Tank vs. Tankless Water Heater: What should you choose?
Choosing between a tank and a tankless water heater involves balancing upfront costs, energy efficiency, and hot water needs, as both have distinct pros and cons. Tankless units are more efficient and long-lasting, while tank units are less expensive to purchase and install.
Tankless Water Heater
- Pros:
- Energy efficient: They heat water only when needed, leading to lower energy bills.
- Endless hot water: You won’t run out of hot water, even with high demand.
- Space-saving: They are smaller and can be mounted on a wall, freeing up space.
- Longer lifespan: They can last up to 20 years, about twice as long as traditional tanks.
- Cons:
- Higher initial cost: The purchase price and installation can be significantly higher than tank models.
- Maintenance: They require annual flushing and maintenance by a professional to prevent mineral buildup, especially in hard water areas.
- Minimum flow rate: A minimum flow rate is needed to activate the unit, which can be a problem for very low-flow fixtures.
- Hot water delay: There can be a short delay before hot water arrives at the faucet as the unit senses flow and heats the water.
Traditional tank water heaters
- Pros:
- Lower initial cost: They have a lower upfront cost for both the unit and installation.
- Simpler maintenance: They require less frequent maintenance than tankless models.
- Steady hot water: They provide a steady supply of hot water and don’t have a delay, though the amount is limited by the tank size.
- Cons:
- Higher operating costs: They use energy to keep water hot 24/7, which leads to higher energy bills.
- Limited supply: You can run out of hot water if your household has high simultaneous demand.
- Takes up space: The large tank occupies a significant amount of floor space.
- Shorter lifespan: They typically last 10 to 15 years, which is shorter than tankless models.
Comparison of Tank vs. Tankless Water Heaters
| Feature | Tankless Water Heater | Tank Water Heater |
|---|---|---|
| How it works | Heats water on demand as it flows through the unit. | Heats and stores a large volume of water continuously. |
| Hot Water Supply | Unlimited continuous supply of hot water. | Limited by tank capacity; can run out during high demand and requires recovery time. |
| Energy Efficiency | Highly efficient (up to 34% more for low usage homes) as it only uses energy when needed, eliminating standby heat loss. | Less efficient due to standby heat loss, as it constantly reheats stored water. |
| Initial Cost | Higher purchase and installation costs, often requiring electrical/gas line upgrades. | Lower initial purchase and installation costs. |
| Lifespan | Longer lifespan of 15–20+ years, with replaceable parts. | Shorter lifespan of 8–12 years, and tanks are not repairable if they leak. |
| Space | Compact, wall-mounted design saves significant space. | Bulky, requires dedicated floor space. |
| Maintenance | Requires annual descaling/flushing (especially in hard water areas). | Requires occasional flushing to remove sediment and anode rod checks. |
| Simultaneous Use | May struggle with multiple simultaneous high-demand uses (e.g., shower and dishwasher) unless properly sized. | Handles multiple simultaneous demands well until the tank is depleted. |
Key Considerations
- Hot Water Demand: Large households with high, simultaneous hot water demands may find a tank system more consistent, or might need multiple or properly-sized high-flow tankless units to cope.
- Long-Term Value: While the upfront cost of a tankless heater is higher, its greater energy efficiency and longer lifespan can lead to significant long-term savings on utility bills and replacement costs.
- Installation/Infrastructure: Switching from a tank to a tankless unit might involve costly plumbing, gas line, or electrical upgrades, which should be factored into the decision.
- Space: Tankless heaters are an excellent option for homes with limited space, as they can be installed in tight quarters or even outdoors.
- Power Outages: Tank water heaters provide a limited amount of stored hot water during a power outage, while tankless units (gas or electric) will not work without power unless a backup system is in place.