M-Series Technical Manual
91
Cambridge Air Solutions
INDIVIDUAL HEATER COMPONENT
DESCRIPTIONS
AIR FLOW SWITCH, High and Low (AFH &
AFL)
The air flow switches sense the
pressure drop across the burner
profile plate. They are factory set and
not adjustable. They are designed to
prevent burner operation if the
pressure drop across the burner
drops below 0.40
inch
WC or
increases above 0.85
inch
WC for natural gas
applications or below 0.60
inch
WC or above 1.12
inches
WC for LP gas applications.
AMPLIFIER (AMP)
The amplifier creates a voltage output
to drive an electronic proportioning gas
valve to maintain the selected discharge
temperature (Maxitrol Series 14) or
space temperature (Maxitrol Series 44).
On Maxitrol Series 14 control systems,
the discharge temperature is set either
on the amplifier (AD1014) or the
Remote Heat Adjust (TD114). On Maxitrol Series 44
control systems, the range of the discharge temperature
is set on the amplifier (A1044), but the space
temperature selector controls when more or less heat is
required.
CONVENIENCE OUTLET
A convenient 115 volt GFI duplex receptacle is provided
inside the heater’s electrical enclosure. The electrical
supply source for this device can be either the heater’s
control power transformer (5 amps max.) or a separate
outside source (15 amps max.).
DAMPER MOTOR (D)
The damper motor operates on 24
Volts AC and transmits power to
the motor starter when the
damper blades are fully open by
the closure of the damper end
switch. The damper end switch is
an adjustable internal auxiliary
switch which has been factory set to operate when the
damper is fully open. The damper motor will power closed
when the heater cycles off. The damper motor will not
close unless the blower service switch is in the
“
REMOTE
”
position. Refer to detailed instructions
regarding the replacement and adjustment of the damper
motor (see page 95).
DISCHARGE TEMPERATURE SENSOR
(DTS)
The discharge temperature sensor is
mounted on the fan housing and is a
component of the Maxitrol Series 14
and Series 44 temperature control
systems. It senses the average fan
discharge temperature and
transmits a resistance signal back
to the amplifier that corresponds to
the discharge temperature. The
Maxitrol Series 44 and Maxitrol Series 44/Tamperproof
temperature control systems use the Maxitrol Series 44
sensor (TS144). The Maxitrol Series 14 control systems use
the Maxitrol Series 14 sensor (TS114). The Maxitrol
SC25S signal conditioner utilizes a Maxitrol discharge
temperature sensor TS194Q.
DISCONNECT SWITCH (DISC)
The non-fused disconnect switch
is provided on all heaters and
includes a lockable operating
knob. The disconnect must be off
before accessing the electrical
control enclosure. Once the control
enclosure is open, experienced service
technicians may activate the electrical
circuit to assist in troubleshooting.
