Wood-fired boiler heating questions

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Re: Wood-fired boiler heating questions

Postby CaresAboutHealth » Tue Jul 23, 2013 3:10 pm

Although wood-fired boilers are nice to look at, like conventional log-burning heaters, on average they create as much health-hazardous pollution in 10 hours as the average new car emits in an entire year.

As well as causing more global warming than other forms of heating http://environmentprogress.com/?p=7724 wood smoke contains lots of toxins, including polycyclic aromatic hydrocarbons (PAH) that cause genetic damage in babies and reduced IQ when children start school - http://woodsmoke.3sc.net/pah

Woodsmoke also contains dioxins and Polychlorinated dibenzo dioxins (PCDDs) and furans (PCDFs) and dioxin-like polychlorinated biphenyls (PCBs), which amongst the most toxic pollutants known. A 12-month study of 6 locations in Australia covering industrial and residential sites, showed that levels of these harmful pollutants were close to zero, except when wood heaters were in use, when concentrations were up to 10 times higher than the non-heating season - http://woodsmoke.3sc.net/toxic-chemicals

If you are out in the back of beyond, your choices are limited, and luckily whatever the wind direction, it will blow the smoke away from your own house, minimizing the effect on your health. However, people in urban areas should consider the adverse effect on the climate and neighbours' health and not use wood heating.
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Re: Wood-fired boiler heating questions

Postby Cherokee Solar » Tue Jul 23, 2013 8:08 pm

Hi CaresAboutHealth,

Just out of interest - given that you are lecturing people here - what sort of heating do you use in your house?

Also, I'd be interested to know whether you have air conditioning too?

As a disclosure I use wood to heat, cook and provide hot water and it all comes from my own wood lots.

Regards

Chris
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Re: Wood-fired boiler heating questions

Postby bpratt » Wed Jul 24, 2013 9:16 am

I wonder about the concerns that 'caresabouthealth' has, and if in a properly operating fireplace that any of this is really much of a concern ?

I'm thinking that a fireplace that isn't overloaded with green fuel, but naturally dried out timber, and that is also allowing sufficient air in to it burn cleanly, that all of those concerns are pretty much null and void.

Of course burning CCA treated pine and wood that has been painted or coated is a different kettle of fish.
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Re: Wood-fired boiler heating questions

Postby Tracker » Wed Jul 24, 2013 9:51 am

...... However, people in urban areas should consider the adverse effect on the climate and neighbours' health and not use wood heating.....


I would agree here.. not sure about the chemistry side off things, but suspect it is likely correct..

You really notice when folk have wood burning heating in your area. THEY don't have any problem as the smoke always blows away from them..
I do so remember the childhood days of wood fires around Tempe (Sidiney), and how that smoke filled the valleys.. :evil:

.....Also, I'd be interested to know whether you have air conditioning too?....

And we know where that is going, but, I can say that I have no idea when the neighbor is running theirs.. I bloody well DO know when someone has a wood fire.
AND, at least with a RAC there is the potential for self sufficiency from SOLAR power.. :D
..
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Re: Wood-fired boiler heating questions

Postby CaresAboutHealth » Wed Jul 24, 2013 11:25 am

When I built my house about 25 years ago, I naturally chose to have north-facing living areas, R3.5 insulation and painted the concrete slab (no expensive carpets), so it doesn't need much heating, and has no air conditioning. I'm told that some of the newer reverse cycle air conditioners are so efficient they can provide 10 units of heat to the living area for every 1 unit they use in electricity, so this may be the ideal form of heating, even it it does take a small proportion of the electricity I currently export to the grid. Matthew Wright, chairman of beyond zero emissions argues that RCAC are more climate-friendly than any other form of heating http://www.climatespectator.com.au/comm ... nditioners

I’m not trying to lecture, simply provide accurate information to people who are considering new heating. Most people know that snake venom and cigarette smoke are natural, but nonetheless harmful. For some strange reason, even though the tests on mice and bacteria show that woodsmoke causes 12 to 30 times as many tumours and mutations as the same amount of cigarette smoke, some people mistakenly argue that it’s harmless.

Operating the heater correctly doesn’t void these concerns. Most people cannot operate their heaters as perfectly as in the lab tests, and even if they could, the average new perfectly-operated log-burning heater emits as much health-hazardous PM2.5 pollution in 24 hours as the average new diesel SUV does in a year’s worth of driving. The particles are so tiny you can’t see the smoke, but it’s still there, and still capable of causing serious health damage. PM2.5 is defined as particles less than 2.5 microns (millionth of a meter) in diameter – so tiny they infiltrate the deepest recesses of our lungs (where they cause inflammation leading to heart and lung diseases as well as causing lung cancer). Their small size means they behave like gases and seep into homes even when all doors and windows are closed.

A UN Environment Program and the World Meteorological Association report recommends phasing out log-burning heaters in developed countries to reduce global warming as well as improve health - http://www.redorbit.com/news/science/20 ... ture_rise/

Prof Piers Forster, Coordinating lead author of the IPCC chapter Changes in Atmospheric Constituents and in Radiative Forcing (which sets out the scientific evidence on the changes in the atmosphere that are causing global warming) explains that "Reducing emissions from diesel engines and domestic wood and coal fires is a no-brainer as there are tandem health and climate benefits. If we did everything we could to reduce these emissions we could buy ourselves up to half a degree less warming, or a couple of decades of respite".

The couple of decades respite that Prof Forster talks about could be the difference between a stable climate in the long term, and melted polar ice and methane hydrates. The amount of greenhouse gas stored in the methane hydrates is several times the total CO₂ release since the industrial revolution. Rapid melting could lead to runaway climate change – otherwise known as a tipping point or point of no return - woodsmoke.3sc.net/greenhouse

So this is now a very real possibility. Tthe Arctic summer sea ice is melting at a rate faster than predicted by conventional climate models, and could be ice free as early as 2015 - https://theconversation.com/final-front ... ctic-12911
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Re: Wood-fired boiler heating questions

Postby Tracker » Wed Jul 24, 2013 1:43 pm

CaresAboutHealth wrote:.....I’m not trying to lecture, simply provide accurate information.....the average new perfectly-operated log-burning heater emits as much health-hazardous... pollution .... as the average new diesel SUV does in a year’s worth of driving. The particles are so tiny you can’t see the smoke,.....


and the proof is in the chimney.. why do they goop up if all is so efficient, and is it not reasonable to think that if that much collect, then how much did NOT collect...

Had a stay at an eco-venue down Gipsland, last year.. Log fire and all.. How nice it was, but how that smoke hung around.. NOT very ECO for the andibles..

Not sure about the 10:1 efficiency of "Modern RAC's" .. I would have thought the best would be 4:1 (COP)...
..
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Re: Wood-fired boiler heating questions

Postby Gordon-Loomberah » Wed Jul 24, 2013 2:17 pm

There are a few with COPs around 5 and one or 2 near 6 now, but only in small capacities of course. The 2.5kW Mitsubishis I have are high 4s.
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Re: Wood-fired boiler heating questions

Postby CaresAboutHealth » Wed Jul 24, 2013 2:44 pm

Gordon-Loomberah wrote:There are a few with COPs around 5 and one or 2 near 6 now, but only in small capacities of course. The 2.5kW Mitsubishis I have are high 4s.

The COP of 10 comes from personal measurements of Matthew Wright (Beyond Zero Emissions) for Melbourne. The 2.5kW Mitsubishis have COP of 3.6 at 2C and 5.6 at 7C. However, if the average outdoor temperature when you need heating is 10 degrees C (as it could well be in Melbourne) COP of 10 seem quite achievable.

Matthew had gas ducted heating that used 3,000 kWh. He switched to small, efficient airconditioners, which he said used 328 kWh to heat his house (allowing him to heat more of the house to a more comfortable temperature than the gas heating) for the entire winter. This is a tiny fraction of the energy generated by his PV array, and a very cheap way of heating your house even at current electricity prices!
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Re: Wood-fired boiler heating questions

Postby Gordon-Loomberah » Wed Jul 24, 2013 4:19 pm

Yes the COP will be higher for a lower deltaT, but there are standard temperatures for which ACs are rated (which I cant think of off-hand) for heating and cooling.
COPs can be worked out by dividing output power by input power and this table:
http://reg.energyrating.gov.au/comparat ... ction=desc

shows single split system RCACs in Australia in the 2-3kW output range.
COP generally refers to heating performance, and EER (Energy Efficiency Ratio) to cooling performance, although they are often used interchangeably.
Presumably the COP ratings at different temperatures will vary in a similar manner, so good performers at the standard rating temp will also perform well at other temperatures.
As you can see, Mitsubishi make a number of 2.5kW rated models, with a bit of COP variation across the range.
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Re: Wood-fired boiler heating questions

Postby Tracker » Wed Jul 24, 2013 6:39 pm

CaresAboutHealth wrote:Matthew had gas ducted heating that used 3,000 kWh. He switched to small, efficient airconditioners, which he said used 328 kWh to heat his house (allowing him to heat more of the house to a more comfortable temperature than the gas heating) for the entire winter. This is a tiny fraction of the energy generated by his PV array, and a very cheap way of heating your house even at current electricity prices!


Now sure that is a good example.. ;) .. Going from Whole-House ducted Gas heating, to localised RAC...

That is what we have chosen... Small RAC's in the main rooms we use.. ie. just heat what is absolutely necessary..

CaresAboutHealth wrote:The 2.5kW Mitsubishi's have COP of 3.6 at 2C and 5.6 at 7C. However, if the average outdoor temperature when you need heating is 10 degrees C .... COP of 10 seem quite achievable.

The implication being that the lower the temperature difference, the higher the COP..
Good in theory, but I thought that COP basically plateaued at a certain temperature...
or , in reverse, worked efficiently to a temp, and below that the COP goes south..

Perhaps new gas combinations are changing things..

Anyway, we know that GAS costs are rising dramatically, and soon, we will not be able to claim "Natural Gas is Best"
They are happy for us to freeze, so that THEY can fill their export contracts, at a tiny fraction of what WE pay..

IMHO
..
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