Thomas & Betts UDAS, UDAP Combustion Air Proving, Limit Control, Pressure Switch Settings

16.Combustion Air Proving

Switch (cont’d)

Pressure Switch Settings

The two Tables on the left below list the approximate water column negative pres- sure readings and switch setpoints for sea level operating conditions for Model UDAP and Model UDAP-CV heaters. The Table on the right lists the approximate water column differential pressure readings and switch setpoints for sea level op- erating conditions for Model UDAS heaters.

DANGER: Safe operation of this unit requires proper venting flow. NEVER bypass combustion air proving switch or attempt to operate the unit without the venter running and the proper flow in the vent system. Hazardous conditions could result. See Hazard Levels, page 2.

Model	Startup	Equilibrium	Setpoint	Setpoint	Label	Switch
	Cold	Hot	OFF	ON
UDAP					Color	P/N
	Negative Pressure Measured in " w.c.
30	1.00	0.78	0.40	0.58	Green	197030
45	0.95	0.75	0.40	0.58	Green	197030
60	1.00	0.78	0.50	0.68	Orange	196388
75	1.00	0.85	0.50	0.68	Orange	196388
100	0.85	0.72	0.50	0.68	Orange	196388
125	0.75	0.60	0.40	0.58	Green	197030
150, 175	0.75	0.65	0.40	0.58	Green	197030
200, 225	2.20	1.50	1.10	1.30	Blue	201158
250, 300	2.30	1.60	1.10	1.30	Blue	201158
350, 400	2.60	1.80	1.40	1.60	Red	201159

Model	Startup	Equilibrium	Setpoint	Setpoint	Label	Switch
UDAS	Cold	Hot	OFF	ON	Color	P/N
	Differential Pressure Measured in " w.c.
30	1.00	0.78	0.65	0.83	Yellow	197028
45	1.05	0.80	0.65	0.83	Yellow	197028
60	1.10	0.85	0.65	0.83	Yellow	197028
75	1.10	0.85	0.65	0.83	Yellow	197028
100	0.85	0.72	0.55	0.73	White	196362
125	0.75	0.60	0.45	0.63	Pink	197032
150, 175	0.75	0.60	0.40	0.58	Green	197030
200, 225	2.20	1.50	1.10	1.30	Blue	201158
250, 300	2.30	1.60	1.10	1.30	Blue	201158
350, 400	2.60	1.80	1.40	1.60	Red	201159

Model UDAP-CV	Startup	Equilibrium	Setpoint	Setpoint	Label	Switch
	Cold	Hot	OFF	ON
with Opt AV6					Color	P/N
	Negative Pressure Measured in " w.c.
30	1.10	0.84	0.65	0.83	Yellow	197028
45	1.10	0.81	0.50	0.68	Orange	196388
60	0.92	0.75	0.60	0.78	Lt Blue	197029
75	0.97	0.78	0.60	0.78	Lt Blue	197029
100	0.88	0.71	0.55	0.73	White	196362

17. Limit Control	All units are equipped with a temperature activated auto reset limit control. The
	control is factory set and is non-adjustable. If the setpoint is reached, the limit
	control will interrupt the electric supply to the gas valve. This safety device pro-
	vides protection in the case of motor failure or lack of airflow due to a restriction at
	the inlet or outlet. (For location, see FIGURE 18, page 31.)

18.Flame Rollout Switch - Sizes 30-125only

CAUTION: The auto reset limit control will continue to shut down the heater until the cause is corrected. Never bypass the limit control; hazardous conditions could result. See Hazard Intensity Levels, page 2.

Sizes 30-125 are equipped with a temperature activated manually reset flame rollout switch. The flame rollout switch is located at the top of the burner assembly. It is factory set and is non-adjustable. If the setpoint is reached, the flame rollout acts to interrupt the electric supply to the gas valve. If the flame rollout switch activates, identify and correct the cause before resetting the switch. Refer to the Mainte- nance Section for information on probable causes and instructions on resetting the flame rollout switch. (For location, see FIGURE 18, page 31.)

DANGER: If the manual reset flame rollout switch activates, identify and correct the cause before resetting the switch. Never bypass the flame rollout switch; hazardous conditions could result. See Hazard Intensity Levels, page 2.

Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 18