This hydronic marine heater from Heater Craft is model 300-H with three ducted air outlets, a 12 V fan, and a rated heat output of 40,000 BTU/h. It utilizes hot cooling water from the boat's engine or a suitable separate heating circuit and distributes the transferred heat as warm air in the cabin.
The heat output of 40,000 BTU/h applies at a water flow of 11 l/min., a water temperature of 76 °C, and an ambient temperature of 15 °C. The power supply drives the three-speed dual centrifugal fan, while the heat itself comes from the cooling water. The power consumption is 4.4 A at low speed, 5.8 A at medium speed, and 8.4 A at high speed.
The heater unit measures 406 mm in width, 237 mm in depth, and 163 mm in height. The housing is made of powder-coated 5052 aluminum. The heat exchanger has 5/8" hose barbs, and the cooling water can flow through the heat exchanger in either direction. The unit should be mounted horizontally whenever possible and must not be placed in the bilge or in a compartment that could draw air from the bilge.
The kit comes with the heater unit, mounting brackets, 4-position panel switch, electrical cable, screws, 5.4 m of flexible Ø 75 mm air ducting, and three adjustable vents. The three fan speeds make it possible to regulate air distribution according to heat requirements. Cooling water hoses, engine-specific fittings, hose clamps, and any circulation pump are selected based on the specific installation.
When mounted more than approximately 457 mm above the engine or with more than approximately 4.6 m of cooling water hose between the engine and the heater, an additional circulation pump may be necessary. In open cooling systems, sufficient circulation may require about 1,200-1,500 engine RPM. During engine operation, the cabin must be sufficiently ventilated due to the risk of carbon monoxide; the installation instructions refer to ABYC A-7, T-22(1), and TH-23.
When winterizing a raw water or open cooling system, the water must be drained or blown out of the heat exchanger and hoses. The blow-out pressure must not exceed 35 psi. For the Ø 75 mm air system, Y-piece 50.263.06, adjustable vent 50.263.08, and air ducting 50.263.11 are available. The H415 circulation pump and wiring harness 2-7061 can be used when the installation requires assisted cooling water circulation.
Key featuresHydronic, engine coolant-based cabin heating
40,000 BTU/h at 11 l/min. and 76 °C coolant
12 V dual centrifugal fan with 3 speeds
Power consumption: 4.4/5.8/8.4 A
3 ducted and adjustable air outlets
5.4 m flexible Ø 75 mm air ducting included
5/8" coolant connections
Heater unit dimensions: 406 × 237 × 163 mm
Complete with panel switch, brackets, cable, and mounting screws
