Truma roof vent pipe

[Mick and Ruth]

Hi, I have a Truma warm air system and when away in winter the wind coming down the vent from the roof vent to behind fire rattles it like mad. I have noticed as the picture below shows I can unscrew the middle pipe which gives the vent grill clearance above side upstand and shorten it allowing plenty of clearance for roof water and would give the grill vent protection from wind but may burn the upstand. Has anyone removed this pipe or could shed light if it’s worth doing. Thanks

 

[Brains]

On a house, the top of the chimney needs to be above the roof line, otherwise you don't get a venturi effect.
A motorhome trauma unit works on the same principal

 

[Mick and Ruth]

On a house, the top of the chimney needs to be above the roof line, otherwise you don't get a venturi effect.
A motorhome trauma unit works on the same principal

Thank you most helpful