Measure at the correct height
To determine the diameter of your downpipe, measure approximately at the height at which the rainwater filter is to be installed. In this way, you avoid determining an incorrect value for slightly conical downpipes.
Using the caliper gauge to determine the diameter
The diameter can be determined directly with the vernacular caliper gauge. When measuring, rotate it slightly around the downpipe to determine a suitable average value.
Measuring the circumference with a tape measure
Use the tape measure to determine the circumference of the downpipe. The diameter can also be derived from this by dividing the value by 3.14.
Relationship between circumference and diameter:
As an example, these circumferences result in approximately the following downpipe diameters:
- 232 - 239 mm circumference are approx. 75 mm downpipe diameter
- 251 - 258 mm circumference are approx. 81 mm downpipe diameter
- 273 - 280 mm circumference are approx. 88 mm downpipe diameter
- 314 - 320 mm circumference are approx. 101 mm downpipe diameter
- 339 - 346 mm circumference are approx. 109 mm downpipe diameter