Immersion heater not heating?

[Burnerman]

I would imagine you are correct with what you say......those are drain down cocks.
I'm not familiar with galvanised tanks like this......I assumed it was a traditional copper cylinder with the element in the top.
Over to the others to deal with that part of the job!
John

 

[UseLeSsDiYr]

Right, I've just done another check. Placing the probes on earth, grey, neutral (blue) and live (brown) does not provide any meaningful results. Most of which came back with 0.00.

However, when placed on grey and blue and meter set to 2000mv, the reading fluctuates between 140 and 190 ish. Does this mean anything?

I don't appear to get readings when placed on grey / brown; earth / brown?

 

[Bosswhite]

The red one looks like the cylinder drain off,
Turn off water supply from tank in roof, and drain down below immersion level, be careful when trying to remove immersion not to damage cylinder, ( be gentle with it !! ) switch off power as well
Good Luck.

 

[Burnerman]

Please - no mV readings! All you'll get are spurious signals.
With the meter on 200 ohms and all electrics off, test between grey and blue, nothing else. Your meter has an internal battery which gives it power.
John

 

[UseLeSsDiYr]

Please - no mV readings! All you'll get are spurious signals.
With the meter on 200 ohms and all electrics off, test between grey and blue, nothing else. Your meter has an internal battery which gives it power.
John

I'm sure I tried 200 ohms and probed the grey and blue terminals; if I recall, I did not get a reading. Nor did I get a reading between grey and brown.

Having had the heater on for 30 minutes again, I think it is wamring up the water, but very very slowly. Would this suggest the element is dying? Or is it a matter of all or nothing?

 

[endecotp]

Right, I've just done another check.

People have given you various instructions. Most of use have told you to turn the power OFF and measure the resistance. One person has told you to turn the power ON and measure the voltage (which is more dangerous, but could also give useful information). What you've done seems to be to try to measure voltage with the power OFF - and that is going to tell you nothing useful. Not that you actually told us if the power was on or off, or what the thermostat was set to when you measured those few millivolts.

You need to be methodical, and follow instructions. (Or stop.). Otherwise something bad could happen.

 

[UseLeSsDiYr]

Right, I've just done another check.

People have given you various instructions. Most of use have told you to turn the power OFF and measure the resistance. One person has told you to turn the power ON and measure the voltage (which is more dangerous, but could also give useful information). What you've done seems to be to try to measure voltage with the power OFF - and that is going to tell you nothing useful. Not that you actually told us if the power was on or off, or what the thermostat was set to when you measured those few millivolts.

You need to be methodical, and follow instructions. (Or stop.). Otherwise something bad could happen.

Thanks for you advice endecotp (and others!) and being patient with me!

Yes, I should have made clear that in all the tests I've made were under the main fusebox being completely OFF.

 

[Newboy]

I feel compelled to take the day off work tomorrow to fix this problem

With respect, you have been given very clear instructions on how to test the thermostat by more than one poster. If you cannot follow those instructions then it's time to call a professional in. You don't seem to be clear about mains on/off and you are dealing with mains voltage which has the ability to kill you.

The fault identification process is a logical series of steps to determine the cause of the apparent fault - using random settings on a multi-meter will not help and may hinder the process.

 

[endecotp]

I'm sure I tried 200 ohms and probed the grey and blue terminals; if I recall, I did not get a reading. Nor did I get a reading between grey and brown

What does "did not get a reading" mean?

 

[Burnerman]

For the element to be working, there must be a resistance across grey and blue......that's effectively across the element itself, bypassing the thermostat.
Now try that again...200 ohms, all power off. Press the meter wire probes firmly against the metal terminals.
Don't touch anything - you don't want your body resistance to interfere with readings.
John

 

[UseLeSsDiYr]

Just leave the multimeter on the lowest ohms setting, and if you touch the leads together it will read zero, showing continuity. With the leads not touching, there won't be a reading - call that infinity.
To test the thermostat, fix the meter onto the terminals, and then turn the dial. You'll see the meter read zero and then infinity as the stat opens - just like an off/on switch. Hopefully the meter will continue to read infinity to determine the stat has gone AWOL!
John

For the element to be working, there must be a resistance across grey and blue......that's effectively across the element itself, bypassing the thermostat.
Now try that again...200 ohms, all power off. Press the meter wire probes firmly against the metal terminals.
Don't touch anything - you don't want your body resistance to interfere with readings.
John

When the probes are touching against each other, I get a reading of 00.4 at 200 ohms. Whn not touching, I get 1 __._ (the _ being blank, so I'll assume infinity. With the stat bought this morning, I get a reading between 00.5 and 00.7 - does this mean it's potentially faulty?

When set at 200 ohms, with the red probe on earth and black against each terminal, I get 1__._

The reading between grey and blue is also 1__._

Sorry everyone, guess that's why I named myself a useless DIYer!

 

[UseLeSsDiYr]

I'm sure I tried 200 ohms and probed the grey and blue terminals; if I recall, I did not get a reading. Nor did I get a reading between grey and brown

What does "did not get a reading" mean?

I think I meant infinity

 

[Burnerman]

First finding.....absolutely fine, you have tested your stat when it was switched on.
Second finding - also fine, you don't want any cross connection there.
Between grey and blue.....no reading, the element has no resistance and is therefore goosed!
John

 

[endecotp]

The reading between grey and blue is also 1__._

If those are the wires that look more like white and dark green to me in the photo you posted, then that means that the element has failed open circuit.

If you're confident of this measurement, you should just replace the element now.

It does raise the question of why the water heats at all, though. A couple of things you can try are:

- See if there is a measurable resistance on the higher ranges, I.e. if the resistance is greater than 200 ohms.

- See if there is a measurable resistance from the live element terminal (grey/white wire) to earth.

 

[Bosswhite]

Just change the Immersion for a new one !!!