Signs you need this fixed
- Tea-coloured hot water, clear cold
- Showers go lukewarm by the second rinse
- Puddle creeping out from under the burner skirt
- Pilot flame dies a minute after lighting
How on-demand heating works
Cold water runs through a heat exchanger. A flow sensor senses the tap opening and lights a burner sized for the job, often much larger than a tank burner. Water leaves at the set temperature for as long as the tap stays open. There is no stored water to run out, but there is a limit on how many litres per minute it can heat at once. Running a pair of showers plus the dishwasher can outstrip a smaller unit in a Toronto January, when incoming water is close to freezing.
Gas supply and venting needs
Because the burner is large, a tankless unit needs more gas than a tank. The existing half-inch line that fed your old tank is often too small, and the meter itself may need to be checked. The vent normally exits a side wall in plastic pipe, and code sets how far it must stay from openings and the lot line. Condensing models also need a drain for the acidic condensate, which should pass through a neutraliser.
Hard water and maintenance
The city's lake-drawn supply carries a moderate mineral load. Mineral scale coats the inside of a heat exchanger slowly, cutting efficiency and eventually tripping error codes. Most makers call for descaling, often yearly in hard-water areas: isolating the unit with service valves and circulating a mild acid through it. We install those service valves as standard so the job takes less than an hour. Inlet screens also need cleaning.
Is tankless right for you?
- Good fit: a household that wants long showers, has room on the gas service, and plans to stay several years.
- Weaker fit: a home with a small gas line, a hard-to-vent basement, or many fixtures running at once.
- Consider: a combi boiler that heats both water and the house, if the furnace is also due.
Compare it honestly with a new tank in our essay tankless vs tank.
What is included on the visit
Tools on the truck
- Pipe cutter, press tool and dielectric unions
- Hose, pump and descaling kit
- Combustion and draft gauge
What we open
Burner access panel, drain valve and the T&P discharge
How we test it
Recovery timing, draft at the hood, soap on every new joint
How the job runs
Ring the line
Say what is dripping, backing up or banging. Water still flowing? We guide your hand to the valve first.
Find the cause
The plumber traces the fault, with a scope or gauge where one earns its keep.
Pick the fix
Options come in everyday language, and nothing starts until you choose.
Repair & prove it
We finish, run the water to prove it, wipe up and leave a short written record.
Calls we field, answered plainly
Will an on-demand heater run during a blackout?
No. They need electricity for controls and the fan. A tank with an atmospheric vent may still heat water without power.
Why does the water go cold briefly?
This is called a cold-water sandwich. It happens when a tap is shut and opened again quickly, before the burner relights.