Best Indirect Fired Water Heaters for Homeowners
Indirect fired water heaters use your home’s boiler to generate domestic hot water, offering efficiency and reliable supply for homes with multiple bathrooms or larger hot-water needs. This guide highlights five relevant products and helps you choose the right option based on size, construction, and application. The selections favor systems that suit households with higher hot-water demands or where a boiler-based indirect setup is already in place. The buyer-friendly table below summarizes key points for quick comparison.
| Product | Best For | Why It Stands Out |
|---|---|---|
| Triangle Tube SMART40 Phase III Indirect 36-Gallon Water Heater | Medium homes with boiler-based systems | Tank-in-Tank design and strong insulation for efficient hot water |
| Crown MS2-50 Mega Stor Vertical Indirect Water Heater | Homes needing robust standby heat | Stainless steel tank and heat exchanger; good insulation |
| Rheem PROE50 M2 RH95 50-Gallon Professional Classic | Roaming replacement in boiler zones | Electric model; compact footprint; reliable Rheem brand |
| Immersion Water Heater Electric, Portable | Supplemental or travel use | Submersible option for buckets, tubs, or camping setups |
| Tankless Electric Options (Under Sink) | Point-of-use hot water | Compact, instant hot water with safety features |
Triangle Tube SMART40 Phase III Indirect 36-Gallon Water Heater
The Triangle Tube SMART40 Phase III is an indirect-fired water heater designed to work with a home’s boiler to provide domestic hot water. It features a Tank-in-Tank technology approach paired with 2 inches of polyurethane foam insulation to reduce standby heat loss. This model is best for households that want efficient, cost-conscious DHW from an existing boiler system and can benefit from a 36-gallon capacity for mixed showering and faucet use. The design emphasizes long-delayed recovery and consistent hot water delivery during peak demand.
Who it’s best for: buyers with an established boiler or combi system seeking reliable indirect heating and moderate storage capacity. Why chosen: the exclusive Tank-in-Tank concept can help minimize heat loss while delivering consistent output. Caution: installation and performance depend on boiler size and system design; ensure compatible piping and zoning before purchase.
Crown MS2-50 Mega Stor Vertical Indirect Water Heater
The Crown MS2-50 Mega Stor is a vertical indirect water heater designed for larger households or boiler-based installations. The tank and heat exchanger use 444 stainless steel, offering corrosion resistance and durability. Its superior insulation helps it retain hot water during standby periods, and adjustable feet assist with leveling on uneven floors. Best for homes where long standby storage and robust materials matter. This unit is a solid choice when a vertical indirect tank is preferred for ease of installation within an existing boiler loop.
Who it’s best for: homes needing durable materials and better insulation for standby hot water. Why chosen: stainless steel components extend life in humid boiler environments. Caution: like other indirect systems, it relies on a compatible boiler loop and proper plumbing; additional fittings may be required for exact boiler compatibility.
Rheem PROE50 M2 RH95 50-Gallon Professional Classic Electric
This model from Rheem is an electric storage water heater with 50 gallons of capacity. Although not an indirect-fired unit, it is included here as a compatible alternative when a boiler-based indirect system isn’t feasible and the home relies on electric resistance heating. It’s suitable for larger households with multi-bath scenarios and tight spaces because it offers a compact footprint relative to its capacity. Best for: homes that need a reliable electric storage solution in kitchens or utility rooms. Caution: not an indirect-fired product; performance depends on electrical capacity and local codes.
Tankless Water Heater Electric 110V, 3000W Under Sink
This is an electric tankless option intended for under-sink use. It can deliver on-demand hot water with a 3000W rating and features an LED or digital display, with safety protections like water isolation and IPX4 waterproofing. Best for point-of-use needs where space is at a premium and you want immediate hot water at the sink or a small kitchenette. Caution: not suitable for whole-house hot water; flow rates can be limited, especially if multiple outlets run simultaneously.
Immersion Water Heater Electric, Portable Bucket Heater
The Eaakkoom immersion heater is a portable, submersible option suitable for buckets, camping setups, or temporary hot-water needs. It uses a 304 stainless steel construction and includes safety features like automatic cutoff at 165°F. Best for short-term or auxiliary applications where you need quick hot water in a non-permanent container. Caution: purely portable; not designed for household hot-water heating or continuous use in a fixed plumbing system.
Rheem 11kW 240V Tankless Electric
This Rheem tankless electric unit provides on-demand hot water with a self-modulating power control and a digital temperature display. While not an indirect-fired product, it offers a high-flow option for homes that prefer on-demand electric heating without storage. Best for households aiming to reduce space usage while delivering consistent hot water for common-use baths and sinks. Caution: electric tankless systems require proper sizing for peak flow, and installation should consider electrical service capacity.
Tankless Electric Under Sink 110V Mini
A compact under-sink tankless heater with digital display, designed for quick hot water at the point of use. It’s a practical option for kitchens, RVs, or small apartments seeking immediate hot water without a full-size heater. Best for: space-constrained setups needing localized hot water. Caution: not suitable for shower or high-flow needs where larger GPM is required.
Buying Guide: Key Purchase Considerations
- Indirect system compatibility: Is your home’s boiler compatible with an indirect-fired heater, and does the system have appropriate plumbing, zoning, and heat exchanger loops?
- Capacity needs: How many bathrooms or simultaneous hot-water demands exist? Indirect systems vary from 36 to 50 gallons in standard configurations.
- Insulation and standby loss: Look for advanced insulation to minimize heat loss during standby periods and improve overall efficiency.
- Material durability: Stainless steel components resist corrosion in boiler environments; consider tank-and-exchanger materials that align with water chemistry.
- Space and installation: Vertical tanks may require more floor space; confirm clearance and venting requirements for the boiler room.
- Electrical versus gas boiler integration: If your home uses electric resistance heating for indirect units, ensure electrical capacity and code compliance.
- Cost of ownership: Indirect-fired systems can reduce operating costs when paired with an efficient boiler; weigh initial installation against long-term savings.
- Safety features: Look for protective features like leak protection, dry burn protection, and temperature controls for all options.
Frequently Asked Questions
- What is an indirect fired water heater?
An indirect fired water heater uses a boiler to heat water stored in a separate tank, providing domestic hot water without a dedicated gas or electric burner.
- Who should consider an indirect water heater?
Homeowners with a compatible boiler system looking for energy efficiency and reliable hot water, especially in larger homes with multiple bathrooms.
- What capacity is typical for indirect systems?
Common options include 36 and 50 gallons, chosen based on household hot-water demand and boiler output.
- Can I upgrade to an electric tankless unit instead of indirect?
Yes, if your home layout and electrical service support on-demand electric heating and you don’t rely on boiler-based DHW.
- Are indirect systems more expensive to install?
Initial installation can be higher, but operating costs may be lower with efficient boilers and longer equipment life.
- Do indirect heaters require special maintenance?
Maintenance typically involves boiler servicing and periodic checks of the indirect tank’s insulation and connections.