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Troubleshooting Hydronic Heating Issues

What Is Hydronic Heating?

Hydronic, or radiant, heating is an energy efficient system that heats your home by using tubes that run hot liquid through radiators, along baseboard heaters, or beneath the floor itself. A smart green building choice, hydronic heating has recently increased in popularity as people have learned about how it can lower your heating bills and decrease your impact on the environment. Plus, when the system is set up, multiple zones can be designated. This allows you to choose different temperature settings for each zone, rather than be limited to one level of heat throughout your home.

How Does Hydronic Heating Work?

A hydronic heating cycle begins with an energy efficient boiler that heats the water or alternative liquid. The heated liquid then flows to a plumbing manifold system, which is the control center that connects to the thermostat and directs the correct temperature of water to the different heating zones around your home. The hot liquid circulates through loops of plastic piping. Usually, this piping is installed as radiant flooring in the floor joist system or concrete slab of your home. The tubes are installed in such a way that the heat evenly radiates across the surface of the floor. However, radiators and baseboard heating units can also be used as sources of radiant heat. Pumps constantly push heated liquid into the tubing, displacing the cooler water and sending it back to the boiler to be reheated so the cycle can continue.

Why Is Hydronic Heating More Effective Than Forced Air Heating?

While the more commonly used forced air systems only use conduction to transfer heat, hydronic systems use both conduction and radiation. Conduction transfers heat through physically touching objects (e.g., cold air blowing on you cools you). But the denser the cooling or heating agent, the more effective it is. So, cold water cools you quicker than cold air does. Thus, even without its use of radiation, the hydronic system’s use of water rather than air already makes it more effective.

However, radiant heat transfers heat better than conduction because it transfers heat through invisible waves that cannot be blown away or moved. Instead, the heat is absorbed by what lies in its path. So, by using both a denser form of conduction as well as radiation to transfer heat, hydronic systems heat more efficiently than forced air systems.

How to Troubleshoot Hydronic Heating System Issues

Hydronic heating systems are designed to be reliable, but like any automatic system that is regularly used the parts can wear out and problems can arise. Before you call in a registered engineer, you can troubleshoot the following problems to determine whether your issue is a simple fix that you can handle yourself. Even if you are not a DIY person, being able to narrow down what the issue may be can save you time and money when you do schedule a repair person to come.

Is the Thermostat Having Problems?

Sometimes thermostat problems are simply due to the fact that it is not hung in a good location. Ensure that it is mounted on an inside wall, because outside walls are more affected by the outdoor temperatures. Move it, if necessary.

If your thermostat is located appropriately and set to heat mode but is not turning the system on, check the temperature settings. If the settings seem appropriate, try changing the heat a few degrees (up or down) to see if the thermostat will now kick in. If nothing happens, the thermostat may be failing to properly emit signals to the heating system. Open the casing and check the wiring and contacts. Ensure that everything is clean and securely attached. If there are signs of burned wiring or scorched connections, these will need to be replaced. It is recommended that you consult with a professional to determine what caused this, so that it, too, can be fixed.

Is the Boiler Running?

If the heat levels in your home are not what they should be, the boiler may not be working. This could be due to a tripped breaker or blown fuse. Check your main electrical panel and reset the switch or replace the fuse, as needed. If the breakers and fuses are fine, the issue may be with the boiler itself. Consulting a professional would be wise.

Is the Pilot Light Lit?

If you cannot see a pilot light, try reigniting it with the ignition system. If this does not work, there may be a defective part that will need to be addressed by a professional.

Is the Water Level Correct?

It is critically important to maintain the water level in your boiler. If the water is less than half full, this could be the source of your problems. The boiler system is designed to self-maintain a proper water level (12 to 15 pounds per square inch). If your system does not have a pressure reducing valve, you can manually fill the boiler. Simply open the water feed valve and add water until the boiler pressure reaches 12 pounds per square inch.

Is the Valve End Switch Making a Connection?

If the valve end switch is not making a connection, there might be an insufficient supply of voltage to the valve. Check to see if the transformer is faulty. If too many valves were being powered by the transformer, you will need to add a transformer. If the overcurrent was overheating the end-switch blade or burning out the contacts, check to see whether the actual current draw matches the specified levels of the end switch. If not, you will need to get a different switch. If the valve is installed backwards according to the correct direction of flow, you will need to reinstall it. If you hired someone to do the initial install, contact the installer to discuss how this can be resolved.

Is the Valve Working?

If the valve is prematurely failing, the issue could be caused by O-ring, rubber plug, or plug shaft failures. Hydronic valves used in closed-loop heating systems cannot handle oxygen. So, if oxygen somehow enters the closed system, it can damage the guts of the valve. Check for loose or damaged O-rings, rubber plugs, or plug shafts, and secure or replace them as needed.

Is the Valve Motor Running?

If the valve motor has prematurely failed, it could be due to a lack of lubricant inside the motor. If the motor has been affected by too high temperatures and voltage combined with numerous high-duty cycles, the lubricant can dry out, causing the motor to fail. Sometimes, simply reducing the duty cycle of the valve can help resolve this issue.

Has Air Entered the System?

A properly installed system should have an air separator in the common supply piping, as well as air vents on the radiators and boiler. The expansion tank should be located near the intake side of the pump and should be on the high-temperature supply side of the boiler. This setup helps increase the pressure throughout the system when the circulator operates, which prevents air problems within the system. Check to ensure the arrangement is correct and that the air separator and air vents are securely in their right places. If components are not in their right places and you had someone else install the system, contact the installer to discuss how this can be resolved.

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