From DemotechResearch

Design: D15Experiment1

This is what we are heading for and we ask your comment and very specially your knowledge about prior experience with a similar setup:

1. Air intake and outlet close together in a wall to prevent differences in pressure because of wind.
2. Forcing the draft through the stove with the smallest ventilator possible. A bit similar to the high-efficiency gas powered central heating units.
3. We fuel the stove by a container, from which the wood sacks into the fire. As this happens at a slow continues pace, we should provide for an adequate quantity of air. is there a rule of thumb how much more air should be sucked in than is actually used to burn the fuel? This for preventing tar build up in the system.
4. We play with the idea to drive the ventilator with a primitive Stirling engine. It may be a very simplified system, as there is plenty heat available in relation to the little power needed to force the draft.
5. Smoke jetted from the outlet should of course not pollute the environment. Smoke from a well designed heat box burning at 1200 C would not contain much polluting parts, however it is feasible to 'wash' the smoke when the force of the ventilator is available for such a process.
6. Who is doing experiments with alternatives for chimneys? We like to share our experience with such people through the "Open Source" principle, as described in our website (sub:37)

This experiment is described at 1, 2, 3.

Findings
Re. 1: Only the exhaust was led to an opening in the wall. Air was sucked in underneath the stove. The idea of preheating could not be checked, as the tiles used to line the firebox cracked immediately when heated. The tiles were shielded off with thin stainless steel sheet metal. Being occupied with moving Demotech from Dieren to Maastricht at that time Hans Baarslag and I did not give a follow-up to the first testing. Re 2: We used an electric ventilator from a kitchen unit. Its capacity could be regulated with a dimmer. There was no danger for burning the plastic ventilator rotor, as temperature at that spot was no more than luke warm. The stove was build in haste and had plenty leaks. So the ventilator has to suck hard to force enough air through the fire box. The hot air from the fire box first passed through a stone channel, then moved outside the bricks, but inside metal sheets. For this reason the brick stove started producing heat immediately after firing. Because the brick walls in the stove retained part of the heat, the stove remained warm long after the fire in it extinguished.