Tankless water heater

Jameshearon

Is there a minimum distance required from tank less unit to gas line connection?

Jamie Hall

eh? The gas line connection on the tankless connects to… the gas line? What am I missing here?

GGross

Most condensing appliances need a minimum volume of gas to fire correctly, some brands have more issue than others, some brands claim there is no issue with short gas lines, some don't mention this at all. Basically it is brand specific and I would check with your specific manufacturer for your specific model. Personally I try to keep at least 10' of correct size gas line between the regulator and the condensing appliance to avoid issues of low volume at ignition leading to flame failure, I haven't really noticed this issue much on tankless water heaters but it comes up fairly regularly with condensing boilers which are somewhat similar, if the unit is already installed a proper gas pressure test will tell you if your line is sized correctly or not.

hot_rod

this Rinnai document dhows you how to size the gas piping

https://media.rinnai.us/salsify_asset/s-f905168b-b0a9-4b7c-a205-bbb8071597bb/TB-111%20Half%20Inch%20Gas%20line.pdf

Intplm.

There are gas pipe "size" requirements to help properly supply the fuel to the unit. The requirements are different according the the size of the unit as well as what type of gas, that being Natural gas or propane.