Electric Boiler Is Not Heating Up Water ? A hot shower provides a way of calming and relaxing yourself at any time of day. However, this soothing experience quickly becomes very unpleasant when it turns into a cold shower… and not because someone’s used all the hot water. Why won’t the hot water boiler heat water any more? You can actually investigate some of the possibilities yourself before calling in a professional.
Why Doesn’t Electric Boiler Heat Water?
The boiler is no longer being properly supplied with water
The first thing to check is whether the fault is due to a plumbing issue. Turn on a hot tap. If hardly any water comes out, this means there’s a problem with the pipes. Call in a plumber so they can investigate what the issue is. If water does come out of the tap but it’s cold or lukewarm, the fault will likely be electrical in origin instead.
The circuit breaker has tripped
Check your fusebox to see whether a circuit breaker has tripped or a fuse has blown, as this will prevent the boiler from coming on. You may well have a switch that puts your boiler into off-peak electricity mode. Try putting the boiler in forced operation mode to see if your meter begins registering the additional electricity being consumed. If it doesn’t, this means the electrical problem is coming from the boiler itself. If the circuit breaker trips again, there may be leaking water coming into contact with electrical circuits and causing a short-circuit.
DID YOU KNOW? To prevent the tank corroding too quickly, the hot water cylinder has a kind of rod known as an anode inside it. There are three different types of anode:
- magnesium anodes (also know as sacrifical anodes), which are normally used in regions that have low-calcium water: the anode slowly dissolves and deposits its ions on the walls of the tank. This means these anodes have to eventually be replaced.
- titanium anodes (also known as impressed current anodes): with the help of a weak electric current, these anodes capture the minerals in the water (magnesium and calcium) and direct them onto the walls of the tank. These types of anodes therefore activate the elements already naturally present in the water. They also don’t wear out and are effective in water that’s rich in calcium and magnesium.
- hybrid anodes: these are made from titanium and coated in magnesium. Hybrid anodes combine the properties of the previous two anode types.
The safety thermostat has tripped
Before carrying out this check, switch off the electricity to the boiler at the fusebox. Using a cross-head screwdriver, remove the access cover, which is normally located underneath the boiler and held in place by a few screws. You will now be able to see the thermostat (a head torch will prove very useful here!). On the thermostat you will see a small slot that has a red button visible inside it. Using a slotted screwdriver (electrically insulated), try to press the button in.
If it wasn’t already in its pressed position, the boiler must have tripped into safety mode. This can sometimes occur following a storm or a power outage, or as a result of the hot water cylinder overheating. Next, switch the electricity back on (warning: do not touch the system underneath the boiler from this point forward), and try putting it in forced operation mode again.
If the thermostat trips again, this could be because:
- The thermostat is faulty and will need to be replaced;
- Or the thermostat is being tripped into safety mode due to the cylinder being too furred up with limescale.
The thermostat is faulty or not correctly set
It’s possible that the boiler thermostat is not set correctly, or the temperature setting dial has been accidentally knocked when someone has been doing something on the boiler previously, and is now set too high (too hot). If this is the case, simply turn the adjustment dial to select a suitable heating temperature then switch the power to the boiler back on.
Still nothing? The thermostat could perhaps be faulty and need to be changed. You can check its condition using a multimeter in ohmmeter mode. Disconnect the connectors from the thermostat and place the multimeter’s probes on the thermostat’s terminals, which will normally be indicated visually (most boilers have a wiring diagram to help and guide you). If there’s no continuity, you will need to replace the thermostat.
DID YOU KNOW? A boiler should ideally be set to between 50°C and 60°C. Any colder than this, and bacteria could build up in the tank. You’d also find yourself needing to turn the hot water on stronger in the shower! Any hotter, and the higher temperature will encourage limescale deposits to build up.
The water heater and element are furred up
Boilers often need to be drained and descaled (i.e. when you notice that the water is flowing more slowly and starting to get less and less hot). In fact, if you live in a hard-water area, limescale will end up building up at the bottom of the tank and on the element even at moderate temperatures; and this will happen to such an extent that the boiler will eventually end up no longer able to heat the water. It may also cause the appliance to go into safety mode. Always remember to turn of the electricity at the fusebox before doing any work on your boiler.
The heating element is faulty
If the boiler still won’t work, despite checking all these things, the element will likely have failed. It’s possible to check and test it with a multimeter, if you happen to have one. First disconnect the connectors from the element. Next, ensure your multimeter is in ohmmeter mode. Then, place the meter’s two probes on the elements’s two terminals to check it has continuity (you should get a value). If your appliance is not too old, it will be worth changing the element. Otherwise, it will be better to replace the whole thing!
IMPORTANT: if the thermostat has any traces of burning, the plastic is slightly melted, or there’s a smell of burnt plastic, you absolutely must (in addition to changing the thermostat) replace the connectors or cut and restrip the end of the cable from your mains. Don’t forget to properly tighten the screws on the new thermostat, otherwise the problem will quickly return due to the electrical contacts overheating.