Roberts Gorden UHD[X][S][R] 125 Duct Heater Installation 5.1 General, Minimum Inlet Duct Length

SECTION 5: DUCT HEATER INSTALLATION

SECTION 5: DUCT HEATER INSTALLATION 5.1 General

To connect the inlet and outlet ducts to the heater, Duct-Mate or similar flanges may be slid over the duct connector flanges supplied on the unit and secured with screws. The connection to the duct then can be made using the Duct-Mate clips. The ducts must have removable access panels upstream and downstream of the heater. These panels must be of appropriate size and placement so that smoke or reflected light could be observed to indicate the presence of leaks in the heat exchanger. Covers for these openings should be sealed to prevent leakage.

Any transition into the inlet of the heater should be smooth, with a taper of no more than 15 degrees. If elbows are required, they should be of either broad radius or fitted with properly designed air turns.

Consult a professional to ensure air turns are properly designed.

The heater must be installed on the positive pressure side of the circulating air blower. Air flow through the heater must be as shown on Page 7, Figure 2 and may not be reversed. The air flow must be adjusted such that it is within the acceptable

5.1.1 Minimum Inlet Duct Length

range shown on Page 7, Section 5.1.3. The minimum inlet duct lengths shown on Page 7, Section 5.1.1 should be observed. Pressure drop through the heat exchanger at various air flows is given on Page 7, Section 5.1.2.

Figure 2: Air Flow Direction

OUTLET DUCT

AIR FLOW

INLET DUCT

Model	Duct Length	Duct Size (W X H)
UHD[X][S][R] 75	32" (81 cm)	16 1/8" x 15 7/8" (41 cm x 40 cm)
UHD[X][S][R] 100 &125	37" (94 cm)	21 3/4" x 15 7/8" (55 cm x 40 cm)

5.1.2 Temperature Rise and Pressure Drop Ranges

	UHD[X][S][R] 75			UHD[X][S][R] 100				UHD[X][S][R] 125
Airflow	Temperature	Pressure Drop	Airflow		Temperature	Pressure Drop	Airflow	Temperature	Pressure Drop
(CFM)	Rise (°F)	(in wc)	(CFM)		Rise (°F)	(in wc)	(CFM)	Rise (°F)	(in wc)
850	68.0	0.06	950		78	0.05	1,020	92	0.06
1,200	48.3	0.10	1,500		50	0.18	1,650	57	0.14
1,625	36.4	0.16	2,500		31	0.28	2,340	41	0.27
1,965	30.3	0.22	3,000		26	0.39	3,480	28	0.56
2,450	24.4	0.31	3,300		24	0.46	4,240	23	0.80
2,650	22.0	0.36	3,660		22	0.55	4,750	20	0.98

5.1.3 Air Flow and Temperature Rise Ranges

Model	Rate	Air Flow		Temperature Rise
	(Btu/h)	Minimum (CFM)	Maximum (CFM)	Minimum (°F)	Maximum (°F)
UHD[X][S][R] 75	75,000	850	2,650	22	68
UHD[X][S][R] 100	100,000	950	3,660	22	78
UHD[X][S][R] 125	125,000	1,020	4,750	20	92

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