Water – How to connect a portable propane bottle to a tankless hot water heater

Where is the tankless water heater to be located? If it is in a space that is heated, then freezing will not likely be a concern as there will be plenty of heat gain through the equipment enclosure.

If freezing is still a concern, look for a tankless unit that has a electric element for freeze protection. This will use a lot of energy if the unit is located in a cold garage, so best practice would be to locate the unit inside a heated space.

For most threaded connections, first hand-tighten and then using a wrench, tighten in quarter-turn increments. If it leaks, give it another quarter turn. You shouldn't need excessive force with a wrench to tighten it.

For anything other than compression fitting, use Teflon tape and/or pipe dope on the threads.

Make sure that it is not cross threaded. If you need excessive force from the beginning, there is a good chance you have cross-threaded it (assuming the correct thread type).