You have a whirly bird / roof mushroom but it doesn't seem to 'twirl' any more.
The whirly bird might have been 'tied' upon the installation of the Ventis, some of the installers tied them up and some didn't.
If you feel that you want your whirly bird untied it's just a cut of a cable tie.
If you feel that you can't do that as it may require a ladder in your roof cavity, we can come out and assist you with it. (fees apply)
Respond to your case email and we will contact you and arrange a time to come out
Revision 1.0