Retrotec RSH Pressure Relief Vents - Manual (Page 7)

QG700 Page 7 of 8 rev-2010-08-13
FITTING AN RSH SERIES PRV INTO AN EXTERIOR MASONRY WALL
a) Mark out and cut a hole through the wall 1/2 inch (12mm) larger than the body of the PRV. (note
the orientation of the vent, it isn’t square). The hole must be cut carefully in order to leave
sufficient sound stonework around the hole into which the holding screws must fix.
b) When necessary, support the stonework above the hole as per building regulations. (the PRV is
not designed to support any part of the opening into which it is to be fitted and the surrounding
masonry must be self supporting).
c) Place grill onto PRV and fix using 1 inch (25mm) tech screws. (it is advisable to do this first so as
to avoid conflict with a PRV fixing screw point). Do the same with the outside shutter on the wall
liner.
d) Dry fit both the PRV and the wall liner marking where the tech screws protrude onto the
masonry. (Please note: It is essential that the unit is fitted square. Do not try to force into a
hole that is not cut correctly cut, distorting the body of the PRV can jam the blades and affect
its performance. It is also essential that the PRV is fitted upright. 3° either way is acceptable).
Remove and drill clearance holes with a masonry bit to the depth of protruding tech screws.
Remove both the inside grill and outside shutter from the PRV and wall liner.
e) Mark fixing holes to be drilled into the PRV flange and Wall liner flange. It is advisable to be on a
line around 1/2 inch (12mm) in from the outside of the flange edge to allow for the maximum
amount of masonry to fix into. On this line drill 4 of 5/32 inch (4mm) diameter holes at each
corner (these points typically are best supported in the masonry) and then holes every 8 inch
(200mm) along the flange.
f) Hold up PRV and wall liner into hole and mark through fixing holes. Drill into masonry with a
13/64 inch (5mm) masonry bit and install plastic wall plugs.
g) Apply a bead of intumescent fire-rated caulk around the opening to form a seal under the PRV
flange and using 1 1/2 inch (35mm) no.6 steel screws fix PRV into wall.
h) Follow the same fixing procedure with the wall liner except instead of fire-rated caulk, apply a
good weather sealant under the wall liner flange, e.g. silicone caulk. Screw liner into wall with 1
1/2 inch (35mm) long no. 6 steel screws into pre drilled wall plugs. Where the wall liner meets
the PRV seal joint with silicone caulk.
i) Check that each and every blade of the PRV opens freely. If blades are rubbing against the side
casing check to make sure the frame of the PRV has been fitted square and is not twisted and
there is no part of the wall opening that is jamming on the vent casing. (it may be possible to
free slightly rubbing blades by tapping out casing where they touch with a hammer).
j) Fit grill to PRV and shutter to Wall Liner.
k) Finally attach decal ‘Do not block....’ signs next to the PRV in both sides and where visible.