There are a number of possible reasons for noisey hot water pipes or a noisey hot water system and they should all be investigated by a plumber.

1. The sudden stopping of the water flow espesially if a non-return valve is installed can result in a “thumping” noise. Suddenly turning the hot water tap off can cause a small wave of energy to travel back down the hot water pipe. Usually this wave of energy diminishes as it passes through the water in the pipe. If a non-return valve is fitted the wave of energy comes to a sudden halt causing a “thump” sound.
2. If a contined knocking, vibration or whining noise is heard try replacing the tap washer. This usually means that there is a split, damaged or defective tap washer in the tap housing.
3. A knocking or tapping noise may be heard if long runs of water pipe are not properly attached inside the floor, wall or ceiling. This knocking is called ‘Water Hammer’ and is caused when the pipes vibrate against a floor, wall or ceiling cavity. To remove the knocking or tapping noise try securing the water pipe to prevent movement.
4. If a knocking or tapping noise is heard during the heat-up cycle of an electric hot water heater there may be some mineral build up on the hot water heating element or it could be that the water quality is poor. Check the cold water supply quality for mineral build up and clean the heating element. If required, drain any sludge from the hot water heater.
5. if you can only hear a noise when water is flowing through the water heater, check for faulty pipe work or valves. Check it is not water hammer and if the water pressure is excessive (above 700kPa) it may be necessary to install a pressure limiting valve .

A gas or electric water storage heater is essentially a vessel filled with water and it has no moving parts. Therefore, it is unlikely that any knocking or tapping noise in the hot or cold water system can be attributed to the water heaters function and performance.

If you need more help call us on (08) 8444 7311.

A Temperature and Pressure Relief Valve (T&PR Valve) may be supplied with your hot water system. It provides your hot water system with both temperature and pressure relief, whenever it is required. You can see this as water flowing from the valve.

There are 4 flow types of which you can see from the T&PR Valve.

• Under normal operation. Water heated up through a 50°C temperature increase, will increase its volume by around 2%. This increase is discharged through the T&PR valve. It is typical for the T&PR valve to dribble or discharge water throughout the heating cycle. The T&PR valve will discharge water equivalent to 2% in volume of the full amount of hot water used in 24 hours. Therefore, a drainage line ought to be coupled to the T&PR valve to take discharge clear of the heater to an appropriate place. This initial kind of release happens only when a non-return or check valve is setup on the cold water supply line after the stop cock. It is typical that this valve permits a little amount of water to escape throughout the heating cycle. However, if it releases over a bucket full of water in one day, there could be another issue.
• When there is a continuous dribble. A constant dribble might be released if there is dirt or grit under the seat of the valve which prevents the valve seat from closing correctly. This dirt or grit can be dislodged by working the easing lever and allowing a complete flow of water to wash over the valve seat.
• If there is a steady flow for long period of time – often at night. It might be a possibility the incoming cold water pressure level to be over the pressure rating of the T&PR Valve. This will give you a constant flow of water from the T&PR Valve without cycling. You will need to ask your installing plumber to fit a pressure limiting valve; make sure you DO NOT substitute the relief valve with one of a higher pressure rating.
• If there is a heavy flow of hot water til the water heater is cold, which then pauses until the water reheats. The T&PR Valve also functions as a safety device which is activated through temperature. Should the ‘thermostat’ and or the ‘over temperature energy cut-out’ fail on your water heater, then your system would be trying to heat water continuously. For safety, when the water reaches a temperature of 98-99°C, the T&PR Valve will open. This will permit a large flow of hot water to discharge, then the flow will stop only to flow again when the water once again reaches too high temperatures. The high temperature of the water causes a polythene rod inside the temperature probe to expand, this in turn causes a steel rod to open the valve. When the water cools, the polythene rod contracts and allows the steel rod to close the valve.

If this thermal relief does occur, the water heater must be switched off at the switchboard if it is an electric water heater. If it is a gas water heater, the gas control must be turned off using the knob on top of the gas control thermostat. Phone your Adelaide Hot Water ^TM agent to arrange for inspection. (08) 8444 7311.

Note: It is very important the T&PR Valve is connected to a drain line to allow the discharge to terminate at a location where the water will not cause damage. The drain line should be as short as possible (maximum 9 metres), have no restrictions, maximum three bends and have a continuous fall to the outlet. The drain line should terminate in a drained position so any discharge can be readily seen.

Remember: If a Temperature and Pressure Relief Valve requires replacement, then the correct valve must be installed. Never install a T&PR Valve with a pressure rating higher than the rated working pressure of the water heater.