Request for help with immersion heater

[Onoff]

Lad I know, At his French place had to get a DIGGER in and install a dirty great earth PLATE. No piddly little rods!

[richi]

On 7/4/2017 at 10:53, vivienz said:

I have tested the ohms and got zero

Are you sure? Or did you get infinity or 9.999, either of which would indicate an open-circuit.

A reading of a few Ohms would say the element is working fine.

A reading of zero would say there's a short (unless your meter is set to a high range).

[vivienz]

I'm bumping this thread as we're back in France and hoping to get our immersion heater fixed this weekend.

 

We ordered all the bits that arrived just before we left last time and have now taken out the old stat from the tank.  Please excuse me for what is a really thick question for the brains on this forum, but we've never done this before.  The old thermostat is 450mm and the new one is 270mm - does this matter?  I'm guessing that there is a reason for the difference otherwise all thermostats would be the same length, but is it one that means we need to get a 450mm version.

 

Thanks, all.

[Onoff]

When you say thermostat I'm guessing you mean the immersion heater elelement length? They do vary in length as I said previously. 

 

Can you post a picture?

 

Wasn't the one I thought it might be 470mm long? (So longer than the new one you've got and the same as the old one).

 

 

[Jeremy Harris]

IIRC, the last immersion thermostat I replaced was around half the length of the immersion heater element, so 270mm sounds about right.   That was a long time ago, though, probably well over 20 years ago now.

[A_L]

21 hours ago, vivienz said:

The old thermostat is 450mm and the new one is 270mm - does this matter?  I'm guessing that there is a reason for the difference otherwise all thermostats would be the same length, but is it one that means we need to get a 450mm version.

 

Thanks, all.

 

If the immersion heater is side-entry low down in the tank then no. I however it is a top-entry then there are some complications. If you actually mean the heating element of the immersion heater then they do not heat the water below their lowest point well and obviously the volume heated will be less with a shorter one. If you really do mean the thermostat then the shorter one will switch off when the water higher up reaches the set point leaving the water below it less warm due to stratification, although this effect may be small if the water heated is turbulent and mixes to some extent.

[Nickfromwales]

Can we have a pic of what you have already got and what you've bought . 

A lot of uncertainty here at the moment of thermostat vs element. An immersion is made up from both. 

[vivienz]

Morning all

 

Here are the photos of what's there now and what we've bought.  All the working end/access to the boiler controls are at the bottom of the tank; our access panel is located in the ceiling of the ground floor and the heater itself is in a panelled corner of the upstairs, directly behind the shower.

 

I've looked again at the French plumbing spares site and it does say that the 450mm can be replaced by the 270mm version.

 

 

[Jeremy Harris]

If it's at the bottom of the tank then it will make no difference if the thermostat is 450mm or 270mm, it will still be measuring pretty much the same temperature. 

 

For those unfamiliar with French tanks, they are often configured very differently to UK ones.  I had to repair one at a friends place we used to stay at, and found that the French ones are more like the US ones than UK ones.  The one I fixed was enamelled steel, for example, and was horizontal, rather than vertical, and bolted to the inside wall of the garage.

Edited September 4, 2017 by JSHarris

[vivienz]

We've taken the plunge and Mr Vivienz has put the replacement thermostat in and, voila, it's working!  Fingers crossed that this means no more cold showers for the time being.

 

Thanks again for all the help and guidance, all.