Raypak 503-2003 manual SECTION C Installation

SECTION C: Installation

pump relay and the blower receives power but does not energize at this time and terminal L1 the ignition module is powered.

3.The 120/24 VAC transformer sends a 24 VAC hot power signal to the 24V Terminal Block.

4.24 VAC is sent from the 24V Terminal Block to pin L1 of the Low Water Cut Off, the 24 VAC terminal of the ignition control module, the green LED on the front of the heater to signify “Power On”, terminal R (pin #24) of the modulating tem- perature control, the NC contacts of the manual high limit, pin P3-1 of the UDB board, pin P1-1 of the UDB board, pin J5-5 of the UGB board, the NC contacts of the alarm relay, the red LED on the front of the heater to signify “Service” if in alarm mode and the NO pump contacts on the tempera- ture controller.

24 VAC is sent from the NC contacts of the man- ual high limit to pin P3-2 of the UDB board and to the common terminal of the Low Water Cut Off (if equipped).

Upon loss of water in the heater, the Low Water Cut Off will send a 24 VAC signal to pin P3-4 of the UDB board to indicate a safety fault.

5.A 24 VAC signal is sent from the NO contacts of the Low Water Cut Off to the common terminal of the Blocked Vent Switch.

During a blocked vent condition a 24 VAC signal is sent from the NO open contacts of the Blocked Vent Switch to Pin P3-5 of the UDB board to indi- cate a safety fault.

6.During normal operation of the heater, the 24 VAC signal will exit the NC contacts of the Blocked Vent Switch and is sent to the common terminal, of the Low Gas Pressure Switch (if equipped).

During a low gas pressure condition, 24 VAC is sent from the NC contacts of the Low Gas Pres- sure Switch to Pin P3-6 of the UDB board to indicate a safety fault.

7.24 VAC is sent from the NO contacts of the Low Gas Pressure Switch to the common terminal of the High Gas Pressure Switch (if equipped).

During a high gas pressure condition, 24 VAC is sent from the NO contacts of the High Gas Pres-

sure Switch to Pin P3-7 of the UDB board to indicate a safety fault.

8.24 VAC is sent from the NC contacts of the High Gas Pressure Switch to energize the alarm relay coil and to the common terminal of the Auto Reset High Limit (if equipped).

If the Auto Hi Limit opens, a 24 VAC is sent to Pin P3-3 of the UDB board to indicate a safety fault.

9.24 VAC is sent from the NC contacts of the Auto Reset Hi Limit to the common terminal of time de- lay relay.

10.24 VAC is sent from the NC contacts of time delay relay to the common terminal of the burner switch located on the front exterior panel of the heater.

11.Power then travels to the enable/disable connec- tion and to the Ht D (heat demand) connection of the modulating temperature control.

Power splits from the enable/disable and goes to the stage contact of the modulating temperature control.

12.When the stage contact closes on the modulating temperature control, 24 VAC is sent to the com- mon terminal of the flow switch and to pin P1-3 (CFH) of the UDB board. 24 VAC is now sent di- rectly to the amber LED on the front of the heater to signify a “Call For Heat”.

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

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

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

16.Upon sufficient flow, the flow switch closes and sends 24 VAC to the common terminal of the air pressure switch, the lockout relay coil and the NO contacts of the lockout relay. A 24 VAC signal is also sent from the common terminal of the air pressure switch to pin F1 of the ignition module.

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.

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