Boiler out of action, need hot water

[Simpo Two]

My boiler won't run for more than 30 seconds before cutting out in a maelstrom of popping, banging and gurgling. I suspect it's terminally furred up.

While I wait for the local boiler man to come and see it, I need to rig up some hot water. The HW cylinder has an immersion heater in it, but it's never been wired up. I thought it should be fairly simple to connect some cable to it, run that to a 13A socket and make some hot water.

However it won't be thermostatically controlled. So my question is - how long should I run the immersion heater for in order to get a tank of usably hot water, but not boil/explode it? The HW cylinder is about 122cm high x 46cm diameter (including insulation) and the system is standard 1980s gravity fed.

Thanks!

NB I checked the overflow tank in the loft to make sure the system han't run dry and there was a thick brown foul-smelling crust of gunk on the water that looked mould/fungus. Could that be a factor? (But that was on the top and the outlet is at the bottom)

[Amused2death]

Whilst mucking about with my immersion heater years ago, I took off the cover plate under which the immersion is located and in the top of the immersion heater element is a dial you can adjust to set temp. I.E. built in thermostat.

Have you taken your cover off to have a look?

[Gingerbread Man]

Immersions come preset for the correct temp. They often have a dial which can be moved but with no figures as it's not for user interaction.

Immersions are just wired in to a switch spur. So you'll do nothing wrong just doing that.

So basically wire it in and turn it on. It'll look after itself.


As for the boiler, it sounds like circulation issues. Heat not getting away.

[forest07]

Sounds as though the pump may have failed on your heating system. Should be fixed easily.

I would be wary of connecting an immersion heater to a standard domestic socket. They run at 3kw and need a 30 amp fuse & should be wired into the correct isolating switch.

[Simpo Two]

Thanks all, very useful. The heater does indeed have a thermostat in it! I presume the two short white wires go the terminals, and the cable from those to the socket. It's rated at 2.75-3Kw.



This is a general view showing the HW cylinder thermostat on the left, and the place where all the cables go on the left (cover removed):



As you can see it's rather busy in there - somewhere under all that lot is mains, though it's not clear what the current rating is. The circuit breaker downstairs labelled 'immersion heater' is 16A. And my basic grasp of thingy tells me that 3Kw and 240V is 13A. I'm not keen on disturbing the chocolate block (which doesn't look 16A anyway) so think I'll try it on a normal 13A socket and see what happens. It is only temporary after all.



What does the panel think?

[condor]

I'm certainly no expert but I have used an everyday 13Amp plug in a wall socket to heat up an immersion cylinder. I did it in 3 x 15 minutes sessions ( about 30 mins apart) as the wiring and plug gets very hot. Switch on and off at the wall socket - it's not recommended. I went through a few plugs, fuses and had to replace the wall socket.
It might be easier to boil water in a kettle for when you need hot water

[Simpo Two]

Boiler man coming in 30 mins

[dirkgently]

Simpo Two said:

What does the panel think?

Do not wire into the boiler wiring (why the fk can`t people use a wiring centre) just stick it on a plug top for now it will be fine, just unplug it when not required.

[Gingerbread Man]

Leave the wiring centre alone. As stated, the immersion is stand alone. Nothing to do with the boiler controls. Put the cover back on!

Overheat stat, one wire to the thermostat, one to the post typically labeled T.

Live to the thermostat. Neutral to the Neutral post.

Earth to the earth studding.

[Simpo Two]

Boiler man here, found Grundfos pump failed (27 years old so can't complain). Win to Forest07 and many thanks to everyone else for their input.


NB My only reason for looking in the 'boiler wiring' was to find a source of mains.

[Gingerbread Man]

Simpo Two said:

NB My only reason for looking in the 'boiler wiring' was to find a source of mains.

With a 3amp fuse

[Simpo Two]

Gingerbread Man said:

Simpo Two said:

NB My only reason for looking in the 'boiler wiring' was to find a source of mains.

With a 3amp fuse

That was the spur designed for the immersion heater, and which goes back to the 16A breaker I mentioned. The boiler is downstairs and has its own power supply.

Anyway, the nice new red Grundfos pump is fitted and all running perfectly




On an amusing note, here's a quote from a leaflet that came with the pump:

'Follow these simple instructions to set up the new UPS2 3D-SMartGuide featuring augmented reality. Download the mobile app from your device app store. For augmented reality 3D functions place the 3D SmartGuide card on a flat surface with the Grundfos logo facing up. Tap the AR button to activate AR mode. Toggle to turn AR on/off. Once your camera is activated from your mobile, point your phone at the AR marker to reveal the virtual UPS2 pump.

WTF? It's a pump. It's a simple metal device that pumps water. If I want to look at it I can open the airing cupboard door. 'Oh look there's my pump, just as it was the last time I saw it'.