More Immersion Heater Issues

[AlwaysPondering]

So about a month ago we had a new immersion heater fitted, and after the first one just didn't work, nor the second, we finally managed to get one that worked. Hot water was restored and life was good.

Until last week. Got up to find the immersion heater MCB (16A) had tripped, result no hot water. Strange, turned the MCB back on and everything worked fine for another few days, then pop the MCB tripped again.

Turning the MCB on, with the immersion heater switched off and it stays on. Then the immersion heater on and after about 40-50 minutes the MCB trips again.

I've checked the immersion heater and it's still shown the same resistance as it did when new, so it wouldn't seem like the heater is at fault.

Is really annoying as don't really want to be just testing the MCB as there is clearly an issue somewhere, unless it's the MCB. Especially as we get the gas boiler connected back up and running on Friday, so after then I'm less worried if the immersion heater works or not, or at least there is less pressure to get it fixed.

Anyone got any ideas?

 

[terryplumb]

Have you checked the switch/s that are on the immersion circuit ? Quite odd that you fitted two immersion heater elements and both didn't work. Did you establish the voltages present at the immersion elements that did not work ?

 

[AlwaysPondering]

As far as I can tell the first 2 immersion heaters the thermostat was knackered, as I was getting 240v into it, just not into the actual heater, and if I bypassed the thermostat the heater worked and heated the water.

As far as I can tell the only things that are on the immersion heater circuit are the immersion heater and the shower pump (which the previous owner had installed). However I had switched the shower pump off and that makes no difference.

If I had a current clamp I'd see what current was actual being pulled, but I don't.

Is it possible that the MCB could have been damaged when the original immersion heater failed, and now it's tripping at a much lower amps? At least they're not that expensive to replace.

 

[terryplumb]

The immersion would usually be on dedicated radial circuit .
The MCB could be faulty ,or there could be a fault on the circuit and it's doing its job. Why not get an electrician to check the circuit out .

 

[Harry Bloomfield]

Could you perhaps borrow the 16amp MCB from another circuit in the board for a test?

Yes, the original faulty heater, might possibly have damaged the MCB.

 

[AlwaysPondering]

Could you perhaps borrow the 16amp MCB from another circuit in the board for a test?

Yes, the original faulty heater, might possibly have damaged the MCB.

It's the only 16amp MCB in the CU, all other are 6 or 32 amps.

The immersion would usually be on dedicated radial circuit .
The MCB could be faulty ,or there could be a fault on the circuit and it's doing its job. Why not get an electrician to check the circuit out .

From the looks of it out was on its own circuit, but someone prior to us preening the house has wired up the shower pump to it as well.

Will be contacting an electrician, guess just curious to know if there's anything simple I'm overlooking.