In the exceptionally cold weather we have been inundated with calls from customers (not from boilers we have fitted thankfully) who have suffered boiler brake down due to condensate pipe freezing. This will present as a F28 or F29 fault on a Vaillant, EA – EA229 on most Worcester (these codes can also be for other things).
The boiler installer should have done everything possible to ensure this doesn’t happen when the boiler was fitted. Ideally the condensate pipe should join into another waste inside the property – e.g Kitchen waste, bath waste. These pipes will never freeze due to the high volume of water that passes through them. It is not always possible to due this depending on the boiler location. Sometimes there is no other choice but to run the pipe outside. If this is done the pipe should be as vertical as possible and insulated and for a short distance. Should it be necessary for the pipe to be long and shallow it is worth fitting a condensate pump or Worcester do a siphon product both will dump the water at higher speed than the boiler can. All of this reduces the chance of it freezing.
If your condensate pipe freezes you may be able to clear it yourself.
How do you know which pipe is the condensate?
Most installers will use copper pipes for all connections to the boiler, Flow, Return, Mains, Hot Water, Gas and Pressure relief pipework should all leave the boiler in copper, the condensate will leave in plastic (normally white). If you follow this pipe to its termination and check it you might find the end to be frozen. Clear the ice and try pressing the reset button on the boiler.