a really big question...

[chasfromnorfolk]

I live in rural Norfolk, in an electric-only plus woodburner cottage. I have two groundfloor, well insulated rooms with underfloor heating from an Aztec electric boiler - running cost acceptable, but I'd welcome a reduction in the bills, of course. Elsewhere, a woodburner heats two rads feebly but the room it's in quite well. I have unlimited wood, but lack the energy to consider feeding a serious wood boiler installation - besides, the place doesn't really lend itself to a conventional pipework and rads even if I went onto an automated system. I have pretty much all the insulation and double glazing possible.

I could install a PV system, maybe not the full 4kw but something, on a rack for prime south position.
I could have a wind turbine.
I could add panels to help with the underfloor heating and DHW.
I could (and probably will) buy a Navitron Solarkit for an additional bathroom planned this winter.
If there was running water on site, I'd love a water turbine, but this is Norfolk.

I can't afford all of this kit. I can't really afford any of it, but feel I should be harnessing some solar/wind energy, not just for the FIT but as  prudent, long-term provision for a comfortable old age. The oft-quoted 25 years would just about see me out. It would be cheaper to move somewhere warmer, but I like Norfolk.

I have spent (according to my stats) 10 hours 15 minutes over the past few days reading some very interesting stuff on here and I thank all contributors for it  but like dear old John Ebden used to say: despite my best endeavours, I've come to no serious conclusion...

So, the big question:

If you were to do just one thing to best use current technology discussed in these pages to make life more comfortable - which really means having hot water/electricity/heat without worrying too much about the utility company bills -  what would it be?

Chas

[A.L.]

hello,

almost regrettably, but given the current FIT regime, where an investment of £3000 can produce an annual index linked saving of around £400 I have to say there is one obvious answer (assuming no unknown problems) - solar PV

[chasfromnorfolk]

Is it the 'dash for cash' element that makes it regrettable, A.L.? Coming from a generation that supported the earliest days of Machynlleth, I sort of regret we've got away from a bit of welding and creative work with old radiators too...

However, we are where we are and I can see that the whole PV package including the FIT would help run the underfloor heating both by generated power and FIT and if the combined value for a small system and 3000 of my dwindling pounds is c£400 that must be significant versus £3000 spent with EDF over the next few years buying their leccy.

Are we sure though, pound for pound, that's better than pre-heating the water that the underfloor system uses?

This is my dilemma.

Chas

[Quakered]

The PV will generate more cash than an other option via the FiT and that is what makes it the winner. A the risk of stating the obvious, the PV will generate the most when you need heat the least (sunny summer days!) and nothing when you need heat the most (winter nights). The cash FiT payments will however will provide a better store for the cold than tanks of hot water.......

In your position I think I would be getting a wood fired boiler - free heat and a bit of healthy exercise prearing the free fuel - sounds an excellent recipe for a health old age!

[A.L.]

hello again,

Is it the 'dash for cash' element that makes it regrettable, A.L.?

- in as much as it stifles the alternatives through the uneven payments to the different technologies.

Are we sure though, pound for pound, that's better than pre-heating the water that the underfloor system uses?

A typical 4m² flat plate or 40X58mm evac tube system might produce 1500kWh of hot water annually but you probably would not actually use all of it. In December/January working at low temperatures it might collect 60kWh per month. The system would probably cost £3000-£4000 even after an RHI premium payment of £300. It could potentially generate perhaps £150 per year when stage 2 of RHI comes into effect at the end of next year.

However I have not included the cost of integrating the system into your instantaneous electric boiler UFH system or the complex controls that would be required.

[dimengineer]

If its all electric, Solar thermal is probably the cheapest capital cost for the best outcome. Payback would be a similar 10% ish for an outlay of £3000-£4000 to give you your hot water for 5-7 months of the year.

[dhaslam]

The other  point is that PV  is getting cheaper and more efficient  so waiting a year or two  would save outlay, even though  FITs will reduce as well.  Solar water heating has gone through its development phase and prices are fairly static.   

[Bodidly]

Hi Chas,

As your house sounds like its well insulated and you already have underfloor heating, have you considered a heat pump?  Preferably a ground source if you have enough land.  A worst case scenario an air source heat pump would have an annual efficiency of 250% and a good ground source system can have an efficiency of up to 400% (that is 1kw of electricity being turned into 4kw of heat).  

I am a fan of solar PV and am in the process of installing a system but as already pointed out the times of least sun are normally the coldest.  I have a ground source heat pump in a well insulated house, it does my hot water and can do my underfloor heating when the wood burner is not on.  I find it convenient and efficient.

Beau

[chasfromnorfolk]

I have, in what seems like another, better funded life, considered a ground source heatpump setup  - but while I have the ground, the rest of the kit is likely to be beyond affordance now.

I am attracted to PV, mainly because it comes in different sizes for different budgets, and I can embark on a merry round of meetings with eager suppliers asking for their best prices from their smallest to full 4kw and yes, the FIT (who's picking up the bill for that, btw just UK taxpayers or is it EU funded somehow?) will do very nicely while the winter slow-down only trickles in actual electrickery. What a shame it has to be installed by registered installers, when it can't possibly be beyond the abilities of a competent electrician...

I'm also hugely attracted to a solar installation of some sort for DHW, pretty well exclusively for what will become my main bathroom, upstairs. In the spirit of Machynlleth I would like to recycle some kit from the stores: a big old copper cylinder I have won't take the Fornax system though - its an Economy 7 type with side bosses, so can't take the length of the Fornax immersion.

I do have a veteran 170 litre s/s Megaflo with it's pressure vessel, and it says on the label it has a replaceable copper coil... there are two 22mm s/s tubes protruding from the top where there's a bolt-down circular crown. They were evidently unsused in the previous installation (again, Economy 7, has twin immersions, side fitting) so would that be usable...?

Is there the chance of a Solar DHW system here? I see Navitron do complete kits with cylinders, but what do I need to buy to incorporate my own Megaflo instead and enjoy deep sun-powered baths forever(ish)?

Thanks to all who've shown an interest.

Chas

[jotec]

I made my own solar thermal which gives us our hot water in summer. Cost about £250 in total. If you are interested I have a PDF.
Dick

[chasfromnorfolk]

Cheers, Dick - all info welcome, particularly of the DIY kind.

A touch off topic (but it is my thread)... I did see a very early example of a swimming pool solar collector in the form of three lines of 1/2" copper tube alongside the pool (maybe 20 yards of low retaining wall to clip to, facing south) on which were threaded wine bottles with the bottom (punt) knocked in, neck nestled into punt. A small pump circulated the water from the pool, through the three pipes till it trickled out of the end back into the pool, quite warm. Blimey, that's 40 years ago now and it looked like it had been there donkey's years then...

Chas

[jotec]

Here you go. PDF of DIY solar hot water. Mine works really well.

http://dpks.co.uk/work/solar-power.pdf

Dick

[brackwell]

Chas,
You say you have 2 well insulated rooms with a wood burner and i am therefore surprised that this does not supply all your heating needs directly without the rads.  I would have expected you to be able to heat the DHW instead of the rads.
In summer when the fire is not on then a solar thermal system (using your tank and DIY) costing well less than £1000 would be a good investment.

Solar PV is a good investment at the moment because of the FITS so it boils down to investment V return.

Ken

[qeipl]

Chas,

I live in NW Scotland and get all my domestic hot water and 70m2 of underfloor heating from an air source heat pump that's built onto the top of a 300 litre DHW cylinder.
Mine is an Ecocent. There are other makes available.

The tank has a solar coil which I use for the UFH. I plumbed an electric boiler into the UFH circuit as a backup, in case the heat pump couldn't cope, but it has never been needed.

The unit cost me about £1600 and could be a direct replacement for your old Megaflow.

If you set it up to draw air from outside you'll get a COP of more than 3 in the summer, c.2 for a good chunk of the spring and autumn, and no better than 1 in mid winter, which is when your electric boiler will take the strain. Over the year you'll use less electricity than you do at the moment.

I use my house a solar collector (south facing glass, good insulation/draught-proofing) and the heat pump is set up to draw air from inside, including from the shower rooms when they are humid. This means that the COP is higher on sunny days in autumn/winter/spring. The outside air is drawn into the house and warmed up a bit by the sun before it goes into the heat pump.
I also have a very well ventilated house and get a bit of heat recovery from the showers etc.
In winter, when there's no sun the pump would run all day without heating up the house, so I light a wood boiler in my adjacent workshop which heats rads in two rooms. The hot air from these rooms is sucked in by the heat pump periodically and then redistributed via the UFH.
If your house gets lots of solar gain it would be worth thinking about setting it up like mine.

Many of people on this forum are sceptical about my setup but I'm happy with the performance and the cost of running it.
My total floor area is 100m2.
In addition to the UFH/DHW, my kitchen is all electric, including 2 fridges (one of which is a very greedy 57 year old Electrolux).
My total domestic electricity consumption last year was c.5200kWh.
Over that winter I burned less than 300kg of coal and a small quantity of scrap wood.
Toasty warm and lashings of hot water for showers despite long periods of below -10 degree and sometimes temp of minus twenty something at night.

If you've done all the insulating/draught proofing/double glazing and have limited cash to spend on equipment then something like the Ecocent is a good option.

Cheers,

Malcolm

[chasfromnorfolk]

Cheers, Dick - and that's some info to digest, will be working my way through it later today.

Ken, you sort of misread: the 2 well insulated rooms are fine, heated though they are by the underfloor/Aztec. The woodburner is, as I say "elsewhere" meaning one of the other groundfloor rooms (our lounge in fact) and it seems to struggle to heat the two rads run from it to the adjoining rooms which otherwise have no heating. I inherited the system and originally it did also 'help' a HW cylinder nearby - but seemed unequal to the task and when the cylinder failed on a pipe boss, I installed another cylinder on E7 elsewhere.
I do plan, sometime, to reinstate and possibly improve the system with another cylinder to 'harvest' some heat from the woodburner. While I'm disappointed in the fire's back boiler output, I'm prepared to believe it may be hindered by the cat's cradle of pipework it's hooked to. This would be the cylinder I'm most likely to boost in summer with a solar system.

At least I was, until I saw Malcolm's post re an Ecocent cylinder and airsource heat pump. This is totally new territory for me (have Googled Ecocent and now have more boning-up to do) but it must be considered, particularly with that testimonial and it's apparent multi-function. A bit of a supplementary (or two. Or three):

Directly over the drop down to the underfloor connections (and the underfloor-heated rooms) is an unused hayloft with plenty of headroom where my coldwater storage tank and the header tank for the Aztec are sited. If I insulated the Ecocent well in a purpose made enclosure, but allowed it to draw air from the rest of the loft, would that be ok? The air temperature up there will be just a tad up on outside and it's close to power for any requirement (E7 if useful). There is no shortage of 'air' - it's about 80 feet x 16 with a fairly gappy but sound pantile roof.

You say it has a solar coil (forgive me, I'm yet to read the Ecocent blurb) so, you also have a solar panel connected? Being up in the loft, I have an easy west-facing slope just the other side of the tiles... in fact the front of the house is very sunny in the morning, so maybe even dual E/W panels?

Are there also tappings for a flow and return to the woodburner? though a bit of a stretch, I'd love to think it was contributing a bit.

Thanks all for your patience and info,
Chas