Cold chamber tests for Grade 3 accreditation of a motorhome involves exposing the vehicle to -15 °C for an extended period of time.We were involved in a Panel Van Test which threw up some interesting insights about winterisation and the impact of freezing conditions on the fresh and waste water system.
During a Grade 3 test the vehicle is soaked overnight to achieve a temperature of -15 °C throughout. Using infrared photography we established that the really cold spots on a typical panel van conversion were:
1. Inside bed boxes.
2. The ‘D’ posts or rear corners of the vehicle.
3. The middle of the rear doors.
4. The internal surfaces of the wheel arches, which were particularly cold.
5. Cab foot wells.
6. Cab windscreen and side windows.
Another interesting point was the position of the dump valve for the water heater. If this is located away from the heater, which generates its own ‘warm area’, then the contents of the water heater can potentially be ‘dumped’ early.
Under Grade 3 test conditions the test vehicle is given a period of up to four hours to reach 20°C from a start point of -15°C. An important, but overlooked fact before the test was the effect airflow had on the ability of the heating system to warm the vehicle throughout.
To improve the points above the following corrective actions were taken:
i. The blown air ducting was re-routed through the bed boxes. Small holes were made in the ducting to bleed warm air in to the bed box.
ii. The insulation of the ‘D’ posts was substantially improved.
iii. A removable studded sealing/insulation strip was added to the centre of the rear door, running from top to bottom.
iv. The wheel arches were insulated with WheelarchBlankets. These are one of seven modules of The TankBlanket System, the water tank heater.
v. The flow heated blown air was improved in to the cab foot well.
vi. Silver windscreen guards were installed to improve the windscreen and side window insulation.
vii. The location of the dump valve was moved to a position as close to the water heater to overcome the possibility of its contents being purged early.
To improve the efficiency of the blown air heating system and its effectiveness to achieve a homogenous temperature throughout the vehicle the pathway of the blown air ducting pipework was re-designed.
Drafts can be a problem and in our experience they originate from two sources, the free flowing ventilation and build quality. Caution is required here and any draft from free flowing ventilation either in the roof or floor is best left alone. Those drafts created from build quality are a different matter and we recommend contacting your Dealer or Manufacturer to remedy these issues.
For winterisation tips from around the web follow:
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| The water tank heater |
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