Two Different Jobs, Two Different Appliances
Before chasing the leak, it helps to know what each appliance does, because they are often confused.
A water heater makes the hot water you use at taps and showers, and in most BC homes it is a tall storage tank, though tankless units mounted on the wall are increasingly common. A boiler heats your home, circulating hot water through radiators, baseboards, or in-floor tubing; some combi boilers also produce domestic hot water.
Knowing which is which is the first step. If the leaking unit feeds your faucets, it is the water heater. If it feeds your radiators or floor heating, it is the boiler.
Telltale Signs It's the Water Heater
Several clues point to the water heater as the culprit.
It is usually a large vertical cylinder, often white or grey, with a cold-water inlet and hot-water outlet on top. A leak pooling at the base of the tank is a classic sign of internal corrosion — and that almost always means the tank needs replacing rather than repairing. Drips from the temperature-and-pressure relief valve on the side, or from the inlet and outlet connections up top, are also water-heater symptoms.
If your hot water at the taps has also turned rusty, cooled off, or run out faster than usual, that further points to the water heater.
Telltale Signs It's the Boiler
Boiler leaks have their own signatures.
A boiler is typically a wall-mounted box or a floor-standing unit connected to a network of heating pipes, a pressure gauge, an expansion vessel, and often a circulator pump. Water beneath a boiler frequently traces back to a pressure-relief valve, the pump, an auto air vent, or a fitting on the heating loop. A pressure gauge reading that keeps dropping suggests the system is losing water somewhere.
If your radiators or floors have gone cold, or you have had to top up boiler pressure repeatedly, the leak is almost certainly on the heating side rather than the water heater.
When It's Genuinely Hard to Tell
Sometimes the two sit so close together that water tracks across the floor and the source is not obvious — and a combi boiler blurs the line by doing both jobs.
In that case, do a little detective work. Dry the floor completely, lay down paper towel around the base of each unit, and watch which one dampens first. Check each appliance's pressure-relief discharge and fittings for active drips. Note whether your problem is heating, hot water, or both, since that points toward one unit or the other.
You do not need certainty to call. Describing what you see is usually enough for us to narrow it down.
What Each Leak Means for Repair
The diagnosis shapes the fix, which is why telling them apart matters.
A storage water heater leaking from the tank body generally needs replacement, because the tank cannot be patched. A relief valve or fitting leak on either appliance is often a straightforward repair. Boiler leaks range from simple — an air vent or fitting — to involved, depending on the component.
Whatever you are facing, call GasBoilers.ca at 604-359-1081. Our parent company CanroHeat services boilers, furnaces, heat pumps, and water heaters across Greater Vancouver, so one call covers both possibilities. We will identify the source, explain your options, and give you an exact quote for the repair or replacement.