There is definitely a golden thread that navigates through the successful plumbing contractors in this country. After traveling nationwide I have been able to identify those that the thread passes through. It is those that base there business foundation on the "plumbing sciences". They communicate an incredible confidence in there abilities to install plumbing systems without fault and risk to the end user and community. Because they remain fundamentally diligent and watchful students and scholars committed to excellence.
I had the opportunity to have breakfast last week with a few of these Captains of the Industry. We quickly got to subject of tankless gas water heaters. Most of the discussion focused on apparatus pressure drop ( PSI loss). The concern was the limited publicly available data on tankless gas water heaters concerning apparatus pressure drop as a single unit or in series configuration. Any apparatus in a water distribution system such as meters, valves, backflow devices, tub and shower valves, fittings and piping will have pressure drop (friction loss) factor to consider when designing a system.