[Stoves] Draft problems in Kyrgyzstan

[Ken Boak]

Crispin, Stovers

How about a wind-blown chimney cowl that produces draft when the wind blows?

Been using them in the UK since 1920s - or therabouts


Ken

On 28 November 2016 at 14:33, Crispin Pemberton-Pigott <
crispinpigott at outlook.com> wrote:

> Dear Friends of Chimney Stoves
>
>
>
> There is a plan to install 50 improved stoves in Kyrgyzstan to monitor
> them through the winter, getting fuel consumption, user feedback and air
> quality (in some of them) to support a larger program in the coming year.
>
>
>
> Many of the installations have a chimney that rises from the stove then
> exits horizontally through a wall outdoors, that’s it. No more draft than
> that.
>
>
>
> This is a typical issue: limited draft, exiting through a wall that may or
> may not have a wind blowing against it. Combined with the negative pressure
> on the lee side of the building, it is enough to reverse the chimney flow
> at low power and the gases emerge into the house. There are many reports of
> this happening in Central Asia.
>
>
>
> One of the most important changes to make is to create stoves that are
> very air-tight so that the gas flow is impeded by a restricted entrance,
> rather than a low temperature. If the temperature is much higher in the
> chimney, the loss of heat is not necessarily higher, if the flow rate is
> much lower. This is difficult to understand intuitively because there is a
> common belief that if the exit temperature is higher, the loss is greater.
> That is only true when the gas velocity is the same.  If the gas velocity
> is reduced by a factor of 6 the temperature cam be much higher and the loss
> reduced. For that reason we are getting routine thermal efficiency readings
> of >70% at significantly higher flue temperature readings. Those readings
> should be taken at the roofline – i.e. where the pipe passes through the
> ceiling which is interpreted to be heated envelope.
>
>
>
> The stoves are being placed in homes this month, 5 models. So far the
> ultra-low smoke versions of the GTZ-7 stove (original design from Mongolia)
> is a hit not only with the customers but the producers themselves.
> Producers and project staff are ripping out their own stoves and replacing
> them with project models! That is what I call a Good Start.
>
>
>
> The full drawings of all models are on the newdawnengineering.com website
> in the Library under Stoves/Kyrgyzstan. Look for the renamed GTZ stove in
> the Tajikistan folder under /Model 4. There are two versions there, one
> specifically made for production using only an arc welder and an angle
> grinder which are the only tools many producers have.
>
>
>
> Regards
>
> Crispin
>
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