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4 months ago
If you're considering upgrading your traditional water heater to a tankless system, one of your first questions is probably: How much does tankless water heater installation cost in Illinois?
A tankless water heater can provide hot water on demand, reduce standby heat loss and free up valuable space in your home. However, the total installation cost depends on several factors, including the type of system, household hot water demand, gas or electrical requirements, venting, plumbing modifications and labor.
For homeowners in DuPage County, including Glen Ellyn, Naperville and Wheaton, understanding these costs can help you make a more informed decision before investing in a new water heating system. Whether you're replacing an aging water heater or planning a tank-to-tankless conversion, the installation requirements can make a significant difference in your final price.
In this guide, we'll explain typical tankless water heater installation costs, compare gas and electric systems, discuss conversion expenses and explain what to consider before scheduling an installation.
How Much Does Tankless Water Heater Installation Cost?
Tankless water heater installation costs vary depending on the equipment, installation requirements and condition of your existing plumbing system.
Published 2026 home improvement cost estimates generally place tankless water heater installation between approximately $1,400 and $5,600 nationally. Some Illinois cost guides report installed gas tankless systems in the 3,000–6,000 range.
These figures are general market estimates, not guaranteed DuPage County prices or a quote from Dream Home Plumbing. Your actual installation cost may be lower or higher depending on the project.
The final price can depend on:
- The brand and model of the tankless water heater.
- Gas or electric system selection.
- Required hot water flow rate and system capacity.
- Existing gas line size and available gas supply.
- Venting and exhaust requirements.
- Electrical connections and circuit capacity.
- Water line modifications and plumbing connections.
- Permit and inspection requirements.
- Removal and disposal of the existing water heater.
A straightforward replacement and a complete conversion from a traditional tank water heater can have very different installation requirements.
For an accurate estimate, have your existing system and installation location evaluated by a qualified plumbing professional.
Gas vs. Electric Tankless Water Heater Installation Cost
One of the first decisions homeowners need to make is whether to install a gas or electric tankless water heater.
Both systems heat water on demand, but their installation requirements and operating characteristics are different.
1. Gas Tankless Water Heater
Gas tankless water heaters use natural gas or propane to heat water as it flows through the system.
They are commonly considered for whole-house applications because appropriately sized models can support multiple hot water fixtures.
However, installation may require additional work involving:
- Gas line capacity and sizing.
- Dedicated venting and exhaust connections.
- Combustion air requirements.
- Condensate drainage for applicable condensing models.
- Water supply connections.
- Electrical connections for controls and ignition.
If your existing gas line cannot supply the required fuel flow, modifications may be necessary before installation.
The installer should evaluate the home's existing gas supply, other gas appliances and the manufacturer's requirements before selecting a model.
2. Electric Tankless Water Heater
Electric tankless water heaters use electrical heating elements to heat water as it passes through the unit.
Depending on the model and application, an electric system may require:
- Dedicated electrical circuits.
- Adequate electrical panel capacity.
- Appropriate wiring and breakers.
- Water supply connections.
- Correct system sizing for household demand.
Some electric models are suitable for individual fixtures, while whole-house electric systems can require substantial electrical capacity.
Before selecting an electric tankless system, have the home's electrical service evaluated to determine whether it can support the equipment.
Which System Is Better for Your Home?
The best option depends on your home's existing utilities, hot water demand, installation budget and long-term preferences.
A plumbing professional can help evaluate the requirements and explain which systems are appropriate for your property.
What Factors Affect Tankless Water Heater Installation Cost?
Not every tankless water heater installation is the same. Two homes with similar layouts may require different equipment and installation work.
Here are the main factors that can influence your final project cost.
1. Tankless Water Heater Brand and Model
Different manufacturers offer tankless systems with different capacities, efficiency ratings, features and installation requirements.
Popular manufacturers include Rinnai and Noritz.
When selecting a unit, consider:
- Manufacturer specifications.
- Available flow rate.
- Temperature rise requirements.
- Energy efficiency.
- Warranty coverage.
- Maintenance requirements.
- Availability of replacement parts.
Choosing a suitable model is important because an undersized system may struggle to meet household hot water demand.
2. Household Size and Hot Water Demand
The number of people living in your home and the number of fixtures used simultaneously affect the required system capacity.
For example, a household that regularly runs two showers while using a dishwasher may need a larger-capacity system than a smaller household with fewer simultaneous hot water demands.
Professional sizing should consider:
- Number of bathrooms.
- Shower and bathtub flow rates.
- Kitchen and laundry requirements.
- Simultaneous hot water usage.
- Incoming groundwater temperature.
- Desired hot water temperature.
Proper sizing helps ensure that the selected system can meet your household's needs.
3. Gas Line Upgrades
Gas tankless water heaters can have higher burner input requirements than traditional tank water heaters.
If your current gas line is undersized, a larger line or other gas supply modifications may be necessary.
The plumber should evaluate the equipment's BTU requirements, gas pressure, pipe diameter, pipe length and other connected gas appliances.
For safety and proper performance, gas line modifications should be completed by qualified professionals.
4. Venting Requirements
Gas tankless water heaters require appropriate venting to remove combustion exhaust safely.
The venting requirements depend on the manufacturer's specifications and whether the unit is condensing or non-condensing.
Installation costs may increase if your existing venting cannot be reused or needs modifications.
The installer should verify approved vent materials, termination locations, clearances and installation instructions for the selected model.
5. Plumbing Modifications
A new tankless system may require changes to existing hot and cold water connections.
Additional work may include:
- New water supply connections.
- Isolation valve installation.
- Water line modifications.
- Pressure-related corrections.
- Condensate drainage where required.
- Additional fittings and piping.
The actual work depends on the condition and layout of your home's plumbing system.
6. Permits and Local Inspection Requirements
Depending on your municipality and the scope of work, permits and inspections may be required.
Requirements can differ between communities in DuPage County.
For example, homeowners planning an installation in Glen Ellyn or Naperville should confirm the applicable local plumbing, mechanical, fuel gas and electrical requirements before work begins.
A professional installer can help identify which permits and inspections apply to the project.
7. Removal of the Existing Water Heater
If you're replacing a traditional tank water heater, the existing unit may need to be disconnected, removed and disposed of.
The cost depends on accessibility, equipment size, removal requirements and disposal arrangements.
Ask whether removal and disposal are included in your installation estimate.
How Much Does It Cost to Convert a Traditional Tank Water Heater to Tankless?
Many homeowners consider converting their traditional storage tank water heater to a tankless system when their existing unit reaches the end of its useful life.
A tank-to-tankless conversion can involve more work than simply replacing one water heater with another.
Depending on the home, the project may require:
- Removing the existing storage tank.
- Selecting and sizing a suitable tankless system.
- Upgrading the gas supply.
- Installing compatible venting.
- Modifying water supply connections.
- Adding condensate drainage where required.
- Completing electrical connections.
- Obtaining applicable permits and inspections.
The final cost depends on how much of your existing infrastructure can be reused.
For example, a home with suitable gas capacity and an appropriate installation location may require fewer modifications than a home needing new gas piping, venting and electrical work.
Before converting your system, have a qualified plumber inspect your current water heater and evaluate the installation requirements.
If you're considering an upgrade, explore our tankless water heater repair and installation services.
Is a Tankless Water Heater Worth the Investment?
A tankless water heater may be a good investment for homeowners who want on-demand hot water, a more compact system and reduced standby heat loss.
However, the benefits depend on your household's water usage, utility costs, installation expenses and maintenance needs.
Here are some advantages to consider.
On-Demand Hot Water
Tankless systems heat water as it flows through the unit rather than continuously storing a large volume of hot water.
This can provide a continuous supply of hot water when the system is correctly sized and operating within its rated capacity.
Energy Efficiency
Traditional storage tank water heaters maintain a supply of hot water even when nobody is using it.
Tankless systems avoid much of this standby heat loss because they heat water when needed.
Actual energy savings depend on household usage, equipment efficiency, fuel prices and installation conditions.
Space Savings
Tankless water heaters are generally more compact than traditional storage tanks.
Many models can be mounted on a wall, helping homeowners free up valuable floor space in utility rooms, basements and other suitable locations.
Long-Term Value
A properly selected and maintained tankless system may offer long-term value.
However, homeowners should consider the initial installation investment, maintenance requirements, replacement parts and expected equipment lifespan before making a decision.
How Long Does Tankless Water Heater Installation Take?
Installation time depends on whether you're replacing an existing tankless system or converting from a traditional storage tank.
A straightforward replacement may require less work than a first-time installation.
A more complex project may involve:
- Gas line modifications.
- New venting.
- Plumbing relocation.
- Electrical upgrades.
- Condensate drainage.
- Permit and inspection coordination.
Your installer should explain the expected project schedule after evaluating the property.
Signs You May Need Tankless Water Heater Replacement or Repair
If you already have a tankless water heater, certain problems may indicate that your system needs professional attention.
Watch for these warning signs:
- Inconsistent hot water temperatures.
- Water not heating properly.
- Frequent system shutdowns.
- Persistent error codes.
- Water leaking around the unit.
- Unusual operating noises.
- Reduced hot water flow.
- Repeated ignition problems.
Not every problem means you need a complete replacement.
Some issues can be resolved through professional diagnosis, component repair, cleaning or descaling.
If your tankless water heater isn't working correctly, consider professional tankless water heater repair and installation in DuPage County.
Tankless Water Heater Installation in DuPage County, IL
Homeowners throughout DuPage County may consider tankless water heater installation when replacing an aging water heater, remodeling a home or looking for a different hot water solution.
Dream Home Plumbing Co. is a family-owned plumbing company serving Glen Ellyn and surrounding DuPage County communities.
Our team helps homeowners understand their plumbing needs and available water heater service options.
We serve communities including:
- Glen Ellyn, IL
- Naperville, IL
- Wheaton, IL
- Downers Grove, IL
- Lombard, IL
- Elmhurst, IL
- Oak Brook, IL
- Lisle, IL
- Carol Stream, IL
- Hinsdale, IL
If you're looking for a plumber in Glen Ellyn, IL, to discuss a tankless water heater upgrade, or need help evaluating an existing system elsewhere in our service area, Dream Home Plumbing can help you understand your options.
Whether you're considering a new tankless system, replacing an existing unit or exploring a tank-to-tankless conversion, the right starting point is an evaluation of your home's installation requirements.
Learn more about our tankless water heater repair and installation services.