Chinese Diesel Heater (CDH) Guide — Installation, Safety, and Best Models
Why Chinese Diesel Heaters Are So Popular
A Webasto or Eberspacher diesel heater costs £800-1,200 installed. A Chinese diesel heater costs £80-200 delivered. Both burn diesel in a sealed combustion chamber and blow hot air over a heat exchanger into the van. The difference is brand, quality control, and support.
For the price difference, Chinese heaters are an attractive option — especially on a budget build. But they come with caveats. This guide covers how to choose one, install it safely, and avoid common problems.
How They Work
A diesel heater has four main components:
- The burner unit — contains the combustion chamber, glow pin, and combustion air fan
- The fuel pump — a metering pump that delivers precise amounts of diesel. Makes the characteristic ticking sound.
- The control unit — manages startup, temperature, and shutdown
- The hot air fan — blows interior air over the heat exchanger
The exhaust vents outside through a dedicated pipe. Combustion air is drawn from outside. The system is sealed — combustion gases never mix with the van interior.
Choosing a CDH
2kW vs 5kW
- 2kW — sufficient for a small van (SWB Transit, Vivaro, Berlingo). Uses 0.1-0.2L diesel/hour on low.
- 5kW — sufficient for a large van (LWB Sprinter, Crafter, Relay). Uses 0.2-0.4L/hour on low.
The 2kW is better for most UK van builds. A 5kW in a small van short-cycles (turns on, heats up quickly, turns off), which wastes fuel and wears the glow pin faster.
Brands
The most reliable Chinese heater brand is generally S联合 (S-Lianhe) — identified by the yellow and black box with S联合 printed on the control unit. Vvkb is another reasonable brand. Avoid unbranded units.
What to Look For
- Digital controller with altitude compensation — essential for Scotland and Wales. Without it, the heater soots up at altitude.
- LCD controller — shows temperature and error codes. Basic rotary dials are less reliable.
- UK warehouse seller — faster delivery and easier returns.
Installation Guide
Location
Mount the burner unit outside the living space — under the van, in a garage compartment, or in a ventilated cupboard. Under-van mounting is most common: the unit bolts underneath, hot air ducts up, only the vent and controller are visible inside.
Fuel Supply
The golden rule: mount the fuel pump at a 15-30 degree angle with the outlet pointing upward. This is the most common mistake. A horizontal or downward-angled pump cannot prime.
Run a dedicated fuel line from the tank. Tap into the tank top, not the bottom — this avoids sediment. Use the supplied 6mm nylon tube, secured with P-clips.
Air Intake and Exhaust
The combustion air intake must draw from outside. Do not draw from inside — it consumes oxygen and creates negative pressure.
Route the exhaust outside, away from ventilation intakes. Exhaust gases reach 300°C and contain carbon monoxide. Use the supplied silencer. Insulate the pipe near flammable materials.
Hot Air Ducting
Use 60mm or 75mm ducting. Keep it short — long ducts reduce airflow. Use insulated ducting in cold spaces (under the van).
Electrical
The heater draws about 10A during startup (glow pin). Use 2.5mm² cable from the leisure battery with a 15A fuse. Keep the battery within 2 metres if possible — voltage drop causes startup failure.
Controller Placement
Mount where it senses the average temperature. Not above the hot air outlet, on an external wall, or in direct sunlight.
Safety
Carbon Monoxide
Any diesel heater can produce CO with incomplete combustion. A proper installation with a sealed exhaust is safe. But mistakes — cracked exhaust, loose joints, drawing combustion air from inside — can be deadly.
Fit a carbon monoxide alarm at head height in the living area. Non-negotiable. A CO alarm costs £15-20.
Fire Risk
The heater body and exhaust get very hot. Maintain 50mm clearance from flammables around the body and 100mm around the exhaust. Use a metal heat shield between the heater and any wood or plastic.
Fumes
Diesel smell inside = a leak. Check the exhaust joint, fuel line connections, and heater body gasket. Do not use until fixed.
Common Problems
Won't start — Check voltage. Low battery is the most common cause. The glow pin needs a solid 12V+.
Starts then stops after 2 minutes — Flame-out. Check fuel supply, air intake, and exhaust (clear of snow or mud?).
Soots up quickly — Usually from running on low too long. Run at full power once a week for 30 minutes to burn off deposits. Also check altitude compensation.
Pump ticks but no fuel — Pump angle (15-30° upward) or air leak in the fuel line.
E-01 or E-03 error — Glow pin circuit fault. Check connections and resistance. Glow pins last 2,000-5,000 hours and cost about £5.
CDH vs Webasto vs Eberspacher
| Feature | CDH (£100-200) | Webasto/Eberspacher (£800-1,200) |
|---|---|---|
| Heat output | 2kW or 5kW | 2kW, 3.5kW, 5kW |
| Reliability | Variable (some fail within 1 year) | High (10+ years typical) |
| Noise | Louder pump ticking | Quieter pump and fan |
| Altitude tuning | Manual on some models | Automatic |
| Spare parts | Readily available online | Dealer-only in some cases |
| Warranty | Typically 1 year | 2-3 years |
The Bottom Line
A Chinese diesel heater is a viable option for a UK van build if you are comfortable with the installation and understand the risks. The key is choosing a known brand (S联合), installing the fuel pump at the correct angle, fitting a CO alarm, and running the heater at full power periodically to prevent sooting.
If you want fit-and-forget reliability and have the budget, go with Webasto or Eberspacher. If you are handy and want to save £700-1,000, a CDH will keep you warm — but expect to troubleshoot it occasionally.
My recommendation: Buy an S联合 2kW heater with LCD controller and altitude compensation. Spend the £50 saved versus a cheaper model on a good CO alarm and install it properly.
