. Something like this might do you:
Unfortunately the flame is behind a window; visible but not accessible.
Tim
Now that looks handy (and cheap!). Can't actually see what kind of battery it uses but I guess consumption won't be great in a campervan.
Many thanks.
Tim
Remember these gas-lighters?
Tim Downie was thinking very hard :
Perfectly do-able, just divert the HT wire from the piezo unit, to the new igniter. You can buy 12v, 240v and battery versions needing just a push button switch.
That brings back memories!
I recall these used a platinum wire, which was heated by the chunky battery. The battery heated the wire enough to start catalytic oxidation of hydrogen, which raised the temperature enough to light the gas.
But it only worked with gas containing hydrogen like town gas, and wouldn't work with natural gas (methane), so they wern't used after the conversion to natural gas in the late 60s.
Is there some fundamental efficiency reason why caravan fridges operate on gas and not electicity?
Brian
Not an efficiency reason, no, as they are actually less energy efficient and effective than a compressor type.
They use gas because it's available, while there is no guarantee of an electrical supply in a caravan, and they are also silent in operation. Most of them will work either on gas or 12 volt power, and some have an option of 240 volt operation as well.
Probably because you can store a lot more energy in gas cylinder than you can in a similar sized battery. It's also much easier to replace a spent gas cylinder than a battery.
Brian Gaff explained on 10/08/2013 :
They usually designed to work on three sources - gas, 240v and 12v, but only the 12v whilst being towed due to the current consumed.
And all 3 sources are heaters, the fridges are the absorption type, mix of ammonia and other stuff is circulated around the system of many convoluted pipes, in and out of large and small pipes to get the stuff into a gas and back to a liquid and so on, the heat just makes the liquid move, up a vertical riser tube with the electric heaters attached (100 - 150 watt heaters depending on the fridge size, hence why the 12volt one is wired to only run when the vehicles engine is running)
The gas side has it's flue welded to the main riser pipe, heat rises, so the liquid rises, at the top of the riser tube it turns 90 degrees, then starts it's downward travel, into and out of the cabinet, through small pipes and so on, eventually it reaches the reservoir, and starts journey again.... well, that's one bit of the liquid, it's a continuous motion,
Because the pipes the liquid had to flow through are set at certain angles, if you park up too far off level the fridge performance suffers, modern fridges are a lot more tolerant than the older ones, 3 or 4 degrees off level now, but if you get it off level enough, the liquid can't make it through the mass of pipes, then you get problems with the liquid boiling and creating air locks,
Hence the 'advise' for an absorption fridge that's stopped working is to turn it upside down for a day, allowing the air bubbles to burp into the reservoir that is now at the top of the system, hopefully when put back the right way up, the fridge will work again.
The back side of these fridges gets pretty hot, which is why you see those 2 large vents in the side of caravans and motorhomes, one at the bottom and one above the top of the fridge back, but even with them these fridges can sometimes suffer in very high ambient temperatures, mine failed to cool properly in spain during summer, so i changed to a 12 volt compressor fridge freezer, but i already had 450 watts of solar panels on the roof and 900AH of batteries onboard, worked brilliantly in any weather, but did pull around
80AH in 24 hours, and in winter the solar panels often didnt put that much back, so i had to run the genny for a few hours to re-charge the batteries from the mains charger (40 amp 3 stage jobbie)Anyhoo, the OP's Q has been answered i think, you can buy single outlet electric igniters, but they cost more than the cooker multi outlet ones (tho i found the single outlet ones spark faster than the cooker ones, 3 or 4 sparks a second as opposed to one a second) remember to earth out the unused spark terminals if you use a multi outlet unit, or they will arc across to the housing and reduce the spark power on the one connected to the electrode in the flame path), just connect 12 volts from the vans battery system via a momentary switch, and use the existing igniter electrode,
I had a thetford fridge in my motorhome, and that had a flame meter, the thermocouple was one of those with a junction in it and 2 spade terminals, i've seen them sold for boilers, a small meter was connected to the terminals, and the millivolt signal on the thermocouple was displayed on the meter, just hold in the gas knob in and the igniter button until the meter needle begins to move, release the ingiter button, keep gas knob in until the needle is over halfway, then you could let go,
Much easier than kneeling on the floor with the fridge door open, half the food moved to the floor so you can peer through the flame sight window, and jabbing the damn peizo button for 5 minutes until it lights, then releasing the gas knob too soon and seeing the flame go out,
Mind, that was better than in the 60's, where you had to go outside and remove a cover to spark a lighter style flint wheel to light the gas.
Ordered on the 9th from Hong Kong and arrived today. No instructions but pretty self-explanatory once I'd figured out how to put the battery in!
Anyway it's installed now and works like a charm. Being much quieter than the old piezo igniter, you can now hear the gas ignition which makes life a lot easier.
Many thanks for the heads up.
Tim
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