It allows your boiler to provide domestic hot water without a separate water heater. However, over time, this coil can corrode, clog, or simply wear out—requiring replacement. If you're dealing with inconsistent hot water or reduced water pressure, a tankless coil replacement may be the solution.
This article explains what a tankless coil does, signs it needs replacement, and what to expect during the process.
What Is a Tankless Coil?
A tankless coil is a heat exchanger located inside your boiler. As the boiler heats water for your home’s heating system, cold water flows through the coil and gets heated instantly. The result: hot water on demand without the need for a storage tank.
Signs Your Tankless Coil Needs Replacement
Inconsistent Hot Water
If your water turns cold too quickly or takes a long time to heat, the coil might be scaled or blocked.Reduced Water Pressure
Mineral buildup in the coil can restrict water flow, leading to low pressure from faucets or showers.Water Has a Metallic Taste or Discoloration
This could indicate corrosion within the coil.Boiler Running Constantly
A faulty coil may make your boiler work overtime, increasing energy bills.Visible Leaks or Drips Near the Coil
This often signals a breach or crack in the component.
Benefits of Replacing the Tankless Coil
Restores consistent hot water delivery
Improves water pressure
Increases energy efficiency
Extends the lifespan of your boiler
Avoids costlier repairs from secondary damage
Tankless Coil Replacement: What’s Involved?
Assessment
A professional HVAC technician inspects the boiler and confirms the coil is the source of the problem.Draining the Boiler
The boiler is shut down and drained to safely access the coil.Removing the Old Coil
The old coil is detached from its housing. Depending on corrosion or mineral buildup, this can be labor-intensive.Installing the New Coil
A new coil is installed, sealed, and connected to the domestic water supply.Testing and Restart
The system is refilled and tested to ensure proper function and no leaks.
How Much Does It Cost?
Tankless coil replacement typically costs between $400 and $900, depending on:
Coil type and brand
Boiler model
Labor rates in your area
Whether additional repairs or cleaning are needed
Should You Upgrade to an Indirect Water Heater Instead?
If your tankless coil has failed, it might be worth considering upgrading to an indirect water heater, especially if:
Your hot water demand is high
You want better energy efficiency
You’re planning a boiler upgrade soon
Indirect systems use your boiler but store hot water in a separate tank, offering better reliability and efficiency in many cases.
Replacing a tankless coil in your boiler can restore comfort and performance while preventing further wear and tear. If your boiler is aging or you're experiencing hot water issues, have a licensed technician evaluate whether replacement or an upgrade is right for you.
