hot water tank not heating

[pedro1888]

my hot water tank not heating,when mercer switch on for overnight use.Keeps tripping RCD box.where is the likely fault.thanks pedro1888

[terence7556]

rcd trips because of earth leakage fault so electrical fault is possible cause
is water leak present, any stains? near the spur
after that it may be the element (s)
what is a mercer switch?

[LizB99]

We had exactly the same thing happen to us - the element in the tank had blown, and tripped the fuse box everytime we tried switching it back one. The tank has to be drained of water, then a new element fitted. When we looked at the old one, you could see where the limescale had eaten away at the metal. If your not sure about doing it yourself, get a good plumber to sort it for you.

[gucciman]

job for an electrician probably, most heating engineers/plumbers wont touch the electrical side anymore due to all the govt legislation and regulations/ having to be part p approved etc.
some of the bigger firms who offer a complete service would do it but you pay a premium with them.

[burnhal]

Changing an immersion heater is a doddle if you are confident working with electrics. First job ALWAYS is to ensure the mains supply is isolated at the consumer unit.
If the heater is mounted towards the top of the tank then you dont need to go through the rigmarole of draining the whole tank- turning off the incoming mains water then turning on all the hot taps til they stop is generally enough.
You will likely need to get the old one out first to see what length it is before buying a new one. You can get the right sized ring or box spanner from B and Q. Short sharp jerks on the spanner or a few good clouts on the spanner are generally enough to loosen it enough to start unscrewing- though it is quite easy to crease the top of the tank if the heater is mounted at the top of the tank
Read through this
http://www.ultimatehandyman.co.uk/plumb_immers ion_heater.htm
If you dont feel confident after reading that then dont!!

[terence7556]

i changed an element on a friends cylinder once and the elements were hard to start turning, we were advised to keepthe water in at the level of each element untill we 'cracked' the nut, as it is not hard to damage the sidewalls. if it is very stiff apply heat i.e. hairdrier/paint stripper blower but the nozzle will get hot and its easy to burn the pre foamed insulation
the elements are standard length and the choices involve built in thermostats. the top one was sound and the lower element that does most of the work was rotten/corroded was the problem. it was a pig to drain as well and the spanners we used we threw away as the pressure we exerted buckled them
not a hard job but can be time consuming as its probably your first try
my advice is quite different from burnhals in some ways but give it a go and use which ever method you feel comfortable with. let us know how it goes, good luck

[gselectrical]

Yes definatley the element if your in the northwest please get in touch water heaters are my speciality www.waterheaterexpert.co.uk