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How much is left in my propane bottle?




On one of the wet days earlier in the week I fitted a Truma Sonatic Gas Level System into my elderly Avondale.    The Sonatic system is a piece of kit which was developed fifteen or so years ago and it was fitted as standard equipment in some caravans.    At the time a reviewer wrote about it saying, “As far as I know, this is the only device that actually gives you a true reading of the contents of the bottle.    A transceiver unit beneath the bottle sends and receives ultrasonic pulses to sense the physical level of the liquid.   Unfortunately, technology such as this comes with a pretty hefty price tag.    You have to decide if it's worth around £150 just to know how much gas is left in your bottle.”


Of course, there are now other devices which do the same thing, but when I saw that Magnum Motorhomes eBay site were selling the Truma kits for less than £40 (including p&p, I thought it was worth a punt.     See eBay item No. 173815837510



This is what you get.




A base plate which screws to the floor of the gas locker, and upon which the 6Kg gas bottle sits, plus the display panel and sufficient cable to connect between the two.    To maintain the information within the device, the panel needs to be connected to either a 9-volt battery or the 12-volt caravan supply.


A hole, big enough for the plug and cable has to be drilled into the back of the gas locker to enable them to pass through.    Once they are fitted, the hole is sealed with silicone. Then a suitable place is chosen to fit the display panel.

A few years ago I’d fitted a cigar lighter socket in my van and since I very rarely used it, I removed the socket and fitted the Truma panel into the same box.    Wiring for the display was taken from a fused supply close to the battery box.    All the wiring is hidden within, or behind the furniture fittings.


This is the gas bottle sitting on the pad in the locker.





The connected panel showing the reading for the new gas bottle.





The fused 12 volt supply feeding some additional LED lighting, the supply for the rear view camera and the new supply for the Truma Sonatic.






Edited by Jaydug
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It’s tempting to tinker at that price agreed. I purchased the newer Truma Level Control in 2019 with the INet box in my Knaus and it’s incredibly accurate, but very expensive! It’s all Bluetooth based works well. 

Tempted to get one of the old cheapies for the caravan 😊

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Thanks for the heads-up Jaydug. I have been contemplating a gas measurement instrument of some type and am a bit ‘old skool’ and like plug and play as opposed to Bluetooth to the phone so this fits the bill a treat and as you say for under £40 cant be wrong. I also like the fact the gas bottle sits on the base rather than having the kit magnetised (or fitted to aluminium bottles with a clip as with this I cant forget to remove the unit when bottle empty. I have just ordered one myself and may well order one for parents too.

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Spent the weekend fitting the Truma Sonatic received last week. Seems ok so far. We are spending weekend on the drive in the van so will try it out ‘in anger’ then.

Easy to fit, most time was taken up ‘losing’ the cable from the gas bottle holder + it must not bee too near other cables.

Took 12v + and - from my heating text control which is next to the sonatic display. I fitted the display unit into a plastic junction box and fitted inside a cupboard.


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