IM 685 / Page 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 tailor the shape of the flame to each particular stainless steel combustion
chamber, to match the capacity requirement, and to offer a 20 to 1 turndown ratio. This is a forced
draft burner with a high pressure 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 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.
Units equipped with gas heating must not be operated in an atmosphere contaminated with
chemicals which will corrode the unit such as halogenated hydrocarbons, chlorine, cleaning
solvents, refrigerants, swimming 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 constitutes product abuse and will void all warranty
coverage by the manufacturer. Questions regarding specific contaminants should be referred to
the appropriate local gas utility.
Ventilation and Flue Pipe Requirements
The McQuay applied rooftop unit is equipped with an outdoor 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 has been installed and wired at the factory. See “Gas Piping.” Also note that
models 150 through 200 have the burner removed for shipment; see “Installation: Models 150-200.”
Factory Checkout
This complete heating plant was fired and tested at the factory. 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. 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 normally 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 exercise caution. This equipment is to be installed by an
experienced professional installation company that employs fully trained technicians.
