Chromalox SDRA-RG specifications Wiring cont’d, Accessories

WIRING (cont’d.)

			Temperature Rise vs Duct Length
	100				30 kW
				1500
˚F				RPM
	75
Rise
								1800
Temperature	50							RPM
						2200
	25					RPM
	0
		25	50		75	100	125		150	175
	0

Duct Length in Feet

Temperature Rise vs Duct Length 48 kW

	160		1500
	140
˚F			RPM
	120
Rise						1800
	100
Temperature						RPM
	80
					2200
	60
					RPM
	40
	20
	0	25	50	75	100	125	150	175
	0

Duct Length in Feet

Temperature Rise vs Duct Length

60 kW

	200
	180		1500
	160
˚F			RPM
Rise	140					1800
	120
Temperature						RPM
	100
						2200
	80
						RPM
	60
	40
	20
	0	25	50	75	100	125	150	175
	0

Duct Length in Feet

SDRA heaters can be easily field if modified to vary the fan speed. There may be some circumstances where the use of short lengths of duct may not create sufficient pressure drop to achieve the desired tem- perature rise. This may also be the case of using the unit without a duct. This insufficient static pressure drop may result in high air flow, with the maximum temperature rise below the desired level, (even after the fan speed has been reduced to the minimum rpm). An accessory AD- 16, adjustable damper, is available and can be attached to the heater to produce a static load, ranging from .1” to .19” H2O which will act to reduce the amount of air flow.

The “Friction Loss” Graph 4 provides the actual test data on the friction loss for the AD-16 damper attachment. The losses are stated as the equivalent length in feet of 20” duct.

Friction Loss AD-16 Damper

	90
FT	80		Damper Full Closed
	70
Length
	60
	50
Duct
	40	Damper Full Open
Equivalent
	30
	20
	10
	0	1600	1800	2000	2200	2400
	1400
			Fan RPM

The SDRA Dragon includes 2 thermostats. The thermostat on the air inlet end of the unit is for the minimum air temperature desired. The thermostat on the discharge end of the heater is for the maximum air temperature desired. The two thermostats are wired in series with the heating element contactor coil. The temperature range of both ther- mostats is 60 - 180˚F.

ACCESSORIES

Front of

Heater

Rear of

Heater

Duct

Adapter

1/4-20 Wing nut	Adjustable
Provided with	Damper
AD-16
	Adjustable Damper and Duct Adaptor

3