Boiler Not Heating? Common Causes & Fixes in BC
Six causes account for 90% of no-heat calls in Greater Vancouver. Here's how to diagnose your boiler before you pick up the phone — and when you absolutely should.
Is It Actually the Boiler? Check These First
Before assuming your boiler has failed, rule out the simple causes. In our experience servicing hundreds of homes across Metro Vancouver each winter, roughly one in five "no-heat" calls turns out to be a thermostat, programmer, or zone-valve issue — not a boiler fault at all.
- Thermostat settingsConfirm the thermostat is calling for heat — set it 3°C above room temperature and listen for the boiler to fire. Check batteries if it's wireless. Many Honeywell and Ecobee thermostats in BC homes lose settings during power blips.
- Zone valve positionIn multi-zone hydronic systems, a stuck or failed zone valve prevents heat from reaching specific areas. The valve should open when the thermostat calls for heat — feel the actuator for warmth as a quick test.
- Programmer / timer clockA daylight-saving time shift or power interruption can throw off the programmer so the boiler simply isn't scheduled to run. Check that your weekly program shows heating periods for the current time.
6 Most Common Causes of No Heat From a Boiler
Once you've confirmed the thermostat is calling for heat and the boiler still isn't firing or circulating, one of the following six causes is almost certainly responsible.
1. Pilot Light or Ignition Failure
Older atmospheric boilers rely on a standing pilot light; modern condensing boilers use an electronic igniter. If either fails, the gas valve won't open and the burner won't light. Common causes include a failed thermocouple (standing pilot) or a cracked ceramic igniter (electronic ignition). You'll typically see a fault code on modern boards — E010 on Navien units, for example, directly indicates ignition failure.
2. Low System Pressure
Most residential boilers require 1.0–1.5 bar of system pressure to operate. Below this threshold, a pressure sensor (pressostat) triggers a lockout as a safety measure. The pressure gauge is usually on the front of the boiler. If it reads below 0.8 bar, the system needs to be repressurised before it will fire. A slow drip from any fitting, radiator valve, or the expansion tank can cause gradual pressure loss.
3. Frozen Condensate Pipe
BC winters are mild but not immune to freezing. Condensing boilers (efficiency 90%+) produce acidic condensate that drains to a nearby floor drain or outside. If the condensate pipe runs through an unheated garage, crawlspace, or along an exterior wall, it can freeze solid during cold snaps — triggering an EA fault and immediate lockout. This is especially common in Abbotsford, Langley, and South Surrey during January cold snaps.
4. Circulator Pump Failure
The circulator pump moves heated water from the boiler through your hydronic system. A failed pump means the boiler fires, heats the primary loop, overtemps, and locks out — no heat reaches the radiators or in-floor tubing. You can sometimes identify a dead pump by placing your hand on the pump body: it should be warm and vibrating slightly when the boiler is running.
5. Interrupted Gas Supply
Check that other gas appliances (range, fireplace) are working. FortisBC supply interruptions are rare but do occur. A partially closed gas isolation valve on the boiler's supply line — perhaps accidentally knocked during recent work — is a surprisingly common cause that's easily overlooked.
6. Heat Exchanger or Control Board Fault
A cracked heat exchanger or failed PCB (printed circuit board) can cause the boiler to lock out on an overtemp or internal fault. These are the most serious and expensive causes of no heat — typically requiring professional diagnosis and, in the case of a compromised heat exchanger, a decision about whether to repair or replace the boiler.
What You Can Safely Check Yourself
As a homeowner in BC, you're permitted to inspect and perform some basic checks on your boiler without a gas licence — but you may not adjust, repair, or modify any gas components. Here's what's within your rights:
- Pressure gauge: Read the system pressure. If it's below 1.0 bar, locate the filling loop (usually a flexible braided hose under the boiler) and repressurise slowly to 1.2 bar.
- Reset button: Press the boiler's reset button once. If the fault clears and the boiler runs normally, monitor it over the next 24 hours. If it locks out again, the underlying fault needs professional diagnosis.
- Condensate drain: If the pipe is frozen, you can carefully pour warm (not boiling) water over the external section to thaw it. This is a legitimate homeowner task.
- Thermostat and programmer: Adjust settings, replace batteries, and verify the schedule as described above.
When to Call a Technician Immediately
Stop and call a licensed gas-fitter right away if:
- You smell gas — leave the building, do not operate any switches, and call FortisBC's gas leak line (1-800-663-9911) and 911.
- Your CO alarm is sounding — evacuate immediately. A cracked heat exchanger can vent carbon monoxide into living spaces.
- The boiler is showing repeated fault codes after reset — each reset without addressing the root cause can mask a worsening problem.
- There's visible water damage around the boiler body or on the floor — a leak under pressure can escalate quickly.
Our Red Seal–certified gas-fitters carry parts for the most common Navien, IBC, Viessmann, and Rinnai faults on every service call. Most no-heat situations in Metro Vancouver can be diagnosed and resolved in a single visit — typically within 2–4 hours of your call.
Related Issues
No heat right now? We respond same-day.
Call 604-359-1081 — Red Seal gas-fitters serving Greater Vancouver.