Overview
A coolant parking heater warms the engine antifreeze rather than blowing hot air directly. It pre-heats the engine block on cold mornings and provides cabin warmth through the vehicle's factory heater core. This guide covers installation of a 12V or 24V coolant heater in a heavy diesel truck. Renqiu Chiyu Auto Parts Co., Ltd. supplies both air and coolant heaters for commercial fleets.
How It Works
The coolant heater burns diesel in a small combustion chamber, transferring heat to a separate water loop. An integrated circulator pump pushes warm coolant through the engine block, oil cooler and cabin heater core. On a cold morning, the driver starts a pre-warmed engine that fires instantly and produces warm air from the vents within a minute.
Mounting Position
Mount the unit below the coolant level, ideally on the frame rail or in the engine bay. The circulator pump must be below the system's highest point to avoid air locks. Leave 20 cm clearance around the unit for service. Do not mount near the exhaust manifold.
Coolant Loop Connections
T into the existing heater return hose. Install a shut-off valve on each side so the loop can be isolated for service. Use rated heater hose with stainless clamps. After filling, bleed air from the system by running the circulator with the cap off.
Fuel and Electrical
Tee into the main fuel tank return line. Wire directly to the battery with a 30A fuse. The control panel mounts on the dashboard. On 24V trucks, verify the heater voltage before connecting.
Testing
Fill the loop with 50/50 antifreeze. Start the heater. The circulator pump should run, and coolant temperature should rise to 70°C within 10 minutes. Check all hose joints for leaks. The cabin should blow warm air within 15 minutes.
Maintenance
Check coolant concentration annually. Replace the fuel filter every season. Inspect the circulator pump for leaks. Clean the combustion chamber every 2,000 operating hours.
Benefits
Pre-heating the engine reduces cold-start wear by up to 50 percent, cuts idling fuel use by 80 percent, and improves driver comfort. Fleets in Scandinavia, Canada and northern China use coolant heaters as standard winter equipment.
References
[1] European Union Regulation (EU) 2015/1188 on monitoring and reporting of CO2 emissions.
[2] European Union Regulation (EU) 2015/1186 on type-approval requirements for motor vehicles and engines regarding emissions.
[3] SAE International J1455: Recommended Environmental Practices for Electronic Equipment Design in Heavy-Duty Vehicle Applications.
[4] FCC Part 15 Subpart C: Intentional Radiators.
[5] ISO 6722: Road vehicles – 60 V and 600 V single-core cables.
[6] U.S. EPA Idling Reduction Fact Sheet for Heavy-Duty Diesel Vehicles.
[7] ISO 8820-2: Road vehicles – Time-lapse current-limiting fuses.
