Installation instructions text on a black background.

A masonry adapter is required for installation of a Vacu-Stack® or WeatherShield® on square and rectangular chimneys.

STEP 1: ASSEMBLE ADAPTER

Identify all stainless steel parts:
pipe with adapter plate, one threaded rod, one 1/2" diameter tube, one wing nut, two hex nuts, one flat washer, 2 lock washers.

Insert the threaded rod assembly through the two holes at bottom of adapter collar "B."

Diagram of a mechanical assembly showing a cover plate, a tube labeled 'D', a collar labeled 'B', a wing nut labeled 'C', with measurements for distance 'A'

MASONRY ADAPTER Model AD

STEP 2: MEASURE

Measure inside of chimney opening "A" & "B" and diagonal distance "C." Adapter fastens to inside of chimney flue. The shortest dimension of "A" or "B" determines maximum adapter size that may be installed. Cover plate must be large enough to cover chimney opening.

Line drawing of a rectangular block with an elevated square top. Dimensions labeled as A for the inner square and B for the outer square, with a total height labeled as C.

STEP 3: ADJUST THREADED ROD

Adjust threaded rod so it projects distance "D" from side of adapter collar. "D" equals one-half times the difference between "C" (from Step 2) and collar diameter "E."
D=1/2 x (C-E)

A technical diagram of a threaded rod assembly showing labeled dimensions E and D, with text indicating 'Threaded Rod Assembly'.

STEP 4: PREPARE FLUE TOP

Brush clean top of flue and apply a bead of silicone caulking (available from most hardware stores and home centers).

A sketch of a brick well with a bucket hanging on a rope.

STEP 5: POSITION ADAPTER

Position adapter on flue with fixed end of threaded rod touching on inside corner of flue. Reach into collar and turn wing nut clockwise until tube firmly grips opposite corner of flue. Do not over tighten.

Black and white drawing of a brick chimney with a metal cap and a ladder leaning against it.

STEP 6: SEAL COVER PLATE TO ATTACHED COLLAR

Apply a bead of silicone caulking at the location where the collar connects to the cover plate.

A circular dial with a needle pointing slightly past the halfway mark and an attached handle labeled 'GAULK' on a gray surface.

A faucet mounted on a platform, with two caulking tubes labeled 'CAULK' crossing underneath it, creating a visual illusion of a face with the faucet as the nose.

STEP 7: ATTACH CHIMNEY CAP
Insert the WeatherShield® into the collar. Seat firmly and seal top joint with silicone caulking.

CAUTION: Do not undersize. The size (area) of the chimney cap must not be less than the size of the appliance smoke outlet. For fireplaces, the size (area) must not be less than 10% of the front opening of the fireplace.