Lochinvar SNA400-125, SNA500-125, SNR200-100, SNA285-125, SNR150-100 Shield How it works, Blower

TM

Installation & Service Manual

The Shield - How it works...

1.Access cover - front

Provides access to the gas train and heat exchanger.

2.Air intake adapter

Allows for the connection of the PVC air intake pipe to the water heater.

18.Heat exchanger inlet temperature sensor

This sensor monitors the inlet water temperature to the heat exchanger.

19.Heat exchanger outlet temperature sensor

This sensor monitors heat exchanger outlet water temperature.

3.Air pressure switch

The air pressure switch detects blocked inlet conditions.

4.Air shroud (500-125 Model Only_Not Shown)

The air shroud directs air and gas flow into the blower.

5.Blower

The blower pulls in air and gas through the venturi (item 5). 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 pumps to meet the demand.

9.Electronic display

The electronic display consists of 7 buttons and a dual line 32- character liquid crystal display.

10.Flame inspection window

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 (150-100 - - 285-125 Models Only)

An electrical switch designed to cut power from the gas valve to prevent gas flow to the burner.

15.Gas shutoff valve (400-125 -- 500-125 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.

17.Heat exchanger access cover

Allows access to the combustion side of the heat exchanger coils.

20.High limit sensor

Device that monitors the outlet water temperature. If the temperature exceeds its setting, it will break the control circuit, shutting the water heater down.

21.Ignition electrode

Provides direct spark for igniting the burner.

22.Line voltage junction box

The junction box contains the connection points for the line voltage power.

23.Low voltage connection board

The connection board is used to connect external low voltage devices.

24.Low voltage wiring connections (knockouts)

Conduit entryway for the low voltage connection board.

25.Power cord

Six foot cord allows for quick connection to 120V supply.

26.Pump

Circulates water between the tank and the heat exchanger.

27.Pump relay

Switches power to the pump.

28.Relief valve discharge pipe

Protects the heat exchanger from over pressure and temperature conditions. The relief valve is set at 150 PSI.

29.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.

30.Tank sensor

Used by the control to monitor the temperature of the tank.

31.Top panel

Removable panel to gain access to the internal components.

32.Vent pipe connection

Allows for the connection of the PVC/CPVC vent pipe system to the water heater.

33.Venturi

The venturi controls air and gas flow into the burner.

34.Water heater drain valve

Location from which the water heater can be drained.

35.Water inlet

Copper sweat connection for cold water supply that returns water from the system to the heat exchanger, either 1-1/2" or 2", depending on the model.

36.Water outlet

Male NPT water connection that supplies hot water to the system, either 1-1/2" or 2", depending on the model.

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