Raypak 503-2003 manual Model, SECTION C Installation

SECTION C: Installation

(CFH) of the UDB board. In addition, the amber “Call-for-Heat” LED on the front of the heater will illuminate.

14.The pump contact on the modulating temperature control closes sending 24 VAC to the pump switch located on the front exterior panel of the heater.

15.When the pump switch is closed, 24 VAC is sent to the coil of the pump relay.

16.The pump relay energizes and closes the contacts, starting the heater pump.

17.Upon sufficient flow, the flow switch closes and sends 24 VAC to the common terminal of the air pressure switch, TH terminal of the ignition mod- ule, coil of the ignition lockout relay and the NO contacts of the ignition lockout relay.

If the flow switch does not close, a 24 VAC signal is sent to pin P4-9 of the UDB board to indicate an insufficient flow condition.

When the 24 VAC signal is sent to P4-9 the same signal then de-energizes the coil of time delay re- lay to remove a heat demand from the modulating temperature control and restart the ignition se- quence after the 5 second time delay.

Upon ignition lockout, the module energizes the ignition lockout relay and sends a 24 VAC signal to pin P4-12 (ignition lockout) of the UDB board.

18.When 24 VAC is received at TH on the ignition module, the contacts between pins F1 and F2 close and send 120 VAC to pin 1 of the blower relay.

19.The coil of the blower relay energizes closing the NO contacts sending 120 VAC to energize the combustion air blower motor.

The combustion air blower will operate at 50% of capacity for approximately ninety (90) seconds be- fore the modulating signal from the modulating temperature control will control the fan speed in relationship to the system water temperature.

20.Once sufficient air pressure is achieved in the heater and the air pressure switch closes the NO contacts, 24 VAC is sent to the heater interlock connection on the ignition module.

If air pressure is insufficient or lost during heater operation a 24 VAC signal is sent from the NC

contacts of the air pressure switch to pin P4-10 of the UDB board to indicate insufficient air pressure.

When the 24 VAC signal is sent to P4-10 the same signal then de-energizes the coil of the time delay relay to remove a heat demand from the modulat- ing temperature control and restart the ignition sequence after the 5 second time delay.

21.After receiving 24 VAC at the heater interlock, power then travels to the P Switch terminal of the ignition module.

The ignition module employs a 15 second pre- purge before the next sequence.

22.After 15 seconds of combustion chamber pre- purge, pin S1 sends 120 VAC to the Hot Surface Igniter.

23.The Hot Surface Igniter will be energized for ap- proximately 30 seconds and must exceed 3.1 amp draw during heat up.

24.Once the ignition module determines the proper operation of the Hot Surface Igniter, a 24 VAC signal is output from the Valve pin on the module to energize the gas valve.

25.The gas valve is energized and the blue “Burner On” LED on the front of the heater energizes.

26.The remote sensor is now trying to rectify the flame. If the flame is not rectified within 4 seconds, the ignition module will shut down the gas valve and lock out.

27.When burner flame is rectified, the gas valve will remain at 50% fire for the remainder of the ninety (90) second delay after the CFH was initiated and then modulate in relationship to the output signal to the combustion air blower from the modulating temperature control.

28.When the CFH is satisfied, the heater will return to a standby condition awaiting the next CFH.

Model 1753 – 2003

1.The black (hot) wire lead, located at the right- middle front inside the control compartment, goes directly to the main power switch.

2.When the main power switch is placed in the “ON” position, the 120 VAC terminal block in the control compartment, the N.O. contacts of the

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