Using the central heating / immersion circuit for a different purpose??

[Mr.B]

Just a quick one if I may ....

Having a combi boiler fitted and taking out the traditional hot water cylinder along with its immersion heater.

The house was built in 1996 and has a pretty conventional wiring set up - consumer unit with up and down lights and up and down ring mains. In addition there's a 16 amp MCB in the consumer unit that is marked "Central Heating' and supplies both the immersion heater AND the power to the heating timer/pump /boiler.

My question is this ..... when the HW cylinder (and immersion heater) is removed the switch and cable that supplied the immersion heater will no longer be used. Is it permissible to use that circuit to connect a 40 or 80 watt Dimplex tubular heater which is proposed to provide some heat in the airing cupboard? The Dimplex comes with a three pin plug pre-fitted but I guess it would be OK to remove the plug and wire it into a fused connection unit with flex outlet.

That's it really. Although I was a bit surprised to see that the one 16amp circuit fed both the heating AND the immersion heater ... perhaps that's entirely normal?

Anyway, thanks in anticipation .

 

[Harry Bloomfield]

That's it really. Although I was a bit surprised to see that the one 16amp circuit fed both the heating AND the immersion heater ... perhaps that's entirely normal?

No it's not normal, though not that unusual for the heating supply to be tacked onto another circuit.

The simple way, is to replace the what ever wiring accessory, is in the airing cupboard supplying the immersion heater, with a 13amp socket. Then plug your Dimplex into that.

 

[Mr.B]

Yes I thought that would be the obvious option but then had doubts about having a 13 amp socket with a Dimplex plugged in - on a circuit that was identified in the consumer unit as "Central Heating" and that a socket outlet could be used to plug a variety of stuff into it .... not related to central heating.

 

[davelx]

Yes I thought that would be the obvious option but then had doubts about having a 13 amp socket with a Dimplex plugged in - on a circuit that was identified in the consumer unit as "Central Heating" and that a socket outlet could be used to plug a variety of stuff into it .... not related to central heating.

Change the label!

 

[Mr.B]

Change the label!

Is that a legitimate option? What would you write on a new label instead? ... " Central Heating and socket outlet in airing cupboard " ?

I somehow can't imagine that receiving the approval of a future sparks looking at the unit ... but, obviously, I could be wrong. I often am.

 

[Harry Bloomfield]

I somehow can't imagine that receiving the approval of a future sparks looking at the unit ... but, obviously, I could be wrong. I often am.

There is nothing really, to disapprove of. A single socket, on a 16amp MCB, is simply a radial circuit - Just label the circuit appropriately.

Usually, the boiler would have it's own, separate, 6amp MCB, but many are supplied from the socket circuit, via a fused spur, using a 3amp cartridge fuse.

 

[Murdochcat]

Is that a legitimate option? What would you write on a new label instead? ... " Central Heating and socket outlet in airing cupboard " ?

Adding such a label on the CU is to be applauded but a spark would check if working on said circuit

 

[JohnD]

"Boiler, and airing cupboard"

 

[Mr.B]

All the above received with thanks. Appreciated.

Sorry for delay, I don't seem to get email notifications despite ticking the box.

Does the panel have any thoughts about what size tubular heater would be needed to warm the cupboard sufficiently to dry the towels after showering? 750mm x 700mm x 2300mm high. The present insulated cylinder and associated piework definitely dries the towels nicely every day.

I'm thinking that to have a small radiator PLUS a tubular heater is a bit overkill. My thinking was that the rad only works in the winter but perhaps the tube heater is the better solution all year round. Donr know how much a 40 or 60 watt heater costs to run?

 

[Harry Bloomfield]

Donr know how much a 40 or 60 watt heater costs to run?

Per hour = cost per KwH unit, divided by 1000, then multiply by 40 or 60.

 

[JohnD]

It's well worth having a thermostat on the wall to save on electricity. Modern electronic ones are usually rated at about 3Amp, but the older mechanical rotary "click" ones are often 15A. I have one of those in my garage for the frost prevention heater.

If you are lucky enough to have solar panels, you can use a timer to turn the heater on between about 9.30 and 4pm

 

[ericmark]

Personally, I am glad we still have a cistern and immersion heater, saves us a lot of money, however if you think there is no way in the future you will have solar panels or an off-peak tariff then there is no reason not to reuse the supply for other things.

Personally, the supply to the central heating and the freezers is now taken directly from the inverter, so loss of grid supply will not result in freezers defrosting or central heating not working. Nothing else will work, but I will not lose food, or heating.

The splitting of power in 1996 up/down is a surprise, most houses built then were spit side to side, three reasons:-
1) the loop impedance was better.
2) no need to run cables up/downstairs if one circuit failed.
3) needed less cable.
It was only when we started to use RCD's, and we wanted the lights and sockets in each room to be on a different circuit, that the up/down split came in. today with RCBO's we have returned to side to side again. (If designed, rather than this is the way we have always done it attitude)

Hard to consider the future, I also ripped out the cylinder in last house, I wanted the room, made it into a bedroom for daughter so she did not need to share, and still feel it was the right thing to do, having a dedicated boiler of domestic hot water (Main 7) worked well, including having a mains pressure shower. Now both boilers ripped out and a combination boiler fitted instead. And same with parent's house, the tanks started to leak, so combi boiler used, resulted in loss of power shower, and they had a radiator in the old airing cupboard, so would still dry clothes.

There are pros and cons to the change, the main problem was the delay getting hot water, the boiler had two options, eco on or off. Eco off and water at taps faster, but shower would go from cold to hot back to cold and finally hot again. With Eco on, the taps had to be turned full on to get hot water.

 

[Mr.B]

Per hour = cost per KwH unit, divided by 1000, then multiply by 40 or 60.

Thanks - i checked and my figure for Kw/h unit is 23.06, divided by 1000 and multiplied by, say, 60 equals 1.3836. I presume this is pence per hour.

So that would be 1.3836 pence multiplied by 24 to give 33.2 pence per 24 hour period ... and 33.2 multiplied by 7 equals £2.32 per week.

Does that sound right?

To get back to my uncertainty re. how to dry those darn towels ..... it's been suggested by the good lady here that a heated towel rail in the bathroom would be the glaringly obvious answer rather than the airing cupboard


Regarding John's suggestion of a thermostat, if I went for a wall mounted 'dual fuel' towel rail in the bathroom (supplied by the central heating as well as mains electric), then electric to the towel rail would be via a switched FCU taken from the adjacent RCD protected ring main (outside the bathroom on the landing) and a flex run through the stud wall into the bathroom and straight into the towel rail element ... and I suspect that a thermostat doesn't fit into the equation now that the heater would be in zone two within the bathroom ? I clarify the last point by saying the towel rail would be 200mm from the end of the bath but is rated as IP55 which I believe permits it to be so close to the bath.

I'm uncertain whether the installation of an electric and water heated towel rail in the bathroom has to be notified to the local authority. Presumably a registewred sparks has the means to deal with such things provided it was all in accordance with regs.

Perhaps some sort of timer would be appropriate rather than a thermostat but am unsure how this would be included in the scheme. Regarding the siting of the towel rail my understanding is that it is permitted to be 200mm from the end of the bath as long as it IS rated thus. but, again I say, I could be mistaken .... as stated I often am and the older I get the more often that's the case.

Thanks again for the help offered.

 

[ebee]

The splitting of power in 1996 up/down is a surprise, most houses built then were spit side to side,

Hi Eric, I am a bit puzzled by that statement if I understand it correctly.
It might vary a lot by area and local traditions though.
What I have found in my locality is domestic properties split to two basic floors arrangement for electrics, purely up and down, indeed many kitchens sockets on downstairs circuits (usually rings) and it seems like only yesterday that electricians were being advised to consider putting kitchen sockets on the same circuit as bedrooms to spread the loads a bit.
The electrical cut out and meter, by tradition, is usually based in the middle of the house in older properties but in mine is at the back in the kitchen.
There has long been a slavish tradition of "it`s always done this way" to any circuit design and indeed any installation design by electricians and DIY alike irrespective of the merits and such of different ideas, in fact to the extent of "No it`s wrong to do it that way because it`s always done the other way" with no logical basis for the statement on that particular installation.

With my home I split the lighting the then traditional up/down configuration basically and the sockets I did front/back style much to the surprise of many electricians - Actually I split to 3 not 2 basic circuits being Kitchen/Back/Front for sockets anyway but I was going against the flow as perceived by many of the Up/Down mantra.
I am not aware of any massive change in thinking of the Up/Down thinking to Front/Back (or Left/Right) thinking or vice versa around 1996 even on various regs courses either but I do remember that occasional suggestion of a separate power circuit for kitchens (or combined with lightly loaded areas like bedrooms).
I also remember some of the time served guys stating "Oh yes that could be a good idea I think" whilst a few of us had been doing so for years.
Like I say, the thinking might have varied from area to area and part of that might be due to the age of houses , around here thare are a lot of homes that were built in 1910 +/- a few years .

To some of us in my generation the 1960s houses are till thought of as "The New Houses" and owt built in the last 30 years say as "Those shoebox houses that ours will outlast" .

Some perceptions can be almost impossible to shift, even amongst electricians.

 

[ericmark]

I think collage lecturers can make a huge difference to the thinking of local electricians, if they give reasons to their students showing why something should be done, new practices can start in the area and student report back to their masters.

The guy who locally did the C&G 2391 etc, would tell students to test for figure of 8 with ring finals, I have looked at BS7671 and can't find anything to say should not have a fig of 8, but that one lecturer got everyone testing for a fig of 8.

But in general, my post is to make people think, rather than do this or that because we have always done it.

The big problem with DHW is to fill a bath fast, we needed 22 or 28 mm pipes, with an instant heater it does not matter how big the pipes are, the heater limits flow, so even 12 mm would likely supply the same amount of water as 28 mm, however having the larger pipes means we need to run more water each time we want hot water, so in my house I can nearly fill a bowl of water before I get hot, and add the delay heating the boiler, over a bowl full of water.

I have considered a heater at the kitchen sink, but in the main we don't really need hot water at the sink, mother house boiler in the kitchen, so when combi fitted it was actually faster getting hot water. But even if water is switched off here, it takes a long time to run out, with a combi no reserve.