Woodstock Soapstone Co.August 28, 2013 at 1:33 PM
Primary and secondary air are linked, and operated with a single control. The PH uses a rotating control; this stove uses a sliding damper. You cannot cut off the secondary air, but secondary activity at low burn settings is minimal (partly because secondary flow is reduced, and partly because firebox temperatures are low).
Overnight burns in the 8-12 hour range will be very easy to achieve, and on general principle we will probably never advertise anything that exceeds that range.
For reference, our preliminary EPA testing had a low burn of 11 hours with just 22 pounds of Douglas Fir (and emissions of 0.52 g/hr and efficiency of 84%). Employees burning prototypes in their homes last winter had no complaints about overnight burn times, and we would have heard about it if they did!
Tom Morrissey
Woodstock Soapstone