My multi meter packed up, I replaced it with one that has a temp probe, well probe as in a wire with a bare soldered end.
It wasn't an expensive meter at all, the accuracy of the temp probe is not something I've tested (thinking just dip it in a boiling kettle should work) but it really matters not if you're just comparing one heat source to another.
The heat imaging app is something I'll look into, I see it's available for Android so I'll get it on my phone and play with it, a quick google shows a site that states it does not "read" heat, presumably that means it does not give temp readings but shows differences in temps which once again is fine, my tablet is in Czech Rebulic getting repaired so can't use that, damn new technology eh not much chance of fixing anything these days with a bungie strap and gaffer tape