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!

Hi All - We've been slowly ticking away with our offgrid renovation project about which I posted a few questions a year or so ago. Biggest design challenge (to date) has been trying to find contractors who can look across the different systems at play and getting to a point where I have confidence that we have a workable, cost effective, and not over complicated, whole. At present the solar guys don't do hydro. The hydro guy does do solar, but not heating. The heating guy does not do hydros. So lots of potential gaps for things to fall through. So I thought I'd share the shape of the main information and questions we have on here and see if anyone has thoughts on the interplay of the systems, or thoughts on the questions we should be digging into or asking further. As I mentioned when posting before, this is a fully offgrid property - no mains gas or electric anywhere nearby so we've essentially got to set up a fully functioning micro-grid. Electrical Generation Hydro - We can get a pico hydro on the nearby stream which with two powerspout pelton turbines running off the one penstock should give us a reliable 3kw/72kwh per day. We may be able to add a third to this, which may give us an option for extra generation of 1.5kw in autumn/winter. Solar - In conjunction to this we have a reasonable south facing site which could host 4-6kw of solar. Generator - We'd have a backup generator linked to the system These would feed into a lead acid battery system and from there then feed into the house. Electrical Demand From some rough demand calculations, we think we'll have a daily demand of approx. 40kwh, with a peak load of around about 5kw. (NB I've not yet modelled this based on summer/shoulder seasons/winter to see how different it might or might not be) Cooking Included in the above figures are an electric Everhot 110 range. (Backup gas LPG bottle fed oven in back kitchen) Hot Water & Heating The house is a good 360m2 (two main floors of 155m2 plus couple of attic rooms). Construction is slate slab walls approx. 30cm thick. Roof and attic insulation will be put in and north facing rooms will be internally insulated. The house is south facing, but it is a wet climate around here (its the rain belt of mid-Wales). We'd put UFH under the slate slabs in the groundfloor hallways, back rooms and kitchen. Log stoves would be in three other groundfloor rooms. Heating calculations from one heating engineer suggested a need for about a 45kw boiler. A biomass boiler is not practical as the pellet delivery lorry would find the access difficult and we don't want the physical dependency of needing to feed a log supply regularly. So oil is what we have been thinking about for the fuel (and the local firm is used to access up tracks like ours with the range of farm customers they have). Conversations have been that we'd have a thermal store into which we can dump any extra electricity but I'm assuming the amount we can count on to dump might also be able to reduce the potential oil boiler sizing? However, with potential generation of up to 108kwh (if we were to set up three turbines running) we'd presumably need a fairly large thermal store to handle the potential amount of electricity we need to dump? Given the difference between a potentially large regular electrical supply of 72kwh (or indeed more) for the wetter 6 months of the year, compared to a more volatile say c.50-80kwh or so in the summer, might this make sizing the thermal store difficult as it may be far too oversized for what would work effectively in the summer? Separate to all of this might there be any logic in having a backboiler on one of the woodstoves which can also be an extra occasional winter feed to the thermal store? There would be an argument to get the hydro to generate as much as it can and aim to run the hot water and heating fully from this and the solar. Not sure if the numbers would stack up for this or not, but ultimately even if they did, my worry would be what would happen when a part on the hydro breaks and it take a couple of weeks to get a replacement. Having an oil boiler that's also linked into the hot water/heating, plus the back up gas oven means, makes me think that we'll at least be warm and fed, even if we're using candles and undertaking a digital detox. Hope that provides some context on the aspects at play.

Looking at previous posts, it seems they're for a path! https://lifeattheendoftheroad.wordpress.com/page/10/?s=quadzilla

An update on all of this as we work up the outline spec. Thinking now has shifted away from the whole oil/LPG question for a range/back boiler to a mix as follows: Pellet fuelled stove/boiler (eg http://www.ludlowstoves.co.uk/product/klover-120) for the cooking, hot water and central heating (feeding UFH in the back of the downstairs section - a limecrete/slate flagstone combination), plus radiator/log burner combinations in two front ground floor rooms and radiators in upstairs rooms. These boiler/stoves are eligible for RHI which is a bonus, and pellet deliveries probably more straight forward logistically up the track to the house than bulk LPG or oil. We would have a good supply of firewood (soft) onsite, but speaking to a few folk the verdict is the effort of creating and using your own logs is not worthwhile in comparison to bulk order of bags of pellets, even with the manual tops ups then required into the hopper. The logs we do chop we can instead use in the log burners. Anyone here have other views? Electrical supply still via solar/hydro combination, backup generator and battery pack. Extra renewable electrical supply to also feed hot water. Need to more firmly size the potential v installation cost v cash to fund it equation of the hydro but probably 1kw pelton turbine, and solar would be about a 4 to 5kw set up.

@scottishjohn Just cross posting this in here from our other thread. What do you make of these systems for 'breathable' internal insulation on solid walls: https://www.lime.org.uk/applications/retrofit-insulation-systems-for-old-buildings/internal-wall-insulation-system.html

Here's a rough map of the aspects mentioned yesterday. Plan of service locations.pdf

Yes - lathe and lime plaster on slate walls

That's an option for some internal rooms (as are wood burners), but not for this one in question as that has ornate plaster coving (and it's listed).

I did wonder about LPG for both the rayburn and backup generator. However, I was pointed in the direction of a few horror stories from the shortages last year which has shifted my mind back to oil as potentially more reliable in terms of supply.

I'm drawing up some BTU calculations for our project. Somehow my original finger in the air estimate of 80,000 has come out on my more detailed room by room calculations as....80,000. (I'm bearing in my mind the fact that I can be equally wrong twice!) Anyhow, one front room comes out as 14000 of that (it has a large bay window and a suspended wooden floor above a cellar). We'll get a couple of good sized radiators in there, but there is also a open fire. We'll not put a woodburner in that room (yet to see any that look good with the sort of Victorian fireplace surround it has) but I'm wondering if anyone has a rough BTU for what a standard size open wood fire will generate when it's going?

I'm looking at designing for 20kwH per day. ASHP I'm not sure on - its an older house so feel it will always be relatively leaky and I worry about the effectiveness? The Rayburn was a fixed ask from my wife. It was originally an aga ask but she's happy with a Rayburn, so my thinking is that as we're putting that in anyhow we could go for a Heatranger and thereby use the back boiler for the DHW and CH rather than have/fund another component for those elements. A hydro could have up to a 100m fall, but 20m in on our land/80m on a neighbours. My 'bucket tests' suggested flow of around 15lps even at the height of last summer's dry spell, but a wider initial desktop survey by a hydro firm suggests a mean flow of around 27lps. They calculated potential of a 14kw system so around 45000kwh per annum generation off this but that came with high costs - c£50K - and we'd definitely not need something of that size of generation (and can't export). I want to get a lower cost for a smaller system that is closer to our domestic needs, but ultimately this is all dependent on agreement for the weir and penstock to be installed on the neighbour's land. Having a conversation with them in next couple of weeks, but even then speed of consents or our budget may constrain when we could move on this. If we did do this though a pelton turbine or something like http://www.scotthydroelectric.com/ which could give us 500w or 1kw or so would make a big chunk of the need for a good proportion of the year and be balanced/supplemented by the solar and backup generator.