Wood Burners

Use this board for general non-cycling-related chat, or to introduce yourself to the forum.
pwa
Posts: 10427
Joined: 2 Oct 2011, 8:55pm

Re: Wood Burners

Postby pwa » 15 Jan 2019, 11:09am

Just for a bit of perspective, air quality is generally better now than it was in 1970, and significantly so. When I was a kid practically every house in our cul-de-sac was burning coal as the primary heat source and as we were in the bottom of a valley we often had smog to contend with. Things are much better now.

I agree that wood burners are not right for all locations. If I lived in a Welsh Valleys terrace I would not want one. Too many chimneys (or potential chimneys) too close together in the bottom of a valley.

It should be noted that the figure of 38% of particulates refers to domestic burning of wood and coal so it is not just wood burning. I have been in Welsh valleys streets at night quite recently and I could smell coal burning. It was quite heavy in the air.

roubaixtuesday
Posts: 2241
Joined: 18 Aug 2015, 7:05pm

Re: Wood Burners

Postby roubaixtuesday » 15 Jan 2019, 11:10am

Mick F wrote:So .................. if we can't burn wood or burn coal, what is the GREENEST heating for the home, and is it possible for the majority of homes?


Greenest of all is to use less. So insulation for older homes where possible, high standards for new homes and a good control system, including not being set too high. An Aga is obviously a terrible control system!

Then it depends what you mean by “Greenest”. Burning fuel has a number of negative consequences (“Externalities” in economics jargon). What’s best to minimise one is not necessarily best for another.

However, to make an attempt:

(1) Global warming. The key here is CO2, although methane is also important.

In terms of CO2 emissions, if you’re burning fuel in the home then coal is worst, gas is best. That’s because per unit heat, gas releases less CO2 and more water (methane = CH4). Condensing gas boilers are also very, very efficient, much more so than any way to domestically burn coal.

Using electricity directly for heating depends on the source, but for the current UK mix it’s likely that gas is actually better than electricity, due to the inefficiencies of converting to electrical energy in a power station and then transmitting.

In the long term, either the use of fossil fuels will be restricted to limit global warming, or they will run out. The best option in these circumstances is an electrically powered heat pump. Heat pumps deliver *more* heat than the electricity they consume, perhaps double or so. But they are pricey, so not much used yet.

(2) Local Air Quality

Smoke, NOx and other pollutants. Here it’s pretty simple: gas and leccy are good, all others bad, depending on the details. Hence the original clean air act and smokeless fuels.

(3) Other environmental impacts

It’s very hard to gauge and may be very specific depending on the source of the fuel. But wood can cause deforestation, coal a range of impacts from mining, electricity brings the negatives from nuclear, etc etc.

For *most* people I’d summarise as:

(1) Better conservation
(2) Heat pump
(3) Condensing gas boiler

You can also do things like choosing a renewable electricity supplier.

User avatar
Mick F
Spambuster
Posts: 46766
Joined: 7 Jan 2007, 11:24am
Location: Tamar Valley, Cornwall

Re: Wood Burners

Postby Mick F » 15 Jan 2019, 11:17am

I have often thought of lots old secondhand radiators mounted on the roof and plumbed into the hot water system via thermostatic valves and non-return valves.
Sunshine heats the radiators and convection or a pump sends the water round the system. Good insulation and a huge tank to store the hot(?) water would be quite good. You could save a fortune in water heating like that .......... and it's totally green energy.

If we had stream running through our property, I'd have built a waterwheel generator.
Mick F. Cornwall

kwackers
Posts: 13711
Joined: 4 Jun 2008, 9:29pm
Location: Warrington

Re: Wood Burners

Postby kwackers » 15 Jan 2019, 11:27am

Mick F wrote:I have often thought of lots old secondhand radiators mounted on the roof and plumbed into the hot water system via thermostatic valves and non-return valves.
Sunshine heats the radiators and convection or a pump sends the water round the system. Good insulation and a huge tank to store the hot(?) water would be quite good. You could save a fortune in water heating like that .......... and it's totally green energy.

If we had stream running through our property, I'd have built a waterwheel generator.

Radiators aren't that great, too much water mass.

Easy enough to make a simple heater though, 8mm pipe laid out on a thermally insulated backing, painted black, with a sheet of glass over the top attached to low sides.

Easy and works a treat. It's the rest of the plumbing that's hard (ideally needs a secondary heating coil in the tank, a small pump and thermostats to decide whether or not to run the pump).

Not efficient enough to work in winter though - for that you need proper vacuum thermal tubes.

roubaixtuesday
Posts: 2241
Joined: 18 Aug 2015, 7:05pm

Re: Wood Burners

Postby roubaixtuesday » 15 Jan 2019, 11:36am

Mick F wrote:I have often thought of lots old secondhand radiators mounted on the roof and plumbed into the hot water system via thermostatic valves and non-return valves.
Sunshine heats the radiators and convection or a pump sends the water round the system. Good insulation and a huge tank to store the hot(?) water would be quite good. You could save a fortune in water heating like that .......... and it's totally green energy.

If we had stream running through our property, I'd have built a waterwheel generator.


Solar hot water systems are mainstream, and in the UK, almost certainly more sensible than solar PV.

http://www.energysavingtrust.org.uk/ren ... er-heating

A waterwheel may have pleasing aesthetics, but I would guess a turbine would be far more efficient.

PDQ Mobile
Posts: 2982
Joined: 2 Aug 2015, 4:40pm

Re: Wood Burners

Postby PDQ Mobile » 15 Jan 2019, 1:39pm

Ok couple of issues here.
Wood as a fuel is considered carbon neutral because the cycle is relatively short.
It is not a fossil fuel.
And correctly managed it will not cause deforestation in temperate climate.
It is often a side line waste product.

Gas is clean and efficient but not carbon neutral or infinite.

I was shocked the other day at how much water a friend had to run to get hot water from his condensing boiler. The thing is water pressure sensitive and that is what triggers the burners if no other heating is in use. And he has a metered water supply!!
Last edited by PDQ Mobile on 15 Jan 2019, 2:01pm, edited 2 times in total.

User avatar
Mick F
Spambuster
Posts: 46766
Joined: 7 Jan 2007, 11:24am
Location: Tamar Valley, Cornwall

Re: Wood Burners

Postby Mick F » 15 Jan 2019, 1:57pm

No water meter here and no limit to the trees and logs, therefore no limit to the amount of hot water.
If you fancy a nice deep hot bath, come on round but bring your rubber duck! :D

Off out into the garden this afternoon to slice up another barrowload of logs with the chainsaw for the hearth. I may do two barrowloads as the weather is set to get colder in the next day or two.
Mick F. Cornwall

PDQ Mobile
Posts: 2982
Joined: 2 Aug 2015, 4:40pm

Re: Wood Burners

Postby PDQ Mobile » 15 Jan 2019, 2:05pm

Mick F wrote:No water meter here and no limit to the trees and logs, therefore no limit to the amount of hot water.
If you fancy a nice deep hot bath, come on round but bring your rubber duck! :D

Off out into the garden this afternoon to slice up another barrowload of logs with the chainsaw for the hearth. I may do two barrowloads as the weather is set to get colder in the next day or two.


They'll burn ok...
on a bed of coal or mixed with coal nuggets.

But it's not really proper woodburning!
And defeats much of the potential benefits.

User avatar
Graham
Moderator
Posts: 5932
Joined: 14 Dec 2006, 8:48pm

Re: Wood Burners

Postby Graham » 15 Jan 2019, 2:06pm

O/T
That sounds like a combi boiler to me. i.e. no hot water tank. Mains-pressure cold water "instantaneously" heated on-demand.

Inevitably there is quite a long delay before anything better than tepid water gets to the HOT tap, depending on length of pipe between boiler and tap.

I have disconnected the Hot tap in my bathroom due to the extraordinary waste of pre-tepid water. This high-quality drinking water would otherwise go to waste. I use hot water heated in the kettle.

Other folk concerned by such water wastage, fit instantaneous water heaters ( most-likely electric ) close to the tap.

PS. I have a metered water supply. It's not the money I'm concerned about, but the environmental impact in this dry (SE) corner of england.

PDQ Mobile
Posts: 2982
Joined: 2 Aug 2015, 4:40pm

Re: Wood Burners

Postby PDQ Mobile » 15 Jan 2019, 2:09pm

Graham wrote:O/T
That sounds like a combi boiler to me. i.e. no hot water tank. Mains-pressure cold water "instantaneously" heated on-demand.

Inevitably there is quite a long delay before anything better than tepid water gets to the HOT tap, depending on length of pipe between boiler and tap.

I have disconnected the Hot tap in my bathroom due to the extraordinary waste of pre-tepid water. This high-quality drinking water would otherwise go to waste. I use hot water heated in the kettle.

Other folk concerned by such water wastage, fit instantaneous water heaters ( most-likely electric ) close to the tap.


Yes you are right. No hot water tank.
I am not up to speed on gas!!
My Aunt had something similar in the 1950,s I thought.

roubaixtuesday
Posts: 2241
Joined: 18 Aug 2015, 7:05pm

Re: Wood Burners

Postby roubaixtuesday » 15 Jan 2019, 2:11pm

PDQ Mobile wrote:Ok couple of issues here.
Wood as a fuel is considered carbon neutral because the cycle is relatively short.
It is not a fossil fuel.
And correctly managed it will not cause deforestation in temperate climate.
It is often a side line waste product.

Gas is clean and efficient but not carbon neutral or infinite.

I was shocked the other day at how much water a friend had to run to get hot water from his condensing boiler. The thing is water pressure sensitive and that is what triggers the burners if no other heating is in use. And he has a metered water supply!!


Agree.

I'd note

(1) The question was asked for the majority of homes. There's not enough wood to use for the majority of homes.
(2) The issue on running water isn't specific to if the boiler is condensing or not.
(3) The amount of cold water run is unlikely to be significant on CO2 emissions (it may matter for other reasons)

User avatar
661-Pete
Posts: 9183
Joined: 22 Nov 2012, 8:45pm
Location: Sussex

Re: Wood Burners

Postby 661-Pete » 15 Jan 2019, 2:39pm

Tangled Metal wrote:On the drive home tonight radio 4 had an interview with a boffin who studies air pollution matters. Very interesting. The points I noted is below!:
    38% of all uk particulate pollution is from woodburners
I don't know where that statistic came from, nor what exactly is meant by "from woodburners" - but I did some googling.

This seems to be a fairly authoritative study, hosted by DEFRA. It deals with PM2.5 particulates, which I believe are considered the most harmful to human health (correct me if I'm wrong). You need to scroll quite a long way down the document (page 83 in document numbering, 94 in pdf) to see a chart comparing the various sources of PM2.5 - up to 2010, with projections for 2015 and 2020. In that, 'residential' accounts for about 12-15% and is decreasing.

Of course this study is out-of-date now, and in particular it pre-dates the big diesel-car scandal which may have changed things a lot!

But this doesn't explain where that 38% comes from. Is it all particulates, rather than just the PM2.5?
Suppose that this room is a lift. The support breaks and down we go with ever-increasing velocity.
Let us pass the time by performing physical experiments...
--- Arthur Eddington (creator of the Eddington Number).

pwa
Posts: 10427
Joined: 2 Oct 2011, 8:55pm

Re: Wood Burners

Postby pwa » 15 Jan 2019, 2:55pm

661-Pete wrote:
Tangled Metal wrote:On the drive home tonight radio 4 had an interview with a boffin who studies air pollution matters. Very interesting. The points I noted is below!:
    38% of all uk particulate pollution is from woodburners
I don't know where that statistic came from, nor what exactly is meant by "from woodburners" - but I did some googling.

This seems to be a fairly authoritative study, hosted by DEFRA. It deals with PM2.5 particulates, which I believe are considered the most harmful to human health (correct me if I'm wrong). You need to scroll quite a long way down the document (page 83 in document numbering, 94 in pdf) to see a chart comparing the various sources of PM2.5 - up to 2010, with projections for 2015 and 2020. In that, 'residential' accounts for about 12-15% and is decreasing.

Of course this study is out-of-date now, and in particular it pre-dates the big diesel-car scandal which may have changed things a lot!

But this doesn't explain where that 38% comes from. Is it all particulates, rather than just the PM2.5?

That 38% includes coal, so it is not just wood. Two fuel types lumped together.

User avatar
Mick F
Spambuster
Posts: 46766
Joined: 7 Jan 2007, 11:24am
Location: Tamar Valley, Cornwall

Re: Wood Burners

Postby Mick F » 15 Jan 2019, 3:00pm

PDQ Mobile wrote:They'll burn ok...
on a bed of coal or mixed with coal nuggets.

But it's not really proper woodburning!
And defeats much of the potential benefits.
Ours is a multi-fuel stove made by Aarrow Fires. Back boiler is the top, sides and back.
Not dissimilar to this one.
https://www.aarrow-stove-specialist.co. ... stove.html
Lit with scrap wood and scrap paper/cardboard, and burns well with our home-grown cut logs. The coal ovoids go on later, so it can stay in overnight or to augment the wood supply and/or give more heat.
Mick F. Cornwall

User avatar
Graham
Moderator
Posts: 5932
Joined: 14 Dec 2006, 8:48pm

Re: Wood Burners

Postby Graham » 15 Jan 2019, 3:03pm

661-Pete wrote:This seems to be a fairly authoritative study, hosted by DEFRA.

Thanks for bringing this to my attention.
There are about 180 pages to read before the reference list starts. :shock:

I will be studying it in due course.
I use a woodburner here to try of reduce my fossil-fuel (gas) usage. I only burn very dry, well-seasoned logs.

However, in the vicinity of this house there a number of other houses burning wood and some burning coal-type fuels.

My sense of smell detects that the air quality in this area may not be good. My house is in a cul-de-sac. The surrounding roads only ever get busier. There is a busy trunk quasi-motorway about 1 km away.

I suspect that I will have to phase out the woodburning and / or move to somewhere more rural.