Clogged Condensate Drain Lines In Boilers

Back in the day, boilers were terribly inefficient; there were hot gases that would escape from the boiler. Heating engineers thought to themselves “Hey, we can use that heat for something”, and condensing boilers were born.


One byproduct of condensing boilers is the condensate drain line – which, unfortunately, can get clogged. In this short blog post, we’re going to look at why condensate drain lines get clogged – and what you can do about it.


But first, we have to understand exactly what condensing boilers do.


What are condensing boilers? 

Condensing boilers use heat from water vapour in flue gases to preheat cold water that’s entering into the boiler. During this process, the temperature of the flue gases drops rapidly – from somewhere around 130º Celsius to around 50º Celsius. This causes the water vapour to condense.


This water is more acidic than the water found in the boiler’s tank, and it needs to be drained. It ends up in the condensate drain line, which drains it into your waste water outlet. 


The Government of Canada suggests that buyers consider condensing – because while condensing boilers are more expensive upfront, they can lead to massive overall savings because of their high efficiency.

Why do condensate drain lines get clogged?

Sediment can build up in boiler tanks – and sometimes, that sediment makes its way to your condensate drain line. This can be due to water hardness, or corrosion of the metals in your tank.


Condensate drain lines have traps – they’re often U-shaped, though they can be siphon-based traps. These are the parts of the drain line that are most likely to get clogged.


When the drain lines become clogged, the condensate can begin to flow back into the bottom of the heat exchanger. When this happens, your boiler will turn off automatically for safety reasons.


How do you clean condensate drain lines?

You might find advice on how to clean condensate drain lines yourself online.


Don’t follow that advice.


Cleaning a condensate drain line is a fairly straightforward process, but you are dealing with a line that’s draining water vapour from flue gases. In other words, though the process is straightforward, it’s not safe unless you know what you’re doing. You could be putting your boiler – and yourself – at risk.


That’s why it’s important to call a professional if you suspect your drain line is clogged. 


Better yet, sign up for regular boiler maintenance. Cleaning out the condensate drain line is a part of the boiler maintenance process – and if your drain line is getting cleaned out every year, you should never have clogs.


Whether you suspect your condensate drain line is clogged, or you’re just looking for regular boiler maintenance, we can help. We offer boiler service in Winnipeg, from installation to repair and maintenance. Give us a call!