Combi questions

If it's not practicable to take the PRD down to ground level it's usually terminated in a short pipe turned back to face the wall (not necessarily normal to the wall but at least so the discharge will hit the wall before it falls to the ground).

Should be instructions in the boiler manual but into a sink waste is usually OK. Just make sure the sink waste pipe is plastic not copper. Also, CORGI advise installers not to connect into cast iron soil stacks, but I think this is more to protect installer's arse against later claims that the condensate ate away the stack and caused it to fail rather than a real likelihood of this happening. (Condensate is about as acidic as cocal cola or tomato juice.)

Thanks John, just wanted to make sure I had read everything right. Last house I had the PRD ended as a short u-turn facing the wall. Condensate is going to go into plastic, so again, no problems. Thanks John

From my reading on the subject, it is a matter of preference to drain the condensate into an internal point (normally sink/ washing machine drain), to avoid freezing problems that can occur when external discharge is used.

Does anyone remember when it used to be COLD in winter?

Yes, that's why I am installing CH !! :-))

John