Install Instructions

5
Series 3
Boiler Model
Input (MBH)
(1)
DOE Heating Capacity (MBH)
Net AHRI Rating, Water
(MBH)
(2)
AFUE (%)
303B 70 59 51 84.0
304B 105 88 77 84.0
305B 140 117 102 84.0
306B 175 146 127 84.0
307B 210 176 153 84.0
308B 245 205 178 84.0
309B 280 234 203 84.0
Ratings
SPECIFICATIONS
Boiler
Model
Depth Width Height
Supply NPT
(inch)
Return NPT
(inch)
Vent
(inch)
Gas NPT
(inch)
Relief Valve
NPT (inch)
Drain
NPT (inch)
303B 33 12¾ 41 1¼ 1¼ 4 ½ ¾ ¾
304B 33 15½ 41 1¼ 1¼ 5 ½ ¾ ¾
305B 33 18½ 41 1¼ 1¼ 6 ½ ¾ ¾
306B 33 21½ 41 1¼ 1¼ 6 ½ ¾ ¾
307B 33 24¾ 41 1¼ 1¼ 7 ¾ ¾ ¾
308B 33 27¾ 41 1¼ 1¼ 7 ¾ ¾ ¾
309B 33 30¾ 41 1¼ 1¼ 8 ¾ ¾ ¾
Dimensions and Connections
Electrical Requirements: 120VAC, 60 Hz, 1-ph, 15A
Maximum Allowable Working Pressure - 50 psi. Boiler shipped from factory with a 30 psi relief valve.
Boiler Model
Allowable Supply
Water Temperature
(°F)
Minimum Return
Water Temperature
(°F)
Minimum Flow
(GPM)
Waterside Pressure Drop
at 20°F DT
(Ft. of Head)
303B 130-220 110 None <1
304B 130-220 110 None <1
305B 130-220 110 None <1
306B 130-220 110 None <1
307B 130-220 110 None <1
308B 130-220 110 None <1
309B 130-220 110 None <1
Water Temperatures and Flows
(1)
Input ratings can be used for elevations up to 2000 ft (600 m). Refer to Appendix F for elevations 2000
ft (600 m) or higher.
(2)
Net AHRI Water Ratings shown are based on a piping and pickup allowance of 1.15. Consult
manufacturer before selecting boiler for installations having unusual piping and pickup requirements,
such as intermittent system operation, extensive piping systems, etc.