Fitting cooker hood

Hi. In the process of doing my kitchen and was planning on moving the hob to the left of the window and installing an extractor fan directly above as just 'opening the window' isn't always ideal!

It seems to me that the water pipes running horizontally would be in the way of any extractor fan chimney (there is 1200mm space between worktop and pipe). Clearly not ideal but is there anyway round this? Can the chimney be...

Fitting cooker hood