new boiler install

stretch

Ok here is my question. This is a two pipe system, the supply pipe is a 4". The new boiler has 2.5" taps  coming off. Where should I enlarge the piping at: as close to the boiler as possible or when the new pipe meets the old? Have not called manufacturer yet but I know I will. What do you guys think.

nicholas bonham-carter

steam header piping

have a look at the mfg's installation requirements, and instructions;  and follow them as a minimum. otherwise excessive steam velocity will pick up too much water, and you will have wet steam.

generally, you need full diameter from the supply tappings [use them all]  all the way up to the 24 " above waterline minimum, and if you can do a drop header, so much the better. the transition of boiler size to steam main size should be above that height.--nbc