Re: A lot of snobs in here today.
That fact that you see correctly naming a "heating engineer's" occupation as a plumber, fitter or technician as "putting someone down" probably says more about you.
I wouldn't call a train a car, or a plane a boat, so why call a technician an engineer? They are very different.
I'm a reasonably well qualified electronics and comms engineer, I've designed a fair few bits of kit, and I am capable of installing it, but I infinitely prefer our install technicians to do the installing of it. They have the necessary field experience, qualifications to drive the machinery etc.
Likewise they much prefer that I'm the one doing the designing, as although they could definitely knock up a design, I'm more versed in the regs, compliance, electrical design, emc that would mean we can legally sell and install the kit.
No snobbery at all, we all have our respective roles to play, and appropriate skill sets.