Water Heater tripping fuse on timer

jackattack95

Hi All, out of the blue my water heater (all electric) has started tripping the fuse when on timer. If I put it on using the "boost" function (outside the specified timer times) there is no issue, only when on timer. Any ideas?

fenwick458

the boost function will be using the top element (which is still ok) and the bottom element is likely faulty and will need replaced, or if you're lucky could just be a cable fault between the timer and the immersion

Section62

jackattack95 said:

Hi All, out of the blue my water heater (all electric) has started tripping the fuse when on timer. If I put it on using the "boost" function (outside the specified timer times) there is no issue, only when on timer. Any ideas?

Is this an immersion heater on a hot water cylinder?

If so, you may have a dual element system with a large element to heat the water over night and a smaller element to provide the boost function.

If the "fuse" is a RCD on the consumer unit then it probably means the boost timed element has developed a fault, although the common faults that occur with immersion elements typically trip the RCD whether (timed) power to the immersion heater is on or off.

If the above doesn't describe your situation then we'll need more information, perhaps some pictures, to help you work out what is happening.

jackattack95

Section62 said:

jackattack95 said:

Hi All, out of the blue my water heater (all electric) has started tripping the fuse when on timer. If I put it on using the "boost" function (outside the specified timer times) there is no issue, only when on timer. Any ideas?

Is this an immersion heater on a hot water cylinder?

If so, you may have a dual element system with a large element to heat the water over night and a smaller element to provide the boost function.

If the "fuse" is a RCD on the consumer unit then it probably means the boost element has developed a fault, although the common faults that occur with immersion elements typically trip the RCD whether (timed) power to the immersion heater is on or off.

If the above doesn't describe your situation then we'll need more information, perhaps some pictures, to help you work out what is happening.

Thanks both. Yes attached an image of the manual, looks to be a dual element system (pulsacoil apa 4140) so would make sense if the Off-Peak immersion heater has developed an issue and the on-peak is still working.

jackattack95

jackattack95 said:

Section62 said:

jackattack95 said:

Hi All, out of the blue my water heater (all electric) has started tripping the fuse when on timer. If I put it on using the "boost" function (outside the specified timer times) there is no issue, only when on timer. Any ideas?

Is this an immersion heater on a hot water cylinder?

If so, you may have a dual element system with a large element to heat the water over night and a smaller element to provide the boost function.

If the "fuse" is a RCD on the consumer unit then it probably means the boost element has developed a fault, although the common faults that occur with immersion elements typically trip the RCD whether (timed) power to the immersion heater is on or off.

If the above doesn't describe your situation then we'll need more information, perhaps some pictures, to help you work out what is happening.

Thanks both. Yes attached an image of the manual, looks to be a dual element system (pulsacoil apa 4140) so would make sense if the Off-Peak immersion heater has developed an issue and the on-peak is still working.

Image attached below: 

Section62

jackattack95 said:

Thanks both. Yes attached an image of the manual, looks to be a dual element system (pulsacoil apa 4140) so would make sense if the Off-Peak immersion heater has developed an issue and the on-peak is still working.

Ok, so a packaged system incorporating a thermal store, which is more complicated than the traditional hot water cylinder set up.

Which means it could be a faulty element, or a fault has developed in the control system.

You'll need to get someone to take a look at it who knows what they are doing with PulsaCoil systems, rather than someone who will swap out a few parts and hope for the best.

jackattack95

Section62 said:

jackattack95 said:

Thanks both. Yes attached an image of the manual, looks to be a dual element system (pulsacoil apa 4140) so would make sense if the Off-Peak immersion heater has developed an issue and the on-peak is still working.

Ok, so a packaged system incorporating a thermal store, which is more complicated than the traditional hot water cylinder set up.

Which means it could be a faulty element, or a fault has developed in the control system.

You'll need to get someone to take a look at it who knows what they are doing with PulsaCoil systems, rather than someone who will swap out a few parts and hope for the best.

Got it, thanks for the help!

grumbler

Section62 said:

jackattack95 said:

Thanks both. Yes attached an image of the manual, looks to be a dual element system (pulsacoil apa 4140) so would make sense if the Off-Peak immersion heater has developed an issue and the on-peak is still working.

Which means it could be a faulty element, or a fault has developed in the control system.

Can one just disconnect the heating element (both live wires) and see if the problem still persists? If not, it's the heating element to blame.

Section62

grumbler said:

Section62 said:

jackattack95 said:

Thanks both. Yes attached an image of the manual, looks to be a dual element system (pulsacoil apa 4140) so would make sense if the Off-Peak immersion heater has developed an issue and the on-peak is still working.

Which means it could be a faulty element, or a fault has developed in the control system.

Can one just disconnect the heating element (both live wires) and see if the problem still persists? If not, it's the heating element to blame.

Do you know how the PulsaCoil control circuits respond if one or both of the immersion heaters are taken out of circuit?

I don't.  Which is why I suggested the OP should get someone in who knows what they are doing, rather than someone who would have a guess and hope.

grumbler

I know, it's not everyone's cup of tea, but all electric diagrams are there - in the manual. And, as I expected, it's absolutely clear that the control circuit just controls the relays switching the heating elements on and off.

Section62

grumbler said:

I know, it's not everyone's cup of tea, but all electric diagrams are there - in the manual. And, as I expected, it's absolutely clear that the control circuit just controls the relays switching the heating elements on and off.

Great.

Now does that information allow you to guarantee that the heater element is to blame (and nothing else), before the OP shells out for a replacement element and someone to fit it?

IMV, the answer to that is 'no'.  The fault has not been positively identified.  And the assumption could unnecessarily cost the OP the price of a replacement element plus labour to drain the water off and fit it.

Hence my advice to get someone in who knows what they are doing.