Immersion heater not heating?

[UseLeSsDiYr]

Hi

I'm hoping an expert here will be able to help diagnose or pinpoint what the problem here is.

As titled, our immersion heater is not heating up the water. When we turn on the switch, there is a light, which indicates that power is going through. The fuse at the main box serving this supply seems to be intact, so that points towards maybe the thermostat or heating elements may be up the creek?

1. Is it worth changing the switch (although it lights up), replacing it with another (20A?) unit, or am I wasting time here?
2. If the element has gone, I've read that this usually trips the fuse box. This hasn't happened as far as I'm aware.
3. If I need to someone out, I guess I'll need to call an electrician? How much am I looking at here?

Would appreciate if someone can shed some light.

Thanks for any advice.

 

[Newboy]

It may be equipped with a thermal cutout, the element may have failed, the thermostat may have failed ....

Do you have basic test equipment - multi-meter, are you confident enough to try a little fault finding?

 

[simond]

Turn it off, take the lid off and check to see if it has a thermal cutout, most immersions fitted in the last 9 years orr so should have one. It takes the form of a manually resettable thermostat in series with the control temp thermostat.

Immersion heaters don't necessarily blow the fuse when they die. The element can simply break and go 'open circuit'.

As described above, a multimeter and some electrical knowledge helps. Many plumbers possess neither.

Regarding how much you should pay, that is down to your contractor not an internet forum. The tradesmen here are split between those who suggest a low price (but wouldn't ever turn out for that themselves), and those who are realists. We all know one of the prime contenders for the former approach.

For what it's worth I'd charge £94 to look at it, but I'm not coming so it's just a ballpark. I only work on gear we've originally put in.

 

[UseLeSsDiYr]

Hello newboy & simond

Thanks for the quick replies; sorry, just had dinner!

newboy - I think I have a multi-meter; having had a quick look this morning, I can't see that there's a button to push in? Do I need to swicth off te main supply to use the multi-meter?

simond - I think the unit is probably over 20 years old. Regarding pricing of a job, I was just wondering what prices to expect for this diagnosis and repair; a ballpark as you've provided - thanks.

I'll see if I can take a photo of the unit once the cap is off, probably tomorrow morning, when I can switch the main supply off.

So the water heater switch with the light is ruled out?

 

[endecotp]

The switch could have failed, but it's vastly more likely that the element has gone. Unless there is something about the switch that makes you suspect it? Like a burning smell or something?

 

[Burnerman]

With situations like this, much can depend on the access to the immersion cylinder.
If it's a thermostat issue, the repair is simple and cheap.
However, if it's the element that has called it a day, it's a bit more involved. The water supply to the cylinder has to be interrupted - thats easy enough - but sometimes it's a right job to unscrew the immersion element housing from the cylinder itself. Sometimes they just wind out, sometimes they won't budge.
Certainly I wouldn't buy anything until a few checks have been carried out.
John

 

[Agile]

It is relatively easy for a DIYer to check what is wrong IF they have simple electrical testing experience and are safe to work on live circuits.

I charge a fixed price diagnostic fee.

But that varies according to where it is and when I can come. That means more in the congestion charging zone and more after 5 pm or at weekends.

Usually starting at £84 for somewhere easy to get to within 20 min by car or 30 min by public transport. But parking charges are always extra.

If the element has to be changed then a minimum of £98 plus element but that's assuming all the valves are working and the old element comes out OK within about 15 minutes.

Tony

 

[UseLeSsDiYr]

The switch could have failed, but it's vastly more likely that the element has gone. Unless there is something about the switch that makes you suspect it? Like a burning smell or something?

There are no burn marks or anything on the switch, but I'm hoping it's the switch as it's a relativel cheap and easy fix.

The switch, after 30 misn to an hour, does not get warm (very very mildly) to the touch like it used to.

I assume the fact that there's a ligt suggests the unit is OK?

 

[UseLeSsDiYr]

With situations like this, much can depend on the access to the immersion cylinder.
If it's a thermostat issue, the repair is simple and cheap.
However, if it's the element that has called it a day, it's a bit more involved. The water supply to the cylinder has to be interrupted - thats easy enough - but sometimes it's a right job to unscrew the immersion element housing from the cylinder itself. Sometimes they just wind out, sometimes they won't budge.
Certainly I wouldn't buy anything until a few checks have been carried out.
John

Do either or both replacing the thermostat and/or element need to be performed by a professional?

 

[UseLeSsDiYr]

I charge a fixed price diagnostic fee.

But that varies according to where it is and when I can come. That means more in the congestion charging zone and more after 5 pm.

Usually starting at £84 for somewhere easy to get to within 20 min by car or 30 min by public transport. But parking charges always extra.

If the element has to be changed then a minimum of £98 plus element but that's assuming all the valves are working and the element comes out OK within about 15 minutes.

Tony

I see you're in London Tony - which part?

Preferably / possibly PM me?

So to clarify, the diag starts at £84, but if the element needs changing, then you'll charge £98 + element?

 

[Agile]

Anyone who wants to contact me can phone, text or better email me from the contact details on my profile.

You click on my name or photo to see my profile.

Tony

 

[UseLeSsDiYr]

Hello again

I've eventually managed to take a photo of the thermostat.

As you can see, I don't think there is a switch to reset, so I guess I will have to perform alternative tests.

How exactly will I go about meauring the resistance (3kw heater, therefore ~19ohms?) with a multimeter? Where do I place what (black & red leads) and at what setting on the meter?

I assume I don't power off at the fusebox and have to switch ON the heater switch for electricity to flow through in order to perform this test?

If it's likely to be the thermostat, is it just a matter of switch main power off at the box, remove the brown and white leads, pull out and insert new thermostat rod and reconnect?


Thanks for any advice.

 

[jedi]

DONT/NEVER/EVER/EVER!!!! measure resistance with power going throught it.. or you will fry your gonads, and worst still you will break your multimeter.

 

[Burnerman]

Turn the electrical supply off.
To test the thermostat, apply the meter probes (set to low ohms) to test for continuity. The cables are grey and brown, because its switching the live feed.
To test the element, meter set the same, try for a resistance across the element terminals, grey and blue.
The thermostat just pulls out from its pocket.....for the element, the complete immersion heater has to be unscrewed from the copper cylinder.
John

 

[UseLeSsDiYr]

Thanks for the advice jedi!

I thought that might be the case, but I don't understand how resistance can be measured without some sort of electric flow?

So do I shutoff the main supply at the main fuse box, or will just leaving the heater switch OFF suffice?