Key words are all masonry. Brick face with studded wall behind equals future fire. http://www.fieldcontrols.com/draftcontrol.php
Draft Control (Installation Options)
Recommended Locations for Field Draft Controls
For gas-fired equipment, the preferred location of the control is on the bull head tee. This location provides maximum relief of downdrafts with minimum positive pressure. (See Fig. 1, Dia. A-C)
With oil or solid fuels, the bull head tee is not recommended, so locate the control as shown. (See Fig. 1, Dia. D-J) These locations are acceptable for gas units as well. Except on forced draft systems, locate the control as close as possible to the furnace or boiler, at least 12" beyond a stack switch on oil-fired units, and at least 18" from a combustible ceiling or wall. http://www.fieldcontrols.com/pdfs/02702600.PDFhttp://www.fieldcontrols.com/pdfs/01428000.pdf
Hmmm...seems the various instructions are a bit different the M contradicts the location in a tee that is not allowed in an RC.
You can see how one might say 18" minimum to the stove from the PDF's but it does say "as close to the stove as possible"