I have been soldering some complicated piping. I have done quite a lot of 15mm and 22mm Yorkshire fittings around the house and it has gone fine. I am now, connecting 35mm straight connector to 35-28mm reducer to 28mm straight connector with 15mm T to 28mm 90 then another very close. The whole lot crammed together in about 250mm all with end feed fittings. My initial attempt was not a pretty sight. Things got very hot and nasty with burnt flux and the joints wouldn't run.. I changed the gas on my blow torch for map gas. Can anyone give me a clue how to manage this successfully