Whether it is due to natural causes or due to a conscious effort to cut the water supply, there are a multitude of situations where combi boilers need to function without a water supply. This causes a lot of concern for property owners, and many wonder if it is safe, and, if not, what steps they can take to protect their combi boilers from harm.
This article will act as your guide to handling your boiler when it lacks access to hot water - from causes to tips and more: it contains everything you need to know.
How Does the Lack of Water Supply Affect Combi Boilers?
Most modern combi boilers feature a sealed water circuit, meaning that water circulated through the system in a closed loop, and the system is somewhat self-sufficient even if new water supply isn't introduced to it.
Of course, this doesn't mean that a boiler system can function without a water supply, not in the long-term at least. Whether it is using water for domestic purposes, leaks, or evaporation, the existing water supply in the system will slowly start to dwindle and affect the system.
This has a variety of side effects, among which are:
- Lowering the pressure inside the boiler system: A high water supply is needed to maintain the pressure throughout the heating system. Pressure is not only needed to keep the water flowing, but some subsystems like underfloor heating require high-pressure and circulation to function.
- Causing temperature rises: Without the introduction of fresh supply from the cold water supply tank, the existing water circulating throughout the heating system is in danger of overheating as more energy is introduced to the system. This is why lowering the energy output or turning off the boiler might be warranted if you notice a rise in temperatures.
- It will affect system stability: If the system continues to experience a lack of stable access to water, it will eventually affect critical system functions as there simply won't be enough water left in the storage tank to properly circulate it throughout the system. At this stage, the boiler system is incapable of providing any heating, and property owners run the risk of incidents if they continue operating the boiler.
These scenarios are all incredibly unlikely and only occur if water supply to the central heating system has been cut for prolonged periods, so while it is vital to be aware of the risks, it is also important to keep in mind that these side effects are extremely unlikely and can largely be averted through proper effort and maintenance. And as we'll explore in the next section, there are valid and important reasons to consciously cut water supply from the system boiler.
What Are the Reasons to Cut Water Supply from a Boiler?
- Due to the existence of Leaks: Are there water leaks in the central heating system? To assess the damage and conduct repairs, you need to turn off the water supply temporarily. If the leak is between the cold water storage tank and the central heating boiler and not within the system itself, the boiler can continue functioning and provide heating while you conduct repairs.
- High pressure or air pockets in the system: Is the mains pressure too high? Are there air pockets in the immersion heaters? Cutting off water supply from a combi or conventional boiler is an excellent way to release pressure from the system and ensure it continues working efficiently.
- Performing regular maintenance: Performing regular maintenance is a crucial part of ensuring the efficiency, durability, and longevity of a combi boiler central heating system. Whether you want to inspect the heat exchanger or the cold water supply tank, cutting off the hot water supply will be a necessary part of the process.
- Moving the boiler: The relocation of the boiler isn't possible if there is sufficient supplies of water in it. Not only does the presence of water make the boiler heavier and more wobbly, but it makes it more vulnerable to accidents as well. Cutting off the water supply is a must before you move a boiler!
Tips to Maintain Combi Boilers When There's No Water Supply
Whether it is due to natural causes or repairs, if your central heating boiler has no access to fresh supplies of hot water, there are effective and reliable steps you can take to ensure your boiler continues working efficiently in the meantime until the issue is fixed:
Constantly monitor the mains pressure of the system
The best way to monitor the water level throughout the system and check the system stability is by keeping track of the main's pressure. Whether it is due to the use of hot tap water, evaporation, or leaks, water levels inside the system will progressively dwindle, and this will be reflected in the water pressure gauge.
Check temperatures throughout the system
When the heating system has no access to water supply, you need to constantly monitor the temperature throughout the heating system, starting from the hot water cylinder. Without the introduction of new cold water to the system, the boiler turns into a closed circuit, and when energy is constantly being introduced to a closed circuit, it increases the likelihood of evaporation and overheating. In extreme circumstances, you are even running the risk of running the storage tank dry.
Enable heat-only mode
Barring external interference or systemic issues, the water level within a central heating system can stay consistent for a long time without supplies pressurised cold water. This isn't true, however, is hot water produced by the system is still connected to taps throughout the property. This will quickly deplete the water inside the system and make it functional. This is why it is absolutely vital you use the boiler in "heat-only" mode until the supplies of cold water are restored to the system.
Using a Combi Boiler When Water Supply Is Off FAQ
Can You Use a Boiler When There's No Water Supply?
The short answer is yes. Combi boilers feature a closed circuit, which, barring a water leak or other extrenious circumstances, can function without the introduction of any additional water from a cold water storage tank. However, in the long term, due to evaporation and water loss, the system will experience lower water pressure, higher temperatures, and instability.