Usually it's installers taking the piss on quotes because it's not a standard thing and they don't want to deal with it or think they can get away with it. The

Usually it's installers taking the piss on quotes because it's not a standard thing and they don't want to deal with it or think they can get away with it. The US has a similar issue in some places for heat pumps (but not AC, despite being the same damn thing).