Immersion Heater doesn't heat enough hot water

[rollin]

I live in an apartment that is heated with electric storage heaters and has an immersion heater for hot water.

The make on the hot water cylinder is Gledhill. It heats up water on economy 7 and can also be switched on via another switch on the wall next to it.

Recently its started to not supply a great deal of hot water before running cold (about a quarter of a bath).

When the hot water runs out, I switch on the over ride circuit but no matter how long it is switched on for, it only gives out a small amount of hot water and then runs cold again. This happens even though I can hear that the water is being heated ( sounds like a kettle).

Can anyone tell me the cause of this problem and give an indication of how much it will cost to fix.

Thanks

 

[breezer]

probably needs new element or stat or both, cost, no idea what so ever, best get several quotes

 

[Paul Barker]

The cylinder might have two in if the bottom one has gone you would get a basin of hot water.

 

[kevplumb]

pound bet paul

the bottom imm is shot

 

[rollin]

The cylinder does have 2 heaters.

As I've said above, when I switch on the 24hr option I can hear the water heating up. I can also hear it heating up when the economy 7 kicks in (24 hour option switched off)

Am I right in thinking that one of the elements is for economy seven and the other for the 24hr over ride?

In which case both seem to be heating, but not enough water.

If one of the heaters has broke, is it easy to change?

Thanks for the help so far.

 

[kevplumb]

If one of the heaters has broke, is it easy to change?

in a word no
not easy but not impossible
the biggest prob i have is getting the herberts to come out
after you isolate and drain the cylinder

 

[Paul Barker]

Many times the drain off is at the far back corner and stuck. We are always having to put a length of 15mm pipe down the draw off hole (after first isolating header tank with gate valve if you're lucky, I don't usually even try them just bung the tank as a matter of course, and run hot tap 'till water stops flowing) hose on end of pipe suck for England to start it siphoning. Wait about 1/2 houyr to 1hour for it to drain, when it's drained put new drain off in place you can get to it. Get you immersion spanner, box type is best as you can brace it both sides equilateraslly and so not kink the cylinder.

When puting new immersion in don't overtighten or fibre washer splits, nip it up after you refil until it is just so, if a slight weep it should settle, overtightening is worst thing to do, end up with big leak, undertightening start with slight weap end up with dry joint. (In electrics we don't like dry joints, in plumbing we do)

Bound to be your bottom immersion.

Should have gone to speck savers.

 

[kevplumb]

nice one

 

[bab]

before changing the immersion if u know what u are doin u should check that the bottom immersion hasent got an overheat stat thats tripped or if the thermostat is faulty or if u even have 240 volts there during off peak times at the immersion. Iv even been to immersions claimed to be faulty that have the isolation switched off. NEVER asume anything.