Mr. Tact wrote on Apr 23, 2013, 14:07: So what do you refer to it as subx?
A boiler - burning (natural) gas - heating both the water in the central heating system and the hot tap (faucet) water.
There isn't much residential use of the VAC part of HVAC here so that term isn't used. To service a boiler you have to be certified to work with natural gas, plumbers often are, but the generic term for someone who does this is a "gas man" (which probably ends up sounding humorous :)
Oh, and a heater is a standalone thing that is usually powered by electricity.
This would all be a damn sight easier if you guys just spoke English ;)