Plumbing discussions and local services.
Discussion options
Tankless heater won’t always fire at the sink
What observations help distinguish a sink draw that’s below a tankless heater’s activation flow from an ignition, sensor, or gas-supply fault?
Does the heater show an error code when it fails to start? I’d also want to know whether it fires reliably at a shower or another higher-flow tap, and whether the problem is limited to one fixture or happens at several. If it’s happening at multiple fixtures, or the heater reports a fault, would that point toward having a qualified technician diagnose it rather than changing the fixture flow?
Join the conversation
Share your experience or ask a follow-up question.
1 reply
If it fails only at the sink but starts reliably at a higher-flow tap, that points more toward the sink draw being below the heater’s activation threshold. If it also fails at higher-flow taps, affects several fixtures, or shows an error code, I’d favor qualified diagnosis over changing fixture flow; those signs don’t identify the fault, but make a fixture-only explanation less likely.
Find a local plumber.
Loading local plumbers…