Overnight economy 7 water heating stopped working

[jpxdude]

Hi All

Please forgive my noobiness as I don't really understand much about plumbing etc.

In my flat, I have an Elson Coral E MF 150 litre immersion water heater, and since the start of November, we are getting no hot water overnight.

I've lurked around these forums a little to try and diagnose the problem myself, but my boxy heater looks really different to the more dome top immersion heaters others have.

Things I've checked so far:

* Boost heating is working fine, we stick it on for 2 hours odd every day now.
* Tested our overnight storage heating just in case there was a general problem with Economy 7 electrics, but this works fine.
* Checked our electricity box, and everything seems to be in the right positions
* Curiously, where our off peak switch is in the area near the water heater, red lights appear above it to show that it does trip to Economy 7 mode around midnight, but the immersion heater unit remains cool and makes no noise.

Based on the above, I was just wondering if any of you nice folk have any recommendations, things to try, parts needed, and/or plumbing recommendations (N9 North London area)? It would be so very much appreciated!

Thanks a lot for your help!

-J

 

[OwainDIYer]

Usually there are two immersion heaters on the tank.

If you've got an upper and lower immersion, the overheat thermostat may have tripped on the lower immersion (if it's fairly new - older ones won't have overheat stat). There should be a reset button if you remove the cover to the immersion heater terminals. CAUTION live terminals will be exposed - switch off at mains first. Or the element or thermostat has failed. Thermostats can often be replaced separately without draining the cylinder. Replacing the element means draining the cylinder.

If you've got one immersion heater at the top of the cylinder then it will probably have a long element for off-peak heating and a short element for boost; the long element may have failed.

If you have an ohmmeter you can test the resistance of the elements.

 

[picasso]

It will be the stat or the immersion heater, when the heaters go they normally trip the electrics so worth checking that the stat is working or not, if you are comfortable working with electricty you can check it with a meter.

 

[jpxdude]

Thanks for the reply both. I'm honestly clueless with this so not sure where and how to check these things. Would it be prudent to get a plumber in and will they check the electrics out as you've mentioned as well?

Is there anything relatively simple I could check myself? Thanks again for your help!

Untitled

• jpxdude
• 20 Nov 2012
• 1

Untitled

• jpxdude
• 20 Nov 2012
• 1

Untitled

• jpxdude
• 20 Nov 2012
• 1

 

[jpxdude]

Hi all,

Further to my issue raised above, our boost heating stopped working yesterday so finally called out someone to look at it.

When they opened the upper cover for the boost/on peak immersion heater, it was all rusted and water seems to have gotten into all the wiring, so he deduced that this would need replacing.

Upon checking the lower cover for the off peak heating, he spent a while using what seemed like a multimeter to check the electricity, and kept switching the off peak switch on and off. I explained that the off peak doesn't activate until about 1 am, and he said that is probably why he couldn't get a reading :-/

He mentioned that on the lower off peak cover, that the reset switched had fallen out which would control the temp cut off. He said he reseated it so 'in theory' it should work. I was wondering if this sounds right at all?

He then went off saying that they would need to order a part for the immersion element for the on peak, but the off peak 'looks fine'.

If anyone could offer their opinion on this, it would be most appreciated! Thanks in advance all.

-J

 

[matt1e]

If anyone could offer their opinion on this, it would be most appreciated! Thanks in advance all.

I agree the top element req replacing
As for the bottom one, with the cover off it should have taken no more than a minute to confirm the operational capability of the unit using a multi meter
Telling you "In theory it should work" isn't good enough, they are hardly complicated circuits

Matt

 

[jpxdude]

Thanks matt1e, I did think it was weird when he said that...

Regardless, the hot water did come on overnight, but the next night it didn't . At 4am, I had to open the bottom cover and press the temperature cut/off reset switch thing again, and then it came on, and ran for about 4 hours I had to also do the same thing this morning, but it appears that the hot water only heated for about 30 minutes before switching off again...

Is there a reason that this switch is continually tripping?

Thanks again for all your help everyone!

 

[OwainDIYer]

The bottom thermostat isn't seated properly in its cylinder and isn't registering the water temp. The water overheats and the reset stat trips.

Or the heater may be scaled up and the heat isn't dissipating into the water. You are in London, after all.

 

[matt1e]

Change the bottom stat ( inexpensive)
If it keeps tripping out after changing it then its likely due to scaling
Matt

 

[jpxdude]

Thanks for the reply both!

Since writing this, tonight our overnight heating has completely conked out now I pressed the reset button and this just stays stuck in position, but the heater is not making its usual noises when its meant to kick in around 1am. I had a look behind the cover and don't see anything obviously wrong, slight buildup of scaley stuff I guess and one rusty screw where the green wire is. I have attached a picture of it, not the two red wires going out of the picture above are connected to the reset switch. I was wondering if this looked normal to you?

I also finally received a quote to replace our boost immersion heater which is approximately £200 for parts, and labour for first hour, about £80 for every subsequent hour spent. Does this sound reasonable for the job or am I being ripped off?

Thanks in advance for your help again!

Untitled

• jpxdude
• 29 Dec 2012
• 1