If your dishwasher has a control panel fixed to the door assembly then the chances are there will be a ribbon cable in the hinge area. As you have been working in that area that is where I would look for a broken wire.
I'm not a heating engineer.
Perhaps the filling loop only leaks when hot or boiler is in use. If you can turn off both isolators (if you have them) remove the filling loop and put a bowl underneath to see if water drips into it while in use.
Possibly, but how has blup seen this post after so long. He must have a hell of a memory. Unless he was doing a search for info in DIYNot .com.search. There seem to have been quite a few posts like this recently. Someone suggested it might be a bot.
Insulation won't stop it freezing eventually and not burying it deep enough might cause you problems with other things in the future.
The old saying is do it properly and do it once. Or something like that :giggle:
Going by the tiles I would say the length along each wall. is 800 mm to the outside of the frame. So the one I linked to may be too big for the radius of the screen and doors.
If it's less than 12 months old get the installer back to look at it. Presumably the old one never did that. Sounds like possibly ferrous oxide but you don't have any radiators to corrode.
So you mean both the red and the black go to the outside light. So there should be another cable to the light as well is that correct. Also is it just a normal light fitting or is it a PIR controlled one