Economy 7 Immersion power problem

[notsohandyman2012]

I recently had my immersion heater elements replaced after they stopped working. we had only used the off-peak one since we moved in (3 years ago) but had them both changed becaue they were both very bad (cracked and deformed). with both changed and tank filled we discovered the first problem;

1) connecting the boost element blew the house fuse (yes i have cartridge fuses and not trip switches, but thats a job for another time). So assuming there is one 13A fuse between the fuse box and the two switches; what is causing the one switch to blow while the other (off-peak) is fine.

2) We knew the off-peak switch has been working for the last 3 years (and i desperately needed hot water after 4 days!) so just connected the supply to the off-peak switch. the off-peak system worked for one night and we woke up to hot water. however since then we have had no more hot water. the light still comes on the switch at night suggesting the problem is somewhere between the switch and the element. we have switched the thermostat sections between the two elements and still no change. so has the cable gone wrong or did the brand new element go after just one night? or something else.

I'll describe how the system is wired because its odd (wrong) as it was probably all done at different times:
Fuse box divided into usual sections one of which is a 30A fuse which supplies the bathroom via another two 13A fuses divided into 1) Shower & Shower pump. 2) immersion supply for Boost & off-peak. Rather oddly the same 30A fuse seems to control the sockets in the bedroom too!
The Economy 7 is controlled by two switched that are "off-peak" and boost/peak/on demand. there is no timer suggesting radio signal controlled because it does seem to turn itself on and off during the night/morning.

Please help so i dont have to have the tank draine to see.

 

[stem]

Normally water heating has it's own circuit and fuse / MCB. It is not connected to the ring supplying the sockets. For one thing it will use most of the circuit's available capacity leaving little for the sockets.

I'm not really sure what you mean by "house fuse" if you mean the one in the "cut out" that feeds the consumer unit, this carries the current for everything in the home and it may be that you just had too many electrical items on at the same time and the immersion was the final straw.

Secondly the off peak heater needs a timed supply, either from a separate consumer unit wired to an off peak supply controlled by the off peak supplier, or if connected to the normal day rate supply via a separate timeswitch. (This is assuming you have a twin tariff meter of course, otherwise there is no such thing as "off peak")

It's possible that there is a fault with the "on peak" element or it's wiring inside the head of the immersion heater that is causing the fuse to blow, but under normal circumstances this would blow the 13A fuse, not the "house fuse"

Regarding the "off peak" element that has worked. It's possible that the thermal cut out has operated. It is usually in the form of a small button under the lid that is pressed to reset it. If it has tripped, lowering the setting on the thermostat may prevent it happening again.

To me it sounds like a bit of a dogs dinner and needs a good dose of looking at by a competent person and probably a rewire.

 

[notsohandyman2012]

The house has one meter with two readings which (i was told by the meter reader) is for my peak and off-peak power which switches over automatically in the night. so apparently all my flat runs on cheap rate electricity at night. however there is no visible timer on the immersion heater, just the two neon switches so the bottom element comes on at night when it "senses" cheap rate electricity, (this is shown by the light only being on after 1am even when switched on in the day).

i might be wrong about the exact wiring for the immersion as it was hard to test in the day when the supply to the off-peak circuit isn't active then. but i do know that the same switch on my circuit board (30A) controls the shower and bedroom sockets. to clarify by "house fuse" i mean the 30A fuse on the fuse box. i have an older style fuse box as opposed to trip switches. so evey time one goes it means changing it instead of a simple flick back on.

further to the origenal post we wanted to test the top element to help eliminate causes before we opt to drain and replace what are already brand new elements. so we connected the off-peak supply, which we know works as it lights up at night, to the top element which is brand new and yet to be used. And still not hot water come morining. so:
We have power to the switch,
We have tested the cable to the element,
We have switched the thermostat thingy that slides into the element and
We have tried both the elements on that supply (top and bottom).

Any ideas what we could be missing? (will have a look for that reset button on the thermostat in the mean time but we have tried two different one and they are still factory set.)

 

[Agile]

The only thing missing is a competent person!

An immersion heater is about the simplest circuit possible!

Fues, switch, thermostat and element! Just FOUR components linked by wires.

Quite apart from the danger to yourself you could risk creating a danger.

Get a professional electrician or heating engineer!

Tony

 

[stem]

OK, so you do have an off peak supply. Something is doing the switching of the "off peak" element if it's not live all of the time. Either there is a separate "off peak" consumer unit connected to the meter or a timeswitch somewhere. The immersion won't "Sense" cheaper electricity. But that's a side issue really.

More importantly, you say the "same switch" is supplying the shower and bedroom sockets. Do you mean from the same 30A fuse? Previously you said the immersion was also connected to the bedroom sockets. If all of these circuits are connected to the same fuse something is seriously amis. There likely will be other hidden dangerous work and I suggest that you follow Agile's advice sooner rather than later.

 

[notsohandyman2012]

Thanks guys. firstly all the original work was done by a plumber who sorted it all out and got the bottom element working (for one night). He recommended an electrician to sort out the wiring in my house and the top element. I cannot get one in until after the weekend so im just trying to think how to get the bottom element working again seeing as it did one for night, before it went dead. i wont do any repairs that are above my skill level, don't worry.

yes it is a simple 4 component circuit!!! and we have tested all 4 components! the Neon switch is fine (and lights up at night during off peak power so show such), the wiring and thermostat and element have all been tested with a multimeter. so this simple circuit has a problem!

yeah im on economy7 elec. so at some point i switch over, and yes i have two readings on my bill and there is a second read out/consumer unit. sorry, not to up on the actual workings of it. yes we have discovered that my fuse box for the most part is divided normally; lights, rooms, cooker etc. but the 30A fuse that supplies the shower also controls the bedroom sockets (because they went off when we shut them off to do the initial work. Although we are not 100% which fuse does the immersion, we are assuming it is the same one for the "boost" circuit atleast because thats the 30A fuse that blew, along with the 13A fuse in the socket, when we first tried hooking it up. i suspect the second supply for the off-peak neon-switch may come from a different fuse because it's not tripped at all in the last 3 years. but YES as you say i deffo need to get a pro in to sort all this out.

(all we want is a hot shower! lol)