Diesel heater safety: read this before you start

A diesel air heater burns fuel in a sealed chamber and sends the exhaust outside through a pipe. When it is installed and working properly, the air you breathe never mixes with the combustion gases. Most of the danger comes from the two things troubleshooting involves: opening the system up, and running a heater that is not burning cleanly.

Carbon monoxide (CO)

• Exhaust gas contains carbon monoxide. You cannot see or smell CO itself, and it can kill people in their sleep.
• Fit a carbon monoxide alarm in every space the heater warms, and test it. Do this before the first night, not after a scare.
• The exhaust pipe must end outside the living or sleeping space, pointing away from doors, windows and vents, and every joint must be gas-tight.
• The combustion air intake must also draw from outside, never from the cabin.
• If you smell exhaust or see smoke inside, switch the heater off, open doors and windows, and get everyone out into fresh air. Find the leak before the heater runs again.
• Headache, dizziness, nausea or unusual sleepiness while the heater runs are warning signs. Get into fresh air and seek medical help.

Before you touch anything

• Switch the heater off with its controller and let it finish its cool-down cycle. Do not cut the power while the fan is still running to cool the burner.
• Then disconnect the power supply before you unplug connectors or remove covers.
• Let the heater cool fully. The exhaust pipe, silencer and burner stay hot for a long time after shutdown.
• Work in a ventilated place, with a fire extinguisher within reach.

Fuel

• Use only the fuel your heater's manual allows. Never petrol (gasoline).
• Wipe up spilled fuel and fix any weeping joint before you restart the heater.
• Repeated failed starts can leave unburnt fuel in the burner. When the heater finally lights, that fuel burns off as heavy smoke. Do not keep retrying indefinitely; find out why it is not lighting.
• Keep the fuel tank and fuel line away from the exhaust.

Exhaust and hot parts

• Keep the exhaust clear of anything that can melt or burn, and do not let it rest against the floor, wiring or the fuel line.
• A blocked exhaust or intake makes the heater burn rich and soot up. Check both for kinks, crushed sections and debris.
• Leave the hot-air outlet and the cabin air inlet unobstructed. A heater that cannot move air overheats.

What this site will not tell you to do

• Never bypass, bridge or unplug a temperature sensor, flame sensor or overheat protection to keep a heater running. Those faults are the heater protecting you.
• Never run the heater in a closed space with no ventilation, and never run it with the exhaust ending indoors, even to test it.
• Never use a fuel the manufacturer does not allow.

Changing hidden settings

Some controllers let you change the fuel pump frequency and fan speed. Those two values set the air to fuel mixture. Write down the original values before you change anything, change one value at a time in small steps, and put the originals back if the heater smokes, smells of fuel or soots up. A wrong mixture burns dirty, and a dirty burn means soot and smoke.

When to stop

Cleaning a fuel filter or reseating a connector is routine owner work. Opening the combustion chamber, replacing the control board or repairing wiring is not. If a step is beyond what you are comfortable with, stop and ask a qualified technician.