Nortek O4HD-091A-12-FB, Installation, Operation And Maintenance Manual, Page: 6 / 35

(service switch) should be clearly marked, installed in an
easily accessible area between the furnace and furnace
room entry, and be located in such a manner to reduce
the likelihood that it would be mistaken as a light switch
or similar device.
The power requirement for the O4HD-091A-12-FB,
O4HD-091A-14-FA-DV and O4HD-091A-V-FA models is:
120 VAC, 1 Ø, 60 Hz., 12A.
Accessories requiring 120 VAC power sources such as
electronic air cleaners and humidifier transformers may
be powered from the electronic
fan timer board where
provisions have been made for connections, but should
have their own controls. Do not use the direct drive motor
connections as a power source, since there is a high risk
of damaging the accessories by exposure to high voltage
from the auto-generating windings of the direct drive
motor.
Thermostat wiring connections and air conditioning
contactor low voltage connections are shown in the
wiring diagrams in Appendix B. Some micro-electronic
thermostats require additional controls and wiring. Refer
to the thermostat manufacturer's instructions.
The thermostat should be located approximately 5 feet
above the floor, on an inside wall where there is good
natural air circulation, and where the thermostat will be
exposed to average room temperatures. Avoid locations
where the thermostat will be exposed to cold drafts, heat
from nearby lamps and appliances, exposure to sunlight,
heat from inside wall stacks, etc.
The thermostat heat anticipator should be adjusted to the
amperage draw of the heating control circuit as
measured at the "R" and "W" terminals of the thermostat.
To reduce the risk of damaging the heat anticipator, do
not measure this current with the thermostat connected
to the circuit. Measure the amperage by connecting an
ammeter between the two wires that will connect to the
thermostat "R" and "W" terminals.
11. HUMIDIFIER
A humidifier is an optional accessory available through
most heating supplies outlets. Installation should be
carried out in accordance with the humidifier
manufacturer's installation instructions. Water or water
droplets from the humidifier should not be allowed to
come into contact with the furnace heat exchanger. Do
not use direct drive motor connections as a source of
power for 120 VAC humidifiers and humidifier
transformers.
12. PIPING INSTALLATION
The entire fuel system should be installed in accordance
with the requirement of CAN/CSA B-139, and local
regulations. Use only an approved fuel oil tanks piping,
fittings and oil filter.
In the United States the installation must be in
accordance with NFPA No. 31 and local codes and
authorities.
Install the oil filter as close to the burner as possible.
For further details of the oil supply tank and piping
requirements, please refer to the instructions and
illustrations in the oil burner and oil pump
instructions shipped with the furnace.
13. OIL FILTER
All fuel systems should include an oil filter between
the fuel oil storage tank and the oil burner. When
using an oil burner nozzle smaller than 0.65 U.S.
Gallons Per Hour, install an additional 7 to 10 micron
filter as close as possible to the oil burner.
14. OIL BURNER NOZZLES
The O4HD-091A-12-FB, O4HD-091A-14-FA-DV and
O4HD-091A-V-FA are certified for multiple firing
rates, ranging from 59,000 to 86,000 Btu/h. By
manipulating the oil burner nozzle, flame retention
head, static plate and temperature rise; the furnace
may be fired at an ideal rate for a wide range of
structures. Refer to Table A-1, and the furnace
rating plate to determine the proper combinations.
15. OIL BURNER ADJUSTMENT
The burner air supply is adjusted to maintain the
fuel
to air ratio
to obtain ideal combustion conditions. A
lack of air causes "soft" and "sooty" flames, resulting
in soot build-up throughout the heat exchanger
passages. Excess combustion air causes a bright
roaring fire and high stack temperatures resulting in
poor fuel efficiency. The O4HD-091A-12-FB, O4HD-
091A-14-FA-DV and O4HD-091A-V-FA furnaces
operate most efficiently with a No. 1 smoke spot on
the Bacharach Scale. This is not necessarily the
optimum setting; however, because dust will
inevitably build up on the air moving components of
the oil burner assembly. This will result in decreased
air supply with the potential result of soot building up
in the flue gas passageways of the heat exchanger.
Soot behaves as an insulator and impairs good heat
transfer. Stack temperature will increase, and the
overall efficiency will decrease. As a means of
avoiding this problem, it is advisable to adjust the air
supply to provide no more than a trace smoke spot
on the Bacharach Scale.
See the Venting Instructions included in the Vent
Kits for set-up details for sidewall vented furnaces.
NOTE: SIDEWALL VENTED MODELS
SHOULD BE SET UP TO DELIVER ZERO (0)
SMOKE.
6