Tankless Water Heater

3 Responses to “Can I Install Tank Less Water Heater With Smaller Gas Pipe, Not 3/4″ Pipe Recommended By Manufacturer?”

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   In order for a tankless water heater to heat enough water, fast enough for typical usage, it has to dump a huge supply of energy into the heat exchangers.
   On a gas model, it needs a larger supply of gas than a tank style water heater. If you tried to use the smaller pipe, the heater will not be able to heat the water as much and so the output temperature will be lower. It depends on various factors to know whether that would be enough for your purposes.
   We recommend tankless water heaters, but one drawback we note is that people often have to replumb their gas supply line. Also, if the unit will be indoors, it will likely require an upgrade to the vent system too. Burning all that natural gas creates a lot more carbon monoxide than the old vent can safely vent outdoors.
   In my own home, not only did we have to replumb the gas supply line, we needed a larger gas meter and a larger gas line to the house. The utility paid for the upgraded gas line to the house, but I paid for the meter upgrade (a state imposed fee) and the local gas line. however, this was for a really big unit that allows two simultaneous showers and one appliance usage. That is a lot of hot water. We could have used a smaller unit and avoided some of the upgrade costs. We could have also used a smaller heater, one for each bath, that could have used smaller gas lines.
   Bottom line, replumbing the gas supply line isn’t a big deal in cost terms. To get the full benefit from the tankless water heater it is worthwhile expense.