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11kw Turbine powering elctric boiler for heat & water ?
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Joined: 27 Nov 2012
Posts: 5
Location: East Ayrshire

PostPosted: Sat Dec 01, 2012 12:50 am    Post subject: Reply with quote

no one is nicking our oil Tarrel, for sure Smile

In a perfect world and starting from scratch... then yup - u could put all the mega insulation in at the start- in all the right bits, put the bunnet on etc... but sorry... that is all running to keep up... it changes year on year... new standards. But for sure... it wont ever keep up with the price increases in oil.. or any other 'new green' energy... soon as there is take up, the prices start to rise.

We have lived here for 30 years, I'm coming up 60, hubby coming up 70 with cancer - so we are looking at quick fix easy options for both of us.

My initial question was about an 11kW turbine being able to power an electric boiler. I have a wind resource where I live... will it work, as we are now Smile

This is the link to the turbine I am interested in - http://www.gaia-wind.com/133-11kw-turbine/
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kenneal - lagger
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PostPosted: Sat Dec 01, 2012 5:05 am    Post subject: Reply with quote

I have a go at people looking for the quick fix solution, Miriam, because that is the way many people go and it is one of the reasons we find ourselves in the environmental and economic predicament we are in now. It's either the quickest or the easiest way that people like to take and it is invariably not the best way. I've told you how to do the job properly and I hope anyone else who is reading this thread in the future, and there will be many, will do the job properly and not bodge the job leaving a dogs dinner for the next residents.

The standards that I quoted are for Passivhaus levels of insulation and are about the maximum that you would ever want to put in. They are also the standards that will be required for Britain's Zero Carbon houses from 2016 onwards. Any more just won't see a financial or, more importantly, an energy payback. If done properly, with proper draught sealing, those levels of insulation will save you at least 80% of your fuel bills.

If the orientation of the windows is correct you could save slightly more, depending on your sunshine hours. If you leave the current insulation in place you might get some overheating on sunny winter days but I would put up with that and store the heat. It would eventually go through the internal insulation and via the partition walls into the stone work eventually coming back as room temperatures dropped. It would work best if the internal insulation were removed but I recognise that you would not want to go to all the expense and disruption of doing that.

The remainder of the fuel bill is a function of the size of the house, which I would think from your description is 2,600 square feet (235sqm) or more. Think on this those of you who are wanting to build a "Grand Design", even a well insulated one. Will you be able to afford the heating in a fuel poor future. And if you go for logs, how long will you be able to keep up with chopping 10 tonnes of logs every year?

Yes an 11kW wind turbine will power an 11kW electric boiler for part of the time when you have optimum wind speed. It will power a 6.5kW boiler for about a half to a third of the time when the wind is blowing (you probably have more details of your wind speed distribution than I do, I would think) and it will power a 2kW boiler for most of the time when the wind is blowing. The smaller the boiler the longer the heat output and the bigger heat sink you will require for when turbine output is above the boiler output. You would be better off putting in two smaller boilers switched in series so that the second comes on when the turbine output is high enough. A third could also be used depending on how much money you want to throw at the system. If you can get a modulating boiler that will take the current available so much the better but I don't know if they are manufactured. A large heat accumulator (a well insulated water tank of several thousand litres capacity) would be an advantage as the dump load from the wind turbine could be used to heat this water which would in turn be used to heat the house.

If "An Inspector Calls" were still around he would suggest that you put in a ground source heat pump but I don't like these, personally.

If it were my decision I would do the job properly because your comfort levels will be higher with a properly insulated house.
Action is the antidote to despair - Joan Baez
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Joined: 29 Nov 2011
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Location: Ross-shire, Scotland

PostPosted: Sat Dec 01, 2012 9:54 pm    Post subject: Reply with quote

Hi Miriam,

If you are using roughly 7000 litres of oil per year, that equates to around 70,000 kWh of energy.

If we follow Ken's thinking and assume a 6.5kW boiler being powered for, say, 40% of the time (approx. 10 hours in 24), that gives you and annual heat output of 6.5 x 10 x 365 = 23,725kWh, or around a third of what your oil is currently delivering. On this basis, you'd save around a third of your oil consumption if the electric boiler was to work alongside the oil boiler to heat your water.

A couple of caveats:
1. Some of this energy will be produced at the "wrong" time of year (e.g. during the summer), when you don't need it to supplement your oil (although, as discussed above, you can sell it back to the grid)

2. You'd need a substantial thermal store to allow the wind-generated heat (which may be delivered in the middle of the night) to be used when you need it (e.g. mornings / evenings).

Have you considered solar thermal as well as the wind turbine? (Sorry if you have mentioned this and I missed it).

I think the nice thing about your plan is that, unlike an off-grid wind turbine providing all your electricity, it doesn't really matter if the wind doesn't blow on a particular day. The oil just makes up for it. From a commercial viewpoint, so long as you know that the average windspeed is going to deliver a certain amount of energy per year, then you can do the sums and see if it makes sense as an investment.

I'm not an expert on electric boilers, but don't forget that, basically, we're talking about an immersion heater - nothing more complicated than that. Many people on here can fill in the technical details, but I guess you'd be looking at one or two 3kW immersion heaters in your hot water tank / thermal store, with a low-temperature thermostat that kicked the oil boiler in if the store fell below a certain temperature (say 60 degrees C).

So long as the immersion heaters were delivering enough heat to replace what was being taken out by your central heating and/or domestic hot water, and the tank was thus maintained above 60 degrees, the boiler would never cut in.

On a cold night, your rooms would lose heat to the environment, so the radiator thermostatic valves would turn the radiators on, draining more heat from your hot water tank / store. If the immersions couldn't keep up then the oil boiler would kick in.

If your wind-turbine was grid-connected, and your immersions ran off the mains, there would always be enough power for the immersions. The only issue would be; are you generating it yourself or buying it from the grid. This would depend on the wind speed. If you're buying it off the grid then it is an expensive way of heating compared to oil (oil approx. 7p per kWh, elec. approx 14p per kWh).

I can't remember if you said you're on Economy 7. If so, the ideal solution would be to have your immersion heaters controlled in a way that they only came on if a) your wind generator was generating enough energy, or b) it was night-time and you were buying your electricity at Economy 7 rates (comparable to oil per kWh). That way you would only be substituting electricity for oil when the electricity was costing you less than the oil.
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PostPosted: Wed Dec 05, 2012 11:25 am    Post subject: Reply with quote

A standard electric boiler may not work well with a wind turbine.
Many types of electric boiler are either on or off, with no provision for part load operation.
The output of a wind turbine is very variable in both the long and the short term.
A better choice would probably be a hot water tank containing several immersion heaters with automatic control so as to fully utilise the variable output of the wind turbine.
The hot water from this tank may be pumped through conventional radiators.
"Installers and owners of emergency diesels must assume that they will have to run for a week or more"

Last edited by adam2 on Fri Apr 12, 2013 2:31 pm; edited 1 time in total
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PostPosted: Wed Dec 05, 2012 12:15 pm    Post subject: Reply with quote


Read through these PowerSwitch discussions; you might get some useful information from them:




Make sure to have a look at the links there, such as:





and especially:



I experience pleasure and pains, and pursue goals in service of them, so I cannot reasonably deny the right of other sentient agents to do the same - Steven Pinker
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kenneal - lagger
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PostPosted: Thu Dec 06, 2012 9:08 am    Post subject: Reply with quote

This talk reminds me of the reason why I go for insulation. The reason was that we were buying a bungalow in 1975 and saw articles in the newspapers about some funny hippy people who had formed a coop called The Centre for Alternative Technology in Wales and were building a solar water heating roof with a seasonal heat store to heat one of their houses. I thought that was a good idea and could be replicated on our bungalow.

After I had done the calculations I found that the heat store was too big for the garden so I thought I would insulate a bit to get the heat store size down. As soon as I started the insulation calculations I realised that I could insulate the place, so that there was only a very small heat loss that could be provided by a log burner, at far less cost than the complicated and maintenance heavy installation I had originally contemplated.

I have been working on that basis ever since 1975 and it has worked very well for me and my clients. However, Miriam's installation is starting to look very expensive and complicated indeed. The maintenance costs, if she can find anyone capable of maintaining it, would put me off for a start even if the capital costs hadn't done so already.
Action is the antidote to despair - Joan Baez
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PostPosted: Thu Dec 06, 2012 5:29 pm    Post subject: Reply with quote

Someone on Board (adam2?) built a simple heater using a WT for power: the power simply ran through an "element" embedded in a concrete or stone "kang" (raised heated platform you can sit or kip on...in Manchuria. We don't seem to have a word for them) in the living-room.
Soyez réaliste. Demandez l'impossible.
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kenneal - lagger
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PostPosted: Fri Dec 07, 2012 3:03 am    Post subject: Reply with quote

You could build a rocket mass heater for less, much less.
Action is the antidote to despair - Joan Baez
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PostPosted: Sat Feb 23, 2013 12:20 pm    Post subject: Reply with quote

It maybe too late, but here is my bit:

The two bladed Gaia turbine is unlikely to be your best bet for several reasons, the main one being that it has a maximum wind speed of about 50mph.

You would be better off with a pair of Evance R9000 turbines which will work right up to 134mph.

We happen to have friends nearby with both the Gaia and the Evance.
The Gaia has been no end of trouble and it exceptionally ugly (partly because the two bladed design attracts the eye, so you cant help looking at its flickering movement.

The Evance runs much faster, creating a fuzzy circle with its blades, which almost disappear in the background.

I believe that for the budget, your should be able to get two Evance turbines, which will consistently produce more power than one Gaia, you have built in greater reliability and you will probably end up with spare cash at the end of the installation.
What a shame, seemed quite promising, this human species.
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