Immersion heater faulty

[bobodhi]

Hi, I've been asked to go look at an immersion heater which isn't working.
I haven't looked at one before and would appreciate a heads up.
Obviously there may be a problem with the power supply or the unit may be faulty.
Would appreciate any comments by those with experience as to a suitable approach to the problem.
Cheers, Kevin

 

[Hawk81]

most likely problem is the element. Other faults could be the stat or the supply to the unit. The switch or cable to the unit.

 

[acat]

As above most likely is the element so test for supply to element first and if thats ok test element hopefully problem solved.


Chris

 

[All Sorts]

Check for supply at element, bypassing the thermostat if necessary. If supply there = faulty element

Very common for some of the older types of immersion to trip RCBO's straight out e.g. when 17th Ed CU fitted (had 10 out of 40 OAP flats do this on a single job!).

 

[bobodhi]

As above most likely is the element so test for supply to element first and if thats ok test element hopefully problem solved.


Chris

Hi, thanks for the reply, just a quickie, best way to test element and expected readings if faulty or not.
Also, how easy is it to remove and replace the element if it is faulty? Do I need to do anything like drain the tank etc?
Cheers Kevin

 

[mogga]

get a spark to test it you will ned to isolate it and drain tank then put new one in if found faulty but a spark will be best placed to test it for you

 

[bobodhi]

Hi, I have access to a meter and want to test it myself. Can anyone advise. Thank you

 

[chris gray]

does the element have a reset button on it?
was the immersion heater covered in clothes?

 

[Notsosmart]

get a spark to test it you will ned to isolate it and drain tank then put new one in if found faulty but a spark will be best placed to test it for you

Don't make the mistake of fully draining the tank; just drain enough so that when you unscrew the element you dont warp the tank (expensive mistake)

 

[m4tty]

Test the element line to neutral on continuity and you should read resistance of roughly

3,000 W / 230V = 13.04A

230V / 13.04A = 17.64 Ohms

Hope that helps.

If the element is shot it may be open cicuit

 

[billy110]

IR test the element also to check integrity

 

[m4tty]

What line & neutral together to earth ? 500v? cheers

 

[billy110]

Disconnect supply to element, clip onto either element terminal and earth. 500v, will tell you if element is split

 

[Notsosmart]

I wouldn't IR test the element if I were you because if it isn't blown now it soon will be, as M4tty said test using a continuity tester.

 

[ringer]

............
Very common for some of the older types of immersion to trip RCBO's straight out .................

So what is the solution to this? Does this mean new immersion elements have to be fitted, or is there a work around?

 

[All Sorts]

Yes new heaters had to be installed (by someone else subsequently so don't know how fault actually manifested itself). I'm sure I heard somewhere in a previous life that you should never megger those elements anyway.. presumably as you'd be shoving x2 or x4 it's normal operating current through a low resistance?

Don't start draining anything until you've proved the thermostat as it's very easy to check that so daft not to prove that as first step. If it's awkward to get at or to see what you're doing just kill power, disconnect the stat and pull it right out. You don't have to drain anything to go that far as the stat rod is covered within the heater assembly. Then it's simply a switch operated by a dial. Any suspicion against the stat just join the 2 wires into it to short it out, then switch on and watch whether the electric meter wheel starts whizzing round or not!

 

[bobodhi]

Yes new heaters had to be installed (by someone else subsequently so don't know how fault actually manifested itself). I'm sure I heard somewhere in a previous life that you should never megger those elements anyway.. presumably as you'd be shoving x2 or x4 it's normal operating current through a low resistance?

Don't start draining anything until you've proved the thermostat as it's very easy to check that so daft not to prove that as first step. If it's awkward to get at or to see what you're doing just kill power, disconnect the stat and pull it right out. You don't have to drain anything to go that far as the stat rod is covered within the heater assembly. Then it's simply a switch operated by a dial. Any suspicion against the stat just join the 2 wires into it to short it out, then switch on and watch whether the electric meter wheel starts whizzing round or not!

Thank you, very useful to hear a commonsense approach to problem solving, it's very easy to miss out the logical first steps (Is it plugged in?) and dive straight into the complexities.