Some boiler problems can wait for a scheduled appointment. Others can’t. Knowing the difference is important — both for your comfort and your safety.

The most serious warning sign is a gas or burning smell coming from the unit. If you detect this, shut off the boiler immediately and call for service. Carbon monoxide is an invisible, odorless danger, but a sulfur-like smell often indicates a gas issue that needs urgent attention. Another critical sign is a complete loss of heat — especially if temperatures outside are dropping fast. No heat in winter is not just uncomfortable, it’s a safety risk for vulnerable family members.

Watch for water pooling around the base of the boiler. A small drip might seem minor, but active leaks can escalate quickly and damage nearby components or your flooring. A pressure gauge reading that’s consistently too high or too low is also a red flag — most systems operate between 1 and 2 bar, and readings outside that range indicate a problem that could worsen without service.

If your boiler is short cycling — meaning it keeps turning on and off every few minutes without completing a full heating cycle — there’s likely a fault in the controls or a blocked flue. Extreme short cycling can damage components over time and drives up your energy costs.

Finally, if you notice the pilot light is yellow or orange instead of blue, that’s a sign of incomplete combustion. A yellow flame can indicate carbon monoxide is being produced — this is a potential emergency.

If any of these situations apply to your home, click here for a full breakdown of warning signs and what to do about each one. Acting early is always better than waiting for a breakdown in the middle of winter.