- A common, quick job when the rest of the system is healthy
- Charged by the job, not by the hour, approved by you first
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Why call OnCall
- Licensed plumbing work: tempering valves must be fitted and set by a licensed plumber
- VBA accredited, licensed and insured
- 300+ five-star reviews on Google
- 15+ years on Melbourne plumbing callouts
- 24 hours, 7 days if the water's running dangerously hot
- Police checked and first aid verified
What our customers say
"Aiden was very professional and on time to the job. Got it done and dusted faster than I expected."
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A Google review of OnCall's plumbing service.
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What a hot water tempering valve does
A storage hot water system keeps water very hot inside the tank, hot enough to stop bacteria growing. That's too hot for a shower or a child's bath.
The tempering valve sits on the hot water line near the unit and mixes in cold water, so the water reaching your bathroom taps arrives at a safer, steady temperature. When it works, you don't notice it. When it wears out, you notice straight away.
In Victoria, new and replacement hot water installations generally need to deliver hot water to bathrooms at a limited temperature, which is why tempering valves are fitted on most systems. Your plumber will make sure yours is set correctly.
Signs your tempering valve needs replacing
- Hot water too hot at the shower or basin
- Hot water fluctuating: hot, then cold, then hot again mid-shower
- Lukewarm water even though the tank is heating
- Low hot water pressure at bathroom taps, while the kitchen is fine
- A tempering valve leaking or dripping from its body or fittings
- No hot water to the bathroom at all, while the unit seems to be working
Not every one of these is the valve. A failing thermostat or element can cause similar symptoms, so we test before we replace. If it's something else, our no hot water page covers the other common causes.
Why tempering valves wear out
Inside a tempering valve is a temperature-sensing element and a small set of moving parts. Over time, scale and sediment build up, the element loses accuracy, and seals wear. The valve then sticks, lets too much hot or cold through, or starts to leak.
Leaking tempering valves are one of the most common jobs we see. Most tempering valves reach a point where cleaning isn't worth it and replacement is the reliable fix. Many manufacturers recommend checking them every few years, something we look at during a hot water system service.
How we replace it: assess, explain, approve, fix
Assess. We test the water temperature at the taps and check the valve, the unit's thermostat and the supply, so we're sure the tempering valve is the culprit.
Explain. You hear what's wrong in plain English. If the valve is the issue and the system is otherwise sound, it's a straightforward replacement.
Approve. You get one price for the job. Nothing happens until you say yes.
Fix. We isolate the system, fit the new valve, set it to the correct outlet temperature, and test it at your hot taps before we go.
What's included
- diagnosis to confirm the valve is the fault
- removal of the old tempering valve
- supply and fitting of a suitable replacement valve
- setting and testing the outlet temperature
- checking nearby fittings and valves for leaks
- a clean, dry work area when we leave
If we spot another issue while we're there, a dripping relief valve, for example, we'll tell you and price it separately. Nothing gets added without your approval.
Tempering valve cost
We charge by the job, not by the hour. The price depends on the valve required for your system, the access around the unit, and whether the surrounding fittings need attention too. Your plumber confirms the fault and gives you a clear price before starting. See hot water repair cost for how we price.
Tempering valve FAQs
What does a tempering valve do?
It mixes cold water into the hot supply so water reaches your bathroom at a safer, steady temperature, while the tank stays hot enough to control bacteria.
Why is my hot water suddenly too hot?
Most often a tempering valve that's failed or stuck. A thermostat fault can also cause it, so we test both.
Can I adjust or replace a tempering valve myself?
No. Tempering valves need to be fitted and set by a licensed plumber.
Is a leaking tempering valve urgent?
A slow drip isn't usually an emergency, but it won't fix itself and it often gets worse. If the water is scalding hot, call us straight away.
Can a tempering valve be repaired instead of replaced?
Sometimes it can be cleaned, but worn valves usually come back to the same problem. Replacement is the reliable fix.
Do all hot water systems have a tempering valve?
Most storage systems in Victorian homes do. Some continuous flow systems control temperature differently; we'll check yours.
Water too hot or all over the place? Let's fix it.
A licensed OnCall plumber can confirm the fault, price the replacement and fit it once you say yes.
Call 1800 571 216: 24/7 · Book online
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What happens next: we'll confirm your details, give you pre-arrival advice if you need it, and send a plumber. You'll get ETA updates on the way.