Why are all my radiators cold?
If every radiator in your home is stone cold, the good news is that the radiators are probably fine—the problem lies upstream, at the boiler, pump, or controls that feed the whole system. That narrows the search considerably.
A total loss of heat is one of the most urgent calls HeatLand receives, especially during a Metro Vancouver cold snap. Some causes have quick homeowner checks; others need a licensed technician.
Drawing on our experience serving the Fraser Valley since 1999, here’s a clear path through why all your radiators are cold and what to do next.
System-Wide Causes to Consider
Because every radiator is affected, focus on components that serve the entire system. First, the boiler itself: if it isn’t firing—due to a lockout, no gas supply, a pilot or ignition fault, or a power interruption—no hot water reaches any radiator. Second, the circulator pump: if it fails or seizes, the boiler may heat water that never moves through the pipes. Third, low system pressure: many boilers refuse to fire below a minimum pressure, and a leak or a top-up that’s dropped too far will trigger this. Fourth, controls: a dead thermostat (flat batteries, a fault, or an accidental setback), a failed programmer, or a faulty diverter can stop the heating call entirely. Fifth, a tripped safety device or a reset that needs pressing. On combi boilers, a hot-water priority fault can also leave heating dead. Working through these in order usually reveals the cause.
Safe Checks Before You Call
A few checks can restore heat or at least speed up the repair. Confirm the thermostat is set above room temperature, in heating mode, and has fresh batteries; check any programmer or timer is calling for heat. Look at the boiler’s pressure gauge—if it reads low (below roughly 1 bar), the boiler may have shut down; a careful top-up using the filling loop can help, but only if you know your system and don’t overfill. Check for a fault code or a lockout light on the boiler and try a single reset if the manufacturer allows it. Make sure the boiler has power and that no breaker has tripped. Confirm your gas supply is on and other gas appliances work. Do not repeatedly reset a boiler that keeps locking out, and stop immediately if you smell gas, suspect carbon monoxide, or see water leaking—these need professional emergency service, not further attempts.
When Professional Repair Is Needed
If heat doesn’t return after checking the thermostat, pressure, power, and a single reset, it’s time for a licensed technician. Diagnosing ignition faults, replacing a circulator pump, tracing a leak that’s dropping pressure, repairing control boards, and any gas-related work all require professional skill—and in BC, gas work must be done by a TSBC-certified gas fitter. A boiler that repeatedly locks out is protecting itself from a real fault and should not be forced to run. Safety comes first: if you smell gas (rotten eggs), suspect carbon monoxide (headaches, dizziness, nausea, or a yellow flame), or see signs of overheating or leaking, shut the system off, ventilate, leave if unwell, and call for emergency service. HeatLand provides emergency service throughout Metro Vancouver and the Fraser Valley, services all major boiler brands, and offers financing on repairs when needed.
Quick Checklist
- Set thermostat above room temp and confirm heating mode
- Replace thermostat batteries and check the programmer
- Check the boiler pressure gauge and top up if safely possible
- Confirm boiler has power and no breaker has tripped
- Verify gas supply is on and try one reset if permitted
- Call emergency service for gas smell, CO signs, leaks, or repeated lockouts
| Cause | Quick Check | Who Fixes It |
|---|---|---|
| Boiler not firing | Fault code / reset light | Technician |
| Failed circulator pump | Boiler hot, radiators cold | Technician |
| Low system pressure | Gauge below normal | DIY top-up / Technician |
| Thermostat or control fault | Batteries, settings | DIY / Technician |
| Tripped safety lockout | Lockout indicator | Technician |
Frequently Asked Questions
Why are all my radiators cold but the boiler is on?
If the boiler runs but no radiators warm up, the most likely cause is a failed circulator pump—the boiler heats water that never circulates. Low pressure, a stuck diverter valve, or a heating-call fault can also cause it. Feel the pipes near the boiler: if they’re hot but radiators stay cold, circulation has stopped, and you should call a technician.
Can low pressure make all radiators cold?
Yes. Most modern boilers won’t fire below a minimum pressure as a safety measure, so if the gauge has dropped too low, the whole system stops heating. A careful top-up via the filling loop can restore operation, but if pressure keeps falling you likely have a leak that needs professional repair rather than repeated top-ups.
Should I reset my boiler if all radiators are cold?
A single reset is fine if the manufacturer permits it and there’s no gas smell or leak. But if the boiler locks out again immediately, stop—it’s protecting itself from a genuine fault, and repeated resets can be unsafe. Note the fault code and call a licensed technician to diagnose the underlying problem.
Is no heat an emergency in winter?
During a Metro Vancouver or Fraser Valley cold snap, total loss of heat can risk frozen pipes and household safety, so it’s worth prompt attention. If it’s paired with a gas smell, suspected carbon monoxide, or a water leak, treat it as an immediate emergency. HeatLand offers emergency service to restore heat quickly and safely.
Reviewed by the HeatLand Heating & Cooling team — licensed HVAC contractor serving Metro Vancouver & the Fraser Valley since 1999. This article is for general guidance only. If you smell gas, suspect a carbon monoxide leak, or are unsure about any electrical or gas component, stop troubleshooting immediately and call a licensed technician or 911.