No hot water but tankless has power in Greater Vancouver

When a tankless water heater shows its display lit and seems powered up, but the taps still run cold, the problem is rarely a power failure. Tankless units only fire when they sense adequate flow and a call for hot water, so a powered unit that will not heat usually points to flow, ignition, or a fault code. Here is how Greater Vancouver homeowners can narrow it down.

What a powered-but-cold tankless is telling you

A gas tankless heater needs three things at once to heat: enough water flow through the unit to trip the flow sensor, a clean ignition of the burner, and an unobstructed path for hot water out to the fixture. Power to the control board only handles the electronics; it does not start the burner on its own.

Common culprits include a low or trickling flow that never reaches the unit's minimum activation rate, a clogged inlet filter screen, scale buildup on the heat exchanger from our mineral-laden water, or a lockout fault code shown on the display. In colder snaps across the Lower Mainland, a frozen or restricted inlet line can also stop flow entirely.

• Flow below the unit's minimum activation rate (a faint trickle will not fire it)
• A clogged inlet water filter screen restricting flow into the unit
• Scale or mineral buildup on the heat exchanger reducing heat transfer
• An error or fault code displayed indicating an ignition or sensor lockout
• A gas supply issue preventing the burner from firing despite electrical power

Safe checks and when to bring in a pro

Note any error code on the display and write it down. Open a hot tap fully and confirm you have strong flow, since low flow alone can keep the unit from firing. Check that other gas appliances in the home are working, which helps confirm the gas supply. Confirm the unit's power switch and breaker are on, and reset a tripped breaker once.

Cleaning the inlet filter screen, descaling the heat exchanger, and clearing ignition or gas-related fault codes are tasks for a licensed technician. Do not attempt burner, gas valve, or heat-exchanger work yourself. If you ever smell gas, leave the home and call your gas utility's emergency line first. A heat-pump water heater is an alternative worth discussing, and qualifying upgrades may be eligible for FortisBC and CleanBC rebates.

• Record any error code shown on the display before resetting
• Open a hot tap fully to confirm strong flow into the unit
• Verify the breaker is on and reset a tripped breaker one time
• Leave descaling, filter service, and ignition faults to a licensed technician

Frequently Asked Questions

Why won't my tankless heat even though the display is on?

Power only runs the electronics. The unit also needs sufficient water flow to trip the flow sensor and a successful burner ignition. Low flow, a clogged inlet screen, scale buildup, or a fault code can all leave a powered tankless running cold.

Could low water flow stop my tankless from firing?

Yes. Every tankless has a minimum activation flow rate, and a weak trickle from the tap may never reach it. Open the hot tap fully and see if the unit fires; if it does, a partially closed valve or a clogged inlet screen may be limiting flow.

What does a fault code on my tankless mean?

Fault codes flag specific issues such as ignition failure, flame loss, or sensor problems. Note the exact code, since it helps a licensed technician diagnose the unit quickly rather than guessing. Avoid repeatedly resetting a unit that keeps locking out.

Does hard water affect tankless heaters in Greater Vancouver?

Mineral content can leave scale on the heat exchanger over time, reducing performance and triggering faults. Periodic descaling by a technician keeps a tankless heating reliably. HeatLand can service the unit and clear persistent fault codes safely.

HeatLand Heating & Cooling is a licensed and insured, TSBC-certified HVAC company serving homeowners across Greater Vancouver. Our technicians diagnose the real fault, explain your options in plain language, and complete the work safely and to code.

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