What Counts as a Boiler Emergency? A Quick Guide

Not every boiler problem needs a same-hour callout, but some genuinely do. Knowing the difference means you're not left waiting on something that shouldn't wait — and not paying for an emergency rate on something that could have been a routine booking.

What's a genuine emergency

A boiler fault is an emergency when it creates a safety risk or leaves a household without essential heating or hot water with no reasonable alternative. That includes: any smell of gas, a carbon monoxide alarm sounding, a boiler that's visibly leaking, a total loss of heating and hot water (especially for households with young children, elderly residents, or anyone vulnerable to cold), and any fault the boiler itself is flagging as unsafe to run.

What usually isn't, but still needs sorting

Hot water working fine but no heating (or the reverse) is often a diverter valve, pump, or motorised valve issue rather than a dead boiler — inconvenient, but rarely dangerous. A fault code locking the boiler out, or pressure that's dropped but stable, are both worth booking in promptly rather than leaving indefinitely, but don't usually need a same-hour response.

The classic cold-weather fault: frozen condensate pipe

Modern condensing boilers produce a small amount of slightly acidic waste water that drains away through a plastic condensate pipe, often routed outside. In freezing weather, that pipe can freeze and block, and the boiler will safely lock itself out rather than run incorrectly. If the pipe is accessible, thawing it with a warm (not boiling) cloth or a hot water bottle often resolves it without a callout — but if you're unsure, or it's not accessible, it's a simple fix for an engineer.

If you smell gas

Turn off the gas supply at the meter if it's safe to do so, open doors and windows, don't use any electrical switches or naked flames, leave the property, and call the National Gas Emergency Service on 0800 111 999 immediately. This applies regardless of who your usual gas engineer is — it's a national emergency line, not something to wait on booking a normal appointment for.

If it is an emergency

See our Emergency Boiler Repair page or call 07472 251465 — we cover all London postcodes with no call-out fee between 8am and 8pm.