Choosing the right water heater to install in your home can be difficult as there are so many options available. You may have heard about an indirect water heater and want to know where that fits into the spectrum of available products. In the right conditions, it can be an effective solution for heating water in your home.
If you are considering installing one of these systems, know that it isn’t necessarily suitable for everyone. First, you will need to make sure that your house and HVAC systems are the right fit. However, if everything is in line, going indirect can provide you with plenty of benefits.
Let’s take a deeper look into understanding the indirect water heating system, and how it could work and be installed in your home.
What Is An Indirect Water Heater?
This water heating system uses a tank to store water and an external heat source to warm it up. Indirect models do not have any heating elements inside the water tank. Instead, they will use the home’s space heating system (a furnace or boiler) to heat the water. Utilizing the space heating system for your water is called an integrated or combination heating system – as the two different units work together.
Basically, an indirect system uses an external heat source instead of its own gas or electric heating elements. This integrated system of using heat transfer in different components is becoming increasingly popular. It is important to understand that not all houses will suit one of these. However, those that do can enjoy a number of advantages that come with this system, which we discuss later on in this article.
To summarise, an indirect water heater:
- Uses an external source (furnace or boiler) to heat the water
- Its tank does not contain any heating elements
- Is part of an integrated heating system
- Only works well under specific conditions
How Does The Heater System Work?
Image from U.S. Boiler Company
Indirect water heaters require a storage tank, although the tank does not actually heat the water. Instead, hot water is created through heat transfer using the home’s boiler or furnace.
This is achieved by connecting a series of heat transfer coils between the water tank and the boiler or furnace (source of heat). The fluid that passes through these coils is warmed up from the heat source and then cooled off in the water tank. This process continues in a cycle.
At the source of heat, the water in the system will turn to steam – as the temperatures here are seriously high. When this water travels back down to the storage tank, the cooler water surrounding it will take the heat away from the coils – condensing the steam back into a liquid. This is then recycled back into the heat supply to continue the process.
Not all furnaces can be utilized in an indirect water heating system. The reason for this is that some of the older models aren’t compatible with newer integrated HVAC systems. Using a boiler in this system is more common. Boilers are also more effective due to their higher intensity steam heating.
As the insulated water tank stores energy, the furnace or boiler won’t need to turn on and off as often as usual. This can save a great deal of energy. When combined with the fact that there are no heating elements being used in the tank, indirect heating systems can be the most energy-efficient solutions available.
Indirect water heaters can be powered by electricity, solar energy, gas, propane, oil, or a combination.
To summarise how this system works, it:
- Uses a water storage tank without heating elements
- The water is heated through a heat transfer coil system
- This is connected between the storage tank and a boiler or furnace
- The tank stores energy, reducing the number of times that the boiler/furnace turns on
- Indirect models can be incredibly energy efficient
Advantages to Using an Indirect Water Heater
Under the right circumstances, using an indirect system can result in many benefits. Here are some of the advantages of using these heaters.
When using an indirect water heating system, you can save a great deal of energy. Thanks to the system vastly reducing the amount of standby heat that is lost, an indirect heater proves to be far more efficient. This is also seen in the reduced running of the boiler or furnace. When compared to a standard tank heater, indirect models are very energy efficient and they reduce heat wastage.
Easier to Maintain
Once set up, this type of water heater is really simple to maintain. These units do not contain any heating elements in their tanks or any additional burners. This means that there are fewer parts to worry about – creating a simpler, more effective solution in terms of maintenance.
Reduced Flue Gas Losses
If you are running a gas-fired indirect water heater, flue gas losses are significantly reduced. This is actually the leading cause of heat loss in standard boilers, so using the indirect system can make a major difference here.
Besides being more energy-efficient, these systems do not require any kind of venting or additional fuel lines. Having no independent energy cost makes them more affordable compared to other tank heaters. The fact that they use a heating source that already exists, means that they can save a great amount of money in the long run.
Convenient to Install
As long as your house has the correct conditions suitable to these systems, an indirect heater can be easy to install. They are also a convenient size for domestic use.
Higher Recovery Rates
Hot water quality is certainly not compromised with indirect systems. They can actually produce more hot water than the average tank heater, with increased recovery rates. This means that, using the right system, you could access a greater amount of hot water faster when you go indirect.
Direct Heaters vs. Indirect Heaters
Making the decision between these two water heater types can be difficult, as each style offers unique benefits. Standard direct water heaters don’t need to transport water over a distance – so in one regard, they can be seen as more efficient. However, indirect heaters are more efficient in other ways.
The major benefit of standard direct heaters is that they can be utilized in any kind of house, anywhere. Indirect units are only really well suited in houses with a complimentary-style HVAC system.
Indirect Heaters vs. Tankless Heaters
The clear difference between these two systems is that indirect heaters use a water storage tank, while tankless heaters have no tank at all. This means that indirect units are limited in the amount of hot water that they can produce, while tankless heaters can produce an unlimited supply.
An important thing to note is that tankless heaters can only supply a certain amount of gallons per minute. Indirect heaters can provide as much hot water per minute as you like – as long as it fits within the tank’s holding capacity.
When to Use an Indirect System
Using an indirect water heater is great for busy homes with larger families. This is because the gallons per minute are not limited (like tankless heaters). If you are considering installing one, you will need to make sure that the external heat source will work with your system.
Indirect /combination systems are usually installed during new construction jobs. It is possible to connect pre-existing units up with your water heater, but this can get more complex.
Some older furnace models cant be used with integrated HVAC systems. This can be seen in models like forced air furnaces, where the exchange pipes cant be heated. If you have a small house or do not require much hot water, then an indirect system is not always the best choice. In this case, a tankless heater may be better (as you will not require the large storage tank).
There is no need to be concerned about using your indirect heater with a boiler in hot climates. If it is too hot for using the boiler, it will still only run when needed – while the indirect system still draws heat from it. These are systems that can be utilized throughout the year.
Setting Up a Combination Water Heater
Setting up a combination water and space heating system can be fairly expensive. It is generally cheaper to install a separate water heater and a separate boiler or furnace than a combination unit. However, this will change over the long run. Combination water heating systems should save you a great deal over time.
Installing a combination water heating system is no easy job, and getting a professional to do it is always recommended. There are many different factors that come into play when installing these systems (fuel type, safety, building code requirements, etc), making installation a fairly complex job.
The Bottom Line
Using an indirect water heating system can be an innovative and highly effective solution for your home. This is not always the most common type of water heating system, as it requires a pretty specific space and set up for it to work at its best. However, when used in the right space, your household can reap great benefits from such a system.
Indirect water heaters can be significantly cheaper in the long run, as well as more environmentally efficient. Using a combination setup is a smart way of making the most out of your home’s heating solutions.
If you are building a new house, or have a suitable boiler, you might want to consider installing an indirect water heater setup.