Why are all my radiators cold?

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How to Narrow Down the Cause: All Radiators vs. Just Some

The first useful question is whether every radiator in the house is cold, or just one or two. If only a single radiator is cold while the rest are warm, the problem is local to that radiator — usually trapped air or a closed valve — and bleeding it is often enough. If all the radiators are cold at the same time, the problem is almost always upstream at the boiler or the main circulator pump, since that's the one shared point every radiator depends on. Metro Vancouver's older housing stock, especially character homes and older townhomes with hydronic baseboard or radiator heat, tends to show these system-wide failures more often simply because the boilers and pumps are older and the piping has had decades to accumulate sediment and trapped air.

The Most Common Reasons All Radiators Go Cold

• Low system water pressure — hydronic boilers need to stay within a specific pressure range (often marked in a green zone on the gauge); if pressure drops too low, the circulator can't move water through the loop
• Circulator pump failure — the small pump that pushes hot water to the radiators has stopped running, seized, or lost power
• Boiler lockout or ignition fault — the boiler senses a problem (ignition failure, airflow issue, high-limit trip) and shuts itself down as a safety measure, often shown as an error code on the display
• Trapped air throughout the system — air pockets in the main lines can block water flow to multiple radiators at once, especially after a system has been drained or serviced
• A stuck or closed zone valve — in multi-zone systems, a valve that has failed closed can cut off flow to an entire zone of radiators
• Thermostat or control wiring issue — if the thermostat isn't calling for heat, or a control board fault is preventing the call from reaching the boiler, radiators never get the signal to heat up

What You Can Safely Check Yourself

Before calling for service, there are a few simple, safe checks a homeowner can do. Start with the thermostat — confirm it's set to heat, the temperature is set above room temperature, and batteries (if any) aren't dead. Next, look at the boiler itself: most modern boilers have a digital display or pressure gauge on the front. If the pressure gauge reads below the manufacturer's recommended range (commonly around 12-15 psi for residential systems, though this varies by unit), the system may need a top-up, which is often a homeowner-accessible valve on the boiler — check your owner's manual before touching it. If the display shows a fault or error code, note it down; it will help a technician diagnose the issue faster.

Checking and Adding Pressure vs. Bleeding a Radiator

If the pressure gauge looks normal and bleeding a radiator doesn't help, or the boiler's fault code returns after a reset, it's time to stop troubleshooting and call for service — repeatedly resetting a boiler that keeps locking out can mask a real safety issue.

What Requires a Licensed Technician

Anything involving the gas valve, burner assembly, venting, condensate system, circulator pump replacement, or control board diagnostics should be left to a licensed technician. In British Columbia, gas-fired boiler work legally requires a Technical Safety BC-licensed gas fitter, and electrical work on the boiler's controls or pump requires a licensed electrician — this isn't just best practice, it's the law, and it protects you from carbon monoxide and fire risks that aren't always obvious from the outside. A stuck zone valve, a failed circulator, or a recurring ignition lockout are all common repairs that a Red Seal certified technician can usually diagnose in a single visit.

What to Expect From a Professional Visit

A typical no-heat service call starts with the technician checking system pressure, inspecting the circulator pump for movement and unusual noise, reading any boiler fault codes, and testing the zone valves and thermostat wiring. Many system-wide cold-radiator calls turn out to be a failed circulator pump or a pressure-related lockout, both of which are usually resolved same visit once parts are on hand. CANRO provides upfront pricing before any repair begins, so there are no surprises once the cause is identified. If the boiler itself is aging and failing repeatedly, the technician can also walk through whether a repair or a full boiler replacement makes more financial sense — high-efficiency boiler replacements in Metro Vancouver typically run $7,500-$15,000+ installed, depending on sizing, venting, and gas line requirements, while a full new boiler installation (including systems without an existing boiler to convert) runs $6,500-$14,000+; a free written quote will confirm what applies to your specific home.

Preventing Future Cold-Radiator Problems

Annual boiler maintenance catches most of these issues before they cause a full system shutdown — a technician can flush sediment, check pressure and expansion tank function, bleed air from the system, and test the circulator pump proactively. This is especially worthwhile in Metro Vancouver's older housing stock, where hard water and decades-old piping contribute to sediment buildup and pump wear faster than in newer systems. If your home is on a hydronic system that's more than 15-20 years old and has needed several no-heat calls, it's reasonable to ask your technician for an honest assessment of remaining service life versus replacement.

Frequently asked questions

Reviewed by the CANRO Heating & Cooling service team — July 02, 2026. CANRO holds Technical Safety BC gas licence LGA0043870 and boiler licence LBP0046450, employs Red Seal certified technicians, and carries WorkSafeBC and liability insurance. 4.9★ from 85+ Google reviews · serving Metro Vancouver since 1999 · (604) 359-1081 · info@canroheat.ca.