Many modern hydronic heating systems are condensing boilers. A condensing boiler is a type of fuel-burning boiler. It uses a second heat exchanger to extract heat from its exhaust gases before venting them. That process creates condensation that needs to go somewhere. Typically, that moisture flows into a condensate pipe that extends from the boiler to outside the home. There’s generally a low volume of water moving through the pipe. When the ambient temperature gets cold enough, that pipe is prone to freezing and eventually clogging.
Schedule a Professional Repair
If you have a frozen condensate pipe, your boiler has likely stopped working. Manufacturers design their systems to trip when there’s a condensate blockage to avoid leaks and other issues. You’ll need to contact a technician for a professional repair even if it’s the middle of the night.
Having a professional perform the work is very important. In the sections ahead, we’ll discuss strategies for fixing a frozen condensate pipe, but we don’t recommend doing it yourself. You can void your boiler’s warranty. It’s also possible to worsen the problem. You may damage the boiler, cause a leak resulting in water damage, or turn the repair into an even bigger expense.
Locate the Pipe
The first step is to locate the pipe. It runs from the boiler to outside the home where it generally connects with an external drain. There may be multiple pipes connected to your boiler. The condensate pipe is usually easy to spot because it’s typically plastic and white.
Check the Condensate Pan
Many systems will have a condensate pan. Condensation will drip from the boiler into the pan. Water will accumulate in the pan and then flow into the condensate pipe and outside the home. This pan also has a wet switch that trips the boiler to avoid flooding. Make sure that the pan isn’t overflowing or at risk of it. It may be necessary to remove some water if it is. Once the condensate pipe thaws, water will flow out of the pan. When that happens, return to ensure that the pan empties. If the pan is dirty, your technician will clean it.
Heat the Pipe
The usual solution to a frozen condensate pipe is to apply heat to cause the ice to melt. It’s important to use just enough heat, as too much can damage the pipe. If the pipe becomes compromised, you’ll need to replace it, which will turn the repair into an even bigger cost.
One option to unfreeze a condensate pipe is to apply a heat wrap. These are not dissimilar to the heat wraps used for muscular aches. You can apply the wrap to the affected area, or there are wraps big enough to cover most of the pipe. The downside to this approach is that it can be slow and only works with minor freezing. The upside is that there’s little risk of damaging the pipe. You can use something like a hot water bottle instead, but the process will be even slower.
A professional repair technician will have a heat gun. This method is effective because the technician can precisely control the temperature of the heat. The technician will run the heat gun up and down the length of the pipe until it thaws. You can use a hair dryer as an alternative, but the process will be slower and less precise. Another alternative is to use hot water. The water should not be boiling, as that can easily damage the pipe.
Clogs Involving More Than Just Ice
If the clog is due to just ice alone, it’ll be gone as soon as the pipe thaws. In some cases, you may find there’s a buildup in the pipe. It’s not unusual to discover this when the pipe freezes because the accumulation can make the pipe more prone to freezing. This issue is most prevalent in homes with hard water. The minerals accumulate on the walls of the pipe as limescale. Over time, the accumulation reduces the diameter of the pipe.
When a clog involves limescale or sediment, you’ll need to do more than just thaw the pipe. Your technician will likely run a vinegar-water mixture through the pipe to remove the scale. In severe cases, it may be necessary to use a chemical cleaning agent or replace the pipe altogether.
Reset the Boiler
Once the thawing process finishes, your technician will check that water flows through the pipe quickly and easily. The next step is to check the drip pan, wet switch, and, if applicable, condensate pump. Some configurations use a pump rather than gravity to drain properly.
If that all checks out, your technician will reset your boiler. It varies from system to system but generally involves holding a reset button for about 10 seconds. If the fault code goes away, the next step is to turn on the boiler and wait for it to heat up. Your technician will then check the system’s temperature and pressure.
Preventing a Frozen Condensate Pipe in the Future
Most boiler manufacturers recommend insulating the condensate pipe. This is necessary in colder climates but also warmer climates where an unexpected freeze can occur from time to time. The insulation is typically a thick rubber foam sleeve that your installer will wrap around the pipe. Some insulation is self-sealing while other products will require tape or another adhesive to secure it to the pipe.
That insulation will deteriorate over time due to sunlight, hot and cold temperatures, rain, and so forth. It’s important to check it on a regular basis and replace it as needed. If you schedule seasonal boiler maintenance, which you should, your technician will inspect the insulation during that appointment.
The thicker the condensate pipe, the less prone it will be to freezing. If you have an older system, it may not be up to code and require a thicker pipe. Replacing the pipe with a larger diameter and then insulating the new pipe may be the solution. Orientation can be an issue as well. Pipes installed vertically rather than at an angle are less likely to freeze.
You may find that changing the pipe is too expensive or that insulation alone is not good enough to prevent freezing. This can be due to exposure, such as a pipe that gets a lot of direct wind. In that case, it may be necessary to install more advanced protection. One option is a trace heater. These systems have a heated cable that your technician will coil along the length of the condensate. There’s a thermostat. When the temperature gets cold enough, the system heats the cable and prevents the pipe from freezing.
Local Plumbing Pros in Canterbury and Nashua
Joyce Cooling & Heating Inc. has served homeowners and businesses throughout Canterbury, Nashua, and the surrounding areas for nearly three decades. Our HVAC technicians install, maintain, and repair boilers, furnaces, heat pumps, air conditioners, and ductless mini-splits. We are available 24/7 for emergencies in the Greater Nashua area. Our team installs and programs Wi-Fi thermostats and specializes in indoor air quality equipment, including whole-home air purifiers. Our team performs oil-to-gas conversions and installs and services tank and tankless water heaters.
For more information or to schedule an heating appointment, call today, or contact us online.
