Roberts Gorden 75 Manuel D’Utilisation

Page de 60
SECTION 6: D
UCT
 H
EATER
 I
NSTALLATION
9 of 47
SECTION 6: DUCT HEATER INSTALLATION 
6.1 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 9, 
Figure 4 and may not be reversed. The air flow must 
be adjusted such that it is within the acceptable 
range shown on 
Page 9, Section 6.1.3. The 
minimum inlet duct lengths shown 
on Page 9, 
Section 6.1.1 should be observed. Pressure drop 
through the heat exchanger at various air flows is 
given 
on Page 9, Section 6.1.2.
Figure 4: Air Flow Direction
6.1.1 Minimum Inlet Duct Length 
6.1.2 Temperature Rise and Pressure Drop Ranges
6.1.3 Air Flow and Temperature Rise Ranges
AIR FLOW
OUTLET DUCT
INLET DUCT
Model
Duct Length
Duct Size (W X H)
UHD[X][S] 75 
32" (81 cm)
16 3/4" x 15 7/8" (43 cm x 40 cm)
UHD[X][S] 100 &125
37" (94 cm)
21 3/4" x 15 7/8" (55 cm x 40 cm)
UHD[X][S] 75
UHD[X][S] 100
UHD[X][S] 125
Airflow
(CFM)
Temperature 
Rise (°F)
Pressure Drop 
(in wc)
Airflow
(CFM) 
Temperature 
Rise (°F)
Pressure Drop 
(in wc)
Airflow
(CFM) 
Temperature 
Rise (°F)
Pressure Drop 
(in wc)
850
68
0.06
950
78
0.05
1,020
92
0.06
1,200
48
0.10
1,500
50
0.18
1,650
57
0.14
1,625
36
0.16
2,500
31
0.28
2,340
41
0.27
1,965
30
0.22
3,000
26
0.39
3,480
28
0.56
2,450
24
0.31
3,300
24
0.46
4,240
23
0.80
2,650
22
0.36
3,660
22
0.55
4,750
20
0.98
Model
Rate 
Air Flow 
Temperature Rise
(Btu/h)
Minimum (CFM)
Maximum (CFM)
Minimum (°F)
Maximum (°F)
UHD[X][S] 75 
75,000
850
2,650
22
68
UHD[X][S] 100 
100,000
950
3,660
22
78
UHD[X][S] 125 
125,000
1,020
4,750
20
92