The Condensate Debate

It’s the 31st March, 2018 and we’ve just defrosted from the heaviest snow I’ve witnessed in 34 years. Before the pot holes have been counted or the precautionary cancellation notices for Lincoln Christmas Market 2018 drafted, there’s talk of changing the regulations to ensure that boiler condensates will never freeze again.

Of course there are bad installations:

But there have also been reports of both insulated and correctly sized pipe work freezing:

frozen boiler condensate

I personally attended a 68mm fall pipe that had frozen (due to a blocked gully).

I don’t feel, as an engineer that I know enough as to how and why certain installations freeze whilst others don’t. If you take this example:

The rising PE mains froze solid, yet the almost horizontal ¾ condensate elbow didn’t. Of course many of these did freeze:


I was stronger at maths than science but I would expect 30-40ºC to pass through a vertical pipe without freezing. I’m not even sure that it is condensate from the boiler that freezes.

So what’s the solution?

Research, education and choice.

Allow those affected to submit pictures and basic information (postcode, model) to a central log. Analyse and feedback with best practice advice to those who participate.

Establish what pipes freeze at what temperatures. Based on what we have seen, open ended pipes are more susceptible to freezing than those bossed into a stack.

Educate Installers so that we can state, for example:

  • An uninsulated Xmm pipe can withstand Y days @ -ZºC if it goes into a stack.

How many minutes of protection does Lagging add??

I would like to see that education is enforced, but that customers maintain some freedom to choose how to spend their money.

Personally I am going to keep my exposed ¾ overflow elbow but reroute the incoming PE mains ASAP!