Modern water heaters are built to last. Many come with long warranties, and you hope to be able to use them trouble-free for many years to come. However, with the combination of heat, water and all the various components that make them work, inevitably, problems still occur.
Many issues are not fatal for your heater, and the key to repairing them is correctly identifying what’s wrong. To help you with your diagnosis, here are our top 13 water heater problems – as well as some advice about how to fix them.
Before you start
There are many types of water heater, including those powered by gas and those powered by electricity. Electric water heaters are high-voltage appliances, which means you should take full precautions when working with one.
Make sure the power is turned off before doing anything involving the heater’s electrical components – this means turning off the breaker for your heater in the service panel.
Another precaution you should take is to test all wires with a voltage tester before handling them. Failure to do so can result in a serious injury or even death.
1. No hot water
If you have no hot water, there are several possible reasons, and you need to work through each of them methodically to eliminate each one – and this will also depend on whether you have an electric or gas-powered heater.
The most obvious reason an electric heater doesn’t work is that it’s not receiving any power.
Start by checking the circuit breaker to see if it has been tripped. If it has, it’s an easy fix – simply turn it off and turn it back on again. You may also have to replace the fuse if it has blown.
The next step is to check the high-temperature cut-off. Open the panel and press the red “reset” button. Check to see if the water will now heat.
Another possibility is that you have a faulty heating element or elements. Test these and replace as necessary.
After checking each of these, if you still can’t find the reason why you have no hot water, it might be time to call a professional.
If you have a gas heater, check to see if the gas valve is open. If this is not the problem, you may have issues with the pilot or the burner. Check #10, #11 and #12 below to see how to address these issues.
For more detailed information on troubleshooting an electric water heater, watch the video below:
2. Not enough hot water or water not hot enough
Again, if you don’t have enough hot water, the reason why will depend on the type of heater you have.
If you have a heater with a tank, it may simply be that your tank is not big enough for your requirements. If your tank is too small for the number of people showering, for example, you may use up all the hot water before everyone is finished.
If this is the case, you need to think about buying a new water heater that can meet your needs.
If your heater produced enough hot water for everyone before but suddenly stopped or no longer heats the water enough, the problem is probably due to a heating element failing. Check them and replace as necessary.
Another quick fix is to check the thermostat – you may just need to turn it up to a higher setting. Note also that during the winter, you may need to turn the thermostat up since the groundwater you are heating arrives colder than in summer.
If you have a tankless heater, you may be trying to run too many fixtures for the unit’s power, so check how many fixtures your unit is rated for. The problem could be that your heater is not powerful enough for your requirements.
Tankless heaters also have to work harder in winter, so if you experience this problem during the colder months, this could be the reason. You may need to consider upgrading to a more powerful unit.
3. Water too hot
This is almost certainly due to the thermostat being set too high, but it’s an easy problem to resolve. Simply turn down the thermostat and you should be good to go.
If this doesn’t do the trick, check the temperature pressure valve – if it is faulty, the heater won’t shut off when it reaches the correct temperature. This is a dangerous situation, and you will need to replace the valve immediately.
4. Water takes too long to heat
Possible reasons for water taking a long time to heat include faulty heating elements, sediment build-up on the elements and a faulty thermostat. Check each of these in turn and replace as necessary.
If you have a gas version, it could be related to the burner – see #12 below for further information.
5. Low water pressure
Low water pressure is often caused by not having wide enough pipes. Older homes mostly have ½” pipes while modern homes usually use ¾” pipes.
If you live in an older home and you are suffering from low water pressure, the problem may not lie with the boiler at all – you may need to consider fitting wider pipes in your home to resolve this issue.
Leaks might result from loose connections, in which case you will need to tighten them with a wrench. They can also come from valves, and these can be replaced.
If the leak comes from the tank, this is more serious since it may be corroded. If you have a corroded tank, it will need to be replaced entirely.
7. Dirty water
If your water starts to turn to a dirty rust color, you are probably looking at corrosion inside your tank. The only solution for this is replacing the tank.
However, it could also be due to a failing anode rod, so before replacing the tank, flush the tank and replace the anode rod to see if this fixes the problem.
8. Smelly water
If your water smells bad, bacteria in your heater could be the culprit. This is especially common if your water comes from a well. Flushing your tank can help, or you can try boiling the water to maximum temperature to kill all the bacteria.
If this doesn’t work, try cleaning it out with chlorine bleach.
If you have water that smells of rotten eggs, it could be due to a failing anode rod – in which case, you should replace it.
9. Tank makes noises
There are a few reasons water heaters may make noises. The most common is that a build-up of scale in the tank and on the heating elements is creating rumbling, popping and banging sounds as the water heats.
If this is the case, try draining the tank and descaling. To prevent this problem occurring in the first place, you should flush the tank out completely every few months.
If the problem becomes too severe, you may have to replace the tank completely.
Sometimes water heaters and pipes can make sounds through normal expansion and contraction due to heat. This is harmless, but there’s not so much you can do about the noise.
10. Pilot doesn’t light
If you are having trouble with your pilot light, there are several possible reasons.
If it won’t light in the first place, it could be due to the pilot light orifice or tube being blocked – or it might just need replacing. Another possibility is that the thermocouple is loose or faulty. You could also have air in the gas line, or the gas valve could be faulty.
11. Pilot lights and then goes out
If it lights but then goes out, the causes could be similar. The thermocouple could need replacing, you could have a bad gas valve, or the vent could have become blocked.
12. Burner goes out
This is likely to be a similar issue to problems with the pilot light. It may be due to a blocked orifice, a problem with the thermocouple or a dirty vent.
13. No hot water for bathtub
If you have no problems using your shower or operating a dishwasher or washing machine but can’t get hot water to run a bath, the problem may be due to the type of heater you have. If you have a tankless heater, this is probably the root cause.
Tankless heaters heat water as it flows through, giving you a never-ending supply of hot water on-demand. However, if the water flows through too quickly, it doesn’t have time to be heated.
Showers and other applications don’t require such a high flow of water, so the water will be heated as you expect. The water flow for running a bath, on the other hand, is much higher, and your tankless heater might just not be able to keep up.
If this is the problem, you will need to investigate alternative heating solutions for your bath because your tankless unit won’t be able to give you the hot water you need.
Identify the problem early
Often, the most important thing you can do is to identify the problem early and take steps to rectify it. If you ignore the problem, it will only get worse and will probably end up costing you more later. And with this guide, now you have a good idea of where to start looking.