hi, im having a new ariston 28kw fitted in kitchen.the meter is 37m away from the boiler including bends ,which i have allowed .5 meter for each bend.it already has agas line of 22mm,do i need to up grade it to 28mm, i have a gas hob on same line,1 corgi man says you need 28mm other says you can get away with 22mm, help !!!!