Life at the end of the road

September 6, 2015

There’s a bomb in my bunker :-)

I started this on Thursday, well, I created the title with the full intention of telling you all about the day’s excitement. For it was on Thursday morning that the thermal store arrived all the way from Finland, if anyone knows about keeping warm it’s the Scandinavians. A quarter of Finland lies within the Artic circle so they know a thing or two about insulation too, hence the size of what is in effect, our hot water cylinder, all 1500lts of it. Of course I knew exactly how large it was, where it was going and how much it weighed but that still didn’t prepare me for the shock of seeing it when it arrived.

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This store is in effect a huge battery for all our renewable energy inputs, but unlike your regular batteries it’s performance doesn’t degrade by using it. In theory at least, it should last forever if the anodes and the corrosion inhibitor are changed regularly. As most of the energy requirement of any house is heating and washing then it makes sense to store that energy as heat rather than electrons in a battery, the conversion rate is far better (especially if using a heat pump) and a cylinder like this is far cheaper than a battery of the equivalent capacity. It’s also far less hazardous and unlikely to short circuit Smile

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Billy Shanks of ‘Shanks Plumbing and Renewables’ supplied the tank and it was himself and Lachie that convoyed it up to Sonas. After a quick cuppa, we all got stuck into moving it into the ‘Bunker’, as usual, the telehandler doing most of the work, but it was far from straightforward due to the scaffolding and slope of the ground. Removal of part of the scaffolding and some blocks under the forklift front wheel sorted that but even so the store could only be deposited at the door. Luckily a convenient strainer post proved good purchase for a small block and tackle which allowed us to tip the store into the shed and push it in on some planks.


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Boring a hole through one of the rafters allowed us to hang the tackle from the roof and right it, after which it was just a case of rotating it into position.



The four red blanks are (top to bottom), DHW out, DHW in, Heat pump out, Heat pump in, G and H on the drawing (just by Billy’s knee) is the solar coil. The hot water for the UFH will be coming in and out via two of the eight 1 1/4” tapings labelled 1 on the drawing, most likely one of the bottom two and then one of the third form bottom (just below the baffle). The idea of the baffle is to aid ‘stratification’ and keep the cooler ‘heating water’ water separate from the warmer ‘washing water’.

Fine oak

As soon as the store was in the ‘Bunker’ I hijacked Lachie’s Ranger and set off for Portree, after the best part of a week underneath the Land Rover a Ford Ranger was starting to look very tempting Smile The oak planking had arrived at Jewson’s in Portree and I needed to collect it, along with half a ton of cement for the rendering.

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Now I’m no expert on timber but this oak that Jewson’s sourced for me looked like ‘the real deal’, straight, knotless, heavy and a lovely dark colour. Best part of a grand right enough but that compared very favourably with prices for American oak on the Internet and those prices didn’t include delivery. This stuff is for the shelving and work top supports in our kitchen and when I dropped it off for ‘Iain the joiner’ he was well impressed. Iain wasted no time, and the day after started to cut it into battens the correct size, apparently it’s some of the best, if not ‘the’ best he’s ever worked with.

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Just as I arrived home the ‘workers’ were just about leaving for home but much had been done in my absence from Raasay. Faith, Hope and Charity, the three turbines at the Raasay WTW were being worked on. My lead flashing for the Bunker had been done and some fine tree felling behind someone’s house Smile

Back under the ‘Old Girl’

Friday was a bit of a ‘write off’ due to the midge, the promised north wind never materialized and the ‘wee beasties’ were out in force. Sure the Smidge worked a treat as far as being bitten was concerned but that doesn’t stop the ‘little devils’ filling your ears nostrils and mouth.

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It really was unbearable outside but Lachie did manage to get the guttering on the bunker and some more of the larch planking before ‘abandoning ship’ for the weekend.

I think I spent the rest of the day in the shed under the Land Rover,

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soldering the ends of the trailer socket wires and under sealing the rear chassis.

Saturday was a pure peach of the day and I’d had enough of the ‘Old Girl’, promising myself that I’d just change a tyre then give it a rest for a day or two.

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Once more it was the telehandler to the rescue, this time for ‘breaking the bead’, normally I’d just drive over it with the Land rover but that does mean having to fit the spare wheel. This method is much quicker Smile even with a tyre of this size, all that’s required to remove it from the rim is a bar (I used the handle of some stillsons) and rubber hammer. Fitting a tyre this width however is a ‘different kettle of fish’. The normal practise of using a ‘ratchet strap’ can be tricky and the ‘red neck’ way is quite scary, so I purchased a proper tool.

Bead breaking The ubiquitous ratchet strap 038 Image result for tyre bead blaster

Normal tyre removal method, regular fitting method, Hillbilly method gone wrong and new ‘bead blaster’ £50 off eBlag.

It was whilst the wheel was off that I spotted some more welding, which I sorted then managed to drop the jack down too far and remove my wheel arch Sad smile Luckily it was fixable, just took me an extra hour or two, which just about coincided with my son getting out of bed Smile Just in time to help me with the Ecocent heat pump I can’t say that I’m a fan of heat pumps, in my book they’re just a glorified fridge and there’s an awful lot of hype about them. Sure under ideal conditions they can produce three times more heat than the energy required to run them, the COP however is highly dependent upon the outside temperature and as it gets cooler the efficiency rapidly falls. This unit has a COP of 2.8 to 3 at around 10 degrees and only uses 810W therefore producing up to 2.5kW of usable heat to the store and matching the output of one of my turbines very nicely.

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The Dude and I made a good strong shelf for it then fitted a bracket for the block and tackle so we could lift it into position for Billy.

That done, we started on assembling the solar hot water arrays,

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just the frames and manifolds that is, the ‘evacuated tube’ on the right was just a trial as fitting it without any water in the system to cool it is not a good idea.

There are three of these going on the bunker roof, that’s sixty tubes in all some 2.2kW in total which is far more than I could squeeze on that roof in PV. Again I’m not a fan of ‘Solar Thermal’ in my situation, which is ‘off grid’ so I need to have inverters anyway so PV makes more sense. However as this roof is directly over the thermal store it would be foolish not to make use of this technology. Solar thermal can basically provide ALL your DHW, even at this latitude from spring until autumn and it’s well within the average DIYer’s  capability to install it if you already have a hot water cylinder, not so easy if you’ve a combi boiler and no tank.


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We did manage one of the mounting rails but yet again where driven in by the midge, and smell of roast beef Smile



  1. Hi Paul

    Impressive beast, that thermal store. You mention solar thermals not being easy to install for a combi-boiler. I did wonder why you have a water cylinder (however different from the usual ones) rather than a combi – is that the reason, or are there others for it being better for you to have a version of a water cylinder?


    Comment by Sue — September 7, 2015 @ 7:20 am

    • Hi Sue,
      if you’re attached to the rest of the world with an electric cable or gas pipe then yes, it does make sense to only heat the water you use because you have unlimited energy on demand whenever you need it. Being ‘off grid’ we need to store our energy in ‘times of plenty’, hence the batteries and the thermal store.

      Comment by lifeattheendoftheroad — September 7, 2015 @ 8:54 pm

      • Thanks for that – should have worked that one out.

        Comment by Sue — September 8, 2015 @ 6:53 am

  2. Gulp…!x

    Comment by SOTW — September 7, 2015 @ 9:09 am

  3. I love all the new shiny kit you have and if I was building a new house would do something similar with a big heat store in a separate building.
    But don’t you think you are going to have too much energy/heat? – How are you going to manage all the separate systems?

    Comment by Kev — September 7, 2015 @ 7:26 pm

    • Hi Kev,
      But don’t you think you are going to have too much energy/heat?

      Undoubtedly, at times we are

      <img src=" photo March gen_zpsksoo3usj.png” alt=”march” />

      Here’s the energy spreadsheet for March this year and the average daily requirement for three adults in a house insulated to current regs is 51kWh per day. As you can see, some days we’re well OTT and some days we’re short but taken over the month our requirement is 1581kWh but we actually produced 1631kWh. It’s just a matter of balancing it all out with the store, batteries and common sense 🙂 I use March as an example because it’s one of the tricky months. Summer is fine with plenty of solar and winter is great for the wind. Of course it may not work, in which case we’ll just fit a wood gasification boiler in the barn but that’s a last resort.

      Comment by lifeattheendoftheroad — September 7, 2015 @ 9:16 pm

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