immersion heater wiring

conserver

Hello, I am new to boards.ie so here goes, I have a dual element (bath and sink) immersion heater fitted to my hot water tank, there are two terminals one coloured black the other white
Can anyone tell me which is the bath terminal, I only have a 3 core cable coming out of the timer so would like to be sure current is going to the bath terminal.
Apparently the dual element was installed about 5 years ago
I dont have a multimeter ect so any info would be greatly appreciated
Many Thanks

alan4cult

Are you rewiring it? Why does it need to be rewired?
You'll need a multimeter to be sure you have the bath terminal.

You need to be able to isolate live and neutral to the immersion, it should not be wired directly from the timer.

conserver

Thank you for your msg, it is already wired to one of the elements connections, there is an isolator wired up prior to the timer, I only want to make sure it is receiving current to the bath element, I just need to know which is the bath terminal, black or white terminal.
ON ANOTHER SUBJECT I have just found out that on the outdoor grant oil boiler, the seperate in house timer clock is not turning so it ca`nt be programmed , the boiler motor is 4.2amp starting current and 90watt max running, could I replace this timer with a mechanical timer
16amp resistive, 8amp inductive
any info would be greatly appreciated

John.G

Normally, a dual immersion is supplied with a length of pre wired cable, black is the sink and brown is the bath., can't comment on the black/white cabling.

conserver

Thanks for your msg, there are 2 terminal posts on top of the heater elements one is coloured black the other is coloured white, one feeds the bath element the other feeds the sink element, I just need to know which is the bath terminal post , black or white as I only have a 3 core cable going to the immersion heater and I would like to make sure it is the bath terminal connected
Many Thanks

John.G

You can do a practical test.....open a hot tap (immersion switched off) and drain all hot water from the cylinder, switch on the immersion, if it is connected to the sink element then it will reach 60C (if thermostat set to this or near it) in ~ 30 mins, if its connected to the bath then it will only be lukewarm/hand hot after 30 minutes and will take a total of ~ 1 and 3/4 hours to reach 60C.

alan4cult

I've only once seen a white wire on an immersion and it was wire to the thermostat and not the bath/sink. Usually immersion bath sink are black and blue, can't remember which is which but a multimeter will tell you.

Can you post a pic of the immersion head?

alan4cult

Also a multimeter will tell you, I'd recommend one here.

John.G

alan4cult wrote: »

Also a multimeter will tell you, I'd recommend one here.

The thermostat always switches the neutral in a dual immersion and in modern immersions just remember " sink the black down the brown bath"

A meter will generally tell you, lowest resistance is the bath element but I have seen one I think with both elements 2,75kw!!

conserver

Thank you all very much for your info, as I dont have a multimeter I will try running the water after 1/2 hour of the immersion heater being on if its hot I will assume it is connected to the sink element
Many Thanks

KlArmy

John.G wrote: »

The thermostat always switches the neutral in a dual immersion and in modern immersions just remember " sink the black down the brown bath"

A meter will generally tell you, lowest resistance is the bath element but I have seen one I think with both elements 2,75kw!!

And I've seen brown/black can be either sink or bath so I would always check