Dual Fuel Supplemental Manual
Ratings
Crest
AHRI Rating
Model Number
Note: Change “N” to
“L” for L.P. gas models.
Input
MBH
(Notes 4 - 8)
Min Max
Gross
Output
MBH
(Note 1)
Net
AHRI
Ratings
Water,
MBH
(Note 2)
FB(N,L,D)2500
125
2500
2300
2000
FB(N,L,D)3000
150
3000
2760
2400
FB(N,L,D)3500
200*
3500
3220
2800
FB(N,L,D)4000
335
4000
3720
4043
FB(N,L,D)5000
500
5000
4650
3235
Maximum allowed working pressure is located on the rating plate.
NOTICE
Notes:
1. The ratings are based on standard test procedures
prescribed by the United States Department of Energy.
2. Net AHRI ratings are based on net installed radiation of
sufficient quantity for the requirements of the building
and nothing need be added for normal piping and pickup.
Ratings are based on a piping and pickup allowance of
1.15.
3. Crest boilers require special gas venting. Use only
the vent materials and methods specified in the Crest
Installation and Operation Manual.
4. Standard Crest boilers are equipped to operate from sea
level to 4,500 feet
only
with no adjustments.
5. High altitude Crest Models 2.5, 3.0 and 3.5 boilers are
equipped to operate from 3,000 to 12,000 feet and high
altitude Crest Models 4.0 and 5.0 boilers are equipped to
operate from 3,000 to 5,500 feet. High altitude models
are manufactured with diff erent control parameters for
high altitude operation, but the sequence of operation
given in this manual remains the same as the standard
boilers. A high altitude label (as shown in FIG A.) is also
affi
xed to the unit.
6. Standard Crest boilers will de-rate by 2.2% for each 1,000
feet above sea level up to 4,500 feet when combustion
calibration is performed and CO
2
’s are adjusted to the
recommended levels.
UNIT EQUIPPED FOR
HIGH ALTITUDE
3,000 FT. TO 12,000 FT.
Figure A High Altitude Label Location
*For LP models the minimum input is 420 MBH.
7. High altitude Crest Models 2.5, 3.0 and 3.5 will de-rate by
1.4% for each 1,000 feet above sea level up to 5,500 feet and
1.8% for each 1,000 feet above 5,500 feet.
8. High altitude Crest Models 4.0 and 5.0 will not de-rate up to
5,500 feet.
9. For Crest Models 4.0 and 5.0, installations above 5,500 feet
contact the factory.
10. Ratings have been confi rmed by the Hydronics Section of
AHRI.
5
Other Specifications
Appliance
Water
Content
Gallons
Pipe
Size
Outlet
Pipe
Size
Inlet
Gas Inlet
Size
Air
Size
Vent
Size
(Note 3)
Weight
w/Water
(lbs.)
161
4"
4"
2"
8"
9"
3650
181
4"
4"
2"
10"
10"
4125
215
4"
4"
2"
10"
10"
4750
291
4"
4"
2 1/2"
12"
12"
6500
380
4"
4"
2 1/2"
14"
14"
8000
