Common Issues And Solutions For Hydronic Radiant Floor Heating Repair

Are you experiencing issues with your radiant heating system and in need of some practical DIY troubleshooting and repair tips? Don’t worry, we’re here to help you.

Whether you’re dealing with a lack of heat, leaks, or uneven heating, rest assured that we’re here to help you and show you how to repair your hydronic floor heating system.

In this guide, we’ll cover common hydronic floor heating problems, symptoms and causes of issues that may arise, and provide you with the knowledge to diagnose and effectively fix these issues on your own.


Hydronic Radiant Floor Heating Repair: Things To Consider

How Does Hydronic Floor Heating Work?

Understanding how hydronic floor heating systems work can be immensely helpful when it comes to troubleshooting and repair. By having a solid grasp of the system’s components and operation, you’ll be better equipped to diagnose issues and implement effective solutions.

Hydronic heating systems utilize radiant heat to warm the floors and objects, providing a comfortable and evenly distributed warmth throughout the space while also heating the surrounding air.

These systems offer numerous advantages, including consistent heat distribution, minimal temperature fluctuations, non-drying heat, and enhanced comfort.

The core components of these systems include a boiler, which heats the water using sources such as electric heat pumps, furnaces (wood, gas, electricity, or oil), and a circulation pump that moves the heated water through a network of PEX pipes installed beneath the floor.

To control the room temperature, programmable wall thermostats are commonly used, allowing homeowners to optimize their comfort levels.

In addition to these elements, hydronic systems employ manifolds to divide the main hot water line into individual loops or zones for each room. Zone valves are used to regulate the water flow through each loop, providing precise control over heating in specific areas.

Hydronic underfloor heating systems are installed using one of the several methods:

  • The staple-up method uses the heat emission plates and PEX pipes installed between the floor joists and under the subfloor. 
  • The staple-down method uses PEX pipes fastened to the subfloor, and lightweight concrete poured on the top.
  • Knobbed mats are rigid plastic sheets with knobs where you snap the PEX piping over which you pour concrete. 
  • In-slab method where pipes are embedded inside the concrete slab.

Common Hydronic Radiant Floor Heating Problems

Hydronic floor heating systems offer numerous advantages and benefits, providing efficient and comfortable heating for your home. However, like any complex system, they can experience malfunctions and issues that hinder their performance, requiring proper hydronic radiant floor heating repair services.

From minor problems to more significant issues, understanding the common challenges associated with these floor systems is essential for timely troubleshooting and effective repairs.

In this section, we will explore the most common problems that can arise with hydronic floor heating systems. Whether you’re dealing with issues such as leaks, insufficient heating, partial heating, or other related problems, we’ll delve into their causes and provide practical solutions to help you resolve them.

While some issues can be addressed through DIY troubleshooting, we’ll also highlight instances where professional assistance may be necessary to ensure the system is restored to optimal functionality.

The most common problems with hydronic floor heating systems are:

Thermostat Issues And How To Fix

A defective thermostat is one of the most common sources of problems when your hydronic floor heating system isn’t functioning properly.

These thermostats, which are of the low-voltage type, resemble those used in traditional air-forced heating systems. They typically come with a floor temperature sensor, a room sensor, and separate wire connections for each zone valve.

Depending on your desired level of control, you can install one or more thermostats. For individual room control, you can use a thermostat for each room, or opt for a single thermostat with multiple sensors to provide customized comfort levels.

The good news is that dealing with a faulty thermostat is often a manageable problem that can be tackled as a simple DIY project.

Here are some recommended steps to address a faulty thermostat:

  • Carefully inspect the thermostat for physical damage, broken wires, or disrupted power supply.
  • Check the circuit breaker, as it may have tripped. Resetting the breaker can sometimes resolve the issue.
  • Use a non-contact voltage tester to check for voltage on the zone valve. If there is no power, your thermostat may be broken and require replacement.
  • If the problem lies with a malfunctioning thermostat, turn off the breaker before replacing it to ensure safety.

Zone Valve Problems And How To Repair It

Hydronic radiant floor heating repair often involves addressing issues with zone valves to ensure proper functionality. By understanding the common problems associated with zone valves and following proper repair techniques, you can effectively resolve issues and restore optimal functionality to your floor heating system.

Hydronic radiant heating systems are commonly divided into multiple “zones,” allowing for specific areas to be heated at different temperatures as needed. Each zone has its own thermostat and a zone valve that opens or closes to regulate the flow of hot water.

These zone valves are powered by electricity (typically 24V) and utilize a small motor to control their opening and closing mechanism. When a zone valve becomes faulty or breaks down, it can disrupt the circulation and room temperature, compromising both the system’s operation and your comfort. In some cases, a zone may fail to heat up altogether.

A malfunctioning zone valve can jam in either the closed or open position. To troubleshoot, you can try tapping the valve with a hammer. If it closes, the issue may lie with the power head. If it remains open, it indicates a damaged or blocked valve head. Additionally, ensure that the manual lever of the valve moves freely.

Replacing a power head is a relatively straightforward process and does not require unsoldering the valve body from the copper pipes. However, valves may also develop leaks, either at the connection to the pipe (requiring resoldering) or from the valve element itself (necessitating replacement).

Here are the step-by-step instructions for replacing a zone valve:

  1. Turn off the circuit breaker supplying power to the zone valve.
  2. Disconnect the wires connected to the zone valve.
  3. Shut off the zone valve to stop the water supply.
  4. Drain all the water from the system using the appropriate valves or drain points.
  5. Remove the old zone valve from its position.
  6. Solder a new valve into place, ensuring a secure and watertight connection.
  7. Refill the system with water and restore power by turning on the circuit breaker.

Problems With A Circulation Pump

If your circulation pump stops working or operates intermittently, it can result in your floor not warming up as it should. Typically, the pump operates quietly, but if you start hearing unusual noises such as rumbling, humming, or hissing, it could be an indication of a problem.

When faced with this issue, the best course of action is to replace the circulation pump. However, it’s important to note that before disconnecting the pump, you must first drain all the water from the loop and detach the circuit wire connections. This ensures a safe and proper removal of the pump.

Airlock Problem

Hydronic systems that utilize PEX pipes are typically sealed and pressurized. However, occasional issues can arise, such as the occurrence of airlocks, where air bubbles restrict or block the flow of water within the system.

If you notice that a specific zone in your hydronic floor system is not heating up, it is likely due to an air bubble problem.

To address this issue and remove the air bubbles from the system, you will need to flush water through the affected zone. This process helps to release trapped air and restore proper water flow and heating performance.

Water Is Leaking From The PEX Tubing

If the PEX tubing in your hydronic system was professionally installed, you should not encounter issues such as leaks or obstructions in the hot water flow.

However, if the tubing becomes punctured, kinked, or pinched during the installation process, a water leak can occur, resulting in damage to the flooring, ceiling surfaces, and surrounding objects.

Addressing this problem typically involves a multi-step solution. You may need to remove the flooring to access the affected area, break up the mortar to expose the damaged piping, and then cut and remove the compromised section of tubing. Finally, a new piece of tubing can be installed to replace the damaged section.

Single Zone Is Not Heating Up

Here are the common reasons and repair tips when only a single zone of your hydronic floor system is not heating up:

  • Stuck actuator pin valve – Try using a silicon spray or a pair of long-nose pliers to free the stuck pin.
  • Faulty actuator – Check the thermostat and electric circuit to ensure proper functioning. If necessary, consider replacing the actuator.
  • Faulty thermostat – Check the battery or electrical supply of the thermostat. If needed, reset the thermostat or replace it if it is not functioning correctly.
  • Wiring issues – If you suspect wiring issues, it is advisable to consult with an electrician who can diagnose and address any wiring problems in your system.
  • Flow gauges not open properly on the manifold – Check the flow rates on the manifold and adjust them if they are not open properly. This can help ensure proper water flow to the affected zone.
  • Airlock – If you suspect an airlock in the system, flush the zone to remove any air bubbles. Flushing the zone can help restore proper water flow and heating.

Multiple Zones (or Entire System) Is Not Heating Up

  • Circulation pump malfunction – Check the power supply and electric wiring connected to the circulation pump. If necessary, consult an electrician to troubleshoot and repair any issues with the pump.
  • Defective pump relay – If the pump relay is faulty, it may prevent proper operation of the circulation pump. In this case, it is recommended to seek assistance from an electrician to replace the faulty relay.
  • Isolation valve closed on the manifold – Ensure that the isolation valve corresponding to the affected zone is fully open. Sometimes, these valves can accidentally be closed, resulting in a lack of heating in that zone.
  • Stuck pin valve inside the thermostatic valve head – If the pin valve is stuck, try using a silicone spray or a pair of long-nose pliers to free the pin. This can help restore proper functionality and allow for the flow of hot water to the zone.

Circulation Pump Is Running Constantly And Won’t Turn Off

  • Stuck pump relay: If the pump relay is stuck, it may cause issues with the circulation of hot water. It is recommended to contact an electrician to inspect and diagnose any potential electrical problems related to the pump relay.
  • Faulty thermostat: If the thermostat is malfunctioning, try resetting it to see if that resolves the issue. For wireless models, check the batteries and replace them if necessary. If the thermostat is broken, it may need to be replaced to restore proper functionality.
  • Malfunctioning actuator: If the actuator is not functioning correctly, it can disrupt the flow of hot water to the affected zone. Contact an electrician to examine the thermostat or electrical panel for any electrical issues that may be causing the malfunction.

Pressure Issues

Since your hydronic floor heating system is a closed system, it is designed to maintain consistent water pressure. However, if you notice any pressure issues, it’s important to address them promptly.

Here’s what you need to know about hydronic radiant floor heating repair and pressure issues:

Low pressure: If you observe low water pressure, it is essential to inspect the system for potential leaks. Check the pipes, manifold, boiler, expansion tank, and other components for any signs of leakage. Low pressure can hinder the system’s efficiency and lead to higher utility bills.

High pressure: Conversely, if the pressure rises, it may indicate water flow restrictions caused by blockages or airlocks. These restrictions prevent water from circulating properly, resulting in increased pressure. It’s crucial to identify and resolve any blockages or airlocks to restore normal operation.

Failed expansion tank: A malfunctioning expansion tank with a faulty diaphragm can contribute to pressure issues. When the expansion tank fails to accommodate the expanding water as it heats up, it can cause an increase in pressure. In such cases, it may be necessary to replace the expansion tank to maintain optimal system performance.


Hydronic radiant floor heating systems provide reliable and efficient heating for homes. While they are generally durable, occasional repairs may be required to address issues that can arise.

Throughout this article, we have discussed common problems that can occur with these systems and provided valuable troubleshooting and repair tips. Whether you are dealing with a lack of heat, leaks, uneven heating, or other issues, understanding the causes and following the appropriate repair steps can help you resolve the problem.

Additionally, regular maintenance and cleaning are key to ensuring the optimal performance of your hydronic radiant floor heating system.

However, it is crucial to emphasize that hydronic radiant floor heating repair can sometimes be complex, especially if you are not familiar with the system’s components and operation. In such cases, it is strongly recommended to seek professional assistance.

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