@ king coal Yes I agree That adjusting the secondary will impact draft after the chimney reacts to the change. But to say one steals from the other is what I'm not on board with.
@ Dusty I'm not out to persuade anyone with fixed ideas. I just don't like seeing people unintentionally misguided.....
Please carry on...
as i watch this DSM 1400 i come to understand that it functions much more like an organism than a machine, esp. in regards to the operation of the fixed secondaries. some one put significant consideration into the location, volume and outlets of this simple looking feature.
SOME HOW, if and when the natural draft inhancers ( outside temp. wind etc. ) are low and the over fire draft is less than -.04 WC, the stove draws more secondary and keeps the exit flow moving with positive momentum. this also checks the chance of CO escape.
alternatively, when the over fire draft is .04 / .06 WC the stove draws less secondary.
how totally escapes me since the inlets and outlets are open the same amount in each case.
i have watched a controlled trial of this using a pair of incense sticks in the same location and height on both sides of the stove.
when i have the stove running at a steady state and use the MPD's to drop the draft to .03, the stove pulls the smoke plume straight away from the stick at a 90* angle and into the inlets.
when i use the MPD's to allow -.05 or more the plume meanders around and expands next to the stove and is slowly but steadily drawn in. i have no explanation for this, just recurrent observation.