I’m going to be installing a Bosch 250sx tankless water heater of 175,000 BTU/hr capacity. Gas supply must be no smaller than 3/4″ and must be easy to remove to service the in-line filter screen.
Flex tubing would be easy, but all the 3/4″ ones I have found have 3/4″ connections but less than 1/2″ ID.
Thanks in advance,
BruceT
Replies
Buy a larger diameter flex tube and put a bushing or bell reducer at each end.
Have you been looking at standard appliance hook-up flex, or at the new yellow jacketed flex piping?
Standard? Heck, my Whirlpool gas cooktop came with a mediocre flex pipe that looks pencil-thin. And this cooktop sucks at heating water (+30-minutes to boil a gallon or two of water).
There are a couple of types of flex gas tubing. The yellow jacketed 'GasFlex' is for running permanently installed gas lines, and is designed to be stubbed out at the face of the wall. From there you connect with a flexible appliance connector, which has the threaded connectors on both ends. I assume you are talking about the latter, and most of the ones you can buy at retailers are 1/2+/- ID because that's all you need for a typical water heater or cooktop.
You should get a plumber to connect your tankless. They will have the appropriate appliance flex connectors and will be able to test for low pressure leaks after it's installed.
Also... that 3/4" requirement is based on a certain maximum run length. Longer runs require larger diameter piping to deliver the same BTUs.
Once you get the gas line in, make sure the plumber checks the gas supply pressure under full load. Unless the meter and lines can maintain pressure, you won't get the rated BTU output from the heater. When we installed a tankless, the regulator in our 20 year old gas meter couldn't deal with the load, and the pressure dropped below 7" WC. The gas company replaced it with a newer model, and all is fine now.