Thermal Comfort - Blown Air Heating Systems for Motor Vehicles
Comfortable temperature is an important consideration when designing working or living spaces in motor vehicles.
Blown air heating provides interior temperature control, warmth and ventilation in all seasons.
Heater applications:
Leisure vehicles including camper vans, motorhome, caravans, van conversions, and boats.
Buses, minibuses, and ambulances to provide warmth and improve passenger comfort.
Commercial vehicles including Hgv truck lorry cab heating.
Welfare vans, utility service vans, mobile canteens, mobile shops, library and sales vehicles.
Construction plant cab heating for excavators, bulldozers , and dump trucks.
Off-grid living area heating
How Blown Air Diesel Night Heaters Work
Key components of blown air heaters include:
Heater unit outer housing for attachment to blown air intake , outlet ducting and vents.
Electronic controller
Blower fan assembly
Combustion chamber, burner tube, atomisation screen and glow pin
Flame detection and overheat sensors
Ventilation ducting
Wiring harness
External controller which may include on/off switch , timer, temperature setting, and sensing.
Fuel pump
Fuel lines
Combustion air intake duct
Combustion exhaust tube (24mm or 22mm stainless flexible tubing)
Heater Operation
When the night heater is switched on a ticking noise may be heard as the fuel metering pump operates to transfer fuel from the supply tank
and prime pressurised fuel to the heater.
The pressurised fuel is injected through an atomising screen creating a fuel mist.
A red hot glow pin initially ignites the fuel mist causing combustion and heat within a combustion chamber heat exchanger unit.
A speed controlled blower fan module sucks air into the night heater inlet then blows air across the exterior fins of the heat exchanger causing output of warm
blown air which may be directed through ducting and vents. You may hear the speed of the fan turbine increase gradually during start up to full speed
then gradually decrease as the heater shuts down.
Hot exhaust fumes produced inside the night heater combustion chamber during the combustion process are expelled
safely outside the vehicle via the nightheater exhaust.
Combustion flame, blower fan speed, and blown air temperature are monitored by a control unit.
Temperature Control
Room temperature control setting is selected using a thermostat and controlled by temperature sensors.
Safety features
Onboard night heaters have inbuilt safety features to prevent diesel fuel being pumped to the heater if the flame is absent.
Startup, running , and shutdown is monitored and controlled by an electronic control unit (ecu).
Repeated failure to start may cause the night heater to enter a lockout mode
preventing further operation until reset procedures, sometimes requiring diagnostic equipment, are undertaken.
Safety Recommendation
We recommend fitment of Carbon Monoxide detectors where any nightheater is fitted in a vehicle. The combustion intake and exhaust must be fitted so as to draw air and exit exhaust gases to the fresh air atmosphere outside of any enclosed area. Do not run night heaters inside built up environments without suitable exhaust gas extraction equipment.
Typical faults which may prevent heater operation.
Glow pin failure
Carbon build up may cause the heater to discharge excessive white smoke from the exhaust.
Build up of carbon inside the heater combustion chamber and
glow plug screen may cause ignition or combustion faults. Excessive smoke from the heater exhaust indicates that the heater needs servicing.
Servicing will require fitment of new gaskets when reassembling the heater.
Electronic control units rely upon having a reliable power supply at the correct voltage
and good electrical connections.
Low or excessive battery voltage level may prevent heater operation and cause error codes to be logged.
Wiring and connection faults can also prevent the heater operating.
Some common faults which may prevent night heater working or cause excessive white or black smoke :
Low power supply voltage may cause the night heater to log an undervoltage fault particularly where a night
heater has been wired to operate from an auxilliary battery split charge system in camper van conversions and the split charge system is not operating.
Battery voltage too high may log an overvoltage fault typically due to an overcharging vehicle alternator.
Heater lockout may prevent startup until error rectified and fault codes reset.
Electrical wiring harness looms, connections, and controls.
Fuel supply faults - Blockage, Fuel pump failure
Blower fan motor failure. Blower fan speed is controlled and monitored by the night heater ecu.
Ensure all pipework and ducting is kept clean and free of obstruction.
Night heater exhausts are generally stainless steel but may deteriorate over time due to damage.
Cab Night Heater Repairs Shropshire
We stock certain Eberspacher and Webasto cab night heater components in case of breakdown.
Local vehicle nightheater breakdown callout around Shrewsbury Shropshire & Mid Wales (UK) area .
Vehicle Night Heater Application
Night heaters combine quiet operation to provide warmth with fuel efficient operation
without the need for the vehicle engine to be running.
May also be referred to as:
FBH : Fuel Burning Heater
Parking Heater
Night Heater Electronic Diagnostics
Specialised computer diagnostic equipment, software, and specific interface leads may be required to access 12v or 24v night heater diagnostic features.
for example:
Eberspacher EDITH
Webasto Thermotest
Connection of control unit diagnosis equipment may enable the heater to be run off the vehicle for bench testing.
Heater fault codes
Many night heaters have fault code diagnostic functions allowing in service testing should a breakdown occur.
Manufacturers provide a list of heater specific fault codes listed within workshop manuals.
Specialist night heater diagnostic equipment and software may be required to access.
Problems during start up or operation may cause the heater control module to log error codes and lock out preventing startup.
Fault code memory may need to be reset to allow system start.
Some night heater component faults may require removal of the heater from the vehicle to allow stripdown and rebuild.
Blown Air Heater Output
Night heater kits are available for 12v and 24v vehicles in a range of models and outputs to suit the volume and interior space to be heated.
2 kW blown air heater
A 2kW night heater is the most popular size for cabin heating applications in vans, lorry sleeper cabs, camper vans and motorhomes.
3-5kW blown air heater
3 to 5 kW air heaters are popular for applications including minibuses ambulances and motorhomes.
Certain catering vans use blown air heating to keep mobile ovens warm.
Above 5kW blown air heater
Heaters above 5 kW may be specified for heating of larger vehicle interiors such as Library vans, Buses, Cargo areas etc.
Vehicle Heater makes and models
Manufacturer : Eberspacher
Popular blown air heater models include
D1L D1LC D1LCC
Airtronic D2 D2L M2 S2 D4 D4 D5 D8LC
Hydronic
Manufacturer : Propex
Propex manufactures a range of LPG gas and mains powered heaters for installation in vehicle conversions, motorhomes and caravans
link to Propex website (opens in new tab)
Manufacturer: Truma
Truma produces a range of blown air and water heaters generally aimed at the caravan and motorhome leisure markets.
Manufacturer : Webasto
Popular models include Airtop 2000 , Airtop2000ST, Thermotop
Manufacturer : VVKB
Manufacturer : Planar
Manufacturer : Airo
Oem names are used for reference purposes only
Unbranded Diesel Heaters
It is common knowledge that a wide range of relatively low cost unbranded diesel 'parking heaters' are widely available in the UK from online marketplaces.
These unbranded heaters are often of far east manufacture and of varying quality with sometimes difficult to source repair components should they fail.
Quality control appears to be the major problem with many 'chinese' unbranded diesel heaters causing premature failure.
Budget electronic designs may result in radio frequency interference (RFI) which can consequentially affect other critical components.
Excessive CO gas emission can also be detrimental.
Which is the right specification of heater for my vehicle?
Many factors affect the specification selection of a standalone heater to heat your vehicle;
Use of vehicle
Times when heat is required
Seasonal Use
Volume of air to be heated : Length (L) x Width (W) x Height (H) in metres = Cubic capacity in Metres cubed.
Number of air changes required - number of times doors will be opened per hour
Ambient outside temperature
Body construction material and insulation - insulated - uninsulated - double glazed - single glazed -
Any ducting required and temperature affect of direct hot air on load or personnel.
Power system voltage - volt drop due to cable length and conductor size
Means of control and access to control panel
Fuel supply : Stand-pipe in existing fuel tank. T connectors to fuel lines. Standalone fuel tank. Mounting position of fuel metering pump. Noise insulation of fuel metering pump.
Air intake and exhaust
Purchase budget
Cost of maintenance and service parts
Mounting position of heater to maintain serviceability - is additional protection against water, road dirt and weather conditions required?
If heater is to be mounted in a box consider blown air intake and ventilation output, combustion air intake and exhaust access for servicing and drainage