Ultimate List of 35-50 Gallon Indirect Water Heaters!

One of the most energy-efficient means of heating water today are indirect water heaters. These large tanks of water deliver hot water all year round. Once, these unit were large and clumsy and needed a lot of attention, but with the ever-increasing efficiency of modern technology, indirect water heaters are becoming more unobtrusive and reliable. Although, whenever one does break down you are reliant on a professional to come and fix them.

Photo	Product	Capacity	Size	Details
	HTP SSU45 SuperStor Ultra	45gal	39.25”x20”D	View on Amazon
	Rheem MTS50200 Marathon	50gal	52.5”x23.5”D	View on Amazon
	Burnham AL35SL Alliance	35gal	39.25”x20”D	View on Amazon
	Weil-McLain 633500001 Aqua Plus Pewter	39.9gal	46¼”x21 7/8”D	View on Amazon
	Crown MS2-50 Mega Stor	50gal	49¾”x23½”	View on Amazon
	GMO Indirect Water Heater	40gal	59.68”x20.47”D	View on Amazon
	Lochinvar EGS040	40gal	41.25”x22”D	View on Amazon
	Amtrol HM-41Z	41gal	55”x22”D	View on Amazon
	Triangle Tube SMART80 Phase IIIr	70gal	61”x46”D	View on Amazon
	Dunkirk H2Oi40DK	40gal	44”x232.5”D	View on Amazon
	HTP PH76-60 Phoenix	60gal	54.75”x23”D	View on Amazon
	HTP RGH-75F	20gal	38.6”x21”	View on Amazon

Since the installation of a water heater is a technical issue, where you have to consider all the cumulative piping and levels for delivering the water, the size and power of the unit you need has to match the demands that the system will place on it. This guide will provide you with the top 12 indirect heating unit brands that we found were suitable for most average-sized homes.

What we looked for in these systems is capacity, water pressure in GPH and size.

Here are 35-50 Gallon indirect water heaters

1. HTP SSU45 SuperStor Ultra Stainless Steel Water Storage Tank 45 Gallons

Introduction

This is the HTP Superstor 45-gallon single-coil model; it comes in a 316L stainless steel tank that resists corrosion. There are 4 Sizes Available, and all have the HTP high output finned, cupronickel heat Exchanger that comes with 11 Fins per inch.

Tank Capacity: 45 Gallons

Continuous Draw: 212 @ 141^oF

Dimensions: 52.5” x 19.25”D
 

 

2. Rheem MTS50200 Marathon 50–Gallon Tall Thermal Storage Tank

Introduction

The Marathon® thermal electric storage tanks were specifically designed for installation as a thermal storage tank and come with a backup electrical element that provides over 40 gallons of heated water. The unit also incorporates large water connections for lower pressure drops. This model uses a seamless, blow-molded, polybutene tank which is impervious to rust and corrosion.

Tank Capacity: 50 gallons

Dimensions: 52.5” x 23.5”D
 

 

3. Burnham AL35SL Alliance SL Hydrastone-Lined Indirect-Fired Water Heater, 35 gal

Introduction

The Alliance SL uses a stone interior, what they call hydra stone. This lining absorbs water and then removes all the oxygen pockets over a short period of time, rendering the water inert. This retained water within the stone acts as both a heat barrier as well as an anti-corrosion protection.

Essentially what you get is a more efficient heat preservation process that saves on money, the large layer of high-density R-16 (hydra stone) insulation leads the system to lose less than 1^oF per hour

Tank Capacity: 35 gallons

Continuous Draw: 162GHP @ 135^oF

Dimensions: 39.25” x 20”D
 

 

4. Weil-McLain 633500001 Aqua Plus Pewter Indirect-Fired Water Heater, 39.9 gal

Introduction

The Weil-McLain316L stainless steel tank is a single coil tank with the standard temperature and pressure relief valves and a thermostat connection already installed for fast wiring. These tanks have magnesium anodes installed, and all their wiring and connections are placed on the side for ease of access.

Tank Capacity: 39.9 Gallons

Continuous Draw:  335GPH @ 190^oF

Dimensions:  46 ¼” x 21 7/8”D
Manual PDF
 

 

5. Crown MS2-50 Mega Stor Vertical Indirect Water Heater

Introduction

The Mega-Stor II is a stainless-steel, indirect water heater that uses a Honeywell L4080B adjustable aquastat.  This model comes with a removable inspection cap on the top and on the front which can be opened for viewing inside the tank and coil. It comes with a drain at the bottom for flushing sediment from the tank. The Mega-Stor tank is insulated with 2” polystyrene foam minimizing standby heat loss.

Tank Capacity: 50 gallons

Continuous Draw: 193GPH

Dimensions: 49 ¾” x 23 ½”
 

 

6. GMO Indirect Water Heater 40 Gallon – Enamel – 1 Coil

Introduction

The GMO one coil indirect water heater contains 40 Gallons in an enamel-coated container with 50 mm thickness of insulation. The heating element is made of a highly resistant Incoloy 840, and this unit incorporates the Emerson 59T66T thermostat with a Watts T/P Valve.

Tank Capacity: 40 gallons

Dimensions: 59.68” x 20.47”D.
Data Sheet PDF

Video

 

 

7. Lochinvar EGS040 Double Wall Energy Saver Indirect Water Heater

Introduction

The Lochinvar Energy Saver is an indirect-fired, potable water storage vessel. It comes with Non-CFC foam insulation covering the tank with a 2″ thick blanket of insulating foam. This non-CFC polyurethane closed-cell foam reduces standby losses of heat to the minimum, thereby maximizing heat retention.

This is a glass-lined steel tank; the glass lining is fused to the tank interior at 1600°F assuring lasting protection against rust and corrosion. The Anodes are aluminum, so they are naturally protected from electrolytic corrosion.

Tank Capacity: 40 gallons

Continuous Draw: 210GPH @ 140^o

Dimensions: 41.25” x 22” D
Spec. sheet PDF

 

 

8. Amtrol HM-41Z Top Down Boiler Mate

Introduction

This is the Amtrol 41-gallon BoilerMax indirect water heating unit that is made of a steel outer shell with an internal Bimodal High-Density Polyethylene (HDPE) bottle. The insulation is a molded urethane over inner and outer shells. The heat exchanger is Finned Construction; Hi-Delta TBimodal HPDE Poly Bottle.

This brand provides twice the strength of traditional constructed models and is easy to install. It is also easily removable for cleaning and servicing.

Tank Capacity: 41 gallons

Continuous Draw: 173GPH

Dimensions: 55” x 22”D
Brochure PDF
Installation Manual PDF
 

 

9. Triangle Tube SMART80 Phase III Indirect 70-Gallons Water Heater

Introduction

This double tank Stainless Steel Indirect Fired Water Heater is heated by the hot water from your boiler. This means that you heat your domestic water as your home is being heated as well. This model comes with a 2″ Polyurethane Foam insulation and heats up3 Times faster than conventional gas or electric water heaters. The heat exchange is also Self-cleaning and self-descaling.

Tank Capacity: 70 gallons

Continuous Draw: 400GPH

Dimensions: 61” x 46”D
Manual PDF
 

 

10. Dunkirk H2Oi40DK 40 Gallon Indirect Water Heater

Introduction

Dunkirk’s H2O Stainless Steel Single Coil Indirect Water Heater is a 316L stainless steel constructed unit that holds 40 gallons of water. This model includes a stainless-steel dip tube and a thermoplastic jacket together with 2.25″ EPS Insulation that provides a maximum 0.5F° per hour standby loss.

Tank Capacity: 40 gallons

Continuous Draw: 166GPH @ 140^oF

Dimensions: 44” x 232.5” D
Manual PDF

 

 

11. HTP PH76-60 Phoenix Light Duty High-Efficiency Stainless Steel Gas-Fired Water Heater

Introduction

The Phoenix Light Duty is Energy Star rated for operating at up to a .90 UEF. This unit is made of stainless steel with laser welded joints for extreme precision fabrication. This model comes with 2” PVC, CPVC or ULC S636 pipe and a combined vent length of 150 feet. HTP has in integrated an easy to read LCD (icon and text) display, and the unit provides a 3:1 turndown ratio of 25,000 to 76,000 Btuh.

Tank Capacity: 60 gallons

Continuous Draw: 140GPH

Dimensions: 54.75” x 23”D

 

 

12. HTP RGH-75F High-Efficiency Crossover Hybrid Water Heater

Introduction

This is the HTP natural gas cross-over indirect water heater that combines extra-thick insulation with small water volume storage. It also works in all altitudes and is certified to work up to 10,000’. The tank is stainless steel and comes with a recirculation system and has a NOx combustion system for better safety performance.

While this unit only has a 20-gallon tank, it’s built-in fire tube heat exchanger will heat the water up to 167-degree hot water, and then mixes the delivered temperature down through an ASSE 1017 mixing valve. This feature enables the unit to pour out 40-gallons at the same rate as a standard 50-gallon tank

Tank Capacity: 20 gallons

Continuous Draw: 107GPH

Dimensions: 38.6” x 21”

Manual PDF
 

 
Conclusions

There are many types and models of indirect water tanks; the choice is not personal, it is technical and objective to the house requirements. Unless you are a water professional, we strongly urge you to consult with a water heating professional that can help you decide which of these 12 best indirect water tanks best suits your home water heating needs.