Of course there are a few rather large problems with the alternative, copper tubing. Most of these revolve around the fact that it’s best soldered, which in turn requires a modicum of skill and risks burning down your home. Reducing your home to smouldering rubble is known within the plumbing trade as “a bad thing”... and so the heat mat was invented.
In the bad old days I suspect that heat mats were made of asbestos and lasted a life time – partly because they killed you early. These days they may be safer but they have the life expectancy of a Mayfly with a chesty cough, mainly because they can’t cope with direct heat.
This is a real same because more often than not the time you really need a heat mat is when you have no choice but to aim your blowtorch directly at a flammable surface.
However there is an alternative to the heat mat, which is a spray on gel called “La-Co Cool Gel” which I’m fairly certain I failed to mention in the book - It’s only writing this up now that I’ve realised it’s not called LL Cool Gel. Which is a shame as that is what I always ask for.
Cool Gel is known as a heat barrier spray and from what I can make out it’s basically water made firm by holding it in gel form.. and it’s superb! I wouldn’t spray into on carpets and the like – although it would probably work - but, aside from that it can be used everywhere else you might want to use a heat mat.
It’s also very handy if you have to heat up a pipe that is very close to a valve. The valves themselves often contain rubber washers which melt or deform when heated. To prevent this just spray the pipe with the cool gel between the valve and where you’re heating. The heat now travels as far at the gel where it is miraculously stopped in its tracks, preserving the valve whilst you solder your joint.
Alas, it’s not cheap but it is well worth the investment as it’s still considerably cheaper than a new home.