Wood Burning Stoves in the popular science press

[Jeremy Harris]

9 minutes ago, SteamyTea said:

The real problem is that even if the logs/pellets/chippings are at the correct moisture, the stove fitted correctly and used right, they still pollute like hell.

I think that message is not getting across.

 

 

You're absolutely right, but it's like smoking and drinking, a well-proven health risk simply doesn't change behaviour. 

 

I doubt that putting warnings on cigarette packaging has made any difference to the number of people who smoke, and I similarly doubt that putting the things in plain packets, or hiding them behind screens in shops has made any difference.  What has made a difference is making them expensive and creating laws that prohibit smoking in many places.

 

The analogy with burning wood is that just publicising the health risk is not going to convince people it's a bad thing.  Either the price of wood has to be artificially increased (and here the increase isn't artificial - demand outstrips local supply, so the price is high) or legislation needs to be put in place, as has happened elsewhere.

Edited February 8, 2017 by JSHarris

[Wrekin1]

All,

 

Thanks for the interesting thread and discussion points. I for one certainly hadn't realized the effects were this bad and had been planning installing wood burners as a selling point in the houses I'm planning to build.

 

Now, as a result of reading the above, I'm seriously wanting to avoid this option. Do you have any recommendations of alternatives? I would be looking for something that would give a realistic 'fire', reasonable and efficient heat output and thus focal point for the room and where the wood or coal effect materials don't look obviously fake.

 

I would prefer floor mounted but would consider wall mounted if there are good energy reasons for doing so.

 

Thanks

[Crofter]

Ethanol fuelled stoves are supposedly quite nice, and avoid the considerable expense of a flue.

[Jeremy Harris]

18 minutes ago, Wrekin1 said:

All,

 

Thanks for the interesting thread and discussion points. I for one certainly hadn't realized the effects were this bad and had been planning installing wood burners as a selling point in the houses I'm planning to build.

 

Now, as a result of reading the above, I'm seriously wanting to avoid this option. Do you have any recommendations of alternatives? I would be looking for something that would give a realistic 'fire', reasonable and efficient heat output and thus focal point for the room and where the wood or coal effect materials don't look obviously fake.

 

I would prefer floor mounted but would consider wall mounted if there are good energy reasons for doing so.

 

Thanks

 

Where you don't really need much heat output ( and that applies to many new homes, with their lower heating requirements) but still want "real flames", then bioethanol stoves are a reasonable choice.  They have the advantages of not requiring a flue or external ventilation, they give a realistic flame effect and they have no smell and cause no pollution (just a bit of pure water vapour).

 

The other alternative is to have a dummy stove with a realistic flame effect.  I saw one recently that had an LCD screen internally and it was very realistic indeed, but gave out very little heat.

Edited February 8, 2017 by JSHarris
Cross posted with Crofter - saying much the same!

[Wrekin1]

11 minutes ago, JSHarris said:

 

Where you don't really need much heat output ( and that applies to many new homes, with their lower heating requirements) but still want "real flames", then bioethanol stoves are a reasonable choice.  They have the advantages of not requiring a flue or external ventilation, they give a realistic flame effect and they have no smell and cause no pollution (just a bit of pure water vapour).

 

The other alternative is to have a dummy stove with a realistic flame effect.  I saw one recently that had an LCD screen internally and it was very realistic indeed, but gave out very little heat.

Thanks. An interesting option.

 

The houses have to have external chimneys, or at least the structure, as requirement of planning to fit with similar other properties in the area so would gas be a better option? I know I have the cost of installing a flue which I wouldn't with the bioethanol, but I'm thinking that giving the future buyers greater flexibility in what they may choose to have installed in the future might not be a bad thing from a selling point, even if their choice is not something we may choose to use.

 

The one consideration is that the chimneys will be on the opposite exterior wall to where the gas lines will come into the houses and what issues/restrictions I should be aware of with running the gas line even if I decided just to run the line and install the flue to give that future flexibility?

 

 

 

[Jeremy Harris]

It really depends on what sort of ventilation heat loss you're prepared to accept.  A chimney is a massive cause of heat loss and if you don't need the hole for one for an appliance, than I'd personally just stick with the dummy chimney.  There's a big development near me that must have a planning requirement to have chimney stacks, as one morning I followed a big flat bed loaded up with dozens of prefabricated dummy chimney stacks, that were just stuck on the semi-completed roofs!

[Crofter]

A dummy chimney will be cheaper and give fewer problems with leaks etc, and of course allows you to keep the thermal integrity of the building intact.

If you install a flue for a gas appliance, I understand that you cannot use it for other appliances- solid fuel flues must be to a higher standard, and may be larger diameter much of the time as well.

[Wrekin1]

Food for thought. Thanks for the inputs.

[Ferdinand]

"Hang on the wall" electric flame effect fires are also surprisingly good.

F

[jamiehamy]

We're going for this. Either that or bio-eth as suggested above. http://www.firesonline.co.uk/acatalog/Esse_525_Flueless_Gas_Stove.html?gclid=CPzs9anPgNICFe-d7QodN2oMeA

[Jeremy Harris]

Probably worth noting that, although some (me included) bang on about how poor our building reg standards are, if a house is built to actually meet all of Part L, then it won't need a great deal of heating.  The problem is that the majority of mass-market new builds aren't built to comply with the regs!

 

A new house that's a bit better than Part L requires, won't need a great deal of heat input, and something like a wood burner may well be just too much heat for a room, anyway. 

[Gimp]

10 hours ago, SteamyTea said:

One of the things that the report highlighted is that it is not just a problem for neighbours (or from neighbours).  Even using an approved stove the pollutants may be staying in your own house.

 

" Press-Kristensen has been measuring that pollution inside homes in Copenhagen. In three out of seven tests done so far, he has found very high levels. In one home with a modern log-burning stove, he found particulate levels several times higher than the highest ever recorded outdoors there (see diagram, above). "

 

And why would people collect timber when the weather is wet and cold.  Surely the idea is to get it when the weather is warm and dry and dry/store it until it is needed.

In Wales it rains a lot, particularly where my plot is located. So if you don't happen/can't store enough or run out then its either get more and wait for it to dry or use an alternative. Odds are I would just use an electric fan heater in such as situation since going out and collecting wood in cold, wind or rain kind of defeats the object of keeping warm. Obviously I accept that collecting wood in the rain would be a bad idea but human nature being what it is I'm not sure whether I would be able to keep up enough supply to demand situation. For me I think it would be all a bit labour/time intensive and I'm not willing to pay for a supply as this defeats the objects of getting a free fuel supply which is no doubt the point of it all.

 

I'm also assuming that the cover to the stove doesn't help keep the particles damaging to human health out of the home enough? Since the cover has to be opened to resupply the fire every so often and my not be air tight to these particles at any rate?

 

I've looked at ethanol but some say the problem is that it can't be assumed these are health risk free either:

 

http://www.treehugger.com/gadgets/are-ethanol-stoves-safe-or-green.html

 

i.e if you are burning substances that there is likely to be a bad health/environment spin off.

 

I know that water vapour from e-cigarettes are supposed to be bad for the lungs, possibly causing ammonia in the extreme. Then of course water vapour is not good for the building either. Add onto that any other possible spin off's we might not quite be aware of of burning ethanol.

 

My thoughts at the moment is maybe electric stove/fireplace may be the most sound option, it requires no flue so keeps house integrity, gives of no moisture or harmful chemicals and they can look rather nice these days, but of course maybe more expensive running costs. Other than that gas stove as a second option, cheap running costs but then back to flue so perhaps not gaining as much as hoped as loosing heat there. So when adding the heat loss inefficiency of the gas flue to the cheaper cost of supply, i.e having to heat the home more through gas, are we really back to similar money as to an electric stove installation?     

[Jeremy Harris]

If the bioethanol is just ethanol, then the products of combustion are just CO₂ and water vapour, both of which people exhale is reasonable quantities.  The problem is if the bioethanol contains impurities, or the burner bed contains materials that degrade with heat.  The primary issue is that the law requires that bioethanol be contaminated with some form of bittering agent and/or colouring.  How safe the bittering agent is depends on what it is, and whether or not it's been properly assessed for that purpose.  The bittering agent is required simply to dissuade people from drinking the stuff, nothing more!

 

The oxygen requirement is a bit of a red herring in a house with MVHR, as that will easily cope with the small additional ventilation demand - it's no worse than having a few friends around.

[Gimp]

Still it's essentially a food crop so competing on price for feed for cattle and food for ourselves. The US look like they have presently reached the peak for production from corn. If demand for ethanol was to increase like it has for wood burners then cost of using it would rise needless to say of the environmental and social impact on food production and field/forest use.

 

My thoughts at the moment are towards electric fireplace use and offset the cost from two small domestic windturbines. As you stated earlier Jeremy if I insulate well then heat generation needed will hopefully be minimal.

[Jeremy Harris]

8 hours ago, Gimp said:

Still it's essentially a food crop so competing on price for feed for cattle and food for ourselves. The US look like they have presently reached the peak for production from corn. If demand for ethanol was to increase like it has for wood burners then cost of using it would rise needless to say of the environmental and social impact on food production and field/forest use.

 

My thoughts at the moment are towards electric fireplace use and offset the cost from two small domestic windturbines. As you stated earlier Jeremy if I insulate well then heat generation needed will hopefully be minimal.

 

 

I agree, and got into an unpleasant argument with an idiot somewhere else (and it's rare for me to use such a term about anyone, but believe me it was well-deserved in this case!) about just this point.  I did a few quick sums comparing our energy requirements, the energy yield from biocrops and our available land area, including woodlands.  The inescapable conclusions were:

 

a) We don't have anywhere near enough land area, if even if we stopped growing crops, keeping livestock or having woodlands and open spaces.

 

b) Growing any form of plants for energy is a very poor use of land, as solar panels are two to three times more efficient at converting sunlight into energy than even the very best biocrop.

 

c) When you add the processing and transport energy to the biocrop side the land use efficiency drops to perhaps 1/4 of the same land covered in current technology solar panels.

 

The argument developed because the person in question argued that growing vertically stacked crops was more efficient, and refused to accept that the limiting factor was solar irradiation - vertically stacking doesn't suddenly increase this, it would break the laws of physics.............

 

[SteamyTea]

31 minutes ago, JSHarris said:

The argument developed because the person in question argued that growing vertically stacked crops was more efficient, and refused to accept that the limiting factor was solar irradiation - vertically stacking doesn't suddenly increase this, it would break the laws of physics.............

 

Was that the same idiot that I used to row with, the one that could grow an energy crop in the winter and then drag PV onto the same field to get electricity.

The same one that thought David MacKay was a fraud and that grass cutting could power a house.

If it was, he was not alone in his thinking, I went to meet a couple of contributors from the other place who thought a few kilos of household waste could power a house.

The whole thing was a joke (as the guy who bought a system found out).

[Jeremy Harris]

4 minutes ago, SteamyTea said:

Was that the same idiot that I used to row with, the one that could grow an energy crop in the winter and then drag PV onto the same field to get electricity.

The same one that thought David MacKay was a fraud and that grass cutting could power a house.

If it was, he was not alone in his thinking, I went to meet a couple of contributors from the other place who thought a few kilos of household waste could power a house.

The whole thing was a joke (as the guy who bought a system found out).

 

 

Indeed it was...............

 

The household waste energy thing was an indication of how the gullible can be taken in and then sell a product on to a customer who believes them and loses thousands.  I've spoken to the said customer - he is not a happy bunny.  Come to that, neither am I, over the way my photo copyright has been abused.  Let's not forget the cause of ebuild going down, either...................

Edited February 9, 2017 by JSHarris
typo

[SteamyTea]

I spoke to the customer too, he had resigned himself that he had lost about 50k on the project.

I don't want to get into slagging people off, but when I meet for a coffee with a local member of other place for a chat said.

"I stick to the laws of thermodynamics, usually sorts it out"

There are still people trying to break them (a good thing), but so far they have been very robust (the laws), even as we get a better understanding of the quantum world (which really plays no part in observing everyday life).

Maybe we need a 'sticky' (whatever that is) with a brief description of the laws and why they are important.  Would save a lot of trouble.

 

Edited February 9, 2017 by SteamyTea

[Jeremy Harris]

I've never understood why some people are happy to use physics to understand something, yet at the same time believe that well-proven laws of physics can be arbitrarily broken just because they like the idea and want it to succeed.  Often it's not about making money, either.  Those we refer to haven't, as far as I know, personally profited at all.

 

I mean, few could argue with Newton's laws of motion, we feel them around us all the time.  So what's different about the first law of thermodynamics that makes people think it can be broken at will?

[SteamyTea]

I don't know, especially as they are not so different.

It could be that Newtonian stuff is easy to see, energy stuff is not.

 

Purely as an aside, we have a card machine at work and it accepts contactless payment.  Many people do not trust it and will put their card in the slot and punch in the PIN.

I have christened contactless payment as "Voodoo", as it is black magic and not to be trusted.

[Crofter]

It's not really fair to compare biofuels with PV solely on the basis of which one is a more efficient use of land area. What would a cradle to grave assessment of cost and environmental impact look like? Considering factors such as the sourcing of the raw materials for PV, the lifespan of the arrays, storage of energy, biodiversity, and of course cost to establish and maintain.

 

I know my situation is atypical for the UK, but I am gradually planting more of my croft with willow cuttings at no cost (except my time). In theory I could cover four acres in this way. What would the same area of PV cost??

 

Eventually, this will produce wood that I can burn in the winter. Whereas if I went down the PV route, I could look forward to shivering under a blanket all winter muttering about how much excess I produced all summer...

[SteamyTea]

1 hour ago, Crofter said:

What would the same area of PV cost

As you say, the direct comparison is not fair.

Two way you could compare this is to look at the total energy yield for the given area between technologies.

Another way would be to compare the amount of energy you can store from your short rotation coppice and then calculate the area of PV needed to supply the same energy at the same time of year i.e. winter time.

 

So for a giggle, let us assume that that you can harvest between 8 and 18 tonnes of dry mass per hectare (https://en.wikipedia.org/wiki/Short_rotation_coppice)

That will be between 0.8 kg/m² and 1.8 kg/m².

If the usable energy content is 4 kWh/kg, then that is somewhere between 3.2 kWh and 7.2 kWh.  I do not know the real energy content of short rotation willow (SRW) in real life, maybe someone else can waste time looking that up.

 

Now a quick look at John O'Groats in PVGIS and using a 250W 1.6 m² PV module, which is 156 W_p/m², will give a yield of in kWh/month:

Nov 4.46

Dec 2.69

Jan 4.01

Feb 4.86

 

Total of 18.02 kWh

 

So a lot better than the best that SRW can supply (7.2 kWh).

 

 

Edited February 9, 2017 by SteamyTea
edited as I added up the numbers wrong