Hot water systems come in many shapes and sizes. They may be powered by electricity, gas, solar, wood or chip; large or small storage types; main pressure (unvented) or gravity feed (vented), or instantaneous.
Hot water systems may be all copper, enamelled steel (glass lined), or bronze alloy. Some seem to last indefinitely, while others only last about 8 years or so. Generally, copper units that are not under constant pressure, such as vented in-ceiling units, will last the longest.
There are a few things which may need repair on hot water services. Rust on casings should be treated by sanding, priming and repainting — but any hole or leak in the vessel will require replacement of the tank. Hot water storage systems are pressure vessels, and can’t be repaired.
If an electric hot water service stops heating, check the fuse or circuit breaker in the meter box. It may have blown, and if so, needs to be replaced. If it is not the fuse, a service call will have to be made to have the element replaced. Similarly, if heating occurs, but the temperature is low, too high, or unreliable, the thermostat may need to be adjusted, serviced or replaced.
A gas system relies on the pilot light to be on to light the gas when hot water is needed. Most systems have automatic controls; if the pilot light goes out for any reason, the gas will automatically shut off to stop a dangerous situation developing. If any fault is suspected in the gas system, or the system is ancient, it should be referred to the conversion or maintenance division of your local gas supplier.
If a gas leak is evident, in the first instance make sure there is good ventilation and avoid any naked flames or source of sparks, such as electric motors, heating elements, poor switches that flash, or metal striking metal.
Poor Hot Water Flow
A common complaint with hot water is that the pressure is much lower than with cold water. This invariably occurs with gravity feed or vented hot water systems in the ceiling.
The problem is that the feed pipe is the same diameter as the other piping, but the pressure from a small ceiling tank is nowhere near that obtained from mains pressure — therefore the flow we experience from taps in the house, requires deft adjustments for optimum use.
The flow can be improved in these situations by replacing the standard 18mm or 12mm pipes, with 25mm pipes, which will allow a greater flow of water, and evens up the comparative water pressures.
Hot Water Trays
If a hot water unit is situated in a house, or in the ceiling overhead, it is safest to install it on a tray. This means that if a leak develops, or the tank is damaged, the water can be collected by the tray, and the water directed into the drainage system or outside.
Trays should be made of copper; if they are made of galvanised iron they tend to rot out before the hot water unit. Replacing a tray is normally very difficult due to the weight of a tank full of water. If the tank is lifted slightly, a new tray can be slid in underneath. To do this, one side of the tray will have to be bent flat, and when in position, bent up again.
Pressure Relief Valves
Pressure relief valves on hot water units allow the unit to get rid of excess water if a preset pressure is passed, thus saving the unit from physical damage. They are quite simple devices which work automatically; they should be manually operated once every six months to ensure good operation and to check that nothing is blocking the pipe.