extremely difficult to say without seeing the propert you would be best advised to get a local installer in to give you a quote they will discuss any issues with you make sure that they are GAS SAFE registered.
all as above just wondering what you mean by airbricks, as you mention good old fashioned bricks and mortar. are you refering to breaze blocks which are pretty much the modern brick just may be a confusion on description.
firstly it depends upon the appliance in question. most modern appliances are ROOM SEALED and do not rquire ventilation for combustion purposes however may require purpose made ventilation for cooling. on the other hand many new appliances do not require ventilation for cooling within a compartment ...
I HAVE BEEN IN THE GAS INDUSTRY FOR 32 YEARS AND KNOW A LITTLE. 20MM IS TOO CLOSE . AS WITH ANY GAS OR INDEED ANY APPLIANCE AT ALL THEY SHOULD BE INSTALLED TO MANUFACTURERS INSTRUCTIONS AS THEY ARE THE PEOPLE THAT DESIGNED THE APPLIANCE BOTH FOR USEABILITY AND SAFETY. ASK YOUR INSTALLER FIRSTLY FOR ...
