Tankless water heater expansion tank: essential or not? find out now!
What To Know
- An expansion tank is a device that absorbs the excess pressure created by the thermal expansion of water in a closed plumbing system.
- Instead of storing a large volume of hot water in a tank, tankless units heat water on demand as it flows through the unit.
- Even in areas where codes do not mandate it, an expansion tank is highly recommended to protect the plumbing system and extend the life of the water heater.
When it comes to tankless water heaters, one common question that arises is whether they require an expansion tank. Expansion tanks play a crucial role in traditional water heater systems, but their necessity in tankless setups is often debated. In this comprehensive guide, we will delve into the intricacies of tankless water heater operation and explore whether an expansion tank is a vital component.
What is an Expansion Tank?
An expansion tank is a device that absorbs the excess pressure created by the thermal expansion of water in a closed plumbing system. As water heats up, it expands in volume, which can lead to a dangerous buildup of pressure. Expansion tanks provide a buffer space for the expanded water, preventing it from damaging the plumbing system or causing leaks.
How Do Tankless Water Heaters Work?
Tankless water heaters operate on a different principle than traditional storage-tank water heaters. Instead of storing a large volume of hot water in a tank, tankless units heat water on demand as it flows through the unit. This eliminates the need for a storage tank and reduces standby heat loss.
Do Tankless Water Heaters Need Expansion Tanks?
The answer to this question depends on several factors, including the type of tankless water heater, the plumbing system configuration, and local building codes.
Open-Loop Systems
In open-loop systems, cold water enters the tankless water heater directly from the main water supply. As the water heats up, it expands and flows out of the unit into the plumbing system. Since the system is open to the atmosphere, the excess pressure can be released through the open vent. In this case, an expansion tank is not necessary.
Closed-Loop Systems
In closed-loop systems, the water is circulated through a loop of pipes that includes the tankless water heater. As the water heats up, it expands and increases the pressure in the loop. If the system is not equipped with an expansion tank, this pressure buildup can damage pipes, fixtures, and the water heater itself.
When is an Expansion Tank Required?
Local building codes may require the installation of an expansion tank for all closed-loop tankless water heater systems. Even in areas where codes do not mandate it, an expansion tank is highly recommended to protect the plumbing system and extend the life of the water heater.
Types of Expansion Tanks
There are two main types of expansion tanks used in tankless water heater systems:
- Bladder-Type Expansion Tanks: These tanks have a rubber bladder inside that separates the water from the pressurized air.
- Diaphragm-Type Expansion Tanks: These tanks use a diaphragm to separate the water from the air.
Sizing an Expansion Tank
The size of the expansion tank required for a tankless water heater depends on several factors, including:
- The flow rate of the water heater
- The temperature rise of the water
- The volume of the plumbing system
Installing an Expansion Tank
Installing an expansion tank for a tankless water heater is a relatively straightforward process that can be performed by a qualified plumber. The tank is typically installed on the cold water inlet line, close to the water heater.
Benefits of Using an Expansion Tank
Using an expansion tank with a tankless water heater offers several benefits:
- Protects the plumbing system from excessive pressure
- Extends the life of the water heater
- Reduces the risk of leaks and damage
- Complies with local building codes
Final Note: The Importance of Expansion Tanks for Tankless Water Heaters
While not always required by building codes, an expansion tank is a valuable addition to any closed-loop tankless water heater system. By absorbing excess pressure, expansion tanks protect the plumbing system, extend the life of the water heater, and provide peace of mind. When considering a tankless water heater installation, it is highly recommended to include an expansion tank as part of the system.
Frequently Asked Questions
1. Can I install an expansion tank myself?
While it is possible to install an expansion tank yourself, it is recommended to have a qualified plumber perform the installation to ensure proper sizing and connection.
2. What is the lifespan of an expansion tank?
Expansion tanks typically last for 5-10 years. It is important to have the tank inspected and replaced as needed.
3. How often should I check the expansion tank?
It is recommended to check the expansion tank annually to ensure it is functioning properly. Check the water pressure and inspect the tank for any leaks or damage.
