I have a 15mm gas pipe to freestanding cooker. I am to get a new hob and oven. The gas consumption(?) for oven is 2500 and for the hob 7500 . Will this gas pipe be okay or does it need to be a 22mm pipe.? I have called baumatic and they will not tell me if this is okay and have told me to speak to a gas safe person! Would appreciate your help. Thank you