Boiler Not Heating? What to Check Before You Call for Repair

Most residential boilers want to sit around 12-15 PSI when cold. If the gauge reads low, the system has lost water somewhere — a weeping valve, a bled radiator that was never topped up, or a slow leak — and a safety cutoff can stop the boiler from firing until pressure is restored. Topping up the loop yourself is sometimes possible, but repeated pressure loss means something is leaking and needs a real look, not another top-up.

Same as any heating call: confirm the thermostat is calling for heat, batteries aren't dead, and the boiler's own power switch (often a household-style switch near the unit) hasn't been bumped. Check the breaker too. It sounds obvious until it's the actual answer on a cold Tuesday morning.

Most boilers have a reset button and an indicator light that shows an ignition lockout, low water, or a flame-sensing fault. One reset is reasonable to try; if it locks out again immediately, stop resetting it and call — repeated resets on a genuine ignition or gas problem isn't a fix, it's a delay.

Uneven heat on a hydronic system often points to air trapped in the loop, a stuck zone valve, or a circulator pump that's failing rather than dead. Radiators or radiant zones that need regular bleeding, or one zone that's always cold, are worth mentioning when you call — it narrows down the visit before we're on site.

Any smell of gas, soot near the boiler, a pressure relief valve that's discharging, or a lockout that won't clear on one reset — that's a call, not a DIY project. Otherwise, checking pressure, the thermostat, and the switch first saves you a diagnostic fee for something you could rule out in two minutes. We serve boiler and hydronic calls across Georgina, Markham, Newmarket, Richmond Hill, and the rest of our York Region coverage from our Keswick and Markham offices.