I'm considering switching to a tankless gas-fired water heater when my conventional gas-fired water heater starts to die. The tankless models I've been looking at require about 155K Btu/hr, compared to 75K Btu/hr for the water heater I have now, and there is another load of 95K Btu/hr in the same location for my hydronic boiler. So I am looking at a peak demand of about 250K Btu/hr in this location. My main concern is that I have a long run of pipe from my meter to this location...about 90 ft. The piping at the meter starts out as 1-1/4" but, after about 60', it reduces to 1", which is what I would be hooking up the tankless water heater and the boiler to. My meter is sized to theoretically supply all of the gas demands in the house, but I want to make sure that the 1" supply line is big enough over this distance to deliver at least 250K Btu/hr to the tankless heater and the boiler. My power company told me they supply gas at 6.0" WC, but they weren't able to answer my question about the line sizing. Does anyone have familiarity with this who could either answer this question or refer me to a calculator or table that would be useful? Thanks.