Best Indirect Water Heater Review in 2021 – New Guide

Best Indirect Water Heater Review

LAST UPDATED: January 13th, 2021

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Hot water is a necessity not only during the months of winter but all year round. It is key for some people’s health, while it is merely comfort for others. Hence, it is important to have a water heater that will serve you for years on end.

For those looking to install or replace a water heating system, it can be confusing and tiring to go through all the products available to make the perfect pick. That is why we have created a refined list of the best indirect water heater depending on different factors such as price, capacity, and so on.

Best Indirect Water Heater Comparison in 2021

Last update on 2021-04-17 / Affiliate links / Images from Amazon Product Advertising API

Best Indirect Water Heater Review in 2021

As always, only the best options on the market have made it to our list! One of these systems is bound to strike your fancy as service all your requirements.

Burnham AL35SL Alliance SL Hydrastone-Lined

Burnham AL35SL Alliance SL Hydrastone-Lined

The truly unique feature of this water heater is the hydrastone lining. Though it is not a new concept, it is still one of the most effective technologies available. Hydrastone lining makes the water healthy for use and consumption and elongates the service life of the water heater too.

This feature is especially useful for areas where the municipal water supply is acidic. The limestone helps neutralize the water and protect the fittings from any damage. Additionally, the lining makes water inert and non-corrosive, protecting the heater itself from corrosion.

Moreover, the construction and materials utilized for the heater also make this a great pick for environmentally conscious and economic buyers. How so? The material makes sure the water heats up evenly at all times. As a result, less energy is consumed in uniform heating.

An insulated body prevents heat loss too. High density R-16 insulation results in minimal heat loss, and as a result, more energy does not need to be used to reheat the same volume of water.

In terms of aesthetics, the porcelain surface does not disappoint. However, the benefits of porcelain do not stop here. It also results in easy cleaning and maintenance of the external body of the heater. The exterior is also powder-coated, meaning it is somewhat resistant to staining and tarnishing.

Your purchase will also include a high capacity heating coil. If the coil is maintained and cleaned on a regular basis, it will serve for several years alongside the heater itself. The unit also requires a side-mounted coil that needs to be purchased separately.


  • Indoor installation
  • Easy to install
  • Hydrastone lined for corrosion resistance
  • Porcelain surface, easy cleaning
  • Heating coil included


  • Low capacity
  • Only one size available

Check out: oil boilers review and buying guide.

Triangle Tube SMART80 Phase III Indirect 70-Gallons

Triangle Tube SMART80 Phase III Indirect 70-Gallons

Our fourth pick comes with the much sought after ‘tank in tank’ technology. The heater consists of a boiler that generates hot fluid. This fluid surrounds the main tank, which holds water in order to heat it up. Once the heating cycle is complete, the fluid returns to the boiler to be reheated.

The model also features 2 inches of polyurethane lining, which acts as a great insulator. As a result of this feature, the hot water loses less than 1 degree Celsius of heat every hour. Moreover, a very little amount of energy goes into reheating stored water, thus making the heater energy-efficient.

Cleaning is not a task anyone wants to take up, even more so when it comes to cleaning such intricate and heavy equipment. Luckily for us, this particular indirect water heater is also self-cleaning. It has natural cleaning features that make your life simpler.

But wait – that’s not all. The heater is also self-descaling. Buyers from hard-water areas, rejoice! Your municipal water supply will not result in the premature degradation of your water heater ever again. The heater is also structured with high-quality stainless steel, which fights rust and corrosion.

Steering clear from corrosion also prevents the water in the tank from becoming contaminated, keeping the color, taste, and smell clean.

You must be thinking there’s a catch; there is no way a simple water heater can do so much. Well, there really isn’t. This is truly one of the best purchases you can make. With so many desirable features, this heater is set to serve you for years on end and be worth every penny!


  • Self-cleaning
  • Self-descaling
  • Lowest pressure drop in the industry
  • Polyurethane lining
  • Large capacity


  • Problems with leakage
  • Relatively expensive

Crown MS2-50 Mega Stor Vehicle

Crown MS2-50 Mega Stor Vehicle

Are you willing to make a one-time investment that comes with the guarantee of a very long service life? Our next recommendation is a powerhouse product. Suitable for small to medium families, this particular product offers top-notch, uninterrupted performance. It is truly an investment worth making.

First of all, the heater is made of ‘444 stainless steel’. Confused as to what exactly that means? 444 is one of the highest grades of stainless steel available on the market. It fights corrosion, tarnishing, contamination and is made of a low carbon formula. The material gives the heater superior strength.

To ensure corrosion resistance, the manufacturer only releases robotically welded, passivated, and hydrostatically tests models to the market. In terms of strength, the heater also features a heavy-duty polymer top and bottom to ensure that the body remains crack and abrasion-proof.

A coated steel jacket further boosts the durability of this model. The tank is also insulated heavily to make sure the water does not lose any heat on standby. Insulation also helps save energy on reheating water, and as a result, you end up saving quite a significant amount on utility bills.

Furthermore, the manufacturer recognizes that there may be uneven flooring in areas where you may install such products. Hence, the model comes with adjustable feet to ensure proper installation on uneven floors. Under any condition, the heater will remain steady and stabilized.

Like we promised, this a product worth investing in. The same product is also available in several other sizes, meaning you can still purchase this heater of the same quality if this one exceeds or does not meet your required capacity.


  • Uses 444 stainless steel
  • Superior insulation
  • Heavy-duty polymer top and bottom
  • Crack and abrasion-resistant
  • Available in various sizes


  • Anode rod required
  • Not suitable for larger families or offices

Indoor/Outdoor Hot Water Storage Tank

Our last pick comes with the promise of long-lasting performance. Perfect for families of 2 to 4, the heater has an inner tank made of enamel. Enamel can withstand more heat than stainless steel. Unlike stainless steel, the enamel is not affected by oxygen, making it more suitable for water systems.

The exterior of the heater is constructed with galvanized steel. Galvanized steel is extremely durable and resistive to corrosion. You can install the heater in moist or humid areas without having to worry about the effect it can have on the exterior body.

Corrosion is further reduced by a technique that has been used industry-wide for several years now. The heater comes with a magnesium rod (or anode rod), which further reduces corrosion inside the tank as well. This keeps the water from becoming contaminated too.

A 1.85-inch CFC-free polyurethane lining makes for a great insulator too. Insulation prevents heated water from cooling off when in standby. Further energy is not required to reheat the water in this case, and as a result, you save some money on energy bills and lots of time in reheating purposes.

And the models come with pressure and temperature release valves. These are great safety features more manufacturers should offer. In case of excess pressure build-up or temperature hike, you can simply use the valve to drain the contents of the tank into a pipe embedded in a floor trap through a pipe.

All in all, it is a great water heater for the money. Energy-efficient, sturdily built, offering high functionality and corrosion-resistant, this water heater checks all our boxes!


  • Enamel inner tank, galvanized steel exterior
  • Long-lasting performance
  • CFC-free polyurethane insulation
  • Includes temperature and pressure release valve
  • Anode rod included


  • Not suitable for larger families
  • Anode rod required

Benefits and Drawbacks of Indirect Water Heater

Still, considering whether or not to invest in the product in the discussion? We have compiled some of the biggest benefits, as well as drawbacks, to make sure you are making an informed choice.


  • Low Maintenance: They do not have any additional burners that need to be maintained separately; hence they are easier to install and use as maintenance takes up little to no time.
  • Compact and Easy to Install: These heaters tend to be smaller in size. As a result, they can be fit into more corners of the home than their traditional counterpart. Installation is also easier and more straightforward on this kind of water heater.
  • Capacity: They use some less space relative to the volume of hot water it can offer at a given time. This makes this particular type of heaters space-efficient.


  • Requires an HVAC System: An existing HVAC system will make these water heaters more effective and efficient. If your house does not have one, but you still want to install an indirect heater, you will have to incur several additional costs for the HVAC.
  • Cost to Conserve: It takes some extent of energy to store gallons of water and to keep it heated. If you are looking to avoid such costs, a tankless, direct water heater may be a better option.

What to Look for Before Buying Indirect Water Heater

What makes them great? And what makes it a failed investment? Keeping in mind capacity, utility bills, strength, and so on, we have compiled for you this comprehensive buying guide.


First and foremost, you need to start paying attention to the amount of water being used in your home or office every day before making a choice. 35-50 gallon heaters are likely to suffice for single occupancy homes, given that a single shower takes up to 40 gallons of water.
For medium to larger families, 50 to 70 gallons tend to be standard. If you are purchasing heaters for an office space or such, you would be better off investing in models that offer 80-100 gallons of hot water at a time to prevent the risk of running out.

Energy Consumption

Higher capacity does not automatically mean higher energy consumption – and this is something you should pay close attention to before checking out. Look out for models that offer the highest capacity while making the most efficient use of energy. This way, you can avoid experiencing a hike in your utility bills.

Drain Valves

Most people are likely to look into the body of the heater; as a result, that is the point where manufacturers invest in attracting consumers with great materials. However, you should also pay attention to the smaller parts, such as the drain valves.
Look for models with brass drain valves. These last longer than their plastic counterparts. As a result, your overall water heater experiences a boost in its service life.

Build Material

Stainless steel usually makes for the most corrosion-resistant heaters. Anti-corrosion is a key feature your heater must have as handling, heating and holding large amounts of water can make any cheaply built unit disintegrate prematurely.
Welded or molded units are also more likely to be stronger and leak proof. Leak proofing is necessary for all models but even more so for those with large capacity.

Frequently Asked Questions

It is normal for buyers to have several questions to help solidify their decisions. That is why we have taken it upon ourselves to answer some of the most common queries regarding the topic.

How much does an indirect water heater cost to purchase?

They can cost between $800 and $1500. However, for capacities larger than 70 gallons, you may have to invest a bit more. The more capacity a model promises, the stronger the build and quality on the heater needs to be. As a result, they tend to be more expensive.

For single occupancy homes or those with up to three occupants, $1000 will fetch you water heaters with ample capacity, great build, and long service life.

Can the system be installed without a professional visit?

There are several models on the market that are geared towards DIY installation, so it is not entirely impossible. More complicated models that require professional installation will explicitly say so.

Tankless vs. Tank Water Heater: Which one is a better pick?

The verdict on this question is not black or white – it simply depends on each buyer’s demands and requirements from their purchase. Tankless water heaters can last up to 20 years, while tank heaters promise up to 15 years. Tankless units also take up less space, so overall it may seem better.

However, tankless heaters also have higher upfront installation costs due to the necessity of additional equipment and materials. The installation also takes longer and is more costly for a tankless heater.
So, all of it really comes down to how much time, energy, money, and elbow grease you are willing to put towards a hot shower.

How long does an indirect water heater last on average?

An indirect water heating system can be expected to last a minimum of ten years. Anything below that indicates cheap build quality and several other technical issues. On average, indirect heaters usually need replacement after 12 years of constant service.

How do I pick the right capacity for my home and usage rate?

The solution is simply to monitor your usage. However, it is not easy to guess the amount of water being used in a day. In that case, you can use several guides available online to match the number of occupants as well as activities being done regularly to estimate how much water is needed per day.

Final Words

As discussed before, instant hot water may be a luxury or even a necessity. Whichever it may be, the choice in heating systems is not an easy one to make. We hope that this article will help you make all the necessary considerations and purchase the best indirect water heater for catering to all your needs.

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