Does a Tankless Water Heater Need a Bigger Gas Line?

Published: July 20, 2026 — CANRO Heating & Cooling — Greater Vancouver, BC

Gas Line Requirements

Tankless water heaters have higher BTU input (150,000-199,000 BTU) than tank heaters (36,000-50,000 BTU). This often requires a larger gas line — typically 3/4-inch instead of 1/2-inch. The gas fitter calculates the required pipe size based on distance from the meter.

Upgrade Cost

If the existing gas line is undersized for a tankless unit, upgrading costs $300-800 depending on distance and accessibility. This is in addition to the tankless installation cost. Some homes with short gas runs and existing 3/4-inch pipe may not need an upgrade.

Planning Checklist

Before purchasing a tankless water heater, have a gas fitter: measure the existing gas line size, calculate total BTU load of all appliances, determine if an upgrade is needed, and verify the gas meter capacity is sufficient.

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Safety Reminder

If you smell gas, suspect carbon monoxide or believe there is an immediate danger, leave the property and contact emergency services or the appropriate gas emergency authority. Do not remain inside — exit the building immediately and call for help from outside.