Why this matters
Sudden temperature swings are uncomfortable and can scald. Modern valves in Ontario must limit scald risk, but worn or scaled parts lose that protection.
Common causes
| Symptom | Likely cause |
|---|---|
| Cold burst when toilet flushes | Pressure-balance spool worn or scaled |
| Never hot enough | Limit stop set too low or worn cartridge |
| Weak flow | Scaled shower head or valve |
| Hot then cold | Water heater running out or thermostat issue |
| Dripping after shutoff | Worn cartridge seals |
Most faucet drips come down to a worn cartridge or seat, not a whole new fixture.
Step by step
- Unscrew the shower head and soak it in vinegar to remove scale.
- Check whether all hot taps are weak, which points to the water heater.
- Remove the handle and look for the limit stop, often a plastic ring on the cartridge stem.
- Rotate the stop a notch to allow more hot water, then test carefully.
- If the valve still swings or drips, the cartridge needs replacing.
Hard water in Markham can scale cartridges quickly. If cartridges keep wearing out, consider a softener or regular cleaning.
Handing it over to us
Call if adjustment does not help or the cartridge is seized. See shower valve repair and hard water.
Markham note: village-core houses tend to hide cast iron and galvanized behind plaster, while Cornell and Box Grove builds run PEX to a manifold. We ask the year your house was built so the right fittings ride along on the truck.
Straight from the phone log
Can I replace a cartridge myself?
Often, if you identify the exact model. Shut off water first.
Why does my shower run hot and then cold?
If it happens after a few minutes, the water heater may be running out.
Ready to get it fixed?
One call, a clear explanation, and work finished tidily before we leave.