Indirect tank water heaters use your home’s boiler or another heat source to warm a storage tank, delivering dependable hot water with minimal energy waste. This guide focuses on top indirect-fired options and practical alternatives for households seeking reliable, space-efficient water heating. Best for homeowners upgrading older systems, those with existing boilers, or anyone prioritizing steady supply and reduced standby heat loss. Below is a quick comparison table of five relevant products to help you choose quickly.
| Product | Type | Best For |
|---|---|---|
| Triangle Smart 60 Indirect Fired Storage Tank | Indirect Fired | Homes with space to store hot water; boiler users |
| Burnham AL35SL Alliance SL Hydrastone-Lined Indirect-Fired Water Heater, 35 gal | Indirect Fired | Compact installs; renovations using Hydrastone lining |
| Rheem PROE50 M2 RH95 50-Gallon Professional Classic Electric Water Heater | Electric | Smaller homes needing an electric option |
| MIZUDO Natural Gas Tankless Water Heater | Tankless Gas | High flow, on-demand hot water |
| VEVOR Electric Water Heater, 18 Gallon | Electric | Compact, on-demand for limited spaces |
Triangle Smart 60 Indirect Fired Storage Tank
The Triangle Smart 60 Indirect Fired Storage Tank is designed for homes with existing boilers, offering a dependable stored hot water supply via indirect heating. Best for households with moderate hot-water demand and space for a larger tank, this model prioritizes energy efficiency by using your boiler as the heat source rather than running a separate electric element. A good pick for retrofit projects where boiler compatibility and improved recovery time matter most. Caution: ensure your boiler can adequately support the indirect storage heater’s demand without overloading the system.
Burnham AL35SL Alliance SL Hydrastone-Lined Indirect-Fired Water Heater, 35 gal
The Burnham AL35SL is an indirect-fired water heater with a Hydrastone lining for added durability. It suits homes needing a compact 35-gallon tank without sacrificing reliability. Best for smaller households or replacements in tight spaces where a larger indirect tank isn’t feasible. Its indirect design leverages your boiler to heat stored water, reducing standby energy loss. Limitation: smaller capacity may require more frequent reheating if hot-water draw is high throughout the day.
Rheem PROE50 M2 RH95 50-Gallon Electric Water Heater
Rheem’s PROE50 M2 RH95 is a 50-gallon electric model offering reliable hot water for families of 3–5 with multiple bathrooms. Best for homes without an existing boiler or when a dedicated electric heater is preferred during boiler downtime. It’s a space-efficient option that can be easier to install where gas lines are not available. Caution: electric-only systems may be less efficient in some climates compared with indirect systems that reuse boiler heat.
MIZUDO Natural Gas Tankless Water Heater
The MIZUDO gas tankless unit provides on-demand hot water with high flow, suitable for homes with multiple outlets and higher simultaneous demand. Best for busy households needing quick recovery and minimal standby airspace. It’s a different approach than indirect storage but useful when you want continuous hot water without tank storage. Limitation: tankless systems require proper venting and careful sizing to avoid undersupply during peak demand.
VEVOR Electric Water Heater, 18 Gallon
The VEVOR 18-gallon electric unit offers compact storage with 1.6 kW heating. Best for homes with limited space or as a supplementary heater to support low demand periods. It uses electric heating elements and is easy to install where gas is not available. Caution: smaller capacity may require more frequent cycling during peak usage.
Buying Guide
Key considerations for indirect tank water heaters and closely related options:
- System compatibility: Indirect models work with existing boilers. Verify boiler capacity and repair history before choosing an indirect tank.
- Capacity needs: For households with 3–5 people, 35–50 gallons is common. Larger homes may require bigger indirect tanks or multiple storage tanks.
- Heat source efficiency: Indirect tanks rely on the boiler. If the boiler is inefficient, overall savings may be limit. Consider boiler performance and standby loss.
- Space and installation: Indirect tanks are bulkier than some electric or tankless options. Measure space and assess ventilation, access, and service clearances.
- Energy costs and climate: Indirect systems can reduce standby heat loss, especially in colder climates where maintaining hot water is energy-intensive.
- Maintenance needs: Hydrastone linings or other protective materials can extend life but require periodic inspection for signs of wear or corrosion.
- Electrical and gas considerations: Electric models avoid gas lines, while gas-fired systems require proper venting and gas supply checks.
Frequently Asked Questions
- What is an indirect tank water heater?
An indirect tank water heater uses a boiler or another heat source to warm water stored in a tank, rather than heating water directly with its own burner or electric element.
- How do indirect tanks save energy?
They reduce standby heat loss because the primary heat source is centralized and can be more efficient when modulating boiler output to meet demand.
- Which homes are best suited for indirect systems?
Homes with existing boilers or combined heating systems, and those seeking steady hot water with a smaller energy footprint.
- Can I use an indirect tank with a gas boiler?
Yes, indirect tanks are commonly paired with gas boilers, using the boiler to heat stored water in the tank.
- What should I consider when sizing an indirect tank?
Assess peak daily hot-water usage, number of bathrooms, and whether the boiler can maintain temperature without excessive cycling.