A tempering valve sits on the hot pipe near your cylinder and blends in cold water, so what reaches your basins, bath and shower is at a safe temperature. It lets the cylinder store water hot enough to control Legionella bacteria without that same water coming out of the shower hot enough to burn.
We fit, test and replace tempering valves and thermostatic mixing valves in Christchurch homes, rentals, rest homes, schools and early learning centres. If a tap is suddenly hotter than it used to be, the shower drifts between hot and cold, or a new cylinder is going in, the tempering valve is one of the first things we check.
Pricing: quotes are free, and every job gets a fixed price before we start, so there are no surprises on the invoice.
Tempering Valves Jobs We Handle Across Christchurch
- Tempering valve replacement
- Thermostatic mixing valve installation
- Tempering valve adjustment
- Hot water too hot fix
- Tmv testing
- Tempering valve repair
The temperature rules in plain English
NZ Building Code clause G12 limits how hot water can be at personal hygiene fixtures such as basins, baths, showers and bidets. For fixtures installed from 2 November 2024 under the acceptable solutions, the limit in most homes dropped from 55°C to 50°C. The change is not retrospective, so older fixtures set at 55°C are not automatically non-compliant. Schools, hospitals and care homes, where people are most at risk, keep a lower 45°C maximum.
At the other end, stored water needs to be heated above 60°C at least once a day to stop Legionella multiplying, as BRANZ's Level guide explains. Kitchen sinks and laundries are usually allowed hotter water than bathrooms. A correctly set tempering valve on the bathroom supply is what lets both rules work at once.
Tempering valve or thermostatic mixing valve?
A tempering valve is the standard choice for houses. It mixes hot and cold to a set outlet temperature and holds it within a few degrees. A thermostatic mixing valve (TMV) is a higher-performance version used in hospitals, aged care and childcare. It holds temperature more tightly and has a fail-safe that shuts off the hot supply if the cold supply fails, so nobody gets a blast of straight cylinder water.
For a family home in Papanui or Hornby, a quality tempering valve is normally right. For a rest home, disability housing or an early learning centre, we look at whether a TMV is the better fit for the people using the taps.
How It Works
Signs your tempering valve is failing
Each valve contains a thermostatic cartridge and small inlet filters, and both wear. Common warning signs:
- Bathroom hot taps suddenly much hotter than they used to be
- Shower temperature drifting without anyone touching the mixer
- Water that stays lukewarm even though the cylinder is hot
- Weak hot flow at every bathroom outlet
- Drips, weeping or white crusty build-up around the valve body
- No record of the valve being tested since it went in
Why scald protection matters
Water hot enough to control Legionella is hot enough to cause serious burns. KidsHealth explains that children's thinner skin burns faster and deeper, and at lower temperatures, than an adult's. Older people can be slow to pull away from hot water. That is why the limits are tighter in schools and care homes, and why a failed valve in a family bathroom is worth fixing promptly.
If you have just had a new cylinder fitted and the bathroom tap is far hotter than before, ask whether a tempering valve was installed and set. This often happens after DIY and budget cylinder swaps. Our hot water cylinders page explains what a complete installation should include.
Testing, servicing and Christchurch water
We measure the delivered temperature at the outlet furthest from the valve, check the cartridge reacts when the cold is cut briefly, clean the inlet filters and confirm the setting matches the rules for your building. AS 4032.3 sets out how tempering valves are field tested and maintained, and NZS 4617 covers the valves themselves. Some makers and plumbers suggest replacement every 5 to 8 years, and we follow the instructions for your specific valve.
Christchurch's town water comes from deep aquifers, and Christchurch City Council's typical analysis gives a total hardness of about 45 g/m3 as calcium carbonate and a pH of 7.8. At that level scale is not usually the main enemy, but sediment from mains work or flakes from a rusting old cylinder can still clog the filters. Testing the valve is part of our hot water servicing.
What affects the cost
The final price depends on whether the valve only needs testing and adjusting or a full replacement, the valve type, how easy it is to reach in the cupboard, roof space or under the floor, whether isolation valves need adding, and how many outlets need testing. In a cold subfloor or garage we lag the new valve's pipework while we are there. We agree a fixed price before we start.
Why Choose Cheeky's Plumbers for Tempering Valves
Measured at the tap
We test the actual delivered temperature with a thermometer at the outlets, not just the setting on the valve, and record the readings in your photo report.
Right valve for the building
Homes, rentals, rest homes and early learning centres have different limits. We set and document the valve to the one that applies.
Checked with every cylinder
Any time we replace or service a cylinder, the tempering valve is tested as part of the job.
Tempering Valves FAQs
What temperature should my bathroom hot water be?
For fixtures installed since 2 November 2024 the Building Code acceptable solution limit is 50°C in most homes, and 45°C in schools, hospitals and care homes. Older fixtures may be set at the previous 55°C limit.
Can't I just turn the cylinder down instead?
No. Stored water needs to reach above 60°C daily to control Legionella. The tempering valve lowers the temperature at the bathroom taps without making the cylinder unsafe.
Where is my tempering valve?
Usually on the hot pipe within a metre or so of the cylinder, in the hot water cupboard, roof space or under the house. It is a small brass valve with three connections.
How long does a tempering valve last?
It varies with water quality and use. Some makers suggest replacement every 5 to 8 years. Regular testing tells you when yours is drifting.
Does a continuous flow heater need a tempering valve?
Many have controllers that can be set to a safe outlet temperature. We check the setting and the maker's instructions to confirm whether a separate valve is needed.
Do rentals need a working tempering valve?
Landlords should make sure hot water reaches taps at a safe temperature. We test and document the delivered temperature so you have a record.
Tempering Valves Across Christchurch
Our tempering valves team works in every Christchurch suburb. Find your local plumbers:
Tempering Valves Guides
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