The underfloor mat is a ProWarm generating 200w per square metre (the area is about 12sqm) - it worked perfectly for about nine months then it went cold all of a sudden....I've checked the resistance and gives nil point/dead/gone/zilch - obviously I'm dealing with an open circuit here...
The mat is still under warranty but the boys at ProWarm are making it difficult and it appears to me I'll have to find a compromise with them...
Still, it would be nice to be able to check these sort of faults independently - there are some cable locators in the market which are quite affordable (e.g. the Mastek - a Fluke 2042 clone - for £129) - how reliable/precise are these instruments? How do these compare to the thermal imaging method? Are 2 transmitters required?