Water heater problems

The water heater here at the house we look after has stopped working a few times. Each time it has been that the wiring inside had burnt out. On one occasion, it had deposited a lot of carbon on the element, which when cleaned off and the wiring replaced, worked fine again.

Our water tank immersion heater cut out once, don't know why, and the culprit was a thermal protection device. It was a tiny tiny button on the end of the heating element, so on the tank and I had to remove a cover to get at it. I was at the point of thinking the element had gone, but luckily all that was needed was to push this button back in until it clicked.

As for the electrical problems, using a meter at the tank would tell you if there was an electric supply issue.

Update. Thanks to Ian for all his help. Electrician came yesterday and ruled out any problems with the meter cabinet. So now the guilty party is likely to be the water heater itself, which is concealed behind a panel. Panel will be removed today to reveal who knows what. The plot thickens!......

Yes but do not add a fuse if there is not one already there.

When the new consumer unit was added all replaced circuits should have been disconnected from the old consumer unit. However a lazy electrician might have just taken the fuse out. If you add a fuse you might make wires live which should not be, or feed circuits from two sources so that you think they are off but they're not.

You are getting into an area where a competent electrician should advise.

Again, Ian, thanks very much. So I should turn off via black switch on left, remove entire cartridge, and see what fuse is in there, and replace?

>No "reply" option at end of your last post.

I think you tried to reply before the 15 minute posting delay was up.

I found the breakers here. The product info says "Complete drawer removal allows the fuse cartridge to be changed when not turned on."

So somehow the bit attached to the handle pulls out revealing a cartridge fuse. Which may have blown.

Hi Sheila,

I'm not familiar with Merlin Gerin stuff but both look like they are not MCBs but somewhat ancient holders for conventional fuse cartridges which are ejected by pulling down the lever. It could be that one is for the water heater - 16/20A and one is for the control circuit - under 10A.



>If you look at photo no. 3, the two switches on the right beside the on/auto/off switch - are they in the correct position and could one of them be faulty?

Hi Sheila,

I can't see them well enough but the earth leakage trip (interrupteur différentiel) is at the left hand side so I would guess that they are circuit breakers (disjoncteurs divisionaires) in which case "UP" means "ON". A fault is unlikely but not impossible. Do they have any note - even scribbled in pencil - about what they feed?



Thanks for taking all this time, Ian. The water tank is located behind a board which has been screwed in, so I assume there is no need normally to access it. However, the house has been empty for some time. If you look at photo no. 3, the two switches on the right beside the on/auto/off switch - are they in the correct position and could one of them be faulty?

<I assume there's no on/off switch on the water heater itself?

Not normally, but there is the thermostat which could be maladjusted or inoperative. Heating element failure is not impossible although usually there are three elements to cater for triphase wiring which will be wired in parallel for monophase and at least one of them should work.

>Water heater presumably is turned off (for holidays and other absences) by switching le >contacteur from auto to off?


If you get it going, run the hot water for some time to flush it out, in case there's any legionella bacteria lurking in the water.

Hi Ian and thanks again. I've replaced the four 16 amp fuses with new ones. I don't The other two are 10 amp and I don't have any, so I'll drive over to nearest town tomorrow and get those 2 replaced. Aside from that, I can't see anything else to replace. The HC/HP switchover does seem to be working. Meter reading shows a consumption of 8kwh on the HC meter since 31/3/2012 - which would reflect the fact that only the fridge/freezer is running during the night. Very frustrating. I assume there's no on/off switch on the water heater itself? Water heater presumably is turned off (for holidays and other absences) by switching le contacteur from auto to off?

Hi Sheila,

Looking at your photos the water heater on/off/auto switch would appear to be the one at the right-hand of the old panneau éléctrique. It's likely that its mains input is either one of the 6 fuses or possibly one of the two circuit breakers. Check to see if one of the 16A/20A fuses has blown, if so replace and retest. It's also possible that there is a 2A fuse feeding the changeover relay - if this has blown the HC/HP switching won't work.

If this doesn't work I should call in a "spark" to investigate the EDF control wiring and the on/off/auto switching. If you can read French circuit diagrams here's a useful one:

Hi Ian and thanks for the reply. We have HC/HP. I have experimented with leaving the panel switch set to both "on" and "auto", but nothing is happening. I was wondering if there was something more I need to do, such as turn off the power at the panel and turn back on, or what? This is all new to me. I was used to an immersion heater with an on/off switch, and basin/bath setting!

Hi Sheila,

It may have been wired for "Heures Creuses/Heures Pleines" whereby the water heater is switched on for several hours overnight and for a short "top-up" period during the day. This switch-over is actuated by a signal sent over the power line and received by a box in the EDF meter cabinet. This box sends a relay control signal to a device in or near the consumer's panel which is usually marked "1", "0" and "Auto". "1' means the water heater is on, "0" that it's off and "Auto" that you leave it up to EDF to switch on when the electricity is cheaper.

Are you on the HC/HP tarif? If so you'll have the requisite box in the EDF meter cabinet. If you've changed to another tarif then you'd better leave the water heater control switch set to "1" (On).