Sorry Badger. I accept that your knowledge of the regulations is much better than mine. I was speaking from my own experience of how our system is arranged that has worked safely for 20 years. I must admit that I have never understood the reason for the hard wiring and thus relying on a minimum contact separation of 3mm at the distribution board, as when I pull out the plug for ours when I wish to adjust the thermostat, there is a contact separation of about 3 feet !
Our Ballon is in the garage which is on its own separate circuit. Yes there are a couple of other power points, but as no-one is ever going to be using them between 02.00 and 06.00 hrs, which is the only time the Ballon is active, effectively the water heater does have its own circuit.
I do think that sometimes there is regulatory over-reach which fails to consider the realities of life. For example; We have some electric convector heaters (rated at 2kw), which were supplied with both wall fixings and feet for free-standing use by the manufacturer. My understanding is that if I fix them to the wall, then there has to be a hard wired separate circuit back to the distribution board, but if I fit the feet, and have them free-standing, then it’s fine to just plug them in to any convenient socket. Seems a bit daft to me. Same heater, same power consumption, the only difference being whether or not it is screwed to the wall.
As the qualified one of the two of us, I would appreciate your views as to why this is deemed to be sensible apart from making work for French electricians and being able to sell more cable.
Thanks.
Thanks, Wozza
Yes, I couldn’t find any reference to Lydis when I looked - thanks for all your input - will certainly put all the suggestions forward.
Atvb
Janet
I would disagree on that, you are solely relying on the boiler thermostat, if that fails there is nothing protecting the boiler from overheating wothout a pump circulating the water you could have a bad situation.
When the boiler is off and residual heat distributed the pump can then be turned off as the OP originally requested.
You want to delay the pump swithing off untill the boiler has cooled off a bit, otherwise wasting a lot of heat, could be an hour of extra heat in the mass of some of these big french boilers.
Regulations can sometimes seem illogical, but in any area of practicality there have to be limits as buildings/machines etc. can’t adjust to every individual use.
The very real reason for NF C 15-100 demanding separate circuits for heavier loads are twofold.
Firstly, using a single direct circuit to a load cuts down on the potential connections involved. Put another way, if you used a socket circuit to run your 3kW water heater then that load could pass through every one of up to 11 sockets before arriving at the load. That’s 22 potentially bad connections that might get hot during the long period of load that a water heater typically has (several hours during the night). A direct connection will drastically reduce the number of potential faults.
The last paragraph can be applied equally to heaters in general. The example you give of a mobile heater is that it’s considered a temporary/limited thing - you wouldn’t heat your whole house via mobile heaters.
Another reason for specialised circuits is to avoid overload of general socket circuits. If your 3kW water heater was plugged into a 20A kitchen socket circuit that also ran a 2kW electric oven, a random mobile 2kW heater & then you plug in a 2,2kW kettle you will overload the circuit &, at best, trip it out or, at worst, start a fire.
Although both above examples are unlikely you have to create a regulatory framework that takes the possibilities into account & create rules that avoid them.
In conclusion, although you might be careful in the way you use your electrical installation the next person who comes along may have zero understanding & plugs in all kinds of electrical toys that you didn’t have, & expect them all to work at the same time.
Although I cannot speak regarding other makes, I can say with certainty that such a situation simply cannot arise with our Franco-Belge boiler.
The circulating pump is driven from the boiler electrics, so when the signal from the wall thermostat stops, both the circulating pump and the supply to the burner unit fioul pump and blower are cut at the same time.
In the event that the circulating pump fails, the temperature detected by the water outflow sensor (a probe into the boiler water jacket) would rise rapidly and cause the burner unit to be switched off. In the event of that sensor failing as well as the circulating pump, then there is a general overheating sensor inside the boiler cabinet that would turn the whole thing off before a critical temperature was reached.
On another point, if one continues to run the circulating pump after the wall thermostat has turned off the boiler burner unit, then heat is unnecessarily continuing to be supplied to the area in which the wall thermostat is sited. So then you end up opening a window or two because one is too hot. Much better to retain that heat within the boiler itself, so that the next time the wall thermostat asks for heat, the boiler is at a warmer temperature than would otherwise be the case, and so requires less time, and less fioul, to reach its normal operating temperature.
Yes true for continuing heating cycle but as you have said even yours doesnt operate that way. I was talking about an end of the cycle scenario possibly shut down overnight where the latent heat will just dissipate anyway.
I think there is a misunderstanding here. Our system works in exactly the way that I described in that when the wall thermostat no longer asks for heat, then the electrical power to the circulating pump and to the boiler burner unit is cut at the same time.
At the end of the ‘heating day’, the residual heat in the boiler slowly dissipates into the cellar where it is sited, and helps to keep that area nice and dry.
That was old regs. Amendement 5 to NF C 15-100, active since 2015 allows the following…
12 outlets on a 2,5mm² circuit, protected by a maximum 20A disjoncteur (fusibles interdit).
8 outlets on a 1,5mm² circuit, protected by a maximum 16A disjoncteur (fusibles interdit).
Under the current regs an outlet is exactly that, one socket e.g. your max of 12 outlets could be reached by having 6 doubles. Under old rules a double counted as one, a triple as two (can’t remember what a quad was).
Re ''‘At the end of the ‘heating day’, the residual heat in the boiler slowly dissipates into the cellar …’
If it’s like my system, once the power is turned off to the boiler and pump, the hot water will continue to circulate on heat rises principal?
When my pump is not operating, the hot water from the boiler still 'manages to circulate through the ground floor radiators (but oddly not those on the floor above) until all the heat is dissipated,
I think that depends on the nature of the pipework and the elevation of the boiler in relation to the radiators. Ours does continue to circulate a little, but then the boiler is in the cellar and the initial pipework leading away from it is massive old steel stuff about 2 inches in diameter. It’s an old system pipework wise, where a degree of convection flow balancing was achieved by using ever decreasing pipework sizes to achieve the desired result — sort of.
Originally the system was coal-fired, relied entirely on convection (no circulating pump), and had a header tank in the attic to maintain gravity pressure in the system. Now it is oil-fired, has been fitted with a circulating pump, has an expansion tank to maintain system pressure, and the majority of the radiators now have thermostatic valves.
As our system has been substantially upgraded over the years, and as it still has a lot of old pipework, I’m sure that the limited convection flow that occurs when the circulating pump is not running is not in any way typical of a more modern set of pipework.
So is your system relatively new or old as the hills like mine ?
Thanks for this, I haven’t worked in domestic electricity since 2007, and before then the order of the day mostly was to choose between BS 7671 ou NF C 15-100 & work to the higher of the 2 depending on the installation, without mixing the 2 standards, either French residential property of FCO estate.
So my NF C 15-100 is well out of date I’ll have to look but I think the last one dates from -around 2015.
From 2007 I’ve mainly worked on projects in & on & on industrial installations/sites mostly in aeronautics or aerospaciale and many NF C 15-100 regs don’t apply, apart from offices, communal, kitchens spaces etc.
Time to buy a new NF C 15-100.
Thanks again.
After all your combined input the plumber hasn’t turned up - well, not so far, anyway. I’m on the 61/14 border - any plumber recommendations welcome as you can imagine - now I know the three ballon options: repair, replace independent of chauffage, or replace as originally installed - I’d really like to get it sorted. Very impressed by the conversation but might have lost the will to live regarding NFC 15-100 updates - however, a lack of understanding by a professional could, indeed, affect the potential for living real-time I guess.
Atvb
Jan