[Stoves] Heat / cook stove

[Darren Hill]

Hello Crispin,

     Thank you for taking the time to respond :)

     I've put my responses in your text below -

On 29/12/2010 01:42, Crispin Pemberton-Pigott wrote:
> Dear Darren
>
> Welcome to the list. There are several people around who will be able to
> offer ideas. Some questions to help everyone think:
>
> How much heat (in kW) are you looking for?

I think 2kw would be enough, its heating a small well insulated space, 
but more than this (4, 5, 6 kw) would not be a problem - as I am hoping 
to catch a fair bit of the excess heat in the heat storage.  Am I right 
in thinking that kw output has quite a bit to do with the type of fuel?  
I mainly plan to burn seasoned hardwood logs / sticks although possibly 
sometimes some softwoods and have the option of woodchip. (I've often 
have access to unlimited supplies as I often work as a tree surgeon / 
live with tree surgeons)

> How wide are you thinking of making the stove body?

Approx 30 cm

> How will you load the wood?

Not sure I guess put it in by hand via a door in the front.  It would be 
useful to be able to just throw in the large amounts of fuel.  The fact 
that the top is taken up by the stack and often the cooking/heat 
exchanger surface I think limits my options.  Am I missing some 
alternative methods?

As I understand it this is not ideal as the burn will progress through 
the material rather than the fuel falling/being fed to a set point for 
oxidisation.  Am I correct?

> Re the chimney, it is likely 100mm will be enough, even 90. It will probably
> work much better if it is 3 metres long instead of 2.


I guess I could have an extension that sticks up a meter out  of the 
roof (It would be better if not)


> It will give enough
> draft to pull the air through without having to be overly hot. Draft is a
> function of temperature and height so if you plant to capture a lot of heat,
> you want the chimney to be a bit taller (to give more draft) and smaller (to
> give more velocity and thus a higher average temperature because the gas
> doesn't have time to cool down so much). You need, absolutely, some heat in
> the chimney or it doesn't work. It is a 'fan' running on the buoyancy of hot
> air.

Interesting about the thinner chimney.   Are there disadvantages to 
going smaller?   I guess that at some point it gets too thin.


> There was a discussion of a stove earlier in the day which is probably worth
> looking into.

You mean the SEDORE ?  I had a look at the video - most interesting.

> It has a low (to the grate) exit at the back so the fuel falls
> down and burns at the bottom, but venting backwards. There is a lot of merit
> in this.

Sorry - you mean the fire box has a grate on the floor which the air 
flows up through?  I get that the fire burns out through the back low down.


> Exiting at the top pretty much guarantees high smoke and CO (lost
> heat) the way the old stoves do.

You mean that the air should draw through the oxidising material either 
sideways or downwards so that the gasses begin to burn as the pass down 
or sideways - I guess through some kind of "grate" into a "combustion 
area" where more air is added + ideally this area should be insulated to 
keep the temperature here high.  Is this right?

> Once you have created clean heat, you can
> pipe it around the stove as you wish. Bringing the fire to the front bottom
> then up past the glass, the under the top is another way to go that retains
> the side-drafting fire.

Sorry I think you've lost me there.  Can you describe as the primary air 
flows?
> It is pretty impressive and cane be refuelled with
> little change in emissions.
>
> There are many things to consider...!
>

I appreciate that and this has been useful.  I guess if I'm following 
you correctly the fact that I want a low height and front loading is 
really not in my favour...  Although I guess I may be able to rejiggle 
things - possibly allowing me to have a much taller stove....

I really appreciate your help here.  Are there any good resources 
anywhere which give a good quick and easy oversight of the most crucial 
elements that require consideration?

Best regards

Darren


> Regards
> Crispin in Waterloo (Ontario)
> ++++
> Hello,
>
> Joined the list a few days ago and have been following the conversations
> with interest.
>
> I'm going to work with my x-partner to make me a wood stove for my living
> truck.  Shes a blacksmith and has previously made a number of ornamental
> stoves.
> http://www.firebird-ironwork.co.uk/stoves-and-fires/
>
> I read a few books a few years back about woodstove design which gave me
> some knowledge about primary and secondary air.
>
> My idea (drawn before I started reading posts here) is attached.
>
> At the moment I'm thinking the dimensions will be A - depth about 60cm B -
> height about 40cm C - stack diameter 13cm
>
> It needs to front load as the top will be a big hot surface which will be
> used for cooking etc.  The front door will be airtight and I was going to
> put in a window so I can see what is going on inside.
> The red pipe will be feeding preheated air.  Actually 2 pipes one for
> primary that will feed to the bottom/back the other secondary) . and both
> will have valves to regulate flow.  Flue pipe will be about 2 meters long.
>
> In addition to this stove I'm going to have a large water tank with a
> connected 'heat exchanger' that I can place on the stove top.  This will
> heat the water tank while the stove is running which will then act as heat
> mass and hopefully keep the well insulated/reasonably draft free living
> space at a reasonable temperature for some time after the stove has gone
> out.
>
> I appreciate that this is not going to achieve a 'perfect' burn but would
> appreciate any ideas for improvements / comments.
>
> Best regards
>
> Darren
>
>
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