Imersion Heater Problems

[Brucewright]

Hi
Wonder if someone can help me. I have an immersion heater which was new in 2005. It is for all our hot water and works via a timer I fitted in 2005. Everything was great until 3 day's ago wife said water was hot as hot as it was and it took ages for the hot water to come through. I checked the timer and it's fine. checked across the I/H and have 240 volts (L&N). I by passed the timer just in case and I can hear the I/H hissing away so something is happening. I check the stat and with a neon have live both sides of it however I thought that when I turned it down or up I should hear a click and it turn off (if water already hot) or no if the I/H required heat. What ever i did the neon stayed live both sides. My first though was the stat had broken but then as it's live all the time would not the problem be that the water is too hot??

The next day we still had just warm water even though I left it on all day.

PLease can someone advise me on what to do. Having just been made redundant I don't want to spend loads of money when A) I don't know what the problem is and B) I can't afford it.

Cheers
Bruce

 

[conny]

was hot as hot as it was

I take it this was meant to say NOT as hot as it was?

If so but you are getting 'warm' water through it sounds to me that you may have a dual element and one side has failed.
Not being an electrician, (elec fitter), I think you would be wise to wait a short while before a qualified spark comes on and points out what you need to do to verify this.
Good luck and let us know how you get on.

Welcome to the forum BTW.

 

[ericmark]

Let me re-cap on what you would have with an immersion heater.
1) An isolator with maybe a fuse and in modern house may be two way switching both up-stairs and down my second one was in Kitchen.
2) Time clock with override.
3) Inside immersion heater two thermostats one which controls the temperature and second to switch it off is first goes wrong re-set has to be manual if it is re-settable at all.
4) Element
From what you say I would expect either it has over heated and the thermostat needs replacing or the element has failed.
If it has overheated without an external heat source then even if there is a reset button the thermostat needs replacing. If however like in my parents house a back boiler or similar could cause overheating then by all means reset it.

Since you say "hissing away" I would expect to find the element gone. Have you got RCD protection as normally with RCD protection if the element goes the RCD will trip. Here where I live we have soft water and kettles etc last for years but in hard water areas they don't last as long. I am told you should keep them quite cool to avoid too much lime? Often you can rip the cylinder trying to remove the elements and you are most likely better to get someone in. A rare job up here so not much experience but easy for a spark to test I just clip on my clip on amp meter and very quickly I will know what is wrong. Warning if it is the element do switch off as it could give you a shock if there are any faults in the earth.

 

[ColJack]

neon screwdrivers are the devils tools..
they're next to useless..

throw it away and get a decent insulated terminal driver and a multimeter instead..

you say you have 240V, but for all you know it might only be 50V and the neon would still light..

by "timer" do you mean a proper immersion timer or an economy 7 type effort? with a "boost" switch for toppin up in daytime use?

if it's the latter then check your fuseboard for any tripped breakers of blown fuses.. might be the eco 7 breaker has tripped..

 

[Brucewright]

Thanks for all the reponses. for clarity I checked across the element and got 240V (well 236V) with a muilti meter. I only checked both sides of the stat with the neon which seem to stay alight what ever I did with the dial (Temp up and down).

The timer is an electronic one which has worked fine for 3 years so I'm happy it's not that. I only have one element which is top entry.

Cheers

 

[ColJack]

so no economy 7 then?
only 1 fuseboard and no storage heaters in the place?

you need to re-check the thermostat with the multimeter, the neon can be missleading...

check with respect to earth..
report your findings..

photo's of the immersion and the timer would be helpfull, with covers off so we can see the connections..

 

[flameport]

First disconnect the mains supply.

Using the multimeter set to ohms or continuity:

1. Test across the L and N terminals of the heater element. Should be a low reading (probably between 10 and 30 ohms). If not, the element has failed.

2. Test between the L terminal and the metal hot water cylinder,
and between the N terminal and the metal hot water cylinder.
Any reading indicates the element has failed.

3. Test across the two terminals on the thermostat. Adjust the thermostat. When set to a high temperature, the reading should be 0 or very low. When set to a low temperature, there should be no reading.
If not, the thermostat needs to be replaced.

Also check the connections for burnt or corroded wires/terminals.

 

[Brucewright]

Many thanks for your help. Here are my findings bear in mind I only had a cheap digital multi meter but this is what I found:

1) disconnecting everything across the element (L to N) 7.03M ohms.
2) L element to earth (tank) 1.1 K ohms
3) N element to earth same reading.
Note I did this on the continuity reading as well and got no buzz at all so I guess the element is at least no leaking to earth.
Tested across the stat and on the ohm setting got 0 whichever way I turned the dial. I also put on Continuity as well and it just buzzed all the time which ever way I turned the heat control knob.

What do you think. I have an issue anyway as I think the stat is 18 inches long and I can only get 9 inches out the top due to the slope of my roof.

What a nightmare.

Cheers

 

[ColJack]

what's the minimum setting on the thermostat though? if it's 50 or so then that's quite hot so unless the water is hot it won't click out..

do us a photo of the fuseboard area, and the immersion heater controls and connections ( with covers off the immersion )

that element reading seems off..
shouldn't be in the Mohms range, should be in the low ohms range.