Mammoth 800 to 5500 CFM: Dedicated Outdoor Air System with Enthalpy Wheels (VHC) - Manual (Page 5)

MAMM-VHC-IOM-1A (JANUARY 2013) 5
balanced, the unit will be even less perceptible if posi-
tioned away from busy offices.
• Locate the unit in an area requiring the least amount
of ductwork and direction changes to allow optimum
performance, to reduce pressure loss and to use less
electricity to achieve proper ventilation. Ductwork
must be in accordance with ducting mechanical rules
to prevent sound issues and system effects.
• The fresh air intake hood must be positioned away
from sources of contamination such as hot chimneys
or kitchen exhaust vents.
• Fresh air intake must also be positioned in a direction
opposite to that of prevailing winds to reduce entry of
snow or rain.
• The unit should be mounted on a level foundation to
allow condensation to flow into internal drains. The
foundation must provide adequate continuous support
to minimize deflection of the unit base frame to not
more than 1/16” [1.6 mm] over entire length. In addi-
tion to these recommendations, a Structural Engineer
must be involved to properly size supporting structural
elements.
• When mounting the unit indoors, if drain connections
are required, mount the unit on a housekeeping pad
of sufficient height to allow for drain trap height and
condensate lines to slope toward the building drain.
• When mounting the unit on a roofcurb check the
height from the finished roof to the bottom of the
intake hood. Consult with Local Authorities or your
building code for minimal intake hood height for the
water-tight height from and above the finished roof
and in snow prone areas, the buildup of snow, to de-
termine the height of the roofcurb. Mammoth optional
roofcurbs measure 18” [457 mm] in height. If addi-
tional height is required from the finished roof to the
top of the roofcurb, to the bottom of the intake hood
or if other than level, custom height roofcurbs must be
ordered.
Roofcurbs supplied by Mammoth should be mounted as
follows:
• The roofcurb is shipped knocked-down with assembly
hardware and instructions provided. The roofcurb
must be field erected, assembled and set in place by
the Installing Contractor.
• Roofcurb dimensions are submitted with the unit me-
chanical drawings which can also be found in the unit
control panel pocket or by calling Technical Support
personnel from the Mammoth factory.
• After the roofcurb has been assembled, ensure that
the roofcurb dimensions suit the unit for which it is
designated.
• The cross members must be positioned as per the
roofcurb drawing to properly support the ductwork
plenums for bottom vertical return and supply connec-
tions and for stability.
• Ensure that the assembled roofcurb is square, plumb
and level to within 1/16” [1.6 mm] over the entire
length. The building structure must provide continu-
ous structural support to the full perimeter of the
roofcurb and all cross members requiring support.
The roofcurb may be shimmed as required to provide
continuous support.
• The roofcurb must be fastened to the building struc-
ture.
• The Installing Contractor is responsible for mak-
ing the roofcurb water-tight by caulking all roofcurb
joints.
Roofcurbs Supplied by Mammoth (External Applications Only)
IMPORTANT
The following items must be completed prior to setting the
unit on the roofcurb:
• The roofcurb roofing must be completed including
insulation, cant strip, flashing and counter-flashing.
• Vertical ductwork must be attached to the roofcurb
cross members and building structure, not to the
unit. See the mechanical drawings for information on
roofcurb installation, recommended ductwork attach-
ment and dimensions.
• If there is no building roof access underneath the
unit and drain or piping connections must be made
(in the roofing), it is recommended to do so before
unit installation using the appropriate materials pro-
vided by the Installing Contractor.
• Remove the length of 3/8” x 1½” [9.5 mm x 38 mm]
polyvinyl gasket strip with adhesive backing supplied
with the unit and apply a continuous strip to the top
perimeter of the roofcurb and duct opening connec-
tions for an air and water-tight seal.
IMPORTANT
The gasket between the unit and the roofcurb is critical for
an air and water-tight seal. An improperly applied gasket
can result in air and water leakage and poor unit perfor-
mance. Position the unit with equal spacing all around be-
tween the roofcurb and inside unit base rail using ½” [13
mm] wood shims as it is being lowered.