Very interesting topic. I was glad to come across it but unfortunately, I didn't manage to find here any results, what was there reason why RCD was tripping? I actually planning to install a heating floor in the bathroom myself, and I was wondering:
What type of flooring will suit best for heating flooring?
30mA RCD would be enough for the whole bathroom or it should be for heating floor only?
I'm sorry nobody has responded to your post! Here are my thoughts:
Re the discussion in this thread, I believe the issue was that a hole was made, accidentally into the UFH cable, and that damaged it. The UFH heating wire appears to be the type with a metal sheath around the heating element, and the damage to the outer sheath and insulation, combined with moisture or ionic contamination, has resulted in a resistance between the element and the earth sheath low enough to trip a RCD.
I imagine you are considering using a UFH heating mat kit?
When you ask what flooring will suit best, I think you are asking about the finish - tiles, engineered wood flooring, vinyl, etc. All these can be used. Obviously if you put carpet or rugs on any of them you reduce the heat input to the room.
You might be governed a bit by what floor structure you have to work with. If it's a solid floor I'd go for porcelain or ceramic tiles as the finish. Floor lay up something like: insulation board, heat mat, self levelling screed, adhesive, tiles.
It it's a suspended wooden floor you might be better off not using tiles, or at least not using large format ones. I've used heat mat with an engineered bamboo wood flooring over in a bathroom. It handles the moisture well, but the warmth on your feet is not as marked as with porcelain tiles.
Vinyl tiles (LVT etc.) or sheet vinyl, would be fine if you use those that are suitable for ufh.
If the UFH is the sole method of heating the room, you will need to do the heat loss calculations to determine what sort of power is needed. If your UFH is supplementing existing heating, and it's just to make the floor cosy, then the sums are less important. There are plenty of calculators out there on the internet.
30mA RCD should be fine for "the whole bathroom", but what else would you be running - towel rail?
Do lots of research before buying anything. Use the right materials for the floor construction. You will no doubt need an underfloor temperature sensor/ thermostat/ programmer, and it all needs wiring up to the regs, regarding zones, appropriate workmanship etc.
if you don't get the floor construction right, after a few years people might be walking on a floor that crunches, is cracked, or tiles wobble, or grout is coming away between the tiles. The techniques and workmanship are important! Good luck!
