XLT XD-9006A (GAS Oven Version – C, AVI Hood Version – B) - Manual (Page 13)

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GAS OVEN THEORY OF OPERATION
V1-V2 & V3- The Multi-Valve assembly has three (3) Gas Valves. The Main Valves (V1-V2)
operate in series, and are wired in series via the Rectifier Plug. The Rectifier Plug rectifies 24
VAC from the Burner Control (BC) to 22 VDC. V1-V2 are solenoid valves and are open continu-
ously during burner operation, regardless of either actual or set-point temperature values. V3 is a
modulating valve, and is controlled by a variable electrical signal from the Signal Conditioner
(SC). There are two (2) fuel pressure testing ports; one for incoming pressure, and one for both
high-bias and low-bias pressure. The upper port is used for incoming pressure, while the lower
port is used for high- and low-bias pressure. There are two (2) hex adjusting nuts; an 8mm nut for
adjusting high-bias pressure, and a 5mm nut for adjusting low-bias pressure.
XFMR- The Transformer steps down line voltage to 24 VAC. It supplies power to the Signal
Conditioner (SC), Burner Control (BC), and the Centrifugal Switch (S2). One terminal on the sec-
ondary side is connected to chassis ground by a green wire. The XFMR is ON whenever the Main
Switch (S1) is on, and is independent of the Cool Down Timer (R1). Note: The XFMR is
equipped with an integrated circuit breaker for standalone protection.