What To Do When Your Boiler's Condensate Pipe Freezes

Posted on: 19 February 2016

When your boiler stops working on a very cold day, there's a good chance the problem is due to a frozen condensate pipe. The condensate pipe is a tube that leads from the boiler to the outdoors. It is supposed to allow condensation from your boiler to travel outside. But when temperatures drop too far below freezing, water may build up in your condensate pipe and freeze, causing the condensation to leak back down into your boiler. This will cause the boiler to shut off.

Luckily, a frozen condensate pipe is an issue you should be able to fix on your own. Follow these instructions to complete this task.

Step 1: Verify that the condensate pipe is the issue.

Locate your condensate pipe. It is typically white or gray in color, and it should lead from the boiler, through an exterior wall, to a drain outside. Once you find this pipe, tap along its length. If you find a section where the pipe sounds solid rather than hollow, you have found the blockage. Another sure sign of a blockage is gurgling noises coming from the boiler or condensate pipe.

If you are unable to find a blockage in the condensate pipe and there are no gurgling noises, then your boiler breakdown is probably caused by another issue. Verify that your circuits are switched on, and that the valve that allows water to flow into the boiler is open. If the valve is open and the power is on, then call a boiler repair professional. You could be dealing with any number of issues, from a broken thermocouple to a wiring problem. Many of these issues need to be repaired by a licensed professional, so it's best to leave them to your technician.

If you are able to locate a blockage in the condensate pipe, however, you can proceed as follows with this simple repair.

Step 2: Pour warm water over the blockage.

If you were able to locate exactly where in the pipe the blockage is, this step will be pretty easy. Take a jug of warm water, and pour it over the frozen section of pipe. (Usually, the frozen section will be outside, so you don't have to worry about the water making a mess. If the blockage extends inside, set a bucket under the pipe to catch the warm water as it trickles down.)  Avoid using water that's actually boiling, as this can cause the pipe to crack.

Eventually, you should either see a chunk of ice slide out of the outdoor side of the pipe, or hear it slide down into the boiler. If you're working on the blockage outside, have a friend stand inside by the boiler so they can tell you when they hear the chunk of ice come splashing down. This means the pipe is clear.

Step 4: Restart the boiler.

Follow the instructions in your owner's manual to re-start the boiler. Generally, this will just require that you push certain buttons in a certain order. If you're not sure how to reset your boiler, your HVAC professional should be able to help you over the phone.

Step 5: Keep the pipe from freezing again.

If you skip this step, your condensate pipe will just freeze again the next time it turns arctic outside. Wrap the pipe in foam insulation if it is not already insulated. If it is already insulated, replace the insulation with a thicker layer or add a second layer on top of the existing layer.

During cold weather, it can also help to turn your thermostat up a few degrees. This will ensure your boiler runs more often, which should keep your condensate pipe warmer so it is less likely to freeze.

If you're not able to successfully thaw your condensate pipe by following the steps above, contact your plumber or boiler repair technician. They'll be able to access your pipe from the inside and thaw it out more effectively. Contact a company like StateWide Mechanical II Inc. for more info.