DESCRIPTION OF THE HEATER
| Gas |
|
Air |
| Exhaust |
|
| Blower |
| Mixer |
|
Inlet |
|
|
(Cold |
|
|
Water) |
|
|
Outlet | Burner |
|
(Mixed | Heating Coils | |
Water) |
|
|
FIGURE 2
Figure 2 is a diagram of the heater showing how it operates. Precisely matched orifice plates meter the air and gas into the mixer. The blower draws the air and gas through the mixer and forces it into the burner’s flameholder. A sealed heat exchanger surrounds the flameholder, discharging exhaust gases out the flue.
Two inch PVC water piping connects directly to the mani- fold/header on the heat exchanger using 2” PVC slip unions provided with the heater. The outer manifold remains cool; no heat sinks are required. A thermal regulator and an inter- nal bypass regulate the water flow through the heat exchanger to maintain the correct outlet temperature.
A plastic jacket with the top half split for access surrounds the assembly. The heater control board assembly, set into the top of the jacket, contains the operating controls.
SEQUENCE OF OPERATION
An electronic temperature sensing thermistor in the mani- fold adapter inlet controls the heater operation. When the inlet water temperature drops below the temperature set on the operating control, the burner controller supplies power to the combustion air blower through a series of safety interlocks. The interlocks consist of
•the pressure switch (PS), which senses that the pump is running,
•the high limit switch (HLS), which opens if the heat exchanger outlet temperature goes above 135°F, and
•the automatic gas shutoff (AGS) switch, which opens if the heat exchanger outlet temperature goes above 140°F.
•the stack flue sensor (SFS), which shuts down the heater if the flue gas temperature reaches 500°F.
The air flow switch (AFS) senses the pressure drop across the air metering orifice. As soon as there is sufficient air flow, the AFS closes, closing the circuit to the hot surface ignition (HSI), which ignites the fuel mixture.
On a call for heat, the blower and HSI are energized. In about 20 seconds, the gas valve opens and ignition occurs. The HSI then switches to a sensing mode and monitors the flame.
The heater is equipped with a digital operating control that enables the user to
OWNER’S OPERATING
INSTRUCTIONS
FOR YOUR SAFETY READ BEFORE OPERATING
IF YOU DO NOT FOLLOW THESE INSTRUCTIONS EXACTLY, A FIRE OR EXPLOSION MAY RESULT, CAUSING PROPERTY DAMAGE, PERSONAL INJURY OR LOSS OF LIFE.
START-UP AND OPERATION
BEFORE START-UP
A.This appliance does not have a pilot. It is equipped with an ignition device which automatically lights the burner. Do not try to light the burner by hand.
B.BEFORE OPERATING check for odor. Sniff all around the appliance area for gas. Be sure to sniff next to the floor, because some gas (such as propane) is heavier than air and will settle on the floor.
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