Does the pressure relief/discharge pipework have to go outside?. I am thinking of putting a system boiler upstairs and dont want a pipe down the middle of the outside wall.

most installers round here are doing that, two elbows on the outside wall

╔| |═══ <-- From boiler
╚| |<--wall


btk

[quote author=billythekid  link=1125229363/0#3 date=1125264168]scruff, are you allowed to send it to waste via a tundish?? can't remember myself, I dont touch heating stuff usually so forget it all quickly! lol


btk [/quote]

Not a good idea to stick boiling water down a plastic waste, but have seen it done.

But lets just say you shouldn't   and I wouldn't advise it.

Yes I was considering running the pipe inside, down a long and difficult route, just to keep it out of sight, was not sure of any max length restrictions, but was looking for some alternatives.
I was hoping I could go dirrect into the 4" soil pipe, the vent part that goes up to the roof, as this is close by. Although the water is boiling, it will not normally be in use and then only for a short period, I would have thought this safer than venting anywhere outside.