Plastic boiler cutting out

[Anton]

I've a plastic 25 litre boiler with a kettle element.  It keeps cutting out on me at around 70 to 80 degrees centigrade.  Usually if I disconnect everything and leave it for 5 minutes then set it going again, it's grand, and I can get to full boil.

Today, I've let unplugged everything, reset all the plugs, etc., no dice. My wort has dropped from 80 degrees to 60 while I've been messing around with this.  Gave it one last try and putting the plug into a different socket on the extension lead, it started off again.  Fingers crossed and touch wood, it keeps going until an hour after I get a boil going this time!

This is obviously very frustrating and is adding 30 minutes to an hour to a brew. Anyone else come across it?  What causes it - gunk building up on the element? I'd cleaned it thoroughly before starting.  Just a dodgy boiler that I need to replace?

[nigel_c]

Build up on the elements will cause this. Give them a good scrub after every brew or at a stretch 2nd and you should be grand. If they go black you can get a scorched taste off the wort which is nasty.

[Anton]

I'd cleaned the element after the last brew, though. I did get it going again, up to a boil, and it kept going for 45 minutes of a rolling boil before cutting out.  What I did find, though, was the extension cord I was using was really hot and so had probably the thermal cut-off had kicked in. 

That at least explains the second cut-out, though not the first one, where I got the wort from something like 55 degrees up to around 70 before it cut.  I think I'm going to pick up an extra extension lead before my next brew, and alternate them every half hour.

[delzep]

Get a 13amp extension cord and make sure you're using the correct lead for the element. One for a computer isn't suitable

[johnrm]

Thermal cutoff and a really hot extension lead are not related.

Do not use an extension lead, if you must, make sure it is as short as possible, never coiled, and ensure it is rated for the load.

[pob]

Is there anything else plugged in on the same circuit? Cooker, fridge, washing machine, tumble dryer, etc

Is the circuit rated for all the load on it?

Remember doing a double brew with someone else, when both systems were on, mine wasn't coming to the boil; we were only getting ~180 volts on the circuit due to the load.

[Sorcerers Apprentice]

Could be the 13 amp socket staring to break down, the load is causing heat between the pins of the plug top and the socket receptacle connection, try another socket, if this fixes it, then replace the plug top and the socket. An older socket and plug top would be vunerable to this type of problem

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[Sorcerers Apprentice]

If the plug top feels hot while it's plugged in and operating, it's a sure sign of wear in both the plug top and the socket

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[iBrau]

SA is right as you should replace the plug-top and socket if the plug is getting hot during use.

However if this happens in the middle of a brew that you need to finish you can try cleaning the pins of the plug top with steel wool.

Also, what are the connections to the back of your heating element like? Do they get very hot during operation? When you say the element keeps cutting out at 70C, it sounds like the thermal cutout on the back of the element near the electrical connections.

[Anton]

So last Monday's brew, I cleaned the boiler before starting, and made sure the element was clean.  It was a warm day so I had everything going in the back garden.  We have a heavy duty 4-socket extension lead on a reel (would normally use it for the electric lawnmower), with a thermal cutout/reset button, so I was using that for the boiler.  The extension lead was plugged in to the wall, alongside two other sockets - one for the microwave, one with another extension lead for my wife's laptop and monitor.

After the last cut-out, I noticed the wound lead of the extension reel was hot to the touch. The plug itself was fine.    Will have a look for a long kettle plug but realistically I'll probably need to use an extension lead if I want to run the boiler in the garden.

The final cut out was after the wort had been on a rolling boil for 45 minutes, so I cut my losses and left it at that. Just doing a simple Irish Red, so no late hop additions required.

[iBrau]

Oh that's an easy one! ... always always unwind an extension lead fully. If you leave even a single turn of wire on the reel it acts as an 'inductor' which means less power getting to your element and more heating of your extension lead.

[Anton]

Oh that's an easy one! ... always always unwind an extension lead fully. If you leave even a single turn of wire on the reel it acts as an 'inductor' which means less power getting to your element and more heating of your extension lead.

That, I did not know!  Every day is a schoolday! Thanks!