My house currently has a gas furnace, water heater, and clothes dryer. I would like to add a gas kitchen range. The drawing below shows the proposed piping layout. Segments AB, BH, HF, and HG are existing 3/4" black pipe. Right now, before adding the range, Segment BD is 1/2" CSST. I am considering installing a tee fitting at point C, replacing Segment BC with 3/4" CSST, and running 1/2" CSST to the new range. Segment CD would remain 1/2" CSST.
The distance from the meter, point A, to the farthest appliance, point D, is 41 feet. The total demand from all appliances is 227 CF/HR. From reading some sizing tables I gather that the pipe for Segment AB ought to be at least 1" diameter. I don't want to replace it right now, however, because the entire plumbing system is going to be redone next summer as part of a major remodeling; replacing that section of pipe would be a lot of work that would be nullified in a few months. I would prefer to wait to install the new range as part of the remodeling, too, but our existing electric range is dying right now and I'd rather not pay to have it repaired.
My question: what would be the potential consequences of leaving the undersized pipe at Segment AB? Let's say that the furnace and water heater are both running, there's a load of clothes in the dryer, the oven is at 450 degrees, and four burners are lit. There won't be enough capacity in gas line. How will the various appliances respond? Is there a potential safety hazard? Is the situation manageable if we just pay attention to how much demand we're placing on the system at any given time, and cut back as necessary?