Friday, May 16, 2014

Plumbing your Geyser’s and T&P Valves

Most consumers take for granted their geyser and rarely think about it once it has been installed. It is "out of sight" and usually "out of mind.” So many home owners are unaware of the need to have their geyser regularly maintained and inspected to prevent a geyser explosion.

Safety standard for geysers SANS 60335-2-21 explains the specific requirements during the installation of a geyser.


The T&P Valve Reduce the risk of abnormally high and dangerous pressures in the geyser in your home and it reduce the chances of a dangerous explosion of the Geyser.

Manufacturers and building codes require that a temperature and pressure relief valve be installed on the geyser - a T&P Relief Valve.

There is a sticker providing information on any T&P relief valve describing its operating pressure. The T&P Valve installed on your geyser is marked with a "set pressure" (the pressure at which the valve will open to relieve pressure) and this pressure must be equal or less than the maximum working pressure of your geyser.

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Testing the T&P Valve on your geyser

Some manufacturers recommend that the temperature and pressure safety relief valve must be tested once every six months.

To test the valve the knob on this valve must be turned or if there is a lever on the valve it must be lifted, which either one should result in (hot) water flushing through the valve and is discharge through a tube to the outside of the building or into a bucket placed below the discharge tube should your geyser be on the outside of the building.

After turning the knob or lifting the lever on the relief valve, lower it gently back to its closed position. Rough handling of the relief valve test lever, such as allowing it to "snap" closed, can damage the temperature and pressure relief valve - a dangerous condition that could lead to a geyser explosion.

If water does not flow freely when the T&P valve is opened, the valve should be replaced by a plumber, making sure that an approved, T&P valve is installed.

If your T&P valve has not been tested or replaced sooner than five years, we recommend that the T&P valve should simply be replaced. More frequent replacement of the safety valve may be needed in areas where hard water is found.

Geyser blanket Covered-Over relief valves

When a geyser blanket is installed to cover your geyser make sure the safety valve has not been covered by the insulation.


This is an unsafe condition as the operation of the temperature or pressure relief valve may be interfered with by the insulation and also because the valve cannot be inspected for evidence of leaks or failure.

T&P Valve Installation Location and Position

The geyser T&P relief valve is installed into an opening directly on the geyser at a location marked for that purpose, usually at or near the top of the geyser (where water temperatures is the greatest).

Watch out: for these unsafe geyser TP valve or pressure-only relief valve installation mistakes:
1.) Never depend on a Pressure relief valve only to protect a GEYSER. Pressure relief alone can't prevent a geyser explosion.

2.) Shutoff valves should never be installed between a relief valve and the tank it is designed to protect

It is the release of heat (or "temperature" or "energy") that prevents a geyser from exploding when it is being overheated, not the release of pressure.

The Temperature/Pressure relief valve mouth opening on the exit side must point down, and a 20mm discharge tube must be attached to the T&P Valve's opening and routed to the outside of the building with the least amount of bends. This permits emergency hot water to be discharged without risk of burning and damages.

Relief valve installed through an elbow, coupling, or pipe nipple:


Never install a T&P valve through any other plumbing fittings by doing this it can cause the T&P valve failing to operate safely, when it should. For example, an air pocked in a coupling can prevent proper sensing of water temperature. It must be installed directly to the geyser itself in the opening made for this purpose, the sensing probe from the T&P valve should be completely inside the geyser.

Leaky or Dripping Water Heater Pressure & Temperature Relief Valves

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T&P valves may open, leak, or drip for a variety of reasons here are some common leak causes:
  • The water heater temperatures are excessive (Thermostat is defect) 
  • The building water supply pressure is too high or periodically water pressure fluctuates and is too high at times
  • Periodic discharge of the temperature and pressure relief valve may be due to a defect pressure release valve.
  • Dirt or debris is preventing proper closure of the relief valve.
  • A deteriorated gasket inside the relief valve or corrosion on the valve seat can cause it to leak.
  • Warning: a dripping or frequently spilling T&P valve is dangerous because those very leaks can eventually cause the valve to clog and then to fail to open when it should.
Never remove or plug a T&P valve. The discharge opening must not be blocked or reduced in size under any circumstance; it is a dangerous situation that has a high risk for an explosion.

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If you live in Pretoria area Call: 081 490 8281 or 079 968 4047

We will make your Geyser safe!