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Author Topic: Advice needed on our new renovation project in deepst darkest rural France.  (Read 913 times)
Le Hobbit
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« on: July 26, 2020, 06:28:58 PM »

After a long, long search we have finally bought an old granite house to renovate in a remote part of Correze in Central France. The property is located in the Millevaches Parc Naturel Regional at an altitude of 800 metres above sea level. Climate is semi-montane with normally warm to hot summers and cold, often snowy winters. More recently winters have been milder and wetter and summers hotter and drier.

The house is a complete renovation and comes with 4 hectares of attached land which is mainly native woodland, hence there is a good supply of wood for heating.

We plan to insulate the house by having a new zinc standing seam roof (bac acier) with 100mm of PIR bonded to the roof panels. Under this there will be an attic floor with 150mm of wood fibre or similar insulation between the rafters. This will be boarded over, with pine cladding on the ceiling side. The external walls of the stone built house will be rendered on the inside with approximately 80mm of hemp-lime and then a lime plaster on top. The ground floor will be pine flooring over an exisiting concrete slab with insulation between the chevrons and in the cellar. In the adjoining 30 m2 stable which we will turn into a lounge we will lay a hemp-lime floor slab with pine flooring over the top. Double/triple glazing throughout.

The house is built into the hillside so all of the ground floor rear wall (north facing) is below ground level. For this aspect we plan build an extra internal wall with a small cavity behind. We will use these cast hemp-lime blocks for this wall.

 https://www.isohemp.com/fr/blocs-de-chanvre-pour-une-maconnerie-naturellement-performante

The ground floor is currently one large kitchen/diner which is approximately 51 m2 and the adjoining stable of 30m2. Upstairs is currently one huge space of 90m2 with the framework timber in place to create a spacious attic (storage only).


Now to the heating system. We have been thinking this over and would like to go for mainly or exclusively wood heating.  This will be a permanent home for us. In the kitchen there is a large fireplace which is big enough to take a woodburning cooker or cuisiniere in French. We are interested in the La Nordica range (Italy) which are good quality and reasonably priced compared to French brands . The difference in cost between one with a back boiler or without is not that great. Ideally we would like a system that can produce domestic hot water and heat a few radiators. This La Nordica range can heat up to 444m3.

https://www.topchaleur.com/cuisiniere-a-bois-bouilleur-termorosa-dsa

I really want to get some advice from you knowledgable folks on here.

Ideally we would like a system which can connect to a dual tank for wood heating and (later on) for solar water heating and also run up to half a dozen radiators. We get copious sunshine here in Correze and the roof faces south. We would have a chauffe eau (French hot water tank - electric) for back up.

As I understand it there can be both vented and unvented systems and also pumped and gravity fed systems? We once rented a cottage in North wales which had a Rayburn which ran rads and a hot water tank and that was fantastic.

We are finding it difficult here to find an artisan that will do the install for a reasonable price or at all? French artisan charges are very high because of the high taxes here in France. We would like to work with someone so that we can do a lot of the donkey work and install the more basic elements of the system. (radiators; cuisinere etc)

Has anyone on here installed their own system? How difficult is it? Is it a job for a professional.

Does anyone know of a good book on installing your own wood heating system. We would rather go down this route initially then h=just woodburners and back up electric radiators.

Hope someone can advise. We have a healthy budget but I was quoted Ä15,000 by one artisan and I think that didn't include the tank or cuisiniere!! Seems steep to me?





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daveluck_uk
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« Reply #1 on: July 26, 2020, 08:58:42 PM »

Sounds lovely!

300m2 over 3 floors in northern spain

As a non professional who fitted our own....I learnt it all from a book as I went along! I kid you not.

If I did it again I would get at least 1000lt vented store ( currently 475 )

I'd have a solar coil - for solar hot water. Although because my tubes are lower than the tank and I kept getting problems with the sealed system I went direct

3 immersions - at least 1 tied to excess pv I've only 1 and not tied to pv

Tappings for wood stove, pellet stove and gas / oil boiler - got all of these

2 Ch pumps to run 2 circuits or maybe even 3 - only 1 pump for all the system which I've effectively room zoned with smartish trvs

Oodles of pocket sensors - I lack sensor pickets

A generous amount of 3\4 and 1\2 tappings for future proofing - got loads!

Flats plate heat exchanger for you domestic hot water - they are fantastic...mains pressure hot water!





« Last Edit: July 26, 2020, 09:00:54 PM by daveluck_uk » Logged
brackwell
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« Reply #2 on: July 26, 2020, 09:41:12 PM »

I am wondering why you need a heating "system" with rads if you have one large room downstairs and one upstairs as just normal convection from a stove would do the job. I believe that you would be disappointed with a cooker/stove/back boiler concept and fixated by cheap wood.

You do not want to be using a very inefficient cooking stove for heating your HW for 9 months of the yr.  I would be looking to fill my south facing roof with solar PV and possibly have batts for storage.  Excess leccy will heat the water possibly all yr round in France.  It will drastically cut your leccy bills and make you prepared for the future EV world. As a standby you could use a Heat Pump (HP) as additional heating and hot water using the your own leccy which would be more efficient.
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Le Hobbit
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« Reply #3 on: July 27, 2020, 08:06:25 AM »

I am wondering why you need a heating "system" with rads if you have one large room downstairs and one upstairs as just normal convection from a stove would do the job. I believe that you would be disappointed with a cooker/stove/back boiler concept and fixated by cheap wood.

You do not want to be using a very inefficient cooking stove for heating your HW for 9 months of the yr.  I would be looking to fill my south facing roof with solar PV and possibly have batts for storage.  Excess leccy will heat the water possibly all yr round in France.  It will drastically cut your leccy bills and make you prepared for the future EV world. As a standby you could use a Heat Pump (HP) as additional heating and hot water using the your own leccy which would be more efficient.

Thank you for your reply. Currently there is one large open plan room downstairs and an adjoining stable which will be converted into a living space. However upstairs will be divided up ino three bedrooms, a bathroom and a couple of ensuites. Above that will be an insulated attic. We need to be able to get heat up to those rooms? I understand what you are saying about Solar PV, but it is a large financial commitment. We are hoping that setting up a stove with say 5 or 6 rads and a tank is cheaper than a roof full of solar?
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daveluck_uk
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« Reply #4 on: July 27, 2020, 08:23:02 AM »

Obviously solar is only good during the day unless you have a battery bank.

An inefficient wood stove will work anytime.

I stopped worrying about wood stove efficiency when I stopped paying for fuel. Like you all our wood is free other than, felling, logging and stacking.


It's all about getting the balance right between the various sources of energy available to you. Plus nothing beats sitting in front of a fire, that you installed, fired by wood you processed on a cold miserable winter's day or night.

Still, horses for courses I suppose.


« Last Edit: July 27, 2020, 08:26:17 AM by daveluck_uk » Logged
todthedog
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« Reply #5 on: July 27, 2020, 08:53:30 AM »

We renovated a Breton farmhouse similar metre thick walls. The external and internal faces are good the middle is rubble.
Our experiences and those of friends  were as follows.

To start we cleaned off the old plaster and the cracks between the stones and re pointed with lime putty, it looked very pretty but provided diddly squat in the way of insulation. It was cold. We ended up dry-lining with stud track and a shed load of insulation, lovely and cosy.  Clockman did similar with his Norman restoration project, his walls were straighter so he used insulated plasterboard and MAAP. Both of theses can be seen on here.   Another friend used lime plaster with hemp, over 150mm  internal lining. All were successful, none of us went for EWI as this  way too expensive and not suitable to retain original characteristics. Personally,  aesthetically I liked the hemp solution but it is a messy old process and not suitable if you are living in the house.

We had thermal solar for water 200l tank with back up immersion in the solar tank for winter months in wet and windy finisterre it was used on average intermittently for 3 months of the year even in mid winter in coming water was 7 degrees and was regularly heated to the mid 20's even on rainy days so it did not have to burn huge amounts of leccy. ST worked unaided for 9 months.  We did look at having instant water heater and shower for winter but the strange French pricing on electricity meant that it would push us into the next band of standing payment (you pay for the amount of electricity available to you as well as usage) so just not cost effective.

Heating and cooking  We had no direct experience of aga style cooking water heating but had a close friend who self installed at some expense a wood burning aga type and radiators. Again the temptation was limitless free wood called 'the beast' I think I can describe it as a complete failure. It required constant feeding and the associated work of log cutting stacking drying. Plus side it did provide hot water and keep the house warm, a complete pain in the Summer,  as funds allowed was replaced with a modern woodburner and a chauffe eau and electric stove. The radiators and stove stood as  cold stark reminders of  something that sounds great and isn't.
We had a very efficient wood burner (don't be tempted by the cheap rubbish on sale in the local DIY stores) they are a false economy, sealed external air source is good. This heated the whole house 150m2. The chimney was lined stainless steel tube and then sealed and insulated. Quite adaquate for our sized house friends with larger properties used hot air, an additional tube above the fire and a small switched fan in the outlet upstairs to provide a boost if required if not natural convection worked just fine.  A really efficient wood burner lasts for ages on a single filling produces little ash and will stay in easily overnight. Navitron used to sell rebranded Burley stoves which were excellent.

Our heating was supplemented by an air/air ASHP in the downstairs 50m2 which we used during the shoulder months when you wanted something for sitting in the evening but were too lazy or not cold enough  to light the wood burner.  We inherited a gas stove using bottled gas which worked just fine but was replaced by a induction top and electric fan oven which were loads better.

We had PV,  5kW and a 2.5 kW wind turbine the excess electricity being sold to EDF in those days we came out with a hefty profit to amortize the PV cost over 5 years. Again the cost of having PV installed was very high in France (it may have changed) we did a self import and install with both that and the windmill.

Water is quite expensive all metered so if you have a well do consider buying a pump and using it for the garden.

I guess you will not have collective sewage if your fosse is working well great, if not think very hard about the replacement, a lot of companies will try and sell an old stye replacement that involves inspection pits and sand and gravel soakaways with miles of piping a traditional system at great expense look at modern aerobic systems single tank and small air driven fan (mini station de epuration) or other alternatives to meet EU standards. Paul (Camilltec) has more recent experience.

Anyhow it sounds a great project. Look forward to seeing your photos.
Tod

A small addition, rural electricity supplies can be a tad haphazard in deep rural France a small gennie is a lifesaver during power cuts. We had a small holding and our years meat supplies were in 3 large chest freezers running the gennie for a couple of hours a day saved our bacon facepalm

« Last Edit: July 27, 2020, 09:24:24 AM by todthedog » Logged

Kidwelly South Wales
Pile-o-stone
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« Reply #6 on: July 27, 2020, 09:39:04 AM »

While having access to free wood is a fantastic resource, I'd be careful about relying on it for your space and water heating. Cutting down trees, chopping them into the correct size, stacking them in your wood shed all takes a lot of a time and energy. Not something you want to be doing in your 60s (I'm in my 50s and I can't be bothered with the faff). You also need to sweep your chimney more often (boiler stoves create more soot) and you have the worry of overheating (the boiler stove we inherited when we bought the house overheated because the overheat radiator didn't do its job and the house was flooded - we replaced this with a standard wood burner).

Instead I'd install a non-boiler wood burning stove for occasional use on summer and early shoulder month nights when it's a bit chilly, but not cold enough to warrant turning on the heating system.  I would install a GSHP (it sounds like you have a lot of land to lay the ground coils) and solar PV connected to an immersion on a water tank sized correctly for your family (you don't want to heat litres and litres of water that you don't use and have it go cold again).

I'd not install solar thermal. This is an old technology that is prone to leaking, freezing and is NOT 'fit and forget' like solar PV is. Plus it stops working when your water is hot, whereas PV panels will both heat your water and supply electricity.

I'd fit underfloor heating pipes in every room - I would not rely on convection moving heat around (i.e. from downstairs to upstairs) as you will want to reduce drafts not rely on them. You should insulate the ground floor ceiling for acoustic and thermal reasons and that'd prevent heat from moving into the room above. Also, in all of the houses I have lived in, the ceiling void was cold and had a gale blowing through it. More heat would be lost in the void than would get upstairs.
« Last Edit: July 27, 2020, 09:45:05 AM by Pile-o-stone » Logged

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Bugtownboy
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« Reply #7 on: July 27, 2020, 10:23:26 AM »

Iíd second not having wood as your source of heating - a dry stove plus a secondary form of heating is an essential.

Having experience of living in the Correze (Priezac & Lubersac), it, unless the local climate has changed significantly, can get very cold (-25 one winter) with significant snow falls. Conversely, it can get blisteringly hot in the summer.

Insulation is going to be your friend.

As well as managing wood in advancing years, consider the benefit of a secondary form of heating to cover periods of ill health, eg, flu. It ainít fun traipsing through in excess of a foot of snow to the wood shed when youíre feeling like $***.
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brackwell
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« Reply #8 on: July 27, 2020, 08:49:33 PM »

Tod,
Thanks for that interesting read. Very educational and well done.

The story of Aga type stoves is legendary and i have heard many such stories over the yrs.  I think the reason they do not work very well is their inability to burn hot and therefore efficiently, being little better than open fires. Modern wood stoves burn very much hotter seemingly producing twice the heat with 1/2 the fuel. Also with the Aga type stove there is a huge amount of metal to be heated before anything can happen and made worse again if cooling water is going through it.

The technigue of cooking (or not) on a Aga store is very much an acquired skill and not akin to modern cooking.  Do yourself (and wife) a favour and fit a modern induction hob and electric oven.  If you wanted to do some simple stew like meals and hot drinks you could do that on top of your flat top stove.

The PV will pay for itself and you cannot say that about much else. If it was done at same time as roofing then savings to make.

My wood stove,dry, as the ability to duct of hot air vents,2 i think but, i do not use them.
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renewablejohn
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« Reply #9 on: July 27, 2020, 10:13:28 PM »

Totally wood here and would not do without it although split into 3 units. Esse cooker for cooking and heating the hot water tank on gravity feed. Does the job but will be replaced with a Lohberger as technology has moved on and the covenience of auto ignition using pellets and logs as well will replace the crude esse. Central heating and hot water using a Dunsley Yorkshire wood stove and in the Snug a Dunsley Highlander dry stove. It all works due to the house being sealed with triple glazed glass direct into the stone mullions sealed with burnt mastic and outward opening scandinavian double rebate sealed doors. Ventilation by Partel MVHR units installed in tied pairs. That said I have future proofed the UFH by installing electric as well as the wet system.
Also have electric oven and induction hob for backup but rarely used.
« Last Edit: July 27, 2020, 10:24:02 PM by renewablejohn » Logged
Le Hobbit
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« Reply #10 on: July 28, 2020, 06:05:00 PM »

Lot's of great replies thank you to everyone who took the time to respond. It seems the jury is out on wood powered central heating and I can agree with comments about having to process tonnes of wood each year especially as age take's it's grip!! We probably need to rethink our heating plan.
 
We lived with a wood central heating system in a rented house in Wales and we found it very good and it kept the house cosy. It was an old dual fuel Rayburn (wood/coal) but keeping it in overnight on wood was very difficult.

As the house we are buying is very sheltered but open on the south facing side then solar makes sense, but this will have to be added down the line as finances permit. I know that French chauffe eaus are very efficient, but we prefer to pay EDF as little as possibleso solar water heating is definitely on our list for later on.

The house we are renting at the moment (at 480 metres asl) is heated by a 9KW pellet burner and has back up electric radiators in every room. It's well insulated for an old French house (90% drylined with a well insulated roof but it is in a very exposed position on the ridge of a hill. When that easterly blows in February you can feel that the pellet burner is struggling a bit. We have barely used the radiators and if you do you them for heating the electricity bill skyrockets!

The place we have bought is much higher up on the plateau and hence will get regular frosts and snow as even in mild winters here there always seems to be some snow above the 700 metre level. Being built into the hillside will really help and with tall trees and forest on the hill behind will be protected from northerly winds. I think we are coming around to the idea of having a decent cuisiniere in the kitchen diner (probably about 12kw), but just a space heating one. In the adjoining snug of 28 m2 we have our trusty Jotul woodburner to install which is around 7 to 8kw. I think we will go for back up electric radiators upstairs in each of the three bedrooms and heated towel rails in the bathrooms. They do ones here with a 1000w timed blower heater which is sometimes all you need.

We plan to insulate, insulate, insulate as much as possible and the house will be double glazed and also have wooden shutters which can be closed in severe weather.

We will not dryline it but the floor and the roof/attic will be very well insulated. We plan to render all the bare granite walls on the inside with a hemp-lime mix (80-100mm) and then lime plaster on the top. This should give a significant improvement to the R value of the 500mm thick stone walls. Dividing walls upstairs to create the rooms will be made from timber studwork and hemp lime shuttered to create 120mm thick solid walls. Cabling for electrics will be routed within the studwork walls before they are formed with the hemp lime mix.

In addition the rear wall of the house on the ground floor (which is below ground level at the rear) will be lined using IsoHemp blockwork which is 90mm thick. We have been in touch with the manufacturer and explained that presently there are signs of damp penetration on this rear wall. It has been cement rendered on the inside, with additionally cement splashback and pointing on the outside face. There is also no guttering or drainage for the old slate roof, so all the rain is pouring at the back of the house and accumulating. We are having a new roof and zinc guttering and also putting a drainage channel of gravel immediately behind the house. I think once the wall can breathe properly again and there is guttering many of the issues will be resolved.

However the Iso Hemp manufacturer said that if we install the blocks on the existing concrete (block and beam) floor then we must install a moisture membrane to prevent capillary action. I asked if we should leave a vented air gap bewteen the new hemp block internal wall and the rear granite wall and we were advised not to but to infill with a hemp lime mix as the wall is constructed? The manufacturer said if all the damp had not resolved in the rear wall then we could install a damp proof membrane between the rear wall and hemp lime infill? Any thoughts on this.

Also the current ground floor in the 51 m2 kitchen/diner is a tiled concrete (block and beam over a tiny and low cellar. We plan to insulate the underside of this floor with PIR board where access can be made. Above we plan to remove the tiles and have a pine floor on chevrons with insualtion between the chevrons.

With all this in mind I would appreciate some advice on heating output? With a possible 12kw wood cooker and the Jotul 8kw in the adjoining snug do you think this will be enough for a toasty house? Recent winters have not been that cold with -10 rare now. Historically -30 is not unknown!! What about getting that heat to the upstairs rooms? Does ducting with fans work well? What about vents in the ceiling on the ground floor?
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Countrypaul
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« Reply #11 on: July 28, 2020, 06:33:19 PM »

Since you are puting a new insulated roof on and replastering all the walls with DG windows in place, you will probably reduce drafts significantly.o Presumably the wood burners be room sealed. Are you looking at an MVHR system? I know you are working on the principle the lime walls will breath, but without any airchanges you might have a poor quality of air inside. I know the MVHR systems can have heaters included to ensure that the fresh air being deliverd in the house is not cold, but I would not think that would be sufficient to heat upstairs but ou may want to try calculating the heat losses to check.
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pantsmachine
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« Reply #12 on: July 28, 2020, 09:55:10 PM »

I'm reading this on a mobile device, maybe not processing it all. As a rough outline you are in the excellent position of renovating an old school/style building in France at altitude, south facing as well. On a first pass I'd say that you'll come up against the building age of design no matter how much you insulate and will have thermal bridge losses. How big who knows? If I was doing this I'd absolutely max out all available passive South facing solar gain. Insulate the hell out of it in keeping with the required look, hunt down as many air leaks as possible and most certainly put solar pv on the roof as part of the overhaul. Not as a luxury but a necessity. It's the gift that just keeps giving! I can't wait to see some photos.

We had fan driven warm air heating years ago and it's not great. The further the rooms you need to heat are the more you'll need to send and the hotter your source will need to be, not that comfortable or practical at either end.
You've got to think about power(heat) to the point of use and make it effective  Otherwise it can be a bit....
« Last Edit: July 28, 2020, 10:03:50 PM by pantsmachine » Logged

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TT
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« Reply #13 on: July 29, 2020, 09:57:35 AM »

Please also consider some air to air heat pumps, mini split air con that does cooling and heating.
And ASHP or GSHP especially once you have improved insulation levels.
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todthedog
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« Reply #14 on: July 29, 2020, 11:04:59 AM »

Totally agree TT
We have used air/air ashp in France, Sweden down to -15 in winter, now here in Wales. Cheap to run, very easy to use and install, we have always used mitsubishi because of their reputation for reliability.  My view subject to debate, is that you can burn a lot of electricity to differentiate the installed cost of ashp v  gshp.
Dare I say it on here, but when it was really hot last year used it in aircon mode in the lounge, running off the solar panels bliss Roll Eyes

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Kidwelly South Wales
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