small 2kw builders generator can be back feed into the system via an outside socket

Posted By: an02ewsmall 2kw generator

Is the correct answer for what is a fairly unlikely scenario.

Posted By: an02ew can be back feed into the system via an outside socket

Is a very foolish idea. You would need a widow-maker cable - one with live pins. You will be back feeding into the mains.

If you are going to do this either put the things that you want to supply on a separate circuit which can be disconnected from the grid and safely connected to the generator, or have a proper break before make changeover switching arrangement. (Will probably cost more than the generator.)

As billt says. Not just because of the widow-maker cable but also because of the possibility of screw ups with (non-)disconnection of the mains supply and questions about earthing.

In the unlikely event of me doing this my first thought would be to have two consumer units: one for high power stuff (cooker, immersion) and the other for the rest fed through a 32 A blue “commando” plug and socket:

https://en.wikipedia.org/wiki/IEC_60309#Blue_P.2BN.2BE.2C_6h

then make up a short tail to be able to plug in a 16 A version from the generator. Don't know if an electrician would be happy to sign off on this just because it's a bit odd and perhaps doubts about the earthing but it seems to me to be the cheapest safe approach.

Also, an inverter run off a car might be a suitable source in some circumstances. Why buy another generator when you already have one? A powerful inverter (for more than just the heating) would not be cheaper than a generator but might well have other uses.

Can you run the essentials off a 13A socket, is so, then you can run an extension lead, or 3, from any 230V supply.
Not pretty, or clever, but flexible, cheap and easy.

If you're anticipating days of power outages, UPS's aren't the answer. The cheap ones will only run for a few minutes and they don't have a reputation for killing batteries. Big ones are expensive and usually have quite a high parasitic power consumption. Mine uses 80W even when it's not doing anything.

Posted By: EddoSo, what's wrong (I ask myself) in being prepared, just in case?

It's a waste of time and resources for something that is very unlikely to happen. By the time it happens you may well find that your batteries are dead or the generator won't start.

In such a catastrophic event keeping the heating going will be a trivial problem compared to all the others (or do you have a secure bunker and lots of guns and ammunition?).

Yes, I would get new friends if I were you!

With friends like these, who needs anything! Let's take your second friend's ideas first. The two major land masses covered with appreciable amounts of ice are Antarctica and Greenland and have between 4 km and 3 km thick ice sheets covering then respectively. When they go, your friend is correct, the earth's crust will rise due to the reduced mass loading but by then, the oceans will have risen by some 66 m so unless you are living on Snowdon, the odd brown-out will be the least of your worries.

http://nsidc.org/cryosphere/quickfacts/icesheets.html

As for your psychic, get a fix on when the Summer ice in the Arctic is going to disappear. That's going to happen long before you need to worry about your winter heating.

Get a "SinusPRO-1000W 12V / 230V 1000VA" for a coupla hundred quid and a leisure battery for a hundred.

If you expect outages for several days then get the 1000S version into which you can plug a solar panel.

I have one of these, and it works well with my Akvaterm heatstore, wood boiler, thermal panels. motorised valves, pumps, etc.

Posted By: SteamyTeaJust out of interest, why do you think there is greater risk of power cuts?

Because the grid is pretty sensitive and actually very exposed to terrorist attacks. Transformers burn rather ferociously! There is actually no obligation on generating companies to produce sufficient power - they produce as they want. So once the existing power stations get to end of life there is nothing to stop them just closing them. Look at longannet - there is no intention to replace that capacity. Nuclear lifespan is being pushed to the limit with no new generation appearing for quite some time so significant issues with the common type of reactor could knock out a big lump of capacity. Russia is becoming more unpredictable which threatens power and gas supplies. On the plus side we are using a wee bit less and when the wind blows we hove a bit more!

<blockquote><cite>Posted By: borpin</cite>I planned for this - had a second consumer unit fitted with a switch between mains and a commando plug a generator could be plugged into. I can therefore isolate the consumer unit from the mains and feed from the plug/generator. Essential items such as heating controls, mvhr and boiler are on this circuit (as well as a few other that would be switched off, plus a 13A circuit for laptop/phone chargers.


I did something similar, a separate consumer unit powering the boiler and pumps etc. and a changeover switch.
I also put a couple of extra lights on the same circuit.
All this does assumes you're at home when it happens, but I only fire the boiler when I'm at home so not a problem.
I

Impressive natural disasters aside, I reckon all it will take is a really cold winter to put the current national power distribution set-up under severe strain. Power cuts may have to occur due to demand exceeding supply. I actually heard something about this on Radio 4 a few months back.

Under my set-up, in a prolonged winter power cut (say a few hours) I can't keep the boiler stove firing to heat the house if the Akvaterm can't eventually discharge heat back into the system - the CH pump is the weak link in the system. As I am not worried about the rest of the house (candles and oil lamps will do for light , and the cooker runs on propane anyway), I think the option of disconnecting the power to the CH pump (easily done) and plugging a battery (or series of batteries) or very small generator direct to the pump will be enough for my needs.

So do I understand right that if I use car batteries, I would need to change the CH pump to a 12V boat pump? Presumably this means I would then always have to run the pump off car batteries. And if I went for a small generator, it could feed straight into the existing pump's wiring whenever a power cut occurs?

If your friends are right then not having heating will be the least of your problems.

You could always ask them what prep they have made. I mean how confident in their predictions are they really?

Crosbie, the SinusPro looks good - quite elegant really. It would only need to power the CH pump via the battery. So, I need to research now how long a battery will last. Not sure if solar will charge a battery in mid winter though.

All the petrol generators I have looked at so far are too powerful for what I need.

Eddo, the problem is, you don't know how long the cut will last, so it doesn't really matter how long the battery will last - just spend what you think it's worth to keep things running as long as possible.

If you're expecting cuts over several days, then a panel (or several) will still work in the winter even if it provides less power than in the summer. Then you do need to ensure the battery will last 12 hours or so until the sun kicks back in.

Unlike a UPS, a cheap inverter requires you to manually switch it in during a cut. It's also not going to be pure sine wave, so check your central heating pump is compatible with it.

Posted By: EddoAll the petrol generators I have looked at so far are too powerful for what I need.

They modulate down a bit, so don't worry about that.

Posted By: Eddothat inverter may be all I need, and it's simpler, and more affordable!

Yes, but as Crosbie says, make sure your pump can handle it. Most motors will, they just loose efficiency. Some with electronic control may be more problematic.

Posted By: Eddoboth friends agree that a mini ice-age is starting - like back in the 1600's when the Thames froze over and a Christmas Fair was held on it. Apparently any ice-age is immediately preceded by a period of warming, like we just had. They agree the cold snap will peak in 50 years time and take 200 more years to warm up to current temperatures. Apparently next winter will be COLD.

This seems to be confusing many different things.
The main reason the Thames used to freeze over was because of the small span bridges and a relatively short cold spell. There was also the Medieval Warming period. The 1970's scare about a new ice age (that stuck in peoples memory) was a minority view (like your friends views), most climate scientists thought the long term trend was warming.
The last ice age was probably caused by an ice dam failure in the Hudson Bay area of Canada (Hudson bay was not there then). This caused a major injection of fresh water into the North Atlantic, which changed the salinity, which changed the flow of the North Atlantic Drift (Gulf Stream).
We do not currently have any large liquid freshwater being trapped by ice dams (this may change).
The Data I have looked at for the UK shows our winters getting warmer rather than out summers getting hotter. This does not mean that we will not have cold snaps, just that we will have less of them.
I shall make 3 predictions about next winters weather, it will be warmer than the last one, colder than the last one, just about the same as the last one.

More seriously, there is a problem with our old grid network. It is generally at a local level though, not the bulk transmission side. One of the main problems is that we made it too good and expect it to carry on reliably. No one wants to pay for local grid reinforcement (latest estimate I saw was £110bn). I am lucky in the SW, we have two backbones and a DNO that tries very hard to keep the local stuff working (last years storms were testament to this, I had no power cuts). There is a risk of terrorist attacks, and they could be inconvenient and costly, both for terrorists and the public. There are plans in place though. The biggest threat to out electricity supply is under investment in the grid and the generation capacity, but that is a management issue not a physical one. In 2009 our grid was expected to fail in 2014, well apart from the storms causing localised damage, it has not failed (storms are caused by large temperature differences, not smaller ones, that just Physics).

Battery life is pretty easy to work out. say your battery is a 50AH 12V one, then you have two days worth of power at a 1A load, a day at 2A and 10 hours at 5A. Not sure what a CH pump draws couple of amps on a large system. Starting current may be higher. You can't really use a car battery for a reliably system. Car batteries are designed to give a lot of wallop for a very short space of time. You need 'deep discharge' batteries, and these are expensive. To keep these topped up with a PV system you then need a charge controller and enough charge to replenish the batteries over the shortest hours of daylight and run the pump for the longest hours of darkness. So it will be quite a large system, especially if you want to run a fridge and a freezer as well (just got a new fridge as the old one was cold, but always pumping, and a friend has exactly the same problem, so check your fridge, mine was using 2 to 3 kWh/day).

I would personally not bother to do anything until there is a problem (or paranoia gets the better of your friends, ask what they are doing to insure themselves), then rush out and get a 2 kW Honda generator, and small kettle (under 2 kW) and a 2 kW induction hob, a 1 kW fan heater, 5 gallons of gasoline and some 13A extension leads.

Apparently the EU grid is going to be tested to destruction tomorrow because of the solar eclipse. We will see.

Posted By: SteamyTea
Battery life is pretty easy to work out. say your battery is a 50AH 12V one, then you have two days worth of power at a 1A load, a day at 2A and 10 hours at 5A.

and at the end of it a dead battery (If it's a lead-acid battery, as is most likely, then draining it right down is not a good idea).