The air temperature in crawl spaces is normally between +2 and +7 °C in winter. Within this temperature range, frost can form on the inside of the foundation beam even at low humidity levels.
This occurs if the temperature of the foundation beam falls below 0°C and the humidity in the crawl space exceeds the blue curve at the current air temperature in the crawl space.
- Green curve: Risk of mould at relative humidity above the curve at the current temperature.
- Red curve: The dehumidifier emits an alarm when the relative humidity is above the curve at the current temperature.
- Blue curve: When humidity exceeds the curve at the current temperature, frost forms on the foundation beam if the temperature of the foundation beam is 0°C or lower.
Example: At an air temperature of 5°C and relative humidity of 70% in the crawl space, while the foundation beam has a temperature of 0°C or lower, frost will form on the foundation beam.
The risk of mould growth However, it is higher, at 87% at a temperature of 5°C, and the dehumidifier will sound an alarm at 82% at a temperature of 5°C. This means that frost can form even at low relative humidity and in a favourable climate in the crawl space.
As long as the dehumidifier does not emit a climate alarm, which is indicated on the control panel by a flashing C, frost formation does not normally pose a problem.
Read the current moisture content and temperature in the crawl space via the control panel and check these values in the diagram. If the value is below the green curve and also below the dehumidifier's red alarm curve, the climate is good despite frost formation on the inside of the cold foundation beam.
