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OWT – Oil-Fired Water Boiler Series 3

  • Efficiencies 86% – 87% AFUE
  • Enhanced control
    • Temperature limit control
    • LWCO Function
    • Thermal pre-purge function
  • Rear flue outlet
    • Top flue available with optional kit
  • Easy service
    • Swing-away burner door
    • Top access cleanout cover
    • Plug-in wiring harness
  • High efficiency oil burner
    • Solenoid valve
    • PSC motor
    • Solid state ignitor
  • Cast iron sections with built-in air separator
  • Insulated heavy-gauge steel jacket
Boiler Model
Burner Input
AHRI Certified Ratings
Minimum Chimney Size
(x 15′ High)
GPH
MBH
Heating Capacity MBH 
Net Rating (water) MBH
Seasonal Efficiency AFUE%
Rectangle
Round
OWT-3
0.70
98
86
75
86.4
8″ x 8″
6″
OWT-3*
0.95
133
115
100
86.0
8″ x 8″
6″
OWT-4
1.00
140
122
106
86.2
8″ x 8″
6″
OWT-4*
1.20
168
146
127
86.0
8″ x 8″
6″
OWT-5
1.20
168
147
128
86.1
8″ x 8″
7″
OWT-5*
1.45
203
176
153
86.0
8″ x 8″
7″
OWT-6
1.40
196
171
149
86.1
8″ x 8″
7″
OWT-6*
1.75
245
213
185
86.0
8″ x 8″
7″
*The specific higher input rates are compliant when installed with the required High Input Damper kit, Part #381-800-515WT
(sold separately)
Thermoflo has determined the boilers listed below are compliant with ENERGY STAR® Program 3.0 when installed with (optional) OVD kit.
OWT-3-T-S3-D
0.70
86
75
75
87.0
8″ x 8″
6″
OWT-4-T-S3-D
1.00
123
107
107
87.0
8″ x 8″
6″
OWT-5-T-S3-D
1.20
148
129
129
87.0
8″ x 8″
7″
OWT-6-T-S3-D
1.40
173
150
150
87.0
8″ x 8″
7″
Boiler Model
Burner Input
AHRI Certified Ratings
Minimum Chimney Size
(x 15′ High)
GPH
MBH
Heating Capacity MBH 
Net Rating (water) MBH
Seasonal Efficiency AFUE%
Rectangle
Round
OWT-3
0.70
98
86
75
86.4
8″ x 8″
6″
OWT-3*
0.95
133
115
100
86.0
8″ x 8″
6″
OWT-4
1.00
140
122
106
86.2
8″ x 8″
6″
OWT-4*
1.20
168
146
127
86.0
8″ x 8″
6″
OWT-5
1.20
168
147
128
86.1
8″ x 8″
7″
OWT-5*
1.45
203
176
153
86.0
8″ x 8″
7″
OWT-6
1.40
196
171
149
86.1
8″ x 8″
7″
OWT-6*
1.75
245
213
185
86.0
8″ x 8″
7″
*The specific higher input rates are compliant when installed with the required High Input Damper kit, Part #381-800-515WT
(sold separately)
Thermoflo has determined the boilers listed below are compliant with ENERGY STAR® Program 3.0 when installed with (optional) OVD kit.
OWT-3-T-S3-D
0.70
86
75
75
87.0
8″ x 8″
6″
OWT-4-T-S3-D
1.00
123
107
107
87.0
8″ x 8″
6″
OWT-5-T-S3-D
1.20
148
129
129
87.0
8″ x 8″
7″
OWT-6-T-S3-D
1.40
173
150
150
87.0
8″ x 8″
7″

Brochures & Sales Collateral

OWT – Oil-Fired Water Boiler Series 3 Brochure

OWT – Oil-Fired Water Boiler Series 3 Manufacturer Certificate

Manuals

OWT – Oil-Fired Water Boiler Series 3 Boiler Manual

OWT – Oil-Fired Water Boiler Series 3 RW Beckett Burner Manual

OWT – Oil-Fired Water Boiler Series 3 Riello Burner Manual

Warranty Information

OWT – Oil-Fired Water Boiler Series 3 Commercial Warranty (Manufactured on or after 5/2/16)

OWT – Oil-Fired Water Boiler Series 3 Residential Warranty (Manufactured on or after 5/2/16)