Greenheck TSU Base Unit Manual (464441) - Manual (Page 15)

Make-Up Air Unit 15
®
IMPORTANT
If the flame signal is not above 1.25 VDC and steady,
consult the Troubleshooting section.
IMPORTANT
The proper minimum firing rate setting results in a
small ribbon of continuous flame which covers the
flame rod and runs across the entire burner.
IMPORTANT
Do not allow the disconnected wire to come in
contact with a potential ground. Damage to the
amplifier or transformer could result.
IMPORTANT
On units with a burner 42 inches or greater, the flame
safeguard will automatically shut off the pilot after the
burner has been ignited.
NOTE
Adjusting the maximum and minimum firing rate
requires the inlet air sensor to be set higher than the
outdoor air temperature in order to start the burner(s).
Once high and low fire have been set, the inlet air
sensor should be set to the desired temperature.
NOTE
Counterclockwise rotation increases the minimum fire
rate setting, clockwise rotation decreases the setting.
9. Flame Signal Check
To measure the flame signal connect a standard DC
voltmeter to the flame
amplifier test jacks + and
- (com) as shown to the
right. The flame signal
should be above 1.25 VDC
and steady.
Check the flame signal
with the burner at pilot
only, minimum fire, mid fire
and high fire.
DC Voltmeter and Flame
Amplifier
8. Set the Unit’s Operating Temperature
Set the operating temperature. The method to set the
operating temperature depends upon which Maxitrol
controller is used.
Maxitrol Series 14 - The Maxitrol Series 14 should be
set to the desired discharge temperature mode. Place
dipswitch in the “UP” position for local control and in
the “DOWN” position for remote control. Keep LFST
dipswitch in the “UP” position at all times for 10 second
delay. Fig. A is required for remote control.
Maxitrol Series 44 - The Maxitrol Series 44 should be
set to the desired space temperature. The temperature
selector is a stand-alone dial. The stand-alone dial may
be mounted remotely.
Maxitrol Series 44 — 9 terminals
Maximum discharge
temperature setting
(Typical: 100ºF)
Minimum discharge
temperature setting
(Typical: 50ºF)
Low fire time
delay setting
(75% of maximum)
Remove wire attached
to terminal 3 to send
unit into maximum fire
Maxitrol SC25S - The SC25S is an analog signal
converter that will change a 0-10 VDC or a 4-20 mA
control signal provided by an owner-supplied Building
Management System into an output level capable of
driving the modulating gas valve.
The SC25S also limits the minimum and maximum
discharge air
temperatures.
Reference the unit-
specific wiring
diagram and Maxitrol
data sheets included
in the IOM packet.
Set the discharge temp
Typical
65°F
Minimum: Typical: 55°F
Maximum: Typical: 90°F
Fig. A
Low fire
setting
(LFST)
dipswitch
Discharge
temperature
dipswitch
Maxitrol Series 14 — 8 terminals
Remove wire attached to terminal 3
to send unit into maximum fire
Series 44 Temperature Setting
(shown as Space Temperature Control)
Set the space temperature
Typical: 70ºF