When you turn off the power to your boiler, it can be confusing to find that hot water still flows from your taps. This happens because different types of boilers and hot water systems work in different ways. In this article, we will take a detailed look at combi boilers, water heaters, and immersion heaters, and explain why hot water may still be available even when the boiler is off.
Still getting hot water when boiler is off
The reason hot water may still be available even when the boiler power is off is because of the way different types of boilers and hot water systems work. Combi boilers provide hot water on demand, while water heaters and immersion heaters store hot water in an insulated tank or cylinder.
Combi Boilers
Combi boilers, short for combination boilers, are designed to provide both heating and hot water on demand. This means that they heat water as it passes through the boiler, rather than storing it in a tank. When you turn off the power to a combi boiler, the water that is already in the system will continue to flow through the taps. This is because the water has already been heated and is stored in the pipes, not the boiler.
Water Heaters
Water heaters, on the other hand, store hot water in an insulated tank. The tank is kept at a constant temperature and when the hot water is used, it is replaced by cold water that is then heated. So when the power is off, the hot water in the tank will still be available to be used.
Immersion Heaters
Immersion heaters, typically used in conjunction with a hot water cylinder, work by heating the water directly. The immersion heater is a heating element that is immersed in the water in the cylinder. When the power is turned off, the immersion heater will stop heating the water, but any hot water that has already been heated will remain in the cylinder and be available to use.
It is important to note that the availability of hot water when the boiler power is off depends on the system design and the time since the power was turned off. If the power has been off for a long time, the hot water in the system may have cooled down, and there will be no hot water available.
How can faults make hot water flow when boiler is off?
Faulty wiring or piping can cause issues with your hot water system that may result in hot water still being available even when the boiler power is off.
Some examples of how faulty wiring or piping can cause this include:
Short Circuit
If the wiring in your hot water system is damaged or frayed, it can cause a short circuit. This can result in the hot water being heated even when the boiler is off, as the electrical current is bypassing the control circuit and flowing directly to the heating element.
Leaks
If there are leaks in the piping of your hot water system, it can result in hot water flowing through the taps even when the boiler is off.
This is because the hot water that is already in the system is leaking out of the pipes and into the taps.
Cross-Connections
If the pipes in your hot water system are connected incorrectly, it can result in hot water flowing through the wrong pipes. This can cause hot water to be available even when the boiler is off, as the hot water is flowing from another source (such as a water heater or immersion heater) into the taps.
Stuck Valves
If the valves in your hot water system are stuck in the open position, it can cause hot water to flow through the taps even when the boiler is off.
Faulty wiring and piping can also cause other issues with your hot water system, such as reduced water pressure, no hot water, or even dangerous situations such as leaks or electrical hazards.
If you suspect faulty wiring or piping in your hot water system, it’s important to have it inspected and repaired by a professional as soon as possible.
Assuming power is off to the boiler
There are several situations in which you may assume that the power to your boiler is off, but it is actually still on. Some examples include:
Tripped Circuit Breaker
If the circuit breaker that controls the power to your boiler trips, it will shut off the power to the boiler. However, if the circuit breaker is not reset, the power will not be restored to the boiler, even though the circuit breaker itself is in the “on” position.
Faulty Thermostat
If the thermostat controlling your boiler is faulty, it may not be able to accurately detect when the power to the boiler is off. This can result in the boiler continuing to run even when you think it’s off.
Timer or Scheduling Issues
If you have a timer or scheduling system controlling your boiler, it may continue to run even when you think it’s off. For example, if you have set the timer to turn the boiler off at night, but the timer itself is malfunctioning, the boiler may continue to run.
Power Cut
In cases of power cut, the boiler may have shut off automatically but the generator or battery backup system may have turned it on again.
Remote control
If you have a remote control to turn on and off your boiler, it could be malfunctioning or the batteries may be dead, and you may assume that the power is off while it is still on.
Storage tanks
A storage tank with an internal heater is designed to heat and store hot water, much like a traditional water heater. However, unlike a traditional water heater, a storage tank with an internal heater is typically connected to the boiler and is heated by the boiler’s heating system.
If the internal heater in the storage tank is malfunctioning or is not properly controlled, it can cause the tank to continue heating the water even when the boiler power is off. This can result in hot water still being available from the taps, as the hot water stored in the tank is not being cooled down.
A storage tank with an internal heater can also cause other issues, such as overheating and scalding, if not properly maintained or controlled. If you suspect that the internal heater in your storage tank is causing problems with your hot water system, it’s important to have it inspected and repaired by a professional as soon as possible.
It’s important to check the system settings and the controls of the internal heater if the storage tank is connected to the boiler or if it has its own controls. In case the internal heater is malfunctioning, it’s important to have it repaired by a professional to avoid any potential damage or hazards.
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