The Shield - How It Works - Lochinvar Shield SWR125 Installation & Service Manual

The Shield - How it works...

1. Access cover - front
Provides access to the gas train, heat exchanger and controls.
2. Air intake adapter
Allows for the connection of the PVC air intake pipe to the
water heater.
3. Air pressure switch
The air pressure switch detects blocked inlet conditions.
4. Burner door temperature switch (285 --500 Models Only)
An electrical switch designed to shut down water heater
operation in the event the combustion chamber access cover
exceeds 500°F (260°C). This switch may only be reset by a
qualified service technician AFTER the underlying cause has
been identified and corrected. Check the integrity of the front
refractory on the inside of the combustion chamber access
cover if the switch opens.
5. Blower
The blower pulls in air and gas through the venturi
(item 32). Air and gas mix inside the blower and are pushed into
the burner, where they burn inside the combustion chamber.
6. Burner (not shown)
Made with metal fiber and stainless steel construction, the
burner uses pre-mixed air and gas and provides a 5 to 1 firing
rate.
7. Condensate drain connection
Connects the condensate drain line to 1/2" PVC.
8. Electronic Control Module
The electronic control responds to internal and external signals
and controls the blower, gas valve, and pump to meet the
demand.
9. Electronic display
The electronic display consists of 4 buttons, and a liquid crystal
display. The display is used to make adjustments and read
water heater status.
10. Flame inspection window (not shown)
The quartz glass window provides a view of the burner
surface and flame.
11. Flame sensor
Used by the control module to detect the presence of burner
flame.
12. Flue gas sensor (not shown)
This sensor monitors the flue gas exit temperature. The control
module will modulate and shut down the water heater if the
flue gas temperature gets too hot. This protects the flue pipe
from overheating.
13. Gas connection pipe
Threaded pipe connection, either 1/2", 3/4", or 1",
depending on the model. This pipe should be connected
to the incoming gas supply for the purpose of delivering
gas to the water heater.
14. Gas shutoff switch
An electrical switch designed to cut power from the gas valve to
prevent gas flow to the burner.
15. Gas shutoff valve (400 -- 500 Models Only)
Manual valve used to isolate the gas valve from the gas supply.
16. Gas valve
The gas valve senses the negative pressure created by the
blower, allowing gas to flow only if the gas valve is powered and
combustion air is flowing.
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Installation & Service Manual
17. Heat exchanger access cover
Allows access to the combustion side of the heat exchanger
coils.
18. Heat exchanger inlet temperature sensor
This sensor monitors the inlet water temperature to the heat
exchanger.
19. Heat exchanger outlet temperature sensor (not shown)
This sensor monitors heat exchanger outlet water temperature.
20. Ignition electrode
Provides direct spark for igniting the burner.
21. Line voltage junction box
The junction box contains the connection points for the line
voltage power.
22. Low voltage connection board
The connection board is used to connect external low voltage
devices.
23. Low voltage wiring connections (plugs)
Conduit entryway for the low voltage connection board.
24. Power cord (not shown)
The power cord allows for quick connection to 120V supply.
25. Pump
Circulates water between the tank and the heat exchanger.
26. Pump relay
Switches power to the pump.
27. Relief valve
Protects the heat exchanger from over pressure and
temperature conditions. The relief valve is set at 150 PSI.
28. Stainless steel heat exchanger
Allows water to flow through specially designed coils for
maximum heat transfer, while providing protection against
flue gas corrosion. The coils are encased in a jacket that
contains the combustion process.
29. Tank sensor
Used by the control to monitor the temperature of the tank.
30. Pump access panel
Panel used to gain access to the pump and condensate trap;
also used to gain access to the outlet water sensor.
31. Vent pipe connection
Allows for the connection of the vent pipe system to the water
heater.
32. Venturi
The venturi controls air and gas flow into the burner.
33. Water heater drain valve
Location from which the water heater can be drained.
34. Water inlet
Copper sweat 1-1/2" connection for cold water supply that
returns water from the system to the heat exchanger.
35. Water outlet
Copper sweat 1-1/2" connection that supplies hot water to the
system.
36. Over-temp switch (285 --500 Models Only)
An electrical switch designed to shut down water heater
operation in the event the outer back of the heat exchanger,
directly above the flue connection exceeds 604°F (318°C).
This is a one time switch and could warrant a heat exchanger
replacement. Check the integrity of the rear refractory at the
back of the upper coil if the switch opens.