Why Is the Screed Heating System on the Bomag BF 600 P-2 Failing to Reach Temperature?
When the Bomag BF 600 P-2 screed heating system fails to reach the required operating temperature, the most common culprits are electrical supply issues and control unit malfunctions. The screed heating system relies on a combination of resistance heaters and a robust control module to maintain consistent heat across the full screed width. A drop in voltage from the onboard generator, typically rated at 230V, 50Hz, can prevent the heaters from achieving the 120°C to 150°C range needed for asphalt compaction. Begin troubleshooting by checking the generator output with a multimeter at the main breaker panel, ensuring no nuisance trips have occurred. Additionally, inspect the heating element harness connections at the junction box behind the operator’s platform, as loose or corroded terminals can create high resistance and limit current flow.
What Causes Uneven Heating Across the Bomag BF 600 P‑2 Screed Plates?
Uneven heating across the screed plates on the Bomag BF 600 P-2 is typically due to a damaged heating element or a failing control sensor. Each screed section—main screed and extensions—contains independent resistance elements, and a single open circuit in one element will leave a cold spot. To isolate the issue, measure resistance across each heating element while the system is powered off; a healthy element should read between 0.5 and 1.5 ohms. An open circuit yields infinite resistance. Furthermore, the temperature sensor (usually a Type K thermocouple) mounted near the screed plate can drift or break. If the control panel reads “Err” or shows wide temperature fluctuations, replace the sensor. Check the Bomag BF 600 P-2 Daily Maintenance Checklist for Peak Performance for recommended sensor inspection intervals.
How to Diagnose a Bomag BF 600 P-2 Screed Heater That Randomly Shuts Off?
A randomly shutting off heater points to an overheating protection trip or a faulty temperature controller. The Bomag BF 600 P-2 includes a thermal cut‑off switch that opens if the screed plate exceeds 180°C. First, allow the system to cool completely and reset the cut‑off switch manually per the operator’s manual. Then, monitor the temperature rise with an infrared gun; if the controller does not cycle the heaters at the set point, the solid‑state relay (SSR) may be welded shut or shorted. Replace any SSR that shows shorted output when the controller is in the off state. Use the table below to assess the severity of common heater faults.
| Fault Symptom | Likely Cause | Severity Level | Estimated Repair Cost (£) |
|---|---|---|---|
| Screed never heats | Open main breaker or failed SSR | High | £80 – £250 |
| Heater shuts off after 5 minutes | Thermal cut‑out tripping | Medium | £20 – £60 (reset) |
| Uneven heat distribution | One open heating element | Medium | £120 – £350 per element |
| Control panel shows error code | Faulty thermocouple or controller | Low–Medium | £50 – £180 |
What Does the “HT” Error Code Mean on the Bomag BF 600 P-2 Display?
The “HT” error code on the Bomag BF 600 P-2 control display indicates a heating system fault—typically an open circuit in one of the heater banks or a thermocouple failure. The controller continuously monitors current draw from each bank; if the current drops below 5A for more than 10 seconds, the code triggers. Begin by visually inspecting the heater cable connectors at the screed frame. Look for burnt or melted insulation. If connectors appear intact, use a clamp meter to measure amperage on each phase while the system operates. A healthy bank draws between 12A and 16A depending on screed width (base machine 2.5m standard width). Should one bank show zero amps, replace that element group. For detailed hydraulic and sensor integration steps, refer to the Bomag BF 600 P-2 Hydraulic System Maintenance: Essential Tips.
How to Test the Bomag BF 600 P-2 Screed Heater Control Board?
Testing the control board on the Bomag BF 600 P-2 requires careful voltage checks at the terminal strips. Start by disconnecting the main battery and generator power for safety. Then, remove the control panel cover and locate the terminal block labelled “HT OUT”. With the system re‑energised and the heating switch set to ON, measure between each output terminal and ground. You should see 230V AC across every active channel. If one channel reads 0V, the board’s relay or triac has failed. Replace the board as a sealed unit—do not attempt component‑level repair due to risk of electrical fire. Verify also that the control board is receiving 12V DC from the machine’s electrical system; a blown fuse in the distribution box can mimic a board failure. Update your system software if available from Bomag via the diagnostic port to rule out firmware glitches.
What Owners Say About Bomag BF 600 P-2 Heating System Reliability
In online forums and dealer feedback, owners consistently highlight two themes: the system’s fast warm‑up time (under 15 minutes from cold to 130°C) but occasional connector failures after 1,000–2,000 operating hours. Some operators report that the thermal cut‑out can false‑trip in hot ambient conditions above 35°C, requiring a manual reset once the screed cools. Many owners recommend replacing the original plug‑in connectors with IP67‑rated ones to prevent moisture ingress. One owner noted that following the Bomag BF 600 P-2 vs Vögele Super 1800: In-Depth Comparison helped them understand heating efficiency differences. Overall, with regular preventative checks, the system is rated as good for daily paver use.
Frequently Asked Questions
What is the typical warm‑up time for the Bomag BF 600 P‑2 screed heater?
From a cold start at 20°C ambient, the screed heater reaches 130°C in approximately 12 to 15 minutes. This rapid warm‑up is enabled by the 9 kW total heating power across the 2.5 m base screed.
Can I replace a single heating element on the Bomag BF 600 P‑2?
Yes, individual heating elements are serviceable. Each element is bolted to the screed plate and costs around £120 to £180. However, if more than one element fails, consider replacing the entire heater bank for balanced performance.
What fuses protect the screed heating circuit?
Two 15A slow‑blow fuses are installed in the main distribution box near the generator. They protect the primary control power. Additionally, each heater channel has a 20A circuit breaker on the control board.
How do I reset the thermal cut‑out on the Bomag BF 600 P‑2?
Allow the screed to cool below 50°C. Then, locate the reset button on the cut‑out switch, typically mounted on the left side of the screed frame near the hydraulic block. Press firmly until it clicks.
Does the heating system work with all screed extension widths?
Yes, the Bomag BF 600 P‑2 supports hydraulically variable screed extensions. The heater automatically adjusts power to cover the full width up to 5 m. Extension heaters have independent control but share the main breaker.
Where can I find the wiring diagram for the heating system?
The complete wiring diagram is in the Bomag BF 600 P‑2 service manual, section 5.3. You can also request it from your local Bomag dealer with serial number ready.
