FirstCheck
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🍁 Built for Canadian homes — written to Canadian codes and provincial rules. Not intended for use outside Canada.
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No hot water from a gas water heater

Cold showers are miserable, but the fix is often free and takes ten minutes — most of the time the pilot has simply gone out.

tuneWhat are you noticing?
Select anything that matches and the checklist below reorders to fit. Not sure? Skip it.
emergency_home

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Start here

In Canadian homes, check the pilot light first. Open the access panel and look for the small blue flame; if it's out, relight it following the instructions printed on the tank. Free, and the most common fix by far. If it won't catch or you smell gas, stop and call your gas utility.

Ranked from real-world failure data. The order updates as you select what you’re noticing above.

Likely causes, in the order to check them

Showing the typical order
Beginner-friendly Doable, with care Safety-critical Call a pro

visibilityHow to check

report Gas safety before you testYou'll have the pilot lit and gas flowing to test the thermocouple. Work in a ventilated space, keep the burner area clear, and if you smell more than the faint whiff of relighting, stop and leave. If any of this is outside your comfort zone, a thermocouple swap is a fast, inexpensive job for a licensed plumber or gas-fitter.
  1. Relight the pilot per the tank's printed instructions and watch it: if it dies within a minute of releasing the knob, the thermocouple is the prime suspect.
  2. Look at the thermocouple tip — it should sit right in the pilot flame. White chalky buildup, corrosion, or a bent tip out of the flame all point to failure.
  3. To be sure, a multimeter on millivolts across the thermocouple should read above ~25 mV with the pilot lit; below ~15 mV confirms a replacement is needed.
buildmultimeter schedule20 min

handymanHow to fix it

Shut off the gas, remove the burner assembly, swap in a matching thermocouple (match length and connector), reseat it in the pilot flame, and leak-test every joint with soapy water before leaving it running.

  1. Turn the gas control to OFF and close the gas shutoff valve (handle a quarter-turn, crosswise to the pipe).
  2. Disconnect the three lines at the control valve (pilot, thermocouple, burner) and slide out the burner assembly.
  3. Fit a new thermocouple of the same length; hand-thread the nut, then snug a quarter-turn — the metal is soft, do not overtighten.
  4. Reinstall, relight, and brush a 50/50 dish-soap/water mix on every joint. Growing bubbles mean a leak: shut off and re-seat. No bubbles, you're done.
schedule45 min savings$12–25
Universal thermocouple kitMatch the length (usually 18–36") and the connector to your old one
gavel Check your province first AB: homeowner may do this · BC: homeowner may do this · ON: homeowner may do this · PE: homeowner may do this · QC: licensed professionals only
Owner replacement of a thermocouple is generally permitted; gas-fitting for valve/supply work is licensed-only.

verifiedWhy this one goes to a pro

Diagnosing and replacing a gas control valve means live gas work and a leak-tight reassembly. In every province this is work for a licensed plumber or gas-fitter — the cost of the part is small next to the cost of getting gas wrong.

Your notes travel with the request — what you saw, what you ruled out, when it started — so the pro arrives with a head start instead of a mystery.

sort

Why the list is in this order

We don’t sort by likelihood alone. We sort the way a good, honest tradesperson thinks: rule out the free, safe, common causes first. That’s why the cheap checks outrank the expensive repairs — and why anything dangerous gets a hard stop instead of a pep talk. The order exists to save you money, not to sell you anything.