Does your tankless water heater need an expansion tank? the ultimate guide
What To Know
- If the tankless water heater is used in a low-flow application, such as a single bathroom or kitchen, the volume expansion may be negligible and not require an expansion tank.
- If the tankless water heater is installed in an open system, where the hot water is not fully enclosed, the pressure buildup may be minimal and not warrant an expansion tank.
- The installation of an expansion tank with a tankless water heater is generally recommended by manufacturers to protect the unit from pressure surges caused by water expansion.
The question of whether a tankless water heater requires an expansion tank is a common one among homeowners considering this energy-efficient option. In this comprehensive blog post, we will delve into the intricacies of tankless water heaters and explore the role of expansion tanks in their systems.
Understanding Tankless Water Heaters
Tankless water heaters, unlike traditional tank-type heaters, provide hot water on demand without the need for a storage tank. As water flows through the unit, it is heated instantaneously, eliminating the energy loss associated with storing hot water. This results in significant savings on utility bills and a smaller environmental footprint.
Expansion Tanks: Purpose and Function
Expansion tanks are vessels designed to accommodate the volume expansion of water as it heats up. When water is heated, it expands, increasing its volume. In a closed system, such as a tankless water heater, this expansion can create excessive pressure, potentially damaging the unit.
The Need for Expansion Tanks in Tankless Water Heaters
While tankless water heaters do not have a storage tank, they still experience volume expansion of water during operation. This expansion can create pressure surges that can shorten the lifespan of the unit and compromise its performance.
Therefore, many manufacturers recommend installing an expansion tank with a tankless water heater to absorb the pressure caused by water expansion. An expansion tank acts as a buffer, accommodating the increased volume of water and preventing excessive pressure buildup.
Types of Expansion Tanks
There are two main types of expansion tanks used with tankless water heaters:
- Diaphragm-Type Expansion Tanks: These tanks have a rubber diaphragm that separates the water from the air inside the tank. As water expands, it pushes against the diaphragm, compressing the air and absorbing the pressure.
- Bladder-Type Expansion Tanks: These tanks have a flexible bladder that fills with water as it expands. The bladder is surrounded by a pressurized gas, which helps to maintain a constant pressure in the system.
Sizing and Installation of Expansion Tanks
The size of the expansion tank required for a tankless water heater depends on the maximum flow rate and temperature rise of the unit. The manufacturer’s specifications will typically provide guidance on the appropriate tank size.
Proper installation of the expansion tank is crucial to ensure its effectiveness. The tank should be connected to the cold water supply line before the water heater and to the hot water outlet line after the heater. It should be mounted vertically and secured to a stable surface.
Benefits of Installing an Expansion Tank
Installing an expansion tank with a tankless water heater offers several benefits, including:
- Extended Unit Lifespan: By absorbing pressure surges, expansion tanks reduce strain on the tankless water heater, extending its service life.
- Improved Performance: Expansion tanks help to maintain a consistent water pressure, preventing fluctuations that can affect the performance of the water heater.
- Warranty Protection: Some manufacturers require the installation of an expansion tank to validate the warranty of their tankless water heaters.
Exceptions to the Rule
In certain cases, an expansion tank may not be necessary for a tankless water heater. These exceptions include:
- Low-Flow Applications: If the tankless water heater is used in a low-flow application, such as a single bathroom or kitchen, the volume expansion may be negligible and not require an expansion tank.
- Open Systems: If the tankless water heater is installed in an open system, where the hot water is not fully enclosed, the pressure buildup may be minimal and not warrant an expansion tank.
Conclusion
The installation of an expansion tank with a tankless water heater is generally recommended by manufacturers to protect the unit from pressure surges caused by water expansion. By absorbing these pressure fluctuations, expansion tanks extend the lifespan of the water heater, improve its performance, and ensure warranty coverage. However, in certain low-flow or open system applications, an expansion tank may not be necessary.
Frequently Asked Questions (FAQs)
Q: Can I install an expansion tank with an existing tankless water heater?
A: Yes, you can install an expansion tank with an existing tankless water heater. However, it is important to consult the manufacturer’s instructions for proper installation.
Q: How often should I inspect my expansion tank?
A: It is recommended to inspect your expansion tank annually to ensure it is functioning properly. Check for any leaks, corrosion, or damage to the tank or its connections.
Q: What happens if my expansion tank fails?
A: If your expansion tank fails, it may not be able to absorb pressure surges, leading to excessive pressure buildup in the tankless water heater. This can damage the unit and compromise its performance.
