Immersion heater high resistance

[Tadge]

Hi guys, help needed before I change my immersion.

My water seens to heat up slowly and not very hot (im on electric and have immersion only), it has heated up scalding in the past, but seems slow and warm but not as hot as usual.

Stat is fine, but resistance of element is 3.8M ohms across terminals and 1.8M ohms from terminal to earth. Obviously nowhere near the 18ish ohms it should be.

I'm an electrician so know how to test etc, but this reading doesnt make sense to me, just thought has someone else experienced this?

Any ideas?

Thanks

 

[seco services]

its on its last legs then.

 

[Tadge]

due to the high ohm reading? I was'nt sure if the tank is full of sludge as I've only moved into this old house recently. Gonna replace all plumbing for oil boiler/pressurised/solar system in summer so just need this to last a few more months. Concerned if i try to replace elment, i may damage tank......

thanks for reply

 

[seco services]

if it won't budge on unscrewing it just drill it out takes 10mins

 

[Tadge]

cheers, just had immersion on for 4 hrs, water is luke warm only, so will replace tomorrow. So drill out from center and cut towards edge until it peels out? without damaging thread? I'll give it a try.

thanks
tadge

 

[Dan Robinson]

Heat it with a blow torch.

Use a proper box spanner - not one of those ***** flat things.

 

[Tadge]

Replaced the faulty element now . It was wrecked, 6 splits in it see pics

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• Tadge
• 14 Feb 2009
• 1

Untitled

• Tadge
• 14 Feb 2009
• 1

Untitled

• Tadge
• 14 Feb 2009
• 1

.
It was a bugger to remove, had to tap union with a hammer to free up and then tap the box spanner. Thought it wasnt going to shift but it started to move , just had to ease left to right until free then it came out. Couldnt drain tank after it was moving as I reckon the drain is clogged, nothing an old towel couldnt fix.

Anyway, new ones in and switched on, so I'll wait and se if it works better. Thanks for the help.

 

[cider]

Cant believe that didnt blow a fuse or trip out
Was it earthed

 

[seco services]

is a bit of a mess.
least its ok now.

 

[Tadge]

I didnt check the breaker, perhaps thats why it wasnt working.....

Joking, fully earthed, no tripped breaker and voltage/current flow ok. Yeah, it does seem suprising but as the water was getting luke warm only I can only guess that the element did not short to earth and the current was flowing through the water (water providing resistance), hence heating water slowly.

Had a similar thing on a job years ago, the bloke didnt put a drain hole in a watertight switch (MK masterseal)n and the condensation built up and half filled the switch and back box. The circuit did not trip but the whole switchbox became warm.

The new element is working fine, water is roasting, woo hoo! I'm off for a shower.

 

[Tadge]

update, immersion working fine but cheap and nasty thermostat (from toolstation) stopped working 3 days later. Luckily the thermostat which was used with the damaged element was working fine (after 20 years, dont make em like they used to) so I replaced with this one. Sorted.

thanks

 

[seco services]

hope that old stat you have used has a reset.
maybe thats all your new one did was trip. did you check ?

 

[Tadge]

No reset on old one but the tank and rest of system (i've had no boiler since we've moved in september) is comming out for building works and replaced with entire new system in the next couple of months, so I'll live without reset for now.

New one had reset but was mangled and couldnt reset, also the body was wobbly and temp setting didnt appear accurate, i.e switching at wrong temp. Cheap crap