Run a combi boiler off-grid?

[edenbridge]

I've seen a few older threads on similar subjects, but forgive me for starting a new one.

My in-laws have recently moved to a rural area which seems to be prone to frequent power cuts. They are elderly and disabled, and on the EDF "Priority List", but this is of little comfort to them when the power goes out for several hours.

Their heating and hot water is from an oil-fired combi boiler drawing about 270W peak, and I've sprung upon the idea of putting an isolator switch between the mains and the boiler to allow them to switch to an "Emergency Power Circuit" in the event of a grid outage.

Using a petrol generator on this separate circuit would be a stop-gap, but they would be in no fit state to go outside and start it each time the power goes out.

So I was wondering about the possibility of using a small 12V marine wind turbine to power a bank of batteries, and supplying power to the boiler through an inverter? The primary requirement is heat and hot water from the boiler, but any surplus power could be used to charge mobile phones, radios or other critical items. I'm not interested in 'selling power back to the grid'.

I doubt if the turbine mounted on their shed will require planning permission, but how many batteries would I need, and where would I be allowed to locate them (in the loft, for instance??) Any advice on the legalities would be appreciated.

 

[Pensdown]

You could buy and install an auto start diesel generator which would support the whole house for a fraction of the cost.

 

[edenbridge]

Now there's a thought. Could an autostart generator really be as cheap?

I'm figuring on about £400 for the turbine/battery/inverter suite. I guess I like the idea that it's 'green' and could be used solely for the boiler without messing around with the rest of the electrics. The inverter could at least be placed in the boiler cupboard.

Where does such a generator sit with feeding into your mains in the house? Does it automatically isolate the house from the grid so you don't electrocute EDF workers trying to fix the original fault?

And I know this is an electrical thread, but would you be allowed to a generator off the heating oil??!!

 

[JohnD]

how about a UPS just for the boiler, and a few self-contained emergency lighting fitments?

You could leave the boiler connected to the UPS all the time, that would keep it charged up, and the supply would fail over to battery immediately the mains went off, without any intervention. 270w is not much.

 

[edenbridge]

Of course! A UPS is a battery and inverter all in one. Now this is just getting too sensible!

My only misgiving would be the running time. This example has a 'backup' time of 28 minutes at 475W. So the boiler would operate for about an hour, perhaps more if it only draws enough to run the pump. And I suppose it would be "beeping" the whole time as well!

But it's worth some more investigation - thanks for your answers, guys.[/url]

 

[aptsys]

How did you measure the power consumption of the combi? 270W seems a bit high actually. The APC UPS's can be set so they don't beep unless they are a few minutes from running out of power.

 

[edenbridge]

How did you measure the power consumption of the combi? 270W seems a bit high actually...

I got the information from the Worcester-Bosch website and the 270W figure is actually for a bigger boiler I'm planning to fit to my new house. As we're moving to the same area to my in-laws, I thought best to design-in a similar back-up system.

I would imagine the 270W is peak load on startup. At this stage I don't know what the constant current draw is, but I'm guessing no more than 1 Amp.

 

[plugwash]

you really need to find out the average power consumption, I would stick a plug on it and plug in one of theese plug top energy monitoring devices.

 

[boyo]

How did you get on with the UPS project for your combi boiler?
I would be very interested in your experiances.