Tempering Valves
July 15, 2009 by yoursydneyplumber
Filed under Hot Water Systems
Tempering Valves Can Prevent a Burn Injury
Tempered water is compulsory on all new residential developments in NSW. You cannot simply turn the heater down or you will breed Legionella. The tank must stay hot, but the water coming out must be tempered down.
If your hot water heater is being replaced with a different style or different capacity then it must be tempered by law. No exceptions. This is a very important safety message, not a “sell job”. You must now be suspicious of a plumber that does not insist on installing a tempering valve with a new heater; it shows that he is not aware of the current law.
Tempering valves have on average a 5yr lifespan. We recommend replacement after 5 yrs. This valve is a safety valve and cannot be serviced. If the valve fails to operate it is to be replaced.
Many of the instantaneous hot water systems on the market can now be purchase with an inbuilt preset temperature which does not require an extra tempering valve to be fitted.
Here is a quick extract from our code on hot water:
AS 1056.1
With reference to clause 3.2.2 the thermostat for a storage water heater shall be set at not less than 60°C. This clause then explains that a minimum setting of 60°C is specified on the advice of the Department of Health, NSW, that bacteria Legionella pneumophillia do not survive in temperatures above 55°C.
AS 3500.4
With reference to Clause 1.10.2, Part B, all new hot water installations, shall deliver not water not exceeding 50°C in residential buildings, at the outlet of all sanitary fixtures used primarily for personal hygiene purposes.
Here are the facts:
If you have small children then you must read this. The bulk of childrens’ burns victims that present to casualty each year are burns that were caused by hot water scalding. As you can see from the facts below, a burn can be inflicted by hot water to a child very quickly. Childeren do not know to pull away from hot water as quickly as an adult either, so the burn is made worse by an extended exposure.
We are sorry to shock you with these facts, but we feel you should know them.
- at 50°C, a deep scald takes 5 minutes in an adult or child;
- at 54°C, a deep scald takes 35 second in an adult and 10 seconds for a child;
- at 60°C, a deep scald takes 6 second for an adult and 1 second for a child;
- at 65°C, 2 seconds for an adult and 0.5 seconds for a child;
- at 70°C, in a typical factory setting – 1 second for an adult.
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