Lukasantony Posted February 15, 2012 Share Posted February 15, 2012 Hi All,Does anyone have any experience installing a wood burning back boiler (to heat rads, HW)? The lovely (English) builder we've hired for this reno claims these systems are rare in France - can this be true? I would love to know what other folks in France have used for their systems: which wood burner + which heat bank? Any advice would be hugely appreciated! Cheers! L Link to comment Share on other sites More sharing options...
idun Posted February 15, 2012 Share Posted February 15, 2012 Yes rare, we only found one company, (turbofonte) that did it when we did and I don't think that they do anymore.I would not do it again though, ever. In France we would have power cuts and then the water wouldn't circulate and we would have to try and gently damp our fire down. It would be a worry if we were out. I know that it sounds like a good idea, but also we burnt a lot more wood with this sytem too. I've gone down the soap stone stove route and if I were still in France would have a Tulikivi without a moments hesitation. If the electricity goes off we can still be warm and cook. Link to comment Share on other sites More sharing options...
Sunshine24 Posted February 19, 2012 Share Posted February 19, 2012 HiI have just had a quote from a company in the Dordogne www.swansolar.eu who have quoted for a wood burner with back boiler. This for a new Broseley stove , the Evolution which is going to be fitted into my sealed system. A gravity rad is not required as the boiler has a safety cold water system which prevents the wood boiler from boiling in the event of power failure .Hope this helps RonW Link to comment Share on other sites More sharing options...
water rat Posted February 19, 2012 Share Posted February 19, 2012 lots of French go for the insert stove with the hot air circulation, you can see them at any brico. Circulating hot water doesn't seem to be popular round here. Possibly due to the electricity cutting out often ,which has already been pointed out. Link to comment Share on other sites More sharing options...
LesFlamands Posted February 19, 2012 Share Posted February 19, 2012 I've installed dozens of wood burner central heating systems usually based on the Villager stoves with integral boilers and sometimes with bolt in boilers. The systems need to be carefully designed so as to not overrun the boiler which can reduce it's lifespan. Also open vented to avoid problems in the event of power or pump failure.These are simple installations as the customer spec. is usually minimum cost, minimum technolgy. There are much improved systems available that overcome some of the safety issues and allow better regulation of the heat but these are generally a lot more costly and none of them overcome the need to keep putting logs on the fire. The obvious advantage of gas, oil and pellet boilers is that they can be switched on and off as required (by timers, thermostats etc.) and can therefore work out to be more economic in the long run. Link to comment Share on other sites More sharing options...
idun Posted February 19, 2012 Share Posted February 19, 2012 Les Flamands ours was really simple but it still needed a pump to circulate the water and therein lay the most simple of problems for us. The electricity going off, sometimes for minutes, sometimes for hours and as we have seen in the recent past, it can be off for days in very bad weather.And when it was off we could not use our fire, I would have loved to, but the water boiling in the system was frightening. My husband installed a system with spare batteries so that if the electricity went off the pump would change over to the emergency system. But strangely as soon as that happened we didn't have a cut in winter for a couple of years, and something went wrong with this 'emergency' system when he tested it.I would never have another stove with the heating linked in, for all it sounds like a good idea, I wouldn't. I now have two stoves and know that come what may, I can cook on them and heat the living areas. kiss is the best thing for me. Link to comment Share on other sites More sharing options...
LesFlamands Posted February 19, 2012 Share Posted February 19, 2012 [quote user="idun"]Les Flamands ours was really simple but it still needed a pump to circulate the water and therein lay the most simple of problems for us. The electricity going off, sometimes for minutes, sometimes for hours and as we have seen in the recent past, it can be off for days in very bad weather.And when it was off we could not use our fire, I would have loved to, but the water boiling in the system was frightening. My husband installed a system with spare batteries so that if the electricity went off the pump would change over to the emergency system. But strangely as soon as that happened we didn't have a cut in winter for a couple of years, and something went wrong with this 'emergency' system when he tested it.I would never have another stove with the heating linked in, for all it sounds like a good idea, I wouldn't. I now have two stoves and know that come what may, I can cook on them and heat the living areas. kiss is the best thing for me.[/quote]I have to agree that keeping it simple is often the answer.It may be possible using a large accumulator heated on a gravity circuit to overcome the problem of power cuts (from a safety point of view) and still have warm radiators when the fire has gone out - overcoming the two main shortcomings with wood burner central heating but the installation cost is high and as the boiler is not controlled you would still not be using the fuel efficiently. Stand alone woodstoves are a good solution for some houses but they are a lot of hard work. Link to comment Share on other sites More sharing options...
idun Posted February 19, 2012 Share Posted February 19, 2012 I don't mind the work of the wood burner, the heat is wonderful.I have to say that by some miracle we got town gas at my house in my french village. They were digging the road up at the entrance to our lotissment and I went and asked what they were doing. 'Gas' they said and I asked if they could continue to chez nous. They said if one other home owner took it, then they would, so us and the neighbours got it. It was years and years before they came back to the village to put more gas pipes in. And the minute we had our gas heating we stopped using the fire. And it was not tooooo costly as we already had the radiators, so just needed a chaudiere. We used to use 7.5 tonnes of wood every winter whilst using the radiators. I have been told that having the radiators meant that the fire burnt more wood and the truth is that it did. Having the gas heating on, and I would have our salon at 25°c on an evening in mid winter, as we had got used to that sort of heat, with low heat in the rest of the house. Our bills halved, as we had often bought wood, which in our part of the alpes was often expensive. The village wood cuts were about £30. However, the terrain was so inaccessable that we ended up asking for help and owed so many favours to so many people that it gobbled up spare time. And if we hadn't asked for help, we would have had to hire things, in the end it was cheaper to buy in bulk, but when you are using 7.5 tonnes, it still costs a lot. Link to comment Share on other sites More sharing options...
BIG MAC Posted February 19, 2012 Share Posted February 19, 2012 [quote user="LesFlamands"][quote user="idun"] Les Flamands ours was really simple but it still needed a pump to circulate the water and therein lay the most simple of problems for us. The electricity going off, sometimes for minutes, sometimes for hours and as we have seen in the recent past, it can be off for days in very bad weather.And when it was off we could not use our fire, I would have loved to, but the water boiling in the system was frightening. My husband installed a system with spare batteries so that if the electricity went off the pump would change over to the emergency system. But strangely as soon as that happened we didn't have a cut in winter for a couple of years, and something went wrong with this 'emergency' system when he tested it.I would never have another stove with the heating linked in, for all it sounds like a good idea, I wouldn't. I now have two stoves and know that come what may, I can cook on them and heat the living areas. kiss is the best thing for me.[/quote]I have to agree that keeping it simple is often the answer.It may be possible using a large accumulator heated on a gravity circuit to overcome the problem of power cuts (from a safety point of view) and still have warm radiators when the fire has gone out - overcoming the two main shortcomings with wood burner central heating but the installation cost is high and as the boiler is not controlled you would still not be using the fuel efficiently. Stand alone woodstoves are a good solution for some houses but they are a lot of hard work.[/quote] Two mains pressure cylinders in tandem as accumulators and a thermostatic blender to deliver hot water rather than the 85 degrees from the cylinders ...maybe Link to comment Share on other sites More sharing options...
Quillan Posted February 19, 2012 Share Posted February 19, 2012 [quote user="BIG MAC"][quote user="LesFlamands"][quote user="idun"] Les Flamands ours was really simple but it still needed a pump to circulate the water and therein lay the most simple of problems for us. The electricity going off, sometimes for minutes, sometimes for hours and as we have seen in the recent past, it can be off for days in very bad weather.And when it was off we could not use our fire, I would have loved to, but the water boiling in the system was frightening. My husband installed a system with spare batteries so that if the electricity went off the pump would change over to the emergency system. But strangely as soon as that happened we didn't have a cut in winter for a couple of years, and something went wrong with this 'emergency' system when he tested it.I would never have another stove with the heating linked in, for all it sounds like a good idea, I wouldn't. I now have two stoves and know that come what may, I can cook on them and heat the living areas. kiss is the best thing for me.[/quote]I have to agree that keeping it simple is often the answer.It may be possible using a large accumulator heated on a gravity circuit to overcome the problem of power cuts (from a safety point of view) and still have warm radiators when the fire has gone out - overcoming the two main shortcomings with wood burner central heating but the installation cost is high and as the boiler is not controlled you would still not be using the fuel efficiently. Stand alone woodstoves are a good solution for some houses but they are a lot of hard work.[/quote] Two mains pressure cylinders in tandem as accumulators and a thermostatic blender to deliver hot water rather than the 85 degrees from the cylinders ...maybe [/quote]Even better if you use salt as the storage medium. It will release heat at a constant temperature for much longer than stored water in 'accumulators'. Link to comment Share on other sites More sharing options...
idun Posted February 19, 2012 Share Posted February 19, 2012 [quote user="BIG MAC"][quote user="LesFlamands"][quote user="idun"] Les Flamands ours was really simple but it still needed a pump to circulate the water and therein lay the most simple of problems for us. The electricity going off, sometimes for minutes, sometimes for hours and as we have seen in the recent past, it can be off for days in very bad weather.And when it was off we could not use our fire, I would have loved to, but the water boiling in the system was frightening. My husband installed a system with spare batteries so that if the electricity went off the pump would change over to the emergency system. But strangely as soon as that happened we didn't have a cut in winter for a couple of years, and something went wrong with this 'emergency' system when he tested it.I would never have another stove with the heating linked in, for all it sounds like a good idea, I wouldn't. I now have two stoves and know that come what may, I can cook on them and heat the living areas. kiss is the best thing for me.[/quote]I have to agree that keeping it simple is often the answer.It may be possible using a large accumulator heated on a gravity circuit to overcome the problem of power cuts (from a safety point of view) and still have warm radiators when the fire has gone out - overcoming the two main shortcomings with wood burner central heating but the installation cost is high and as the boiler is not controlled you would still not be using the fuel efficiently. Stand alone woodstoves are a good solution for some houses but they are a lot of hard work.[/quote] Two mains pressure cylinders in tandem as accumulators and a thermostatic blender to deliver hot water rather than the 85 degrees from the cylinders ...maybe [/quote] So how does the water circulate if there is no electricity? Link to comment Share on other sites More sharing options...
BIG MAC Posted February 20, 2012 Share Posted February 20, 2012 Hot water is less dense or 'lighter' than cold....give it a path up and it will rise....thus displacing colder denser water which returns to be heated again... Link to comment Share on other sites More sharing options...
idun Posted February 20, 2012 Share Posted February 20, 2012 We lived on the first floor, where I fire was, so we would have needed things in the loft, very very well insulated tanks in the loft and you reckon that would have worked?Also, please remember we used a lot of wood, far more than anyone we knew, I do believe it was because of heating the water in the system, is this wrong? Link to comment Share on other sites More sharing options...
Quillan Posted February 20, 2012 Share Posted February 20, 2012 I think we might be getting a little confused. You can have a simple gravity feed system which apart from the fire has a radiator, usually in a room nearest and directly above the boiler, a hot water tank and a header tank usually in the loft. As BM says hot water rises and in doing so sucks in colder water. These systems do not need any electrical driven device (like a pump) to function. If you go for a full central heating system then the distances and layout is too complicated for such a system therefore a circulation pump is required. If the pump stops a normal gas or oil boiler detects this by the rise in temperature withing the boiler and switches off. They also have 'spring loaded' valves, electricity is used to hold a valve open for the fuel. If there is not power the valve closes and the boiler turns off. This of course is not available on wood or coal burning fires so the boiler, if the fire is not put out, will get hotter and hotter with the water eventually turning to steam which vents back through the header tank. If on the other hand you have a closed system which has no header tank and contains pressurised water even when off you could have a bigger problem. They normally have a pressure release valve somewhere to let out the water which is further pressurised due to the boiler creating steam. So a basic gravity fed system with a rad and water heater is OK but if you want to do more you are much better off with a different fueld system. Link to comment Share on other sites More sharing options...
LesFlamands Posted February 20, 2012 Share Posted February 20, 2012 [quote user="idun"]We lived on the first floor, where I fire was, so we would have needed things in the loft, very very well insulated tanks in the loft and you reckon that would have worked?Also, please remember we used a lot of wood, far more than anyone we knew, I do believe it was because of heating the water in the system, is this wrong?[/quote]It is possible to have the entire system running on gravity circulation without a pump. I've come across a number of installations where a large wood furnace is fitted in the cellar heating a large hot water cylinder 2 floors up and several radiators at ground and first floor level. A pump is used to get good circulation through the rads. but in the event of a power cut the gravity circulation is sufficient to sink the heat from the boiler without it reaching boiling point. This system relies on your house fitting the system requirements rather than the other way round! This would also be the issue with the accumulator on the gravity circuit - you have to have a space, preferably directly above the stove, to fit the accumulator. You then connect your radiator circuit to the accumulator with a circulating pump. Once again in the event of a power cut the accumulator should be large enough to sink the heat from the stove whilst the fires dies down. Boiler stoves are often not very efficient in terms of heating the water. In a purpose built furnace the boiler jacket wraps around the firebox and is still heated when the fire has died down to embers but in some wood stoves the boiler is fitted above the firebox and needs the fire to be going full blast to heat the water, which uses a lot more wood. Link to comment Share on other sites More sharing options...
idun Posted February 20, 2012 Share Posted February 20, 2012 Thanks, I had heard of it. In fact I did ask our plumber if we could have such a system in this house, but he said it wasn't possible and I am more than happy with what I have now. Soap stone stoves, highly recommended. Link to comment Share on other sites More sharing options...
Dave&Olive Posted February 20, 2012 Share Posted February 20, 2012 hi ok Just out of interest ..are you talking poel or chauderies ?? [IMG]http://i83.photobucket.com/albums/j311/daveolive/PDR_0002-2.jpg[/IMG] Dave Link to comment Share on other sites More sharing options...
idun Posted February 20, 2012 Share Posted February 20, 2012 I am talking an insert to be honest, but poele 's can also have water systems too.Does your chaudiere need electricity for the pump? Link to comment Share on other sites More sharing options...
BIG MAC Posted February 22, 2012 Share Posted February 22, 2012 In a single pipe system the single pipe will go up from the boiler / fire say in a lounge..and will tee off into the cylinder usually on a platform in a room above...the return will drop back to pick up on the return pipe below The pipe will continue past upstairs rads and tee-d branches will enter and exit at low and high level respectively to promote circulation in the rads...these rads will have flow restricted to them to prevent them being 'favoured' The pipe will get to a point where it needs to drop back downstairs at this point an upstand with an air emittance valve may be an idea...the water is getting progressively cooler ...but being 'pushed ' by the replenishment of hot..the rad just before the drop downstairs ideally should be in a bathroom and lockshielded in the 'on' position...the same pipe and rad set up continues down stairs..until eventually the pipe reconnects in the 'return position' picking up the return from the cylinder at the same time. Not the most effective of systems...needs to be run in 28 mm in the upper sections dropping back perhaps to 22 lower down (all tees being 15mm or rough French equivalency) No pumps. you could use a thermostatic blending valve to ensure that the dhw does not deliver scalding water...come the power cut break out your Hurricane lamps and toast your muffins...in relative comfort while arguing who goes out for wood. You will need a sizable boiler for this little lot say 16 - 17 kw....and a big pile of wood...yes the rads downstairs will be cooler...but then....the fire is downstairs making it warm anyway Link to comment Share on other sites More sharing options...
Dave&Olive Posted February 22, 2012 Share Posted February 22, 2012 Hi ok Yes the system has pumps , they are needed for the rads at ground level to work , the upstairs ones will work by thermo syphon but a pump helps. To be honest I have never seen an insert with a back boiler ?? , Poel`s yes . Dave Link to comment Share on other sites More sharing options...
BIG MAC Posted February 25, 2012 Share Posted February 25, 2012 Incidentally if you design to circulate by gravity but then put a pump on the 'return' leg..you will promote circulation...you could also install a 'live' closed motorised valve on a pump bypass so that if power fails the bypass is open thus preventing an over heat at the othe rend Link to comment Share on other sites More sharing options...
idun Posted February 25, 2012 Share Posted February 25, 2012 Taking into account that a chaudiere would heat the hot water too, how much wood does it burn a year? Ours didn't heat the hot water system. Link to comment Share on other sites More sharing options...
Dave&Olive Posted February 25, 2012 Share Posted February 25, 2012 [quote user="idun"]Taking into account that a chaudiere would heat the hot water too, how much wood does it burn a year? Ours didn't heat the hot water system.[/quote] Hi oK Unfair question really ...like how long is a piece of string .I have thrown in more insulation into the house than B&Q sell in a year the boiler is a top of the range down burning type ,we get our wood ( pine ) from the local palette factory for €3 a stere so we tend to be heavy handed.. plus we have a poel in the Gite and also one in the workshop ...we have never burnt more than ( been here for over 6 years so have seen some cold winters ) ........................18 stere Dave Link to comment Share on other sites More sharing options...
Dave&Olive Posted February 25, 2012 Share Posted February 25, 2012 ps sorry the boiler can use oil as well .. 300ltrs is norm Dave Link to comment Share on other sites More sharing options...
idun Posted February 26, 2012 Share Posted February 26, 2012 We had a very well insulated house in the alpes and the hard wood logs we bought were expensive, starting at approx £70 a tonne initially and going up after that. We averaged 7.5tonnes over the winters as some were milder than others, although it was rare that we didn't get a very cold spell. We couldn't have burnt palettes with any success, unless they were hard wood ones, which to our surprise is what we get at the moment. 18steres should be about 9 tonnes? that is not a lot, but compares very well with the amount most of our friends burn each winter in their poeles/inserts without radiators. Link to comment Share on other sites More sharing options...
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