Immersion heating top of cylinder only, wiring, faulty or single element only?

Comer1

My sister got an immersion heater installed some time ago but regardless of whether it's switched to Bath or Sink, it only heats the top of the tank. It's been this way since being installed. Could it be faulty, wired incorrectly (picture attached) or just have a single element (my theory)? Any advice appreciated.

astrofool

https://www.boards.ie/discussion/2058302316/immersion-heating-top-of-cylinder-only-wiring-faulty-or-single-element-only

It looks like a single element (3 wires), and may be wired so that "sink" and "bath" do the same thing.

greasepalm

My switch says bath or sink as i dont have a bath and only sink works as possible single element only.

Bruthal.

https://www.boards.ie/discussion/2058302316/immersion-heating-top-of-cylinder-only-wiring-faulty-or-single-element-only

Take a pic of immersion switch wiring and post it. Switch off at the MCB board first.

John.G

https://www.boards.ie/discussion/2058302316/immersion-heating-top-of-cylinder-only-wiring-faulty-or-single-element-only

It looks like a 4 core cable (earth wire underneath the black?) , a dual immersion, with the thermostat correctly switching the common neutral, if S is the sink then the black cable is normally to this terminal and the brown to the other (bath) terminal, this still shouldn't stop both elements from operating except that the sink switces in the bath element and vica versa. You need a M.meter to check out the wiring, or maybe post a photo of the switch with cover removed.

John.G

One other thing, if both elements are, in fact, working OK, apart from being reversed, if you heat the top of the tank, "sink" element and then switch to the bath element, nothing will happen as the stat is still satisfied, you will have to run off ~ 25/30L of water to ensure that the bath element heats the whole tank, maybe she should run off 20/30 litres of water and then change to the "sink" which is probably the bath and see does it then heat the whole tank.

Comer1

Thanks for all the replies, I've asked her to get a picture of the wiring at the switch which I'll post here, but she said that wasn't touched when the new immersion was fitted. Seems from the replies here that the most likely thing is that bath and sink are reversed.

Bruthal.

https://www.boards.ie/discussion/comment/120767259#Comment_120767259

If bath and sink were reversed, it would still work properly except heating the larger volume (bath) would happen when sink is selected on the switch. So a couple of possibilities are the stat switching too early, or incorrect wiring between switch and immersion, all assuming the elements are intact. So a switch photo will at least clear up how it's connected.

Comer1

Rather than start a new thread, I'm posting here. I am about to change my dual immersion switch and I just want to check that my proposed wiring is correct

Thanks in advance

kirk.

Yes that's it

Make sure you get the wiring on the flex right. I always test with a meter

There should be an RCD protecting the heater . The heaters can be faulty on old houses with no RCD on them

Comer1

https://www.boards.ie/discussion/comment/121482967#Comment_121482967

Thank you🖖

kirk.

Make sure connections are tightened fully