I was thinking it might it be a good idea to buy a generator, to power my CH, freezer, fridge/freezer (one of those American ones) in the event of a power cut. What out put do you think I might need? I see Wolf's basic one is 230V output, 720 watts (max), 650 watts. Is that the sort of thing? They are advertising it for under =A350. Thanks for any help you can give!
Cheap generators are usually cheap because they're nasty - noisy 2-stroke engines, poor output voltage stability and God knows what sort of waveform, but unlikely to be a clean sine wave.
Some boilers are quite fussy about the quality of the 'mains' to which they are connected, and may not work properly - if at all - with this type of generator.
You need to spend a lot more than 50 quid to get something half-way decent. Have a look at the Honda inverter-based generators. These are a lot more expensive, but have quiet 4-stroke engines and excellent voltage and waveform stability. Bearing in mind that freezers etc. may require start-up currents way in excess of the steady running level, you need a generator which can cope with that. I have personally opted for a 2kW model (which I bought 2 or 3 years ago as an insurance against power cuts, but haven't yet had to use in anger!)
How are you planning to connect your CH system to a genny? Under no circumstances must you allow genny output to get into the external mains. The best bet is to power the CH via a 13A plug (rather than an FCU) - then you can unplug it from the mains and plug it into the genny instead. You also need to give some thought to earthing, and to whether the genny's neutral connection needs to be tied down rather than being allowed to float.
In message , Roger Mills writes
Without correct earthing arrangements a boiler is unlikely to flame sense properly and so it'll never light
It works here, for all of the above - not all at the same time, but that wouldn't be necessary.
The most difficult one is likely to be starting the motor in the fridge/freezer, and the startup demand will vary from one model to the next. Ours makes the generator thump for a few moments, but the generator always wins.
Between power cuts, it will also run an electric drill or an angle grinder out in the field.
What earthing arrangements would be needed? Please explain.
Well, with the normal electrical supply, earth is connected to neutral at the local substation
Now just connecting the genny neutral to earth might not be such a good idea, but the flame sensing in a boiler is always referenced to earth
Someone will be along later who hasn't drunk as much wine as I have today ...
Based on a similar discussion a while ago, I did some measurements on my Honda genny. I found that - left to its own devices -live to earth and neutral to earth both measured 120v AC - and live to neutral 240v. From the circuit diagram it didn't *look* as if the centre of the output coil was physically connected to earth, and I guessed that it was just an inductive effect - and that I could safely strap neutral to earth with no ill effects. As a precaution, I first connected them through a resistor (60w bulb, or somesuch) to see whether any current would flow. There was certainly no hint of glowing from the bulb, and neutral remained steadfastly at 0v when the bulb was in circuit. So I hard-wired them (by inserting a suitably-labelled
13A plug with neutral and earth connected together) in one of the two output sockets on the genny. The genny works perfectly happily like that, and powers any lights or power tools etc. which I plug into the other socket. I haven't yet tried to run the boiler from it - but I'm pretty confident that it would work.
Some one has already pointed out the problem of starting motors. A rough= rule of thumb is look at the motor rating and multiply that by 2.5 to gi= ve the required generator rating. I wouldn't look at anything less than 2kW= with a long run tank.
That will probably struggle to start the fridge/freezer particulary if i= t is already running the CH and fridge and a few lights... It's also a two= stroke, so you need to faff about mixing oil with the fuel, fairly often= under full load, and it will be noisy(*).
The Honda invertor generators are nice, quiet, clean but expensive. The =
chinese clones might be worth a look at, Kipor seem to have a reasonable= reputation as being OK. They come in two versions (coloured red or yello= w) but I can't remember the techincal differences off the top of my head.
(*) But probably not as noisy as my 2kW diesel but then that will run on= red diesel at about 50p/l and rather than road fuel at >=A31.00/l...
OK I see what you mean. Thanks for that Roger.
I agree with all above to go for at least 2kW. Mine is nominally 2.3 four-stroke, bought at B&Q a couple of years ago. I've used it three times during extended power cuts (living in the country!). It will simultaneously power a fridge, a large and a small freezer, the pump and blower on my oil boiler, the CH pump and quite a few lights (all low energy). What doesn't like it? Well the uniterruptible power supplies I use for my computer network jitter and don't provide steady power, so no work gets done. You have to start with everything switched off and then switch stuff on one at a time. Boiler and fridge startups cause a falter. I guess it wouldn't be good for the LE bulbs to do it too much? I really must get around to putting in a pipe to carry the exhaust out of my workshop. I just stay out at the moment with the door open!
Peter Scott
Interestingly, having said that I'd never used the genny in anger, we had a
4-hour power-cut today [1] so I tried it on the CH. It worked like a dream! [1] Apparently the electricity board had notified *some* of the neighbours that the electricity would be off to enable them to maintain/replace some kit, but they never told *me*. Nice one!
Two people died in the recent flooding from CO due to running a generator indoors. I wouldn't risk CO not making its way through the building fabric over an extended period of time.
No this is a detached shed 20 m away from the house, but thanks for the cautionary warning.
Peter Scott
I'm waiting for the power cut that means I can get the geney out in ange= r. Our power is remarkeably stable and reliable considering we are in one o= f the remotest parts of England. I've made sure that the CH system is happ= y, I don't envisage any trouble with the fridge and freezers.
Not tried that I'm happy for the silence, well with the genny running there won't be that utter quiet you get in a power cut. I suspect the ki= ds will be wanting the PC's or the TV/DSAT to be powered though.
Mine doesn't seem to miss a beat even if drop 2kW of fan heater onto it.= The note changes but there is not hint of faltering, diesels do have a b= it more torque that petrol though.
I've put mine on wheels so I can shift it outside to run. Being a diesel= with a long run tank it's a bit heavy, even with an empty tank. I can mo= ve it just not very far... I've improvised a wheel kit with some bits of wood cut to fit into the horizontal n channels that take the engine/alternator mounts and tie the two tubular frames together. These =
bits of wood are securely cable tied to a cheap convertable flat bed/sac= k truck from Machine Mart (CST3B =A314.09 inc VAT) and the genny just sits= on them.
CO poisoning is not nice it can creep up on you and, IIRC, CO stays in your blood stream for quite a while after exposure depleting your red blood cells abilty to shift oxygen about.
But what is the earth pin on the genny connected to? (yes I know the genny's neutral!)
This is actually quite a complicated part of the wiring regs. You should be creating a suitable earth of your own (e.g. an earth rod), and bonding the neutral to that. This would be a TT or IT installation, and require an RCD. You aren't allowed to assume that any earth provided by your mains supplier continues to provide a valid earth connection during a power cut. Same thing applies to a UPS.
We find the same in rural Scotland. But if a line does come down, it's likely to be part of a very widespread pattern of power cuts (probably involving strong winds and heavy snowfall) so repairs can take several days.
Even a much smaller generator can handle those, as none of them needs to be run continuously, and they don't need to be run at the same time. You only need to charge up the radiators with hot water periodically, and then you can swap to the fridge and/or freezer to charge those up with coolth.
Within those limitations, the little Wolf has been an excellent investment. As well as providing cover for power cuts, it is small and light enough to chuck in the wheelbarrow or the back of a car, along with the rest of the power tools.
Same experience here with the UPS, so I'm content to crank up the wood stove and enjoy an enforced holiday. There are always plenty of other jobs to catch up on.
If you only want to run low power things for a short time, what about a big leisure battery and a DC->AC converter? You store about 1 kW.hr in a normal 100 amp.hour battery.
Robert
We hired a genny once with the centre tap connected to the earth pin (and chassis. The burglar alarm on the installation was wired up incorrectly (IIRC it was neutral/earth transposed, or connected together.) Result: lots of fried cable in trunking to replace. The generator appeared to work ok, until the fry up.
Aye. Cuts here are either a few seconds as the auto-recloser does it stuff or at least 6 hours as men in Land Rovers come out to re-route the local
11kV distribution and find the fault.This is true but the OP has a big american fridge thing. Now it's only a heat pump but does such are large fridge have a more powerful heat pump? The little 650W two strokes do struggle to start some fridges/freezers.
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