Specifications

IM 685-2 3
General
This forced draft gas burner is specifically designed for use
with the furnace on McQuay applied rooftop heating and air
conditioning units which are for outdoor installation only.
Each model size has unique burner head components to tai-
lor the shape of the flame to each particular stainless steel
combustion chamber, to match the capacity requirement, and
to offer a desirable turndown potential when arranged for
modulation. This is a forced draft burner with a high pres-
sure combustion air fan and will operate against pressure.
This eliminates the need for draft inducers, chimneys, draft
hoods, barometric dampers, and Breidert caps.
Warranty Exclusion
Warranty is void if the furnace is operated in the presence of
chlorinated vapors, if the airflow through the furnace is not
in accordance with rating plate, or if the wiring or controls
have been modified or tampered with.
Ventilation & Flue Pipe Requirements
The McQuay applied rooftop unit is equipped with an out-
door air louver to supply adequate combustion air. The unit
also has a flue outlet assembly and requires no additional
chimney, flue pipe, Breidert cap, draft inducer, etc.
Factory Mounting
This burner and gas train have been installed and wired at
the factory. See “Gas Piping” on page 4. Also note that mod-
els 150 through 200 have the burner removed for shipment.
See “Vestibule (Models 150 thru 200)” on page 7.
Factory Checkout
This complete heating plant was fired and tested at the fac-
tory. It was adjusted to the required capacity and efficiency.
Modulating air and gas linkages, pressure regulators, and
stops were adjusted for proper operation at all firing levels.
The unit was fired through several complete start-up through
shutoff sequences to check operation. A check was made of
the air switch, gas pressure switch, high limit operation, and
combustion characteristics including CO
2
and CO (at several
firing rates on modulating burners).
WARNING
Units equipped with gas heating must not be operated
in an atmosphere contaminated with chemicals which
will corrode the unit such as halogenated hydrocar-
bons, chlorine, cleaning solvents, refrigerants, swim-
ming pool exhaust, etc. Exposure to these compounds
may cause severe damage to the gas furnace and result
in improper or dangerous operation. Operation of the
gas furnace in such a contaminated atmosphere consti-
tutes product abuse and will void all warranty coverage
by the manufacturer. Questions regarding specific con-
taminants should be referred to your local gas utility.
If the burner was specified for operation at higher altitudes,
combustion air adjustments were compensated to result in
proper settings at the higher altitude. This checkout nor-
mally eliminates on-the-job start-up problems; however, the
equipment is subject to variable job conditions and shipping
shocks can change adjustments, cause damage, and loosen
connections and fasteners. Therefore, it is necessary to go
through the complete start-up procedure even though the
unit may appear to be operating properly.
Installation
General
The installation of this equipment shall be in accordance
with the regulations of authorities having jurisdiction and all
applicable codes. It is the responsibility of the installer to
determine and follow the applicable codes. Sheet metal
parts, self-tapping screws, clips, and such items inherently
have sharp edges, and it is necessary that the installer exer-
cise caution. This equipment is to be installed by an experi-
enced professional installation company that employs fully
trained and experienced technicians.
Flue Box (see Figure 1)
The flue box is not installed at the factory because it would
increase the width of the unit beyond the allowable shipping
width. All holes are prepunched, the fasteners are furnished
and everything is shipped in a box in the burner section. On
Models 150 through 200 it is shipped in the same crate as
the vestibule. Remove and discard the shipping cover
installed over the furnace tube outlets before installing the
flue box.
1. Remove the screws (2) in the casing of the unit that line
up with the bottom lip holes of the flue box tube sheet
(3). These screws will later be replaced, at which time
they will also attach the bottom of the flue box to the
unit.
2. Install the flue box tube sheet (3), attaching top to roof
dam strip with screws (1). Do not attach bottom at this
time.
3. Apply a 1/8 to 3/16 inch bead of high temperature sili-
cone around each tube to seal it to the flue box tube sheet
(3) and prevent condensate from running back toward the
unit along the outside of the tube. Also apply a bead of
high temperature silicone to seal both sides to the bottom
of the flue box wrapper (4), being careful not to obstruct
the square drain holes in each front corner.
4. Install flue box wrapper sheet (4) by sliding it up from
below so as not to disturb the silicone seal described in 3
above. Attach with side screws (5). At this time reinstall
bottom screws (2)
.