Can I Add A Tankless Water Heater To Existing System?

Adding a tankless water heater to your existing system can be an excellent way to upgrade your home’s water heating capabilities. Tankless models provide hot water on demand and don’t require the storage space of traditional tank-style heaters, which can help save energy costs in the long run. With a few simple steps, you can have yours up and running in no time!

Can I Add A Tankless Water Heater To Existing System?

Yes, you can add a tankless water heater to an existing system. This type of installation is often referred to as a “dual water heating” setup and involves adding the new unit in series with your existing water heater. This process usually requires no additional plumbing and only minimal changes in the wiring of your home’s electrical system. The result is an increased hot-water supply; some manufacturers estimate that households can expect up to 40% more hot water than their traditional tank storage systems. Additionally, this upgrade has been known to reduce energy consumption by up to 34%.

Benefits of Adding Tankless Water Heater

Adding a tankless water heater to an existing system can bring many benefits. Here is a list of the main advantages:

Energy Efficiency

Tankless systems are up to three times more efficient than traditional storage tanks, meaning you’ll save money on energy bills.

Endless Hot Water

A tankless water heater heats only the amount of water you need and replenishes it constantly, meaning you will never run out of hot water again! Plus, they heat up quickly, so there won’t be long waits for hot showers or baths anymore.

Longer Life Span

Tankless units last much longer than traditional tank models, with an expected life span between 10-20 years as opposed to 5-10 years for standard tanks. This makes them a great investment in both the short and long term!

Space Savers

With no bulky storage tank taking up valuable space in your home or business, these compact units provide extra room for other necessities or activities without sacrificing functionality.

Types of Tankless Water Heaters

Tankless water heaters are becoming increasingly popular for homeowners due to their numerous advantages over traditional tank-style models. These modern appliances provide an endless hot water supply, energy savings, and space efficiency.

When considering whether or not you can add a tankless water heater to your existing system, it is important to understand the different types available and how they might best fit your needs.

The two main categories of tankless water heaters include electric and gas models.

Electric units are usually wall mounted in one location near a sink or showerhead and deliver hot water almost instantaneously on demand. They require very little maintenance since no standing water tanks could collect contaminants over time.

Gas units operate similarly but use natural gas as the fuel source instead of electricity, providing more power but higher upfront costs than electric models.

Another type is point-of-use (POU) tankless systems feature small compact designs that can be installed directly beneath sinks or other fixtures where hot water is needed most frequently throughout the home, making them ideal for multiple faucets in larger households with high demand for hot water consumption.

Additionally, whole house systems simultaneously serve all sources of hot water for homes with completely remodeled plumbing infrastructure ready for installation from scratch.

Finally, dual-purpose systems combine both POU technologies into one unit allowing users to draw from either a single point in the home (for example, showers) or distribute heated up throughout the entire property at once when the need arises.

Overall, understanding these various types of tankless devices helps make it easier to decide if adding one will work best in your already established system so you won’t have to compromise comfortability and convenience while saving money on energy bills yearly too!

Cost to Install a Tankless Water Heater

Installing a tankless water heater can be expensive, but it may be worth the initial cost depending on your needs. Generally speaking, the total cost of installation could range anywhere from $1,000 to $3,000 or more, depending on the size and type of unit you choose, as well as any additional plumbing work required by local codes. In addition to labor costs for installing a tankless water heater, associated materials, such as piping and venting components, will need to be purchased for it to function properly.

For those looking to add a tankless water heater onto an existing system rather than replacing one, you’ll likely incur fewer costs overall since some parts may already be in place.

However, if extensive modifications must still be made, your final bill might not differ greatly from that of full replacement. It’s best practice to consult with a licensed contractor who can objectively assess both scenarios and provide an accurate estimate for whichever route is most beneficial for your application.

How to Connect a Tankless Water Heater To Existing System

Adding a tankless water heater to an existing system can be a great way to upgrade your home’s hot water capacity and save money on energy costs. To properly connect the new unit, you will need to follow these steps:

1. Shut off all power sources in the area of installation.

2. Turn off incoming cold water lines that supply hot water equipment in residence.

3. Install two shut-off valves between your current hot-water supply line and the tankless heater’s cold-water pipe connection valve so they can be isolated when servicing either component or both components.

4. Connect copper pipe from existing plumbing to tankless heater using special connectors designed for this purpose and seal with approved thread sealant; make sure nipples are not too long as it could cause kinks in pipes which could restrict flow through heater over time, causing damage to internal components of the unit.

5. Turn on all power sources and test each connection point for leaks before powering up the unit; use a voltmeter or multimeter if necessary, but do not attempt any electrical work unless you are qualified or have someone experienced doing it for you!

Once everything is installed correctly, it’s important to flush out any debris in your system by scalding hot water through all faucets until clear; this should prevent clogs and other issues down the road!

Advantages and Disadvantages of Installing a tankless water heater

A tankless water heater is a great option for homeowners looking to upgrade or add to their existing system. Before committing to this type of appliance, several advantages and disadvantages should be considered.


  • Tankless units provide an unlimited hot water supply, allowing you to take multiple showers without running out of hot water.
  • They are more energy efficient than traditional storage-tank heaters and can save you money with lower utility bills.
  • Installation is relatively straightforward and can often be done as a DIY project if you’re comfortable with basic plumbing skills.


  • Initial costs associated with purchasing a tankless unit can be expensive compared to other water heaters – although long-term savings may eventually offset these costs over time.
  • Maintenance requirements are higher due to filters needing regular cleaning/replacement, which increases overall costs in the long run.
  • Tankless systems require larger diameter pipes than traditional tanks, so installation may need additional changes like replacing old piping, which will also increase initial installation expense

Potential Issues When Adding A Tankless Water Heater To Existing System

When considering whether or not you can add a tankless water heater to your existing system, several potential issues should be considered.

First, if you have an older plumbing system, adding a tankless unit may require additional modifications for it to work properly. In particular, the existing pipes and connections may need to be upgraded to accommodate the size of the new water heater and its fittings. Additionally, any current safety devices, such as temperature-pressure relief valves, may need replacement due to incompatibility with newer models of water heaters.

Another issue is ensuring that your electrical power supply is adequate for running a tankless unit. If not, then some wiring upgrades will likely be needed before installation is possible.

Furthermore, electric systems typically require dedicated circuits, whereas gas units don’t – so bear this in mind when choosing between fuel types.

Finally, depending on where your existing hot water lines are located within the house and how much demand they receive from other fixtures (e.g., showers), installing additional piping could also become necessary, meaning more disruption during installation as well as higher material costs overall – especially if using copper pipe for example which has become expensive recently.

Maintenance Tips For A New Tankless Water Heater

Adding a tankless water heater to an existing system can be a great way to save energy and money. To ensure the heater is functioning properly, here are some maintenance tips for you to consider:

  • Flush out the unit every 6 months with a vinegar solution to remove any build-up of sediment or mineral deposits.
  • Check all piping connections monthly for signs of corrosion or loose fittings, which could lead to leaks if left unchecked.
  • Ensure proper ventilation around the unit and ensure air vents are unobstructed by dirt or debris at all times–this will help prevent overheating issues.
  • Inspect your water heater annually by an experienced professional plumber to identify any potential problems before they become serious and may cost you a lot to repair.

Can I Add A Tankless Water Heater To Existing System Summary

Adding a tankless water heater to an existing system can be done. However, it will require some modifications and careful planning.

The first step is to determine the size of the tankless water heater you need based on your hot water usage needs. Then consult a qualified contractor or plumber who can assess your current system and guide you on how best to incorporate the new unit into your existing setup.

Several things must be considered when adding a tankless water heater, such as gas line sizing, venting requirements, potential electrical upgrades, etc. Additionally, suppose you have an older home or plumbing system. In that case, other issues like corrosion control or structural changes may need to be addressed before installing a tankless water heater.

Furthermore, cost should also factor in when considering whether to add a tankless unit since they tend to be more expensive than traditional storage tanks due to their higher energy efficiency ratings and longer lifespan. However, most homeowners who switch from storage tanks often report significant savings over time while enjoying unlimited hot showers without running out of hot water!

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