This AUTOTERM Flow diesel liquid heater is a hydronic Flow 5D heater for 24 V DC with a heating output of 5 kW. It heats coolant in a closed fluid circuit and can be used for heating cabins and other interior spaces in boats and vehicles, as well as for engine preheating.
The heater measures 220 × 90 × 136 mm and weighs 2.4 kg. The normal electrical power consumption is 42 W, while the power consumption during start-up is 120 W. Fuel consumption is stated at 0.7 l/h. The optimal fluid volume in the circuit is 10–12 litres, and the fluid flow is 1,200 l/h at 0 bar or 800 l/h at 0.18 bar. The coolant connections have an outer diameter of 18 mm.
For boats, the heater is recommended for boat lengths of 10–13 m in a Mediterranean climate and 8–11 m in a Nordic climate. The Flow 5D can also be used for engine preheating at ambient temperatures down to −45 °C and at operating altitudes up to 1,000 metres above sea level. The diesel fuel must meet EN 590, and the heater is certified according to UN ECE R10 and R122.
The installation kit includes a fuel pump with bracket and rubber mounting, electric fluid pump, wiring harness for pump and control panel, air intake hose with filter, 1 m exhaust pipe, silencer with mounting kit, L-shaped exhaust adapter, heat protection, 5.5 m nylon fuel line with protective cover, coolant hose coupling, 2 m coolant hose, and heat insulation.
The digital control panel, item no. 50.251.01, is sold separately and is necessary for operation. The installation also requires a separate 16 mm hot water circulation hose, such as item no. 17.740.16, as well as local fluid-to-air heat exchangers as needed. Fan coils with item nos. 50.267.01, 50.267.02, 50.266.01, and 50.266.02 are designed to receive heated fluid from the heater. Exhaust through-hull fittings 50.255.01, 50.255.02, and 50.255.03 can be used as optional installation accessories.
The heater is mounted horizontally or rotated 90° with the air pump facing upwards. It is fastened to the bracket with at least three M5 × 12 bolts at 10 Nm, while the bracket is fastened with four M6 bolts at 11.8 Nm. The installation site must be ventilated and protected from water spray, dust, and moisture. The air intake and exhaust must be separated by at least 20 cm, and flexible air intake and exhaust pipes may each be up to 2 m long. On sailboats, the exhaust through-hull fitting must be placed at the stern and not on the hull side.
The exhaust pipe can reach up to 500 °C during operation and must be insulated in heat-sensitive areas. The recommended total fuel line length is at most 5 m, distributed with a maximum of 1 m from the tank to the pump and 4 m from the pump to the heater. Electrical connections, fuel and coolant hoses, exhaust, and air intake should be checked at least once a year. The heater should also be activated for 20 minutes at least once a month outside the heating season.
Key featuresHydronic diesel heater for 24 V DC
5 kW heating output
42 W normal electrical power consumption
120 W electrical power consumption during start-up
Fuel consumption: 0.7 l/h
Heater dimensions: 220 × 90 × 136 mm
Coolant connections: Ø18 mm
Optimal fluid volume in the circuit: 10–12 litres
Complete installation kit with pumps, hoses, exhaust parts, and wiring harness
Certified according to UN ECE R10 and R122
