Why An Indirect Water Heater May Be Your Best Choice Today

If you’re in the market for a new water heater, you’ve probably noticed the seemingly endless number of available brands and models. But there’s one type – the indirect water heater (also known as a combination system) that’s distinctly different from everything else out there. And given the right circumstances – it could be the optimal solution for you.

Amtrol 41 Gallon WH-7C BoilerMate Classic Series Indirect-Fired Water Heater

Amtrol 41 Gallon WH-7C BoilerMate Classic Series Indirect-Fired Water Heater. See it at Amazon 

Could An Indirect Water Heater Work In Your Home?

An indirect hot water heater offers significant benefits, like lower energy costs and abundant hot water whenever you need it. But it’s not always the best solution due to what’s required to make it happen.

Most of us don’t give a lot of thought to water heaters. That’s probably due to the fact that these appliances are tucked away in the basement or storage room. It may be a case of “out of sight – out of mind”.

Not New – But Gaining In Popularity

Although indirect water heater systems have been around for several decades, only recently have they increased in popularity. This is primarily due to the widespread concern over the environment and rising energy costs. Indirect systems simply use less energy to heat water.

The concept of an indirect or combination water heater system is that you essentially handle two major home functions in one shot – space heating and water heating. The result is that you use less energy, which saves you money.

What Is An Indirect Water Heater Exactly?

Most of today’s water heater models would be considered “direct” water heaters. That is… they require energy (gas, propane, electricity, etc.) directly and function as stand-alone units. Whether they are the traditional tank-style or tankless water heaters.

Indirect water heaters on the other hand tap into the existing energy generated by a boiler or furnace.

An indirect water heater is composed of essentially two main elements. A tank to store hot water plus an external energy source to heat the water in the tank. Both elements combine forces to supply a residential or commercial building with hot water whenever it is needed.

Indirect water heater system
Image from energy.gov

Get Double Duty From Your Furnace

On the outside, the water tank on an indirect fired water heater looks similar to a standard hot water tank. But in this case, the tank on its own isn’t of much use. It needs an external component to heat the water. But when paired with the right kind of boiler or furnace, an indirect hot water heater works beautifully to provide hot water to all your faucets and appliances like washing machines and dishwashers.

The idea behind an indirect system is that it taps into an energy source that you’re already using.
An indirect water heater utilizes a home’s space heating system to also heat the water. Most are surprised to discover that these water heaters have been around for decades. In recent years, they have become increasingly popular. That’s thanks to the improved efficiency and cost savings over the long haul that these combination systems provide.

Heat Transfer

Every indirect water heating system uses a process called “heat transfer” to transmit heat produced by a space heating appliance to the water inside. These water heaters depend on an internal heat exchange coil. It’s this coil design that maximizes the efficient transfer of heat from the boiler to the water in the storage tank. Essentially there’s a closed loop connection of water pipes joining the boiler to the tank, filling it with hot, ready-to-use water. Heat generated by the boiler circulates through the coiled heat exchanger, which in turn heats the water inside the tank.

An indirect water heater is always part of an integrated system and cannot function as a standalone water tank. It requires an appropriate boiler or furnace to serve as the heat source. That’s because the tank itself is not equipped with any kind of heating element. Given the right conditions and equipment, this efficient transfer of heat can work quite well to provide plenty of hot water to meet demand.

Compatible Equipment Required

When it comes to indirect systems, boilers are more common than furnaces as a heat source. The problem is that not all furnaces (or boilers, for that matter) can be used with an indirect water heater tank. The problem is that many furnaces (like forced air systems, for example) are simply not designed to be used to heat water. Those are meant to be deployed as space heaters exclusively. Similarly, older models of boilers may not be suitable either, due to various reasons.

But between the two types, boilers are more effective as indirect water heaters due to the elevated degree of heat they produce. Boilers use steam heating. When deployed as part of an indirect water heater, extremely hot water is sent to circulate through the coils. This heats the water in the tank quickly and efficiently.

So, if you’re thinking of deploying an indirect water heater, it’s important to keep in mind that boilers in general are more likely the better match. Although some furnaces can do the job too.

How Do You Determine The Best Indirect Water Heater?

For the best indirect water heater results – look for a tank that’s built with better insulation. The reason is simple. The purpose of these water tanks is to store pre-heated water.

Readily available hot water from the tank means you would not have to wait for hot water when you turn on the tap.

With more protective insulation, less heat escapes. This in turn saves energy because the water won’t have to be reheated as often.

Amtrol 80 Gallon HM-80LDW HydroMax Indirect-Fired Water Heater w/Double Wall Heat Exchanger (Ener-G-Net)

Amtrol 80 Gallon HM-80LDW HydroMax Indirect-Fired Water Heater w/Double Wall Heat Exchanger (Ener-G-Net). See it at Amazon 

Although an indirect water heater tank looks much the same as a traditional water tank – they are quite different on the inside. The main difference is that there’s no heating element or anode rod inside. This means there are fewer parts to break down or corrode. Which is the primary reason why indirect water heater tanks typically outlasts their standard hot water tank counterparts.

Today’s Boilers Are Better

Boilers are generally designed to be used over the long term – especially those newer models that have a modulating feature. This allows for adjustable settings, so the unit never gets overworked. And with a boiler – you get the benefit of rapid hot water – thanks to the higher BTU input boilers provide.

The modulating function of a boiler is huge. It allows the boiler to operate at a low or full flame – depending on what is required. This means that in warmer weather – when you would not normally be using a boiler or furnace to heat your home – you can still use it effectively on the low setting to generate the hot water necessary for the shower, sink and dishwasher.

Multiple Ways To Power Combination Systems

As is the case with most types of water heaters these days, you can buy indirect water heater systems that are powered by natural gas, propane, oil, electricity – even solar energy – or a combination thereof. This makes it easier to find a complete system that matches the kind of energy you’re already using. Or planning to use when construction or renovations are complete.

Why You Might Want To Consider An Indirect Water Heater

An indirect water heater is usually more energy-efficient than other home water heating systems. The key is to have compatible components that are capable of supplying your family’s hot water needs on a daily basis.

Having the right set-up is vital if you want to significantly reduce your energy costs. You’ll experience far less standby heat loss with a properly installed indirect system.

This means the boiler (or furnace) won’t need to be activated for heating water as frequently. Less energy required means a more efficient water heating process.

Buderus 53 Gallon LT-200 Indirect Fired Water Heater

Buderus 53 Gallon LT-200 Indirect Fired Water Heater. See it at Amazon 


Once properly installed, an indirect water heater requires little maintenance. The biggest problem with standard water tanks are the heating elements and anode rods that eventually fail and have to be replaced. But with no heating element, no burner, and no anode rod – there are fewer parts in general and nothing that needs to be replaced over time. Therefore, it’s a simpler and more hassle-free way to heat the water in your home or business.

No additional fuel, fuel lines, or venting is required. And with an indirect water heater, you’re not adding a secondary, independent appliance that would require additional energy. You are simply tapping in to a heat source you already have installed – namely – your boiler or furnace.

You can use indirect water heater set-ups in a variety of applications. That means they can be installed in both commercial buildings like hotels, restaurants, bars and apartment complexes – as well as in individual homes.

Faster recovery rates are another way indirect water heaters provide an advantage. They tend to generate more hot water faster than a standard tank-style water heater. With faster recovery times, you can have more hot water flowing through your faucets in less time by going indirect.

Not Always The Homeowner’s Best Option

Standard tank type water heaters are more versatile than indirect water heaters and they can be used in virtually any kind of building. Indirect water heaters are best suited to complementary boilers and HVAC systems. Since not all boilers and furnaces will work as combination units, they’re not nearly as popular as traditional water heaters, though they are trending upwards.

Tankless water heaters are another option that an increasing number of homeowners are choosing. But tankless systems are limited as to how much water they can supply (measured in Gallons Per Minute) and are based on the capacity of each individual model. Indirect hot water heaters can supply all the hot water you need – as long as the holding tank you choose can match the demand for your residential or commercial property.

Who Is The Best Fit For an Indirect Water Heater?

It’s best to opt for an indirect water heater if you have a larger family with a busy home environment. When there is a significant volume of water required on a daily basis, an indirect or combination system can really benefit you. Of course, you’ll need to first make sure that your external heat source is up to the task and is fully compatible with your water tank. That’s where it’s helpful to talk to a water heater professional – someone who has installed loads of indirect water heaters previously. Call 1-888-548-3652

If you’re gutting your home’s infrastructure while building an addition, or undertaking a major renovation – it is prime time to at least consider getting an indirect water heater. If you’re planning to replace your furnace – have a look at the newer models available that have the ability to function as part of a combination system.

Building a new home or business facility? Indirect fired water heaters are being installed with increasing frequency on new home construction sites. After all, it only makes sense to build as energy-efficient as possible today.

New buildings or complete reconstruction projects are probably the best ways to use an indirect or combination water heater system.

Otherwise, you’ll need to have the foundational component – a compatible boiler or furnace – or find a replacement that can be installed without a major overhaul.

Remember, a lot of existing space-heating systems are simply not a good fit when converting to an indirect hot water heater. Home heating systems – like forced air furnaces – are just not made to be used in any other way.

When building a new home or replacing an old boiler or furnace, you should consider an indirect water heater system.
When building a new home or replacing an old boiler or furnace, you should consider an indirect water heater system.

In some cases, combination systems may be a perfect fit. But they may not be needed in other situations. For example, if you live in a smaller home and therefore don’t have as much of a demand for hot water on a daily basis – it’s probably not worthwhile to go with an indirect water heater tank and boiler combination system.

It’s An Investment That May (or May Not) Make Sense

A combination setup is an intelligent way to make the most of your home’s heating system. Just keep in mind that you need both a heat source and a water tank. Installing a new indirect water heating system can be costly if you have to purchase both main components. But if you already have a quality boiler or compatible furnace installed – and functioning as it should – you have a huge advantage. Although the initial cash outlay can seem large – these water heaters are more environmentally-friendly and cost less to operate in the long run. The bottom line is that if you choose the indirect route – however you get there – you will likely see significant savings over time.

Do It Right – Hire A Professional

Be forewarned, installation needs to factor in many different things, including local (or state) building code requirements, job safety, type of fuel you plan to use, as well as choosing pipe sizes and having the settings adjusted precisely.

Although some parts of the installation may be handled by a competent do-it-yourself type – other parts require specialized knowledge and experience.

That’s why we always recommend you engage the services of an expert.

Quick Summary of Pros and Cons of Indirect Water Heater Systems

There are several advantages indirect water heaters offer, including:

  • Combination heater for space and water saves energy (and money)
  • Minimal maintenance and service required (fewer problematic parts)
  • No separate vent pipe or fuel connections are required
  • Tank requires no power. (But thanks to the thick layer of insulation, it keeps the water piping hot and ready to flow immediately)
  • Proper sizing can easily keep up with demand for hot water in busy households
  • Tend to last longer than any other type of water heater (20 years or more)

Disadvantages of indirect water heaters include:

  • Can be expensive, particularly if you’re starting from scratch
  • May not be a feasible solution in some situations (since you’ll need a compatible furnace or hydronic boiler)
  • Need to engage the services of a professional for installation and set-up

How Soft Is Your Water?

Hard water can be a problem for any system and it’s a factor with combination systems too.

When hard water is heated, the natural minerals inside get separated, forming a build-up of sediment in your hot water system. And any buildup will eventually cause problems.

So, if you live in a hard water area, it’s a good idea to make sure you only use water that is first treated by a water softener. Contact a local plumber to get what you need.

Soapy hands in a kitchen sink. If you need lots of soap to wash dishes , you have "hard water"
If you need lots of soap to wash dishes , you have “hard water”

Nothing Is Perfect

Some heat loss can occur whenever water is transported over a distance, like from a furnace or boiler to the holding tank. But today’s water heating systems are quite a bit more efficient than older versions. There are fewer exposed parts (parts that would ultimately corrode or break down over time) and no secondary energy source is required to provide abundant hot water.

To maintain the water’s temperature in the tank requires the furnace or boiler to turn on occasionally. So, some energy (and the associated cost) is required. But with today’s models, the boiler will only turn on when heating is required, as in when the temperature of the water in the tank drops below a preset threshold.

Works Year Round

Any indirect water heater system will draw heat from the boiler – even in the summer months. But a good boiler will only run as needed. If you’ve got a late-model boiler, chances are it’s a more efficient model complete with modulating function, so you can adjust it to suit.

Boilers are typically a more energy-efficient method for producing hot water in the home. In fact, high-performance boilers are capable of up to 96% energy efficiency. Therefore, using such a boiler would be considerably more efficient than the 60 to 80% offered by a standard tank-style water heater.

If you live in a cooler part of the country where you require the services of your boiler/furnace for a significant portion of the year, an indirect water heating system can make a lot of sense. That is particularly true if you already have a boiler or furnace that’s a good match for this kind of system.

If you need to purchase both the boiler/furnace and hot water tank – your initial investment will naturally be higher versus simply acquiring the proper hot water tank. You’re going to need both. But the key is getting the right boiler or furnace, since it will supply two essential functions inside – space heating and water heating.

Hot Water On Demand – For Less

According to the US Department of Energy, the least expensive way to get continuous hot water is with an indirect water heater. But to make the most of this system, you need the proper equipment and the right situation.

Water heaters generally consume even more energy than all of your other appliances combined. Therefore, a more energy-efficient solution makes a lot of sense for many families. Another way you save money (with an indirect water heater) is by not requiring much in the way of service or repair work. There are fewer moving parts and far less wear and tear. So, this type of water heater tends to last longer, leading to long-term savings for you.

A Good Fit

Ideally an indirect hot water heating system is more likely a good fit for you if you already have a suitable boiler or furnace.

When that’s the case, going indirect makes sense because you’ll get reliable hot water as cost-effectively as possible.

When you already have a reliable space heater in your home – why not use it to also heat your water? As long as it can be done effectively – it makes a lot of sense.

Got an old boiler and separate water heater? Replace them with a combination boiler and indirect water heater to save money every month.
Got an old boiler and separate water heater? Replace them with a combination boiler and indirect water heater to save money every month.

Contact a local plumber to get what you need.

Today’s best indirect water heater systems provide an optimal solution. They conserve energy and offer quick recovery times – so there’s no waiting around for hot water. They’re also reliable performers, so you don’t have to worry about much in the way of ongoing maintenance or service.

Sure, an indirect water heater isn’t the best choice in every situation. But with a proper boiler or furnace, it’s an option well worth considering. That’s true, whether you’re heating a home or commercial space. It uses one source to generate the necessary heat to warm your space and heat your water. It can be costly to set it up from scratch, but ultimately, will save you money moving forward. That’s through the increased efficiency and hassle-free operation you’ll come to enjoy. Use the form below:

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