Component
Thermostatic mixing valve
A valve that tempers stored 60 °C water down to the 49 °C BC code limit at fixtures. It protects against scalding while allowing tanks to store water hot enough to limit bacterial growth.
Hot water and scalding
- Water above 49 °C at a tap can scald in seconds, and children and older adults are at most risk. BC's plumbing code limits shower and bathtub water to 49 °C.
- Storage tanks are normally kept hotter (Health Canada advises 60 °C) to limit Legionella growth, with a thermostatic mixing valve tempering the water to the fixtures.
- Never bypass or remove a mixing valve, thermostat or high-limit control to get hotter water.
Official guidance: Government of Canada on water temperature and scalds and HealthLinkBC.
Why storage is hot and taps are cooler
BC's plumbing code limits water at showers and tubs to 49 °C, while storage tanks are commonly kept at 60 °C to limit bacterial growth in the stored water; BC code sets electric storage thermostats at 60 °C, and Government of Canada guidance gives the same 60 °C storage and 49 °C delivery figures. The thermostatic mixing valve is what reconciles the two: it blends the stored hot water with cold so the delivered water sits at the set 49 °C or below.
Some equipment ships with the valve included: Bradford White lists an ASSE-approved mixing valve with its RG255H6N and RG1PV55H6N models. Where a valve is field-installed, it must be ASSE 1017-listed and set with the tank and fixture temperatures measured together.
Failure modes
A failing mixing valve can fail cold (delivering only tempered or cold water to the fixtures) or, more seriously, fail hot, passing 60 °C storage water to a shower. The failure symptoms are temperature swings or water that runs hotter than its setting, and any valve that can pass full storage temperature needs repair before use.
Frequently asked questions
Do I need a mixing valve?
When the tank stores at 60 °C and fixtures are limited to 49 °C, yes: BC's plumbing code requires the fixture limit, and the mixing valve is how a hot-storage tank delivers it safely.
Can a mixing valve cause cold water?
Yes: a valve that fails can deliver only tempered or cold water, or worse, pass full storage temperature. Temperature testing at the fixtures identifies which failure is happening.
Request a consultation
CANRO reviews your hot-water demand, equipment and installation constraints. Requests are confirmed by CANRO.
On-site service in Metro Vancouver, BC. Call to check availability.
Sources and verification
- CANRO Heating & Cooling — About · Canadian source · accessed September 7, 2026
- Government of Canada — water temperature and burns/scalds · Canadian source · accessed September 7, 2026
- BC Plumbing Code 2018, Article 2.6.1.12 Service Water Heaters · Canadian source · accessed September 7, 2026
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.