immersion heater problem

[flukey]

hi all need a bit of advice on an immersion heater fault.

attended site yesterday to an immersion heater circuit that blew the fuse 15A (3036) as soon as it was inserted.

tested insulation res on cable (1.5t/e) and very low reading so this morning run a new 2.5t/e in up to double pole switch in airing cupboard.

connected up and everything worked fine until i went out to the garage where cu is and there was a very fishy smell and fuse holder hot to the touch.

when i removed the fuse there is burn marks to the back of it but fuse wire still intact.

system is tt with 3036 rewirables and in good condition.

immersion heater reading 15.7 ohms across terminals but looks like it wil be a bugger to remove and inspect.

all advice welcomed please

 

[stephenf8542]

Get a clamp meter and measure the current its drawing

 

[flukey]

Get a clamp meter and measure the current its drawing

hi stephen,
i think it goes without saying its drawing way too much current.
the resistance reading seems fine.
not sure if its insulation breakdown on the immersion heater or how to test for it

 

[stephenf8542]

replacement is your best option i think

 

[Spudnik]

Must admit, i wouldnt waste too much time on it.

Just replace the immersion, it could work out cheaper for the client in the long run, especially if spend much more time on it.

All IMO.

 

[stretchyboy]

Do you know that it isn't something like a loose or high resistance connection at the fuse or fuse holder? that would cause it to heat up too you know? ....
just another option

 

[flukey]

Do you know that it isn't something like a loose or high resistance connection at the fuse or fuse holder? that would cause it to heat up too you know? ....
just another option

hi stretchy,
not sure what you mean i have replaced the cable and my connection is fine

Must admit, i wouldnt waste too much time on it.

Just replace the immersion, it could work out cheaper for the client in the long run, especially if spend much more time on it.

All IMO.

thats what i would do too jason but it looks like its going to be a bugger getting the old one out and theres a good chance the cylinder will get damaged

 

[baldsparkies]

If its rewirable would check the push in connections at the board, terminals are probably checked by you anyway. If its a new element who fitted it and is there water in the immersion ? Just a thought.

 

[sparkdog]

I woult think the element I replaced one last week.jTo remove it just get an immersion element box key which is a big hexagonal (after draining the tank) with a bar for leverage.If it won't unscrew bang the end of the bar with a bit of 2x4 wood or similar.Got to be careful as the tanl is soft copper and the immersion insert is sometimes soldered in.

 

[baldsparkies]

I woult think the element I replaced one last week.jTo remove it just get an immersion element box key which is a big hexagonal (after draining the tank) with a bar for leverage.If it won't unscrew bang the end of the bar with a bit of 2x4 wood or similar.Got to be careful as the tanl is soft copper and the immersion insert is sometimes soldered in.

Dont drain the tank until you have cranked the immersion hex loose. Whilst filled with water it greatly helps to keep the tank from distorting, obviously once you have freed the element drain off tank, and dont worry a quarter turn wont make the element any less water tight, but using this method could save you damaging the soft copper on the tank

 

[sparkdog]

A good tip,thanks.Regards,Sparkdog.

 

[Spudnik]

I carefully heat up the tank round the hex with a blow torch on VERY low heat.

Works a treat.

 

[flukey]

I woult think the element I replaced one last week.jTo remove it just get an immersion element box key which is a big hexagonal (after draining the tank) with a bar for leverage.If it won't unscrew bang the end of the bar with a bit of 2x4 wood or similar.Got to be careful as the tanl is soft copper and the immersion insert is sometimes soldered in.

hi sparkdog,
ive changed a few immersion heaters in my time, but this ones a bugger. tried moving it and it doesnt want to know. dont want to strip the neck out of the cylinder

i reckon it can only be the immersion itself as ive renewed the feed im just a bit concerned why the fuse doesnt blow instantly now instead of warm itself up in the cu to the point where it would probably catch fire

 

[baldsparkies]

It's because its a bugger that your hoping the problem lies elsewhere, but to be fair I think a new element is going to be needed, as said you could try a clamp meter and see what the circuit draws, And also check those connection from the consumer lugs to the prongs on the fuses. Very best of luck to you mate I am sure it will shift eventually. Dont forget to leave the tank filled until the hex shifts, it really does help.

 

[flukey]

It's because its a bugger that your hoping the problem lies elsewhere, but to be fair I think a new element is going to be needed, as said you could try a clamp meter and see what the circuit draws, And also check those connection from the consumer lugs to the prongs on the fuses. Very best of luck to you mate I am sure it will shift eventually. Dont forget to leave the tank filled until the hex shifts, it really does help.

cheers baldsparks. could be changing the cylinder when it strips then