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Burning plywood on the woodburner

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murdoch

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Just wondered if anyone’s got any idea whether it’s ok to burn birch ply on the woodburner? I’ve got loads of off cuts from the last few kitchens and getting low on firewood. I’ve just put some on and it burns a treat but will the glue fumes coat the lining? Anyone else burning ply regularly.
 

banjerbill

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Garno":wqa0v3wn said:
Nay, Nay and thrice nay, Not a good idea.
It would be more helpful if you qualified your answer with reasons.
I burn all manner of timber products on mine and would like know what I shouldn't burn and why so I can make a considered decision whether to avoid some items.

Bill
 

MattRoberts

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I presume its because plywood often uses formaldehyde glue.

Also, exterior grade treated wood releases toxic fumes when burnt, so I wouldn't burn that either
 

Doug71

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Am in a similar situation, getting low on the normal firewood/timber off cuts but have plenty of birch ply and mdf I could use, is it really that bad to mix a bit in?

Doug
 

Marineboy

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I’m no expert but the very experienced HETAS fitter who installed mine said he had been called to loads of jobs where the flue had been seriously cacked up due to burning softwood etc. The glues in MDF and ply might have a similar impact. However, I think it would depend on how long the flue is, whether it is insulated, and the amount of draw. This is because if the gases cool too much before they reach the top then more resins and tars would be deposited on the flue liner.
 

murdoch

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MattRoberts":3474231z said:
https://www.google.co.uk/url?sa=t&source=web&rct=j&url=http://www.finehomebuilding.com/1994/09/01/the-dangers-of-burning-plywood&ved=2ahUKEwia9qTJjNLZAhUlB8AKHWkRDxEQFjABegQIAxAB&usg=AOvVaw2uTvDix2LHYLch5y1SE19q
Thanks but still not really giving any reasons. I understand the toxic fumes argument but our wood waste heater in the workshop is suitable and legal for ply offcuts with 6 people working away in there so why not at home?

There’s just a lot of people saying no without any reasons, I’ve also burnt treated timber offcuts for years and without any problems.
 

Marineboy

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The toxic fumes argument is not really relevant for the people in the workshop. The job of the flue is to vent the gases outside, so any adverse effect will be on the general air quality in the environment.

It does seem however that evidence for the softwood/hardwood/plywood debate is more anecdotal rather than empirical.
 

MattRoberts

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murdoch":17swbe1o said:
There’s just a lot of people saying no without any reasons, I’ve also burnt treated timber offcuts for years and without any problems.
I'm definitely not an expert, so no idea how serious an issue it can be - just making an assumption.

Be wary of stating "without any problems" though - who knows what shape their lungs are in until a serious problem surfaces...
 

julianf

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When you "burn" something, you are interested in the exothermic oxidation reaction.

The issue is that not everything is easily oxidised at the same temperature.

Say you have something nasty that, say, boils at 300c, but it's autoignition is 400c, then there is a possibility that, when your stove is between 3 and 400c, you are vaporising that compound and sending it up the stack unoxidized. Ie in its harmful state.

Run the stove at a higher temp than the autoignition of all your nasties, and they will get oxidised, assuming sufficient oxygen.

Run it cooler, and you run the risk of pumping out grim stuff.

Some time on Google will, I'm sure, given you the data for your chosen fuel.
 

Rorschach

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I think it's the sort of thing I would burn when the fire is nice and hot so the glues and chemicals are burned away properly. I have no evidence for that, but it would make me feel better if it were my own fire.
 

Phil Pascoe

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When I first had a stove I went to a very expensive but very good supplier. The woman asked us for details of the room - measurements, size of windows (whether double glazed), door openings, wall and floor construction etc. ........ everything. She then calculated that we needed an 8kw or 9kw stove so we should be looking at a 7kw one. I found this odd at first but she explained that that higher estimation would only be relevant a few days of the year and that the stoves were far more efficient when running hot - better fuel economy, longer flue life and less pollution., so it was better to go slightly smaller. She was correct - barring a few weeks of the year it was the only heating in a large victorian house.
I burn ply, MDF and chipboard on mine but ensure the thing is red hot before doing so. If I don't burn it it goes for incineration. I agree with that and I appreciate that the emissions from that are screened, but I wonder how much pollution is caused by the trucks collecting the stuff, taking it to a sorting depot (and the pollution caused by the workers at the sorting depot getting there and the energy it itself uses?), then a round trip of fifty miles to the incinerator?
 

tomatwark

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murdoch":872kuzhm said:
MattRoberts":872kuzhm said:
https://www.google.co.uk/url?sa=t&source=web&rct=j&url=http://www.finehomebuilding.com/1994/09/01/the-dangers-of-burning-plywood&ved=2ahUKEwia9qTJjNLZAhUlB8AKHWkRDxEQFjABegQIAxAB&usg=AOvVaw2uTvDix2LHYLch5y1SE19q
Thanks but still not really giving any reasons. I understand the toxic fumes argument but our wood waste heater in the workshop is suitable and legal for ply offcuts with 6 people working away in there so why not at home?

There’s just a lot of people saying no without any reasons, I’ve also burnt treated timber offcuts for years and without any problems.
The flue on the wood waste heater in your workshop will be designed it run at a higher temperature, when I had the one installed in my workshop, the flue had to be ordered in for the job as a standard domestic flue would have burnt through with the heat involved in burning ply, mdf and chipboard.

They both look the same but the industrial version is made from thicker material.

It would be bad advice to say it is ok to burn it on a home stove, as it will really depend on the chimney, if it is lined and also what it is lined with.

On my wood stove at home I burn hardwood off cuts only and no manufactured boards, as the chimney is lined with a metal flue liner and I would not want to risk it burning through.
 

Phil Pascoe

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In a bungalow my flue cost as much as the stove - the installer said quite correctly that as I burn crepe there was no point putting cheap flue in. :D
 
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