Gas boiler

Some boilers actually only require an adjustment but that depends on which boiler you have 10 years ago Baxi boilers were that clever it worked out what gas you were using my Glowworm (saunier duval Spain ) is just turn of a screw most Vaillants are small adjustments, I run mine off propane can be relatively pricey for 4-5 weeks seriously doubt I spend 400€ a year 4 bed detached, cold weather time I have it set at 19 deg c