Welcome to the forum. Although you can post in any forum, the USA forum is here in case of local regs or laws
intergas
or a logic if funds are limited
Reply to the thread, titled "Got to spec a combi boiler" which is posted in Boiler Advice Forum on Plumbers Forums.
We recommend City Plumbing Supplies, BES, and Plumbing Superstore for all plumbing supplies.