Reznor OH Unit Installation Manual - Manual (Page 19)

Form I-OH, PN 120390 R5, Page 19
5) The pump will start and the burner ignite. With the burner ignited, check the oil
pressure and adjust, if necessary, to a pressure of 100 pounds for Sizes 95 and
140 or 150 pounds for Size 190.
Burner
Electrical
Switch
FIGURE 19 - Burner Pump
 Check draft. Prior to continued operation, check to be sure that there is sufficient
draft for proper combustion. A draft of negative .01" w.c. is required over the fire.
When firing, the draft measurement in the stack should be a negative .03-.04" w.c.
Instructions for measuring draft:
1) To measure draft over the fire, remove the metal plug in the observation door
(See FIGURE 21, page 20.).
2) Insert air pressure gauge (such as Dwyer pressure gauge). Draft measurement
gauge must read a negative .01".
3) If measurement is not correct, adjust draft regulator until measurement is correct.
4) Replace plug.
5)
To measure flue draft, insert air pressure gauge in the 5/16" hole that was drilled
in the flue pipe halfway between the furnace and the draft regulator. Flue draft
measurement must be a negative .03-.04" w.c.
If there is insufficient draft, it will create a back pressure resulting in oil fumes
in the building and/or pulsating when the burner starts and stops. It may cause
excess deposits of soot. To correct this problem, the height of the chimney may
need to be increased and/or a UL listed draft inducer may need to be installed. If
a draft inducer is used, provision must be made to shut off the fuel supply to the
burner in the event of the failure of the draft inducer.
If there is too much draft, it could cause ignition problems, erratic burner, and
loss of thermal efficiency. To correct this problem, adjust the barometric damper
regulator to reduce the draft.
CAUTION: If there is a backdraft or downdraft, do not continue
operation of the heater until the situation is corrected. Equipment
and/or property damage could result. Back pressure (backdraft
or downdraft) may be caused by the chimney being lower than
surrounding objects, such as buildings, hills, trees, rooftops, etc.
It may be caused by an exhaust fan in the building. The air intake
in the room where the heater is installed must be sufficient size
so that there is no change in the draft reading in the flue with the
exhaust fan running.
□
Check combustion air shutter and air band settings. The heater is shipped
from the factory with the settings shown in the table in FIGURE 21. Ordinarily,
Location of Primary
Ignition Control
(NOTE: Unit illustration
shows older model controller.)
FIGURE 20 - Heater Controls
Primary Ignition
Control with
Reset Button