SECTION 3: C
LEARANCES TO
C
OMBUSTIBLES
NOTE:
1. All dimensions are from the surfaces of all tubes, couplings, tees, elbows and crosses.
2. Clearances B, C and D can be reduced by 50% after 7500 mm of tubing downstream
from the burner.
3. All measurements are in millimeters.
4. Add 60 mm clearance to uncovered U-tube.
FIGURE 15: U-TUBE, OPPOSITE 45° TILT
A
B
D
C
M
od
el
ATH1
5U
T
ATH2
0U
T
ATH2
5U
T
ATH3
0U
T
ATH3
5U
T
ATH4
0U
T
ATH4
5U
T
ATH5
0U
T
A
200
200
200
250
250
275
300
300
B
1370
1530
1530
1630
1780
1830
1880
1930
C
1500
1650
1650
1860
1960
2040
2110
2160
D
560
560
560
560
560
560
560
560
FIGURE 16: U-TUBE, PROTECTIVE GRILLE
A
B
D
C
M
od
el
ATH1
5U
T
ATH2
0U
T
ATH2
5U
T
ATH3
0U
T
ATH3
5U
T
ATH4
0U
T
ATH4
5U
T
ATH5
0U
T
A
150
150
150
150
150
150
200
200
B
890
970
970
1020
1170
1220
1270
1380
C
1580
1730
1730
1910
1980
2050
2110
2210
D
760
940
940
1000
1090
1150
1200
1300
FIGURE 17: U-TUBE, VENTING
M
od
el
ATH1
5U
T
ATH2
0U
T
ATH2
5U
T
ATH3
0U
T
ATH3
5U
T
ATH4
0U
T
ATH4
5U
T
ATH5
0U
T
E
1000
1000
1000
1000
1000
1000
1000
1000
F
500
500
500
500
500
500
500
500
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