Rendall

Yes, we can get oil in 1000l deliveries by 4x4.

Thanks - interesting thought. Not looked at CHP and just been looking at Viessmann Vitovalor (a home made one is far beyond my skills). LPG here would only come in bottles - again due to the access - so I suspect we'd get through a a large number so the oil automation aspect remains a plus in that regard. However the benefit of being able to mix and maximise the heat and electrical generation for the wetter/darker seasons looks like it could be an option.

Mainly the need for daily loading. We do have a lot of accessible timber, but mainly sitka which I once read is not great for log biomass as it creates more residue on the flues (Not sure if that is the reality though in anyone's experience?) Ideally too we'd house the plant for a boiler in a back room of the house, rather than build an ancillary structure for the plant. Hence an oil boiler gave automation and just needed the tank siting outside the back of the house. We did look at automated pellets or chip systems, but the access for local suppliers was an issue as they would only be able to deliver in bulk bags.

Hi all - Our project has been slowly ticking along over the course of this year. The power and heating equations have remained a big areas of questions. Being fully offgrid we need to find the most cost effective/simply designed approach that meets our expected needs - a circa 25-30kWh per day electrical demand, and a heat loss of around 15-20kW plus DHW. We had further quotes from a mains connection in conjunction with some neighbours in our valley, but this is too high a capital outlay (£168k+). We have a stream which present a hydro opportunity so have looked hard at options here in a couple of different ways given that this has such prime potential for electrical generation. The challenge is that whilst the winter flows of the hydro mean we could have up to a 20kW system this would be far more than we need at peak (290kWh per day for around 15% of the year - 55 days), whilst at the other end of the spectrum the driest flows would generate little to nothing for another 15% of the year. The more cost effective solution seems to be a Powerspout turbine which generates up to 1.5kW, but you can also set them up in parallel to increase this. This would still not operate in the driest 15% of the year, but with two turbines we could have a max generation of up to either 70kWh per day across around 85% of the year. So our thinking is that we have a set up which is around 5kW of solar, a backup generator and batteries. For the small hydro permissions and monitoring is likely to take longer so we see this a second phase installation we would then need to graft on to the initial system. Essentially it should balance the solar for the wetter/darker periods of the year and cut down on the generator demands. If we had gone with the larger hydro, we had wondered about the electrical capacity opening up heat pump options for heating. However given that even the larger hydro could have outages or dry/cold periods, we'd need something like the Grant hybrid oil/heat pump to have a contingency. However we are then paying for a premium heat pump product, as well as the higher capital investment for the larger hydro. From a cost/simplicity perspective it therefore feels that an oil boiler remains the way to go forward with the heating and hot water. I do have reservations on oil given the environmental direction of travel, but I think it does give us a cost effective solution at the current moment for the likely capital investment with then an absorbable ongoing running cost (and the fact a local supplier does 4x4 deliveries and can deliver to us as we're a couple of miles up a slate track). In 10-15 years when the boiler needs replacing we'll have to see where the wider world of heating technologies has got too as well as what we can afford by then. Thinking is that we'd link this to a thermal store which can also take dump loads from the solar in summer, but then the hydro when that is added on in 'phase 2.' However I'd appreciate thoughts on this and how to best size it. It seems the view is the larger the thermal store, the better. It would need to work effectively across scenarios of a mix of all, or just one or two aspects of the oil boiler/solar dump/hydro dump during either the first phase when we're just running on solar (in which case any dump load would be very limited) or seasonal permutations in the later phase when the hydro is grafted on to the system. Thanks all.

There is a saying out there somewhere which is something along the line that we name streets after the things that were there before we built the houses, so kingfisher corpse could perhaps be apt!

We bought a cottage once called Merrijig. Vendors said it was named after a place in Australia. It really fitted the place. I wrongly assumed the chances of there being another anywhere were non existent until one day at work when a letter landed on my desk from someone who also lived in a house called Merrijig. I did ask why; they liked dancing.

@Cpd - very compact!

Thanks Jeremy. We've had the water tested - no big problems. Highest anomaly is manganese, but within limits.

Hi All - We'll be using a private spring water supply, and will need a filtration and UV kit to be installed on the supply. What type of indicative space is needed for this? We have an old outside stone toilet approx. 1.5m by 1m in the right place so would ideally like to repurpose this by fitting it in there, along the pump, from where the water will then go ten meters or so into the back of the main house.

Yes - we'll apply to Natural Resource Wales for this.

Well, I was in Suffolk until we came over to Wales three years ago. Denston then Preston St Mary. Suffolk cottages are lovely things; at 6ft 3 though I was always very annoyed with estate agents who did not put heights on the dimensions of room details - we wasted a lot of time going to look at cottages which I'd have to stoop in all the time!

Yup, I still confused @SteamyTea...actually maybe more If I follow correctly, you're saying my 88 kBTU calc is the same as a 26kWh demand; ie by that I'll need 26kW for one hour to get it to the right heat level? Or is the BTU calc I did the daily 24hr demand - so the equivalent of 26kWh/day - and hence your comment that with a 3kW hydro, a third of that (ie 1kW/24kWh per day) is the need for space heating? Presumably then though there is the little and often (or indeed perhaps a lot and often) continuing heat to sustain it and mitigate for heat loss?

Good point Ed. The issue would remain that I mentioned to Jamielad - it might not be a fault that means the hydro can't run, but a hard frozen spell or a excessively dry spell. In that case though to extend your logic, it could be that a hotel room for a few days may be cheaper and more enjoyable than putting in an infrequently used oil boiler!

Yes @jamieled, that's exactly what I want to bottom out. We're about to get the low flows report carried out so hopefully that will provide some additional insight to the equation. A very cold snap which freezes water in the catchment or a dry shoulder season period could drop the hydro generation significantly down, so at that point it would be over to what might be a very minimal solar generation plus the backup generator to handle the input into the system. I suspect we'd adapt to this to some degree - eg using the backup gas oven we can significantly drop the electrical demand by turning off the Everhot - but it will be the heating/hot water which I'd want to be sure will remain sufficient too. How long might a well insulated thermal store retain their heat? That may be part of the answer. However ultimately if we plan for a 3 to 4.5kW hydro feed I understand the thermal store would need to be a very large size to capture all of that dumped electrical generation, and I'm then assuming that may prove problematic as it could be oversized for the solar/backup generator to heat up from the feed they would be able to put in, particularly in an overcast winter or shoulder season.

@ProDave It's one of the questions I have. I've got someone else working up some calcs on the heating demand and heat loss for me to sense check the 45kw figure that I'd previously been given. I have a sneaking suspicion that that first chap had not done the full calcs but plucked the number out of the air when I chased him. My own BTu calcs came up at 88,000BTU, dropping to 80,000 if I can get some decent double glazing through the planning process. However that was just a basic online calculator and my first introduction to the world of BTUs so I'm not trusting them!