Immersion Heater Element Fault....Help Please

[Taylor_J]

Hello.

Ive just got back off a job, I narrowed it down to the immersion heater element causing a b16 60898 mcb to trip.

I disconnected the thermostat to see if that was causing the problem first which in this case it was'nt.

I then put the terminals straight on to the element terminals to narrow the fault down.

I switched the mcb back on and this time i didnt trip.

I noticed i had wired live and neutral differently to how it was so i swapped them around to see if it tripped again and it did.

So yes surely a fault element?

Anyone know why swapping the polarity around causes the element to heat up not trip the mcb?

You cant see which terminals are marked L and N.

I bought a new element but found it impossible to undo it.

The customer has told me nothing has been tampered with and its been there for a good 10 years plus.

Ive disconnected everything for now and left it dead.

Cheers James.

 

[Guest111]

Just a long shot but if the damage is nearer one end of the element than the other this may be why the mcb doesn,t trip if you reverse polarity,too high a resistance,although I would have thought it would trip rcd.best let a plumber change the heater,it,s very easy to tear the boss out of the tank.

 

[telectrix]

first, dis the element & measure continuity, should read around 19 ohms. then IR test element to E. to remove element, i usually find that it's best to tap the spanner sharply with a hammer rather than tugging on it. ( turn off water supply to the tank first and have a couple of towels ready to soak up the small amount that leaks out.)

 

[Taylor_J]

Youre telling me as soon as i started undoing the old one it started to kink the top of the cylinder so decided to leave it.

I stayed there for 30 mins to see if the water got hot in reverse polarity and it did. Thats the thing thats confused me because I dont know hell of alot heating elements.

In the end I decided it was the best to leave it all disconnected.

She doesnt want a new cylinder

 

[Taylor_J]

I put the hammer to the spanner...no chance lol

I

 

[telectrix]

better to forego the repair fee than flood the house. let someone else have the aggro.

 

[Taylor_J]

I totally agree. More hassle than its worth. Thanks for the advice

 

[telectrix]

hmm. reversing the polarity. if there's no RCD on the circuit, and there is a short to E close to the L end of the element. it's conceivable that reversing the polarity would then put a majority of the element's resistance between L and E, and thus not give rise to enough current L-E to trip the 16A MCB.

 

[HandySparks]

have a couple of towels ready to soak up the small amount that leaks out

Unless it's in the side, in which case you'll need an awful lot of buckets. Better to drain it first (after you've loosened the heater).

 

[telectrix]

one's in the side, i get my friendly neighbourhood wet-head to remove them and refill after if necessary.

 

[Guest111]

hmm. reversing the polarity. if there's no RCD on the circuit, and there is a short to E close to the L end of the element. it's conceivable that reversing the polarity would then put a majority of the element's resistance between L and E, and thus not give rise to enough current L-E to trip the 16A MCB.

exactly what i was saying lol

 

[telectrix]

sorry, phil. missed your post . bloody page is jumping all over the place. i try to scroll down and nothing happens. then 1 minute later, it scrolls down 3-4 posts.

 

[Guest111]

sorry, phil. missed your post . bloody page is jumping all over the place. i try to scroll down and nothing happens. then 1 minute later, it scrolls down 3-4 posts.

yep does the same with me sometimes and then it locks and i lose it halfway through a post.How are you getting on with the avo?

 

[One_of_them]

i find best way with elements is to leave the tank full, warm the element up with a gas torch (be careful ) then give it the beans with the appropriate element spanner. Touch wood worked every time and never had a problem.
Depending on size of element will determine resistance measured. 3kW should be around the 17-19 mark depending on your supply voltage.

 

[telectrix]

fine, mate. seems to be quite accurate. how's my hairy female friend?

 

[Guest111]

fine, mate. seems to be quite accurate. how's my hairy female friend?

very growly at the minute,we,ve got the builders in and she,s not allowed to eat any.lol

 

[Geordie Spark]

very growly at the minute,we,ve got the builders in and she,s not allowed to eat any.lol

I know what you mean & sympathise with you - a woman with PMS is a nightmare to live with.

 

[Guest111]

I know what you mean & sympathise with you - a woman with PMS is a nightmare to live with.

the wife lol

 

[Elmer BeFuddled]

Best way to loosen a tight element in a cylinder tank (not that I want to teach anybody how to suck eggs) is to put the spanner on and tap (hit/bladder) it in the clockwise "tightening" direction. That should crack any detrius or thread locking s h i t e that's holding it in place. Un-doing is then, as stated on a famous advertising campaign on TV, "simples".

 

[electric will]

I also found if you use a hammer and a drift, hit down on the topside of the brass flange (if you know where I mean) this shocks all the tread sealing stuff off