Wood burners - and open fires

[ardcarp]

Trouble is .....we live in the middle of nowhere.

So do we and intend hanging on to our very efficient woodburner. An advantage from using wood is that it's a renewable resource, whereas coal in using up miliions of years of deposits of fossil fuel.

it turns out that a duel fuel burner should only be used either with coal/smokeless fuel or wood - but not both mixed

Hmmm. Our chimney sweep, who seems a well-educated bloke, maintains that just burning wood leaves the soot in the flue very sticky and tar-like and difficult to remove. If a lump or two of smokeless fuel are added to the wood, the flue deposits are more crumbly and come away more easily. He ought to know.

[Dave2002]

Hmmm. Our chimney sweep, who seems a well-educated bloke, maintains that just burning wood leaves the soot in the flue very sticky and tar-like and difficult to remove. If a lump or two of smokeless fuel are added to the wood, the flue deposits are more crumbly and come away more easily. He ought to know.

That may be correct. However, would the results be similar if the smokeless fuel were burnt by itself occasionally - do the fuels have to be mixed in each burn?

I thought that it would be OK to add in coal or smokeless fuel to the wood in our burner, but I queried it with the manufacturer. I got a very detailed reply back, suggesting that this would definitely not be a good idea, giving what appeared to be sound technical reasons. The advice was to either burn wood, or to burn smokeless fuel, but not at the same time. Before we had the duel fuel burner we used to mix fuels in the open fire. The smokeless fuel burns hotter than the wood, seemingly - but that's OK.

Re wood being renewable - I think that's questionable - at least on a large scale. I thought that the wood we buy round here would largely be "renewable", as locally produced, and some of the firewood is surplus waste from other processes. Then I wanted to try burning hardwood to get a better burn, so I ordered some ash which was more expensive. When it arrived I asked where it came from "Oh - it doesn't come from round here - there isn't enough. It comes from Lithuania".

I think that tells you something about sustainability and renewability. It does burn better than the softwood, but maybe we'll revert back to other wood types, or simply reduce the amount of burning we do - providing we don't get too cold.

I've heard that putting salt into a fire can help to loosen the soot before the chimney is swept. There are some commercial products which are probably more expensive. I don't know whether is is really a good idea to put salt or any other substance in a stove.

[oddoneout]

That may be correct. However, would the results be similar if the smokeless fuel were burnt by itself occasionally - do the fuels have to be mixed in each burn?

I thought that it would be OK to add in coal or smokeless fuel to the wood in our burner, but I queried it with the manufacturer. I got a very detailed reply back, suggesting that this would definitely not be a good idea, giving what appeared to be sound technical reasons. The advice was to either burn wood, or to burn smokeless fuel, but not at the same time. Before we had the duel fuel burner we used to mix fuels in the open fire. The smokeless fuel burns hotter than the wood, seemingly - but that's OK.

Re wood being renewable - I think that's questionable - at least on a large scale. I thought that the wood we buy round here would largely be "renewable", as locally produced, and some of the firewood is surplus waste from other processes. Then I wanted to try burning hardwood to get a better burn, so I ordered some ash which was more expensive. When it arrived I asked where it came from "Oh - it doesn't come from round here - there isn't enough. It comes from Lithuania".

I think that tells you something about sustainability and renewability. It does burn better than the softwood, but maybe we'll revert back to other wood types, or simply reduce the amount of burning we do - providing we don't get too cold.

I've heard that putting salt into a fire can help to loosen the soot before the chimney is swept. There are some commercial products which are probably more expensive. I don't know whether is is really a good idea to put salt or any other substance in a stove.

The instructions for my stove make it clear that mixing fuels is a no-no, and when the sweep came for the first time he asked whether I did that and confirmed it should be one or the other. apart from anything else the grate needs a different setting for coal than wood to enable efficient burning.
I got chatting to the driver delivering a load of wood down the road in the autumn(a local fuel merchant) and he said that the birch logs he was dropping off were from Russia(so might be Lithuania...) which does make 'sustainability' a bit questionable. It's an issue that angers a colleague at work in connection with the biomass boiler(which augments the two oil boilers) which uses imported woodchip pellets - mostly northern america and associated in some cases with dubious logging practices.
Salt as I understand it is not a good thing as it forms corrosive and unpleasant chemicals, hence advice not to burn driftwood which would have been done by coastal communities out of necessity but that isn't a reason to continue now for the most part. Much more is known now about what happens when wood is burned and that knowledge should inform usage. The type of wood that is washed up now has changed as well - there is going to be a lot that has had treatments - preservatives etc - that will produce toxic fumes. Salt and metal are not good compnions much of the time so that alone would dissuade me from salt ,whether in wood or neat. I would rather ask the manufacturer or sweep for advice about using cleaning products.

[Dave2002]

The instructions for my stove make it clear that mixing fuels is a no-no, and when the sweep came for the first time he asked whether I did that and confirmed it should be one or the other. apart from anything else the grate needs a different setting for coal than wood to enable efficient burning.
I got chatting to the driver delivering a load of wood down the road in the autumn(a local fuel merchant) and he said that the birch logs he was dropping off were from Russia(so might be Lithuania...) which does make 'sustainability' a bit questionable. It's an issue that angers a colleague at work in connection with the biomass boiler(which augments the two oil boilers) which uses imported woodchip pellets - mostly northern america and associated in some cases with dubious logging practices.
Salt as I understand it is not a good thing as it forms corrosive and unpleasant chemicals, hence advice not to burn driftwood which would have been done by coastal communities out of necessity but that isn't a reason to continue now for the most part. Much more is known now about what happens when wood is burned and that knowledge should inform usage. The type of wood that is washed up now has changed as well - there is going to be a lot that has had treatments - preservatives etc - that will produce toxic fumes. Salt and metal are not good compnions much of the time so that alone would dissuade me from salt ,whether in wood or neat. I would rather ask the manufacturer or sweep for advice about using cleaning products.

I think we are broadly in agreement, though perhaps hazy about some of the chemistry. I'm not suggesting we should put salt in the fire every burn. Chlorine release would be one possibility. I do suspect that proprietry products are not necessarily any kinder if used frequently - but that's true for lots of cleaning products.

Our neighbour offered us a quantity of wood to burn recently, and seemed a bit surprised when I declined. I pointed out that fence panels would probably had added chemicals which would not go well in our burner. When we lived in the US, and bought wood by the cord (there's a measure we don't use much in the UK ...) we had all sorts of offcuts which would explode in the burner in the apartment we rented. Yes - the wood did provide warming - but I don't think in retrospect it did the fireplace unit much good. In hard times people will do anything - whatever they need to in order to survive - think about burning furniture as in the film of Dr Zhivago - but under normal times such practices are not necessary and should be avoided.

Another burning experience I remember was in Sweden, when we went up a hill. There was a burning wood smell - not totally unpleasant. It was only later when we returned back to the town that we discoved that it was in fact a house burning down which produced the "rural" effect.

[LHC]

The instructions for my stove make it clear that mixing fuels is a no-no, and when the sweep came for the first time he asked whether I did that and confirmed it should be one or the other. apart from anything else the grate needs a different setting for coal than wood to enable efficient burning.
I got chatting to the driver delivering a load of wood down the road in the autumn(a local fuel merchant) and he said that the birch logs he was dropping off were from Russia(so might be Lithuania...) which does make 'sustainability' a bit questionable. It's an issue that angers a colleague at work in connection with the biomass boiler(which augments the two oil boilers) which uses imported woodchip pellets - mostly northern america and associated in some cases with dubious logging practices.
Salt as I understand it is not a good thing as it forms corrosive and unpleasant chemicals, hence advice not to burn driftwood which would have been done by coastal communities out of necessity but that isn't a reason to continue now for the most part. Much more is known now about what happens when wood is burned and that knowledge should inform usage. The type of wood that is washed up now has changed as well - there is going to be a lot that has had treatments - preservatives etc - that will produce toxic fumes. Salt and metal are not good compnions much of the time so that alone would dissuade me from salt ,whether in wood or neat. I would rather ask the manufacturer or sweep for advice about using cleaning products.

Alot of wood from Russia appears to come from illegal logging in Siberia and the far East. This report refers to wood used in DIY stores across Europe:

https://www.theguardian.com/world/2020/dec/16/diy-shops-europe-wood-russia-lumber-taiga-eu

[gradus]

So do we and intend hanging on to our very efficient woodburner. An advantage from using wood is that it's a renewable resource, whereas coal in using up miliions of years of deposits of fossil fuel.



Hmmm. Our chimney sweep, who seems a well-educated bloke, maintains that just burning wood leaves the soot in the flue very sticky and tar-like and difficult to remove. If a lump or two of smokeless fuel are added to the wood, the flue deposits are more crumbly and come away more easily. He ought to know.

Burning a hot fire turns tar to a crumbly consistency. In my experience a tarred up chimney is down to using unseasoned wood but if you do, you can see and hear what's wrong, the wood will smoulder, smoke and reluctantly burn and you'll hear a distinct gentle sizzling as the moisture evaporates. Kiln-dried or long-seasoned wood (1-2 years stacked under cover) is what is needed and works just fine.

[cat]

It’s hideous around here. The council’s air quality sensors are located in shopping streets and on arterial roads, so they don’t pick up the particulates in dense residential areas at night, worse when there’s no wind.

Lots of smug middle class families campaigning for traffic bans to cut air pollution, and then cycling home and firing up the wood burner. I have a pocket PM10 recorder and the readings on the streets nearby are often over 100ppm.

[gradus]

It’s hideous around here. The council’s air quality sensors are located in shopping streets and on arterial roads, so they don’t pick up the particulates in dense residential areas at night, worse when there’s no wind.

Lots of smug middle class families campaigning for traffic bans to cut air pollution, and then cycling home and firing up the wood burner. I have a pocket PM10 recorder and the readings on the streets nearby are often over 100ppm.

Not much excuse for burning wood in cities but if you live where the alternatives are to burn oil or use extortionately-priced electric heating, no gas being available, a wood fire or similar is the right option.

[Anastasius]

....Then I wanted to try burning hardwood to get a better burn, so I ordered some ash which was more expensive. ....

Sadly, it looks like it will be our ash trees that will fuel the fire for a number of years. Die-back.

[ardcarp]

Our wood supplier only sources local wood, and he stores it for a year under cover in a barn before delivering it. It is of mixed wood type, some birch this year but also (sadly) ash, but as gradus says the secret is to use only dry wood. We take matters further by having two undercover wood stacks, using one of them now and the other will be for next winter...so extra drying time. By the way, we only put a couple of lumps of smokeless fuel on per night, so we are not really using 'mixed fuel'. Wood is the main fuel and the lumps are shoved on near closing time just to act as the tar hardener.

BTW a very environmentally aware friend of mine (not short of cash) has just installed heat-pump central heating. Somehow it gets heat from the surrounding air. That's difficult to imagine in this cold weather, but as he tries to explain, there is a difference between 'heat' and 'temperature' and there is a lot of heat around in the air and the gismo works like a reverse refrigerator. He is a retired engineer and so understands all these thing. He has admitted, however, that the water heated by a heat-exchanger and going around his radiators does not reach the temperature as his old oil-fired system and so he has to install a greater area of radiators in each room. Also, the unit outside has two enormous fan-blades whizzing round which make a constant hum. That would really get on my wick.

Our own take on green issues is not to heat the whole house up to 'shirt-sleeves' temperature all the time. We have a warm kitchen/dayroom (Rayburn) and in the evening a warm sitting room (log burner). We only run our full central heating at getting-up time and going-to-bed time. Otherwise it's warm bedcovers and warm clothes!

[Ein Heldenleben]

Our wood supplier only sources local wood, and he stores it for a year under cover in a barn before delivering it. It is of mixed wood type, some birch this year but also (sadly) ash, but as gradus says the secret is to use only dry wood. We take matters further by having two undercover wood stacks, using one of them now and the other will be for next winter...so extra drying time. By the way, we only put a couple of lumps of smokeless fuel on per night, so we are not really using 'mixed fuel'. Wood is the main fuel and the lumps are shoved on near closing time just to act as the tar hardener.

BTW a very environmentally aware friend of mine (not short of cash) has just installed heat-pump central heating. Somehow it gets heat from the surrounding air. That's difficult to imagine in this cold weather, but as he tries to explain, there is a difference between 'heat' and 'temperature' and there is a lot of heat around in the air and the gismo works like a reverse refrigerator. He is a retired engineer and so understands all these thing. He has admitted, however, that the water heated by a heat-exchanger and going around his radiators does not reach the temperature as his old oil-fired system and so he has to install a greater area of radiators in each room. Also, the unit outside has two enormous fan-blades whizzing round which make a constant hum. That would really get on my wick.

Our own take on green issues is not to heat the whole house up to 'shirt-sleeves' temperature all the time. We have a warm kitchen/dayroom (Rayburn) and in the evening a warm sitting room (log burner). We only run our full central heating at getting-up time and going-to-bed time. Otherwise it's warm bedcovers and warm clothes!

very sensible on the wood sourcing- a further refinement is to get a moisture meter to check the dryness of the wood and ensure you take the measurement in the right part of the wood. Another tip is to have a temperature guage on the flue pipe to ensure you are getting the temp right to ensure optimum exhaust gas extraction and burn. I should stress I am not an expert but some years ago I did some work on the link between wood burning stoves and thatch fires and that was one element the conflicting theorists seemed to agree on! That and how vitally important it is to have regular professional sweeping.

[Dave2002]

Our wood supplier only sources local wood, and he stores it for a year under cover in a barn before delivering it. It is of mixed wood type, some birch this year but also (sadly) ash, but as gradus says the secret is to use only dry wood. We take matters further by having two undercover wood stacks, using one of them now and the other will be for next winter...so extra drying time. By the way, we only put a couple of lumps of smokeless fuel on per night, so we are not really using 'mixed fuel'. Wood is the main fuel and the lumps are shoved on near closing time just to act as the tar hardener.

BTW a very environmentally aware friend of mine (not short of cash) has just installed heat-pump central heating. Somehow it gets heat from the surrounding air. That's difficult to imagine in this cold weather, but as he tries to explain, there is a difference between 'heat' and 'temperature' and there is a lot of heat around in the air and the gismo works like a reverse refrigerator. He is a retired engineer and so understands all these thing. He has admitted, however, that the water heated by a heat-exchanger and going around his radiators does not reach the temperature as his old oil-fired system and so he has to install a greater area of radiators in each room. Also, the unit outside has two enormous fan-blades whizzing round which make a constant hum. That would really get on my wick.

Our own take on green issues is not to heat the whole house up to 'shirt-sleeves' temperature all the time. We have a warm kitchen/dayroom (Rayburn) and in the evening a warm sitting room (log burner). We only run our full central heating at getting-up time and going-to-bed time. Otherwise it's warm bedcovers and warm clothes!

We have a rather awkward underfloor heating system, which we suspect was put in by an early adopter. It has features which seem good, but are in fact problematic, and we have been looking at replacing the oil boiler by an air source heat pump. The coronavirus situation has delayed the replacement by at least a year.

Underfloor heating can be very good, but it may also be difficult to control. One problem we have is that it may be too hot at night time - so ideally we'd like to have the temperature in bedrooms lower at night - which actually means that heat in those areas has to be reduced hours beforehand. Similarly, ramping up the heat in a room which isn't used every day takes time.

We didn't actually know whether the underfloor pipework was installed and working properly for well over a year - perhaps actually nearer to two years. I bought a heat detecting camera which helped me to spot where the pipes are under the floor. It's only approximate though. Perhaps a better way to be sure is to walk around the house in bare feet. There were several areas where I never detected any heat with the "foot" test until quite recently, and we suspected that the pipes weren't working or even installed. However after some recent work on the boiler, which may have made some form of randomised change, we now know that most of the house does have working underfloor pipework. There is now only one area where I suspect that there is no underfloor pipework - and it's a small "gardener's" toilet, so maybe there was never an intention to have heat in that.

One other feature our system has is the compensator box - which is supposed to monitor the weather and temperature outside. However this seems to be well outside the expertise of the average plumber and heating engineer, and very possibly throws additional noise into the control system - making the overall system even harder to control. I believe that air source heat pumps incorporate such a compensator control, so maybe the problems we've experienced with ours integrated into the current oil boiler system would go away - if we get round to replacing it.

Good things about underfloor heating are:

* no need for radiators which take up wall space (really good feature ...)
* pretty quiet - no gurgling or rattling radiators

Things to be aware of if contemplating air source heat pump substitution for a boiler might include:

* lower water temperature - will that be sufficient to adequatey heat a house? [probably will but needs to be considered.]
* an air source heat pump used for hot water heating may not heat the water sufficiently to avoid some problems. The water will probably be hot enough for hand washing and showers, but won't be hot enough to kill off some bacteria. Water tanks need to have an immersion heater fitted which is run periodically to kill off such bacteria. This is now a requirement in the UK.
* the fans can be quiet, but shouldn't be placed too closed to bedrooms. Normal daytime activitities will probably not be affected by the fan noise.

There are of course grants and interest free loans available for air source heat pump installations. If the fan issue really is a concern, then with a big enough garden one can go for a ground source heat pump system, but those are considerably more expensive, or even a geothermal heating system. The latter systems are I think quite rare in the UK.

[oddoneout]

BTW a very environmentally aware friend of mine (not short of cash) has just installed heat-pump central heating. Somehow it gets heat from the surrounding air. That's difficult to imagine in this cold weather, but as he tries to explain, there is a difference between 'heat' and 'temperature' and there is a lot of heat around in the air and the gismo works like a reverse refrigerator. He is a retired engineer and so understands all these thing. He has admitted, however, that the water heated by a heat-exchanger and going around his radiators does not reach the temperature as his old oil-fired system and so he has to install a greater area of radiators in each room. Also, the unit outside has two enormous fan-blades whizzing round which make a constant hum. That would really get on my wick.

Our own take on green issues is not to heat the whole house up to 'shirt-sleeves' temperature all the time. We have a warm kitchen/dayroom (Rayburn) and in the evening a warm sitting room (log burner). We only run our full central heating at getting-up time and going-to-bed time. Otherwise it's warm bedcovers and warm clothes!

Heat pumps aren't a bolt-on direct replacement for oil or gas CH, and neither are condensing boilers (although I have read that such boilers now do work efficiently in normal domestic settings but I remain doubtful). As a properly designed system they can be viable, but that usually means installing in a new build. My nephew has installed a ground source system in his older house which was a complete renovation job so the necessary alterations and accommodations could be put in as part of the renovations, which included other measures such as PV panels.The financial payback time will be long-term (but tending to shorten as fuel costs rise!) but the benefits of control of their heating (an important factor as they live in a cold part of the country) and comfortable domestic environment exist immediately.
Like you, the hum from the fans rules out such a system for me - and I have heard them in action in several different settings. Unlike other sources of noise they can't be soundproofed by boxing in with suitable materials...
Like you I target heating in the house and wear sensible clothes, although the controller on the boiler, like most such devices it seems, isn't designed to enable different area heating so it requires a certain amount of fiddling and working around. That's where the stove comes into its own as either a supplement or replacement in the evenings as necessary, and also an emergency plan for power cuts.

[gradus]

Heat pumps aren't a bolt-on direct replacement for oil or gas CH, and neither are condensing boilers (although I have read that such boilers now do work efficiently in normal domestic settings but I remain doubtful). As a properly designed system they can be viable, but that usually means installing in a new build. My nephew has installed a ground source system in his older house which was a complete renovation job so the necessary alterations and accommodations could be put in as part of the renovations, which included other measures such as PV panels.The financial payback time will be long-term (but tending to shorten as fuel costs rise!) but the benefits of control of their heating (an important factor as they live in a cold part of the country) and comfortable domestic environment exist immediately.
Like you, the hum from the fans rules out such a system for me - and I have heard them in action in several different settings. Unlike other sources of noise they can't be soundproofed by boxing in with suitable materials...
Like you I target heating in the house and wear sensible clothes, although the controller on the boiler, like most such devices it seems, isn't designed to enable different area heating so it requires a certain amount of fiddling and working around. That's where the stove comes into its own as either a supplement or replacement in the evenings as necessary, and also an emergency plan for power cuts.

Our oil burner service man installed ground source heating in his new house 4 years ago and eventually after much heartache got it working, but he tells me it is only adequate, takes ages to respond to temperature changes and was extremely expensive to install. Perhaps systems have improved in recent years but its difficult to see how how either air or ground source can ever respond quickly enough to be as flexible as gas or oil until engineering ingenuity comes up with a solution.

[Dave2002]

Our oil burner service man installed ground source heating in his new house 4 years ago and eventually after much heartache got it working, but he tells me it is only adequate, takes ages to respond to temperature changes and was extremely expensive to install. Perhaps systems have improved in recent years but its difficult to see how how either air or ground source can ever respond quickly enough to be as flexible as gas or oil until engineering ingenuity comes up with a solution.

Ground source heat pumps should have the advantage over air source systems of being relatively quiet. Unfortunately they can also leak, and may additionally cause problems with the ground - causing it to freeze. I know of one such system designed by an engineer which actually drives - satisfactorily I hear - radiators, so it is rather unusual. The usual comination is heat pump + underfloor.

Re retro fitting - it is unusual, but the "new" neighbours we had in our previous house, ripped out the downstairs and put in underfloor heating, though the boiler was a gas one.

Re rapid response - a simple solution is to have a few fan heaters to provide rapid heat if that's really needed. Again, a lot depends on the house. I don't see anything wrong with using an air source heat pump for general economy and keeping a reasonably good background temperature, and then using other heating for short term boosts. The size of house and layout is also a factor.

Re the noise from fans for air source heat pumps, I think that is largely acceptable, and should be barely noticeable, though the fans should be kept some distance away from bedrooms. If the noise is noticeable I'd suggest that the fans are a poor model and design.