After arranging a lunchtime barbeque in a couple of weeks time (to celebrate a wedding anniversary) the power company has informed us that there will be a power interruption from 8.30am to 4.30pm on the day (possibly longer if they meet any snags) so my question is this: am I right in thinking that a
850watt 2 stroke generator would be powerful enough to power the condensing combo boiler to give us hot water (maximum power consumption 140watt) and maybe some small electrical appliances all well under 1kw?
Yes, should be no problem. I presume you would want to keep your fridge/freezer going as well? Best to plan not to have to open the fridge/freezer too often, just in case.
If you could plan your day to only need the central heating, you could beg/borrow/steal a leisure battery and a 300W inverter and do without the genset.
An 850W genset might struggle to start a larger fridge/freezer especially if it already has some load on it. Rule of thumb, motors need 2 to 3 times their rated power to start.
Inverter and battery is another solution but difficult to "refuel" once the battery is flat. The genset can just have some more petrol/oil poured in...
It's *powerful* enough - but whether it will drive your boiler depends on the quality of the output (voltage stability and waveform) and how fussy your boiler is. Another consideration is whether you really want a 2-stroke engine screaming away the whole time.
As others have said, you *may* be able to power it from an inverter connected to a decent leisure battery - but do the sums to see whether you have sufficient capacity.
If you *must* use a generator, a 4-stroke jobby with inverter output (like those made by Honda) would be a better bet. Those are *much* quieter, and have very stable outputs - probably better than the mains!
Oh, and if the boiler has spark ignition, and uses flame ionisation, you may need to strap the generator's neutral and earth wires together to get it to fire. And for good measure, use an RCD at the genny end of your extension lead, and connect the genny's earth to an earth spike.
All at once? Possibly not, depending on what you mean by "well under
1kW". I'd say 500W is "well under 1kW", wouldn't you? But that generator won't power 2x500W.
The other thing you need to know is that the generator isn't 850 watt. It may be plated at 850VA which isn't quite the same thing. And that rating will be a maximum and the generator will probably be closer to a
450VA generator. If it's one of the two stroke generators with an auxilliary 12V output then it doesn't really matter what it's badged as or what the claim is for output, it wil be a 450VA generator. I've got one (badged Cosmo, identical to the Wolf/NuTool/Pro User/Munro etc.) and it's OK for running a drill, powering a few lights in a barn, recharging a tractor battery, operating a TV, and charging a laptop while running a printer. It could certainly power a water pump/boiler for a time.
Just don't expect to power multiple items simultaneously, it won't do it. That 850W figure indicates that it can handle a transient switch on load of 3.5 Amps. Try to maintain that continuously and you would damage the generator. I've seen them with burnt-out windings, melted insulation and damaged sockets from trying to run at 3A continuously. If you try to run a load of 2A you will hear the engine labouring.
If you want a cheap stop gap, they are usable. Two strokes are also ideal for standby use since they are robust, almost maintenance free and you can put it in a garage for years on end and as long as you keep it dry it will run fine when you fill and prime it.
If you do store it remember to drain the carburettor, because if the fuel evaporates the carburettor will be fouled by the two stroke oil residue and then it will be a bugger to get started next time around.
And have price tags >10 times that of a 850W two stroke. They are very nice though.
And fit a 13A plug (correctly fused) and socket into the mains feed to the boiler. It'll almost certainly be fed direct from it's own way in the consumer unit or via switched fused connection unit off a ring main.
Thanks for all the advice and info, it looks like connecting my boiler to a cheap generator risks damaging the electronics so it isn't an option. DIY (Damage It Yourself)
A lot of small generators have a 12v output (intended for battery charging?) and inverters (meant for car use) can be relatively cheap these days. I wonder if connecting the two together would produce stable power (albeit less of it)?
Go for an inverter to power the boiler, but use a decent one with a reasonable output waveform and test it beforehand. Otherwise just don't bother - set up alternative hot water supplies instead as I doubt you'll need heating. A big insulated plastic "tea urn" cooler can be handy here, especially if it has a tap.
A British Army "Boiling Vessel" (look it up) is a great gadget for this situation, and will run off a pair of car batteries. Try eBay or a big (on-line) surplus shop
For the fridge, use "stored cold" in freeze packs.
Anything else, use a primary power source rather than generating electricity and then using that, i.e. oil lanterns or candles, gas stoves for cooking / hot water, wood stove for warmth.
Generators are noisy. If you really must, hire a _quiet_ 4 stroke, rather than buying a Happy Shopper 2 stroke or a 2kW builder's genny. The "market trader" gen sets are a lot better noise-wise and most hire shops will have one.
Yes, although I see that Machine Mart are doing a Clarke 1kW 4-stroke inverter-generator for under £300 - which is a lot cheaper than the equivalent Honda, and may well be OK.
Some do, some produce a "modiyfied sine wave" others are square wave releying on the connected kit to "shape" it.
Probably but when a (reactive?) load switches off (ie a motor) there can be quite a large voltage spike until the genset throttles back. Similary when a load comes on a dip until it throttles up.
Not quite like the gensets we are used to Dave, 100kVA with only a
30kVA load, even banging a 5k on is taken up by the fly wheel... B-)
Interesting I might wander over and have a look to see if they have something in the 2 to 3 kVA range. Though I sometimes wonder about reliablity, with electronics and changing reative loads. A dierctly connected alternator won't worry to much about short over/under voltage but bits of silicon tend to let the magic smoke out if pushed hard for even a very short time.
Heh heh - remember having a low loader car rig. With one of those nice Honda 5kW (IIRC) generators on board. Lighting was bashing two 1.2 HMI through the windscreen - and had all the video stuff fed off it too. I was running off batteries. Sparks 'saved' the HMIs at the same time and took out the vision trolley PS - and the Digibeta too. While I whistled softly to myself. Good for overtime, though.
The filtering on some boiler pcbs is pretty primitive,and when you just have a C-R dropper to the electronics and no regulator, transients have little problem to get through
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