This might help, from the hs2000 installation instructions:
Note: The combustion air pipe can be terminated underneath the vehicle making sure
the end of it is at least 0.5 metres away from the end of the exhaust and that they are
not pointing directly at each other. Take care to ensure that both pipes have a slight
downward slope to prevent any possibility of water traps. Make sure that neither the
flue or the combustion air inlet pipe are terminated in an under-floor box section.
The flue terminals are not to be positioned within 500 mm of a refuelling point or fuel
tank breather outlet or any ventilator from the fuel system(s). The flue terminals are
not to be located within 300 mm of a ventilator for the living space or an opening part
of a window. Where the flue terminal is positioned vertically below an opening part of
a window, the appliance must be fitted with an automatic shut-off device to prevent
operation when the window is open.
Sent from my Pixel 4 using Tapatalk
Note: The combustion air pipe can be terminated underneath the vehicle making sure
the end of it is at least 0.5 metres away from the end of the exhaust and that they are
not pointing directly at each other. Take care to ensure that both pipes have a slight
downward slope to prevent any possibility of water traps. Make sure that neither the
flue or the combustion air inlet pipe are terminated in an under-floor box section.
The flue terminals are not to be positioned within 500 mm of a refuelling point or fuel
tank breather outlet or any ventilator from the fuel system(s). The flue terminals are
not to be located within 300 mm of a ventilator for the living space or an opening part
of a window. Where the flue terminal is positioned vertically below an opening part of
a window, the appliance must be fitted with an automatic shut-off device to prevent
operation when the window is open.
Sent from my Pixel 4 using Tapatalk