My house uses 20kWh of electricity a day -- why so much?

Reed_Richards

Reed_Richards said:

Unplug it from the socket and see what happens.  

Follow my suggestion and the OP will find out if the tank is being heated by gas.  If the water goes cold when the immersion heater is unplugged then the tank is not being heated by gas (in which case switching to a better-insulated tank heated by gas would be a worthwhile investment).  If it stays hot then it is being heated by gas but was possibly being boosted by the immersion heater at the cost of using more electricity than necessary.

Magnolia

alexanderalexander said:

our heating/hot water is gas powered. 

So do you have a condensing boiler?

Robin9

@alexanderalexander  You have spoken about your electricity - what's your gas consumption please ?

Qyburn

JSHarris said:

They are also only rated for 10A continuous current, as that's the maximum continuous rating for a BS1363 outlet or plug.  A 3kW immersion is going to draw just over 13A for maybe an hour or two at a time, so not really safe.

That is commonly stated, and may in fact be a sensible real world limit. But BS1363 actually specifies a current of 14A tested over at least four hours and until temperature stabilises. Does the standard actually state that 10A limit anywhere?  (To state the obvious, not to be confused by the 20A rating for twin sockets, which is actually 14+6 not 10+10) 

JSHarris

Qyburn said:

JSHarris said:

They are also only rated for 10A continuous current, as that's the maximum continuous rating for a BS1363 outlet or plug.  A 3kW immersion is going to draw just over 13A for maybe an hour or two at a time, so not really safe.

That is commonly stated, and may in fact be a sensible real world limit. But BS1363 actually specifies a current of 14A tested over at least four hours and until temperature stabilises. Does the standard actually state that 10A limit anywhere?  (To state the obvious, not to be confused by the 20A rating for twin sockets, which is actually 14+6 not 10+10) 

The proof is to look at portable car charge points, the plug-in units that used to be supplied with EVs as standard equipment (but are gradually being dropped now).  These are rated at the 10A safe maximum, and also have built-in thermal sensors inside the plug (which is why they have bulky BS1363 plugs).  These sensors are there to shut down the charge point if the plug temperature rises above a set limit. The reason they have this extra protection is because these things will usually be used for hours on end, often overnight when the fire risk may go undetected until it's too late.

Given that overheating of outlets is extremely common (I've seen dozens with a burned area around the line socket over the years) it's clear that, no matter what the BS states, in practice 13A is just not a safe long duration load.  A quick web search for "13A plug overheating" will pop up many examples of overheating, often not from overload, just normal use and ageing of the connections, plus the added heat (about half a watt) from the fuse (hence the line always being the one that overheats).

Scot_39

Alnat1 said:

If the OP is using 20kWh of electricity a day then I'm assuming the main heating is gas. If so, why is the tank being heated by electricity and not gas, which would be cheaper?

Assuming that is an immersion tank heater supply - the tank will be het in part by both sources depending on the balance of thermostat settings, effective power ratings and active times etc.

Trying to cut back on gas boiler hw flow coil temps could easily shift balance to increase immersion use for instance.  Water in indirect heating "coil" at 65C will heat slower than water in same coil at 70-75C etc. To get to hse 60C tank min.

If say someone manages to only run their gas boiler a few hours per day once per day rather than simply deactivating the central heating -  the immersion will kick in at all other times for losses and for reheating tank for any significant flow in between. 

If its thermostat - the one on immersion heater is set higher - or drifted higher - than the gas heating - it will always activate first - so again could dominate any low flow regular top up heating etc. The gas would only kick in if a large flow then "overpowered" the immersion typically 3kW rating ability to maintain tank temperature and dropped tank temperature sufficiently to activate gas heating.

But I have never seen an immersion heater wired to what looks like a bog standard 13A socket.  But in theory - at least an electrician told me - he fitted quality mk sockets - were built better and more likely capable of 13A continuous.  But the BS plug spec thermal load check is iirc for over 13A - 14A?  loading.  But of course that's likely done on new clean kit and fuse connections.

I seem to remember post office had a sub 10A (9?) cap at one time due to heating issues. We sold kit and so aware.


If it is an immersion heater on a 24/7 live feed supply a switch or a 16A rated spur timer could be used to allow user time control.

A simple check would be to switch it off at the HW spur - assuming their is dedicated supply isolation for hw immersion-  at fuse box / consumer unit.

Then see what happens to hw temps and daily electric consumption.

Not all gas boilers heat hot water - not all that do will heat hot water if a fault develops. But now heating likely in use may be difficult to tell from consumption.

QrizB

JSHarris said:

Qyburn said:

JSHarris said:

They are also only rated for 10A continuous current, as that's the maximum continuous rating for a BS1363 outlet or plug.  A 3kW immersion is going to draw just over 13A for maybe an hour or two at a time, so not really safe.

That is commonly stated, and may in fact be a sensible real world limit. But BS1363 actually specifies a current of 14A tested over at least four hours and until temperature stabilises. Does the standard actually state that 10A limit anywhere?  (To state the obvious, not to be confused by the 20A rating for twin sockets, which is actually 14+6 not 10+10) 

The proof is to look at portable car charge points, the plug-in units that used to be supplied with EVs as standard equipment (but are gradually being dropped now).  These are rated at the 10A safe maximum

But most of those are designed in China, and the Chinese GB 2099.1‐2008 plug is only rated to 10A. I would assume that the 10A rating of the plugin charger is a "lowest common denominator" standard for the intended market, unrelated to the UK 13A plug spec.

Scot_39 said:

But I have never seen an immersion heater wired to what looks like a bog standard 13A socket.

I'm no electrician but I understand the wiring regs strongly discourage using plug-and-socket connections for fixed equipment.

Arguably, most white goods (washing machines, fridge-freezers etc.) should be wired to fused connection units rather than being plugged into a 13A socket.

JSHarris

QrizB said:

JSHarris said:

Qyburn said:

JSHarris said:

They are also only rated for 10A continuous current, as that's the maximum continuous rating for a BS1363 outlet or plug.  A 3kW immersion is going to draw just over 13A for maybe an hour or two at a time, so not really safe.

That is commonly stated, and may in fact be a sensible real world limit. But BS1363 actually specifies a current of 14A tested over at least four hours and until temperature stabilises. Does the standard actually state that 10A limit anywhere?  (To state the obvious, not to be confused by the 20A rating for twin sockets, which is actually 14+6 not 10+10) 

The proof is to look at portable car charge points, the plug-in units that used to be supplied with EVs as standard equipment (but are gradually being dropped now).  These are rated at the 10A safe maximum

But most of those are designed in China, and the Chinese GB 2099.1‐2008 plug is only rated to 10A. I would assume that the 10A rating of the plugin charger is a "lowest common denominator" standard for the intended market, unrelated to the UK 13A plug spec.

I've owned three EVs, none of the portable charge points they were supplied with were made in China.  My current EV has a portable charge point that was made in Austria, the one that came with my second EV was made in Germany and my first EV had one made in Japan.  All had large plugs fitted with thermal sensors.  All were limited to 10A.  TBH I've never seen an EV portable charger, supplied with a new EV, that has been made in China (although there are lots of Chinese junk ones on Amazon etc).

Anyway, all of the burned and overheated outlets I've seen over the years have been UK spec ones, more often than not outlets in kitchens that have been used to power toasters, kettles, etc (in the days when kettles were close to 3kW, before the EU power reduction was imposed).  I've also seen some burned outlets in living rooms, where they've been used to run electric heaters.  At one time I could pretty much guarantee that any periodic inspection I did would throw up a defective outlet, almost always from overheating.

The evidence that these plugs and outlets get hot and degrade badly when run at close to 13A is overwhelming, as the quick web search I suggested early shows.  Certainly age-related degradation plays a part, but that is applicable in this instance, as both the unswitched outlet and plug in the OP's photo look to be fairly old.  I doubt that either is safe to run for any length of time at the just over 13A that a 3kW immersion heater can draw.  That immersion should be on a proper switched fuse outlet, ideally one with an integral time switch.

chris_n

I rather suspect that was originally a fused spur but someone 'clever' replaced it with a socket so they could use a plug in timer.

JSHarris

chris_n said:

I rather suspect that was originally a fused spur but someone 'clever' replaced it with a socket so they could use a plug in timer.

I rather think you may be right, given the plug-in time switch sat next to it!