Generator

With so many people losing power during the snow I was wondering how your central heating could be rigged up so that you could run the electrics from a small generator? I now own a small suitcase generator and was wondering how easy it would be for an electrician to sort out the central heating electrics to plug a generator in? I could put up with most things as long as I am warm, and I have no alternative heating in my house.
Angela
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Easiest way would be to put a plug on the boiler, and a socket where it was connected, then run an extension lead to it when needed.
Toby...
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Toby presented the following explanation :

Even easier....
If your central heating is on its own circuit/MCB - it should be. Cut the feed where it exits the consumer unit and fix a 13 amp socket on the end coming out of the CS. Take the other end into some sort of joint box so it can be fed via a 3 core flex and a 13amp plug. Normally it will be left plugged into the socket, but if power is lost you just plug into the generator.
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Harry (M1BYT) (L)
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Convert the boiler from Switched Fused Connection Unit (SFCU) to Unswitched Socket & Plug.
Buy a generator with BS4343 IP44 Blue Socket so it can be used outdoor in wet conditions, with a local earth rod spike which you push into the ground.
Buy a BS1363 13A Plug (or BS4343 plug) to BS4343A Blue IP44 Socket lead of sufficient length for the generator.
Fit a BS4343 Blue 16A IP44 Appliance Inlet Surface Mount Plug to the outside wall near where the generator can be located. The Appliance Inlet Plug then supplies a BS1363 13A socket next to the boiler. It is critical that this socket be labelled "generator supplied socket only - do NOT connect socket to house fixed wiring".
Boiler is then unplugged from the house-socket to the generator-socket on power cut.
If necessary you might need to fit a large UPS in between the generator & boiler - they will clean up the mains and provide some backup power of their own if the generator fuel should temporarily run out or generator issue. Most UPS are not "black start" - they require power to their input before the output will turn on to prevent them being used as "silent generators".
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Harry Bloomfield wrote:

I wonder if there are drawbacks to a variation on this theme: conceivably you may want to maintain a few circuits with the generator, say heating lighting and a strategic socket.
"Commando" inline IP44 sockets and plugs can be 4 pole + earth and 32A they're about 10 quid each.
OK the limit would be 32A in the neutral line but it could provide a means of combining 3 outlets from the cu for powering by a generator yet keeping them separate for normal use, are there safety issues?
What worries me about all this is having the change after the cu and thus losing the protection of the cu, wouldn't each circuit be better with an rcb in it for use when powered by the genset?
AJH
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on 09/01/2010, andrew supposed :

How much would one want to spend?
A main cable could be brought in from the generator, a dis-board with several circuits provided and each feeding a 13amp socket. You can then plug in the heating and either plug lighting units into that or do something similar to what was already suggested for the heating circuit, break into the circuits as they exit the consumer unit to fit a plug and socket.
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Harry (M1BYT) (L)
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wibbled on Saturday 09 January 2010 22:59

You can get bigger ones, 63A for example and I think double that too. I expect the latter would be a big bastard though.

Yes - I did mention consideration should be given to RCD protection 9and earthing, also echoed by Andrew).
Interestingly, the Briggs and Stratton transfer switch contains its own RCD.
Either have to incorporate an inline RCD into the generator lead, stick an RCD plug on the boiler feed (less desireable if the circuit is already RCD protected) or if you laid in a second socket and a dedicated feed cable to an outside hookup point, stick the RCD in that (or use and RCD socket).
--
Tim Watts

You know you need more insulation when the snow blanket on the roof makes
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But she will also have to sort out her earthing so that the flame sensing works
and hope that the putput from your genny is clean enough not to knacker your pcb
--
geoff

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wibbled on Saturday 09 January 2010 21:46

As your the man WRT boiler PCBs, any tips on what to look for in either a generator or UPS so it would be clean enough? I suspect a decent UPS will fare better by default (assuming it generates a sine), but do you know if there is anything in the specs of either that gives a good hint?
Cheers
Tim
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Tim Watts

You know you need more insulation when the snow blanket on the roof makes
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I would say that its more the design of the electronics in the boiler
e.g. Lets take the good old suprima vs the worcs 24i
The Suprima uses r-c voltage dropping and not much filtering, its very susceptible to crap coming down the mains
The 24i uses a transformer -regulator LV supply which is less prone to masins variations
As to absolute sensitivity to fluctuations and transients, its not something I've spent much time investigating
--
geoff

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wibbled on Friday 08 January 2010 22:09

If there is a single convenient power feed to the central heating system (eg wiring centre near boiler or tank cupboard) a crude but effective way would be to have a socket installed there and a plug and flex for the feed to the central heating.
Then the CH can be unplugged as a whole and plugged into the generator via an extension lead.
It's the simplest but probably least convenient method.
There are fancy ways of having a method of plugging a generator into the house supply and a proper transfer switch to isolate the incoming supply and switch over to the generator[1] but you still need to think and switch off any other load (eg socket circuits) so as to not overload the generator. It's also the most expensive way. It does have the advantage that you might be able to run some of the lights too, but you didn't ask for that.
It may also be possible to install a second socket next to the first one which is wired down to a generator hook up point outside. You could run this by your electrician and see what they suggest. There may be some matters of earthing and RCD provison for the generator supply to consider - I say that reservedly as I haven't gone down this route, so it is something I would certainly think through. Again, your electrician will be competant to advise.
It may be worth considering using a non standard socket (eg special/nonstandard 13A or 15A round pin (subject to fusing provision) instead to discourage inappropriate use of these sockets.
There would be an issue if your wiring centre is in a tank cupboard in a bathroom so variations on this idea may need to be considered.
How often you expect to use such a provision might help decide how complicated/convenient to make the solution.
Hang around - other folk many have ideas too - I'm sure some here have already done something similar.
[1] One key point, is that you must under no circumstances be in a position that your generator might backfeed into the road supply as this is dangerous for anyone working on the supply, apart from the obvious fact that it won't do your generator any good. That's why the plug and socket method is sound - you must physically transfer the load (plug to your CH in your case) from the main supply to your quite seperate generator supply. there have been cases of idiots putting a 13A plug (as in with pins) onto the output of the generator (dangerous in itself) and plugging that into one of the 13A sockets in the house (dangerous on many levels).
HTH
Tim
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Tim Watts

You know you need more insulation when the snow blanket on the roof makes
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In an earlier contribution to this discussion,

The electrics of central heating systems are usually powered from an FCU (fused connection unit) - usually located near the programmer and/or wiring centre - often in the airing cupboard.
In order to use a generator, the wiring needs to be changed so that power comes from a 13amp plug, plugged into a power point on the ring main instead of from the FCU. You can then unplug it and plug it into the generator instead. You need to think about where you will operate the generator - you won't want it indoors! - and about how you will get power from the generator to wherever your 13A plug is located, so you'll need an extension lead.
It's advisible to earth the generator using an earth spike, and to use a plug containing an RCD at the generator end of the extension lead. Depending on your boiler, you may find that it won't fire unless you connect the generator's neutral wire to earth rather than leaving it floating.
I've wired my heating system so that it is powered from a power point in the conservatory - so I can operate the generator just outside the conservatory with only a short extension lead. Near the power point is a coiled up earth wire with a spade connector on the end for connection to the generator (with the other end permanently connected to an earth spike). My genny has 2 x 13A outlets - one is used for the extension lead's RCD plug and the other has a 'doctored' plug with no external cable, but with neutral and earth shorted together internally.
--
Cheers,
Roger
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I can run mine off an inverter. As others have said, you need to make sure the boiler plugs in to a socket, usually easily done by changing the fused connection unit for an unswitched[1] socket, and putting a plug on the flex. You should make sure that the boiler will remain earth bonded when it's running from some sort of locally generated supply (i.e. it has earth bonding connections independent of the mains lead).[2]
[1] It was a CORGI requirement that if fed from a socket, it must be unswitched so that the socket switch cannot inadvertently used to isolate the boiler from the supply as it might not have a double pole switch.
[2] The issue of earths when running from a locally generated supply is too complex to cover here, but suffice to say that you are not permitted to assume that any earth connection provided by your supplier is still working during a power cut. This means you should strictly provide your own earth when using a generator or inverter, but in reality no one ever does with portable ones.
--
Andrew Gabriel
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Useful answers; I thought there was something about not using plugs and sockets, but couldn't remember what.
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from snipped-for-privacy@cucumber.demon.co.uk (Andrew Gabriel) contains these words:

There's a further point which might be mentioned -- the electronics of modern boiler control units and programmers can be very sensitive to the somewhat erratic voltage and frequency control of many or most small generators. Certainly when Scottish & Southern provide emergency generators for individual houses -- and these generators are bigger and more stable than most householders are likely to have -- they give a warning to that effect.
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Good point. Capacitive droppers used in things like programmers are going to pass more current, and the voltage regulator will run hotter. (I don't have one, as my heating and hot water are driven by a home automation system.) The boiler I've done this with is a Potterton Profile, and that runs fine on my cheap inverter. The pump makes a different noise, but seems to work fine (or at least well enough not to cause any problem). I guess the mid- position valve worked, but I didn't think to explicitly check.
What didn't work was the cigarette plug on the inverter - it got just as hot as the heating system;-) I replaced it with a couple of spade terminals and matching binding posts. It's hard to find good high current 12V connectors. I bought a few different ones, but on inspection they were all crap.
--
Andrew Gabriel
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Angela wrote:

fairly easily. CH is - should be, on one switched fused spur so all the cabling is fully isolatable from the rest of the house.
It wouldn't probably pass elfin safety, but something could be easily arranged..
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Have a 3kW genny - maybe one with two wheels that can be hung on the wall in the garage, then you can use it for other tasks as well as backup. Always leave it on the wall plugged in and ready. It plugs into the home supply, by using a throw-over switch that cuts out the mains supply - the mains & genny cannot be on at the same time. It then only supplies essential circuits: fridge/freezer, boiler, lights, TV, etc. This will need the plug, throw-over switch and an extra Consumer Unit (fuse box) with essential circuits on it.
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wibbled on Saturday 09 January 2010 12:54

Yes you can.
The only problem is they aren't cheap - around a couple of hundred quid.
http://www.generators.co.uk/Product/Mains_Transfer_Switches/BST
Don't be tempted to home brew one of these - re my point about never feeding your local supply back into the utility supply. I transfer switch must obviously be break before make, be guaranteed to isolate the generator from the utility at all times and meet certain levels of isolation.
That's the beauty of a plug and socket - it inherently meets these criteria without much doubt.
--
Tim Watts

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Why don't sonme peopel raed before typing,. I wrote..."plugs into the home supply, by using a throw-over switch that cuts out the mains supply - the mains & genny cannot be on at the same time.
A two wheeled genny can hang on the wall ready and used for other tasks by unplugging and taking it elsewhere. The fridge, TV, heating and lights can work.
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