Swan tea urn off the boil

I admit it. I do get some satisfaction when I divert an appliance, on a journey to the bin, to my workshop for repair.  I have been known to collect the odd item from skips or just dumped on the pavement while supposed to be doing something more productive. I think I just feel sorry for things. Weird, but true.

Make and model: Swan Hot Water Tea 20L Urn

Fault reported: Not staying hot

Cost of replacement: £80ish

Manufacturer support:  3/10

Cost of parts: £1.70

Hours spent on repair: 45 minutes

Tools needed: Screwdrivers, test meter etc

Sundry items: Cleaning materials, heat transfer solution

Repair difficulty: 2/10

Cups of tea: X1

Biscuits: Malted Milk X1

This Swan hot water tea urn was one of those items.  Spotted during an office reorganisation in the ‘scrap pile’, it had been put there as it wasn’t working properly and a new one had now been ordered.

 

Being fairly light-fingered, I spirited the urn away to the workshop for some tinker time.  Not strictly staff policy, but you know, seek forgiveness after etc.

An urn is really just a big kettle.  This one has an all metal 20 litre tank with bar-style tap to brew up, when needed.  There are no real controls as such; just an on/off switch with neon light and two tell-tail lights to indicate boil and keep warm.  Keep warm is usually on all the time when switched on.

The fault seemed to be that the urn reached boiling temperature when switched on, but then switched off totally, allowing the water to cool again excessively.  Timing the switching intervals of the thermostat, 20 minutes or so, and a 15-20⁰ hysteresis confirmed a fault. There was also no ‘keep warm’ green light on, when in use.  To push the thermostat further, I poured cold water into the urn to see if that sped up switching between hot and cold, it didn’t.

Opening up the urn’s base involved just three screws, allowing access to all components.  Such a nice change to not have layers of covers and things to move out of the way first!

Checking the wiring out for logic revealed that someone had been here before! The wiring was incorrect and the ‘keep hot’ element was not wired up correctly and effectively not in circuit with the power source. A small wiring change corrected this and meant that the ‘keep warm’ element was now working again.

The thermal reset fuse/ button seemed to be working OK- proved with a test meter and the thermostat did seem to switch on and off, albeit with excessive hysteresis.  Time to fit another one! Luckily, these thermostats are very common and I managed to get one from eBay, rated at 100⁰ (a couple of degrees over the one fitted) for less than £2. Fitting a new thermostat only involved a couple of screws, a light smear of heat transfer solution and reconnecting back into the wiring harness.

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With all wiring back in place and the cover refitted, it was time to test and brew up.  This time, the urn boiled, switched off and then stayed warm on the secondary ‘keep warm’ circuit.  To prove that the new thermostat was an improvement, I then topped up the urn with cold water and within 5 seconds, the thermostat clicked in and the boiling process started again.

Time for a brew.

(PS, the urn has now returned to its normal place of work)