The Heating and Hot Water Industry Council (HHIC) has issued updated guidance on condensate pipes, advising heating engineers and homeowners to prepare them to prevent freezing and maintain boiler function in colder months1. The guidance was reported by the Institution of Gas Engineers and Managers (IGEM) in November 20241.
The council states that external condensate pipes are particularly vulnerable to freezing if not properly insulated or sealed, which can lead to blockages that affect heating and hot water availability1. Its recommendations cover where a condensate discharge pipe should run and how an external pipe should be finished:
| Situation | HHIC guidance |
|---|---|
| Internal drainage available | Connect the condensate discharge pipe to an internal gravity discharge point, such as a soil stack or bathroom and kitchen waste pipes1 |
| External pipe | Use at least 13mm of UV-resistant, waterproof insulation, seal all joints and terminate the pipe at a 45-degree angle1 |
| External pipe position | End below grid level but remain above the waterline to guard against wind chill1 |
| No internal gravity discharge point | Use a condensate pump to help discharge condensate effectively1 |
HHIC director Stewart Clements called on engineers to ensure compliance with manufacturer guidelines and standards such as British Standard BS 6798:2014, to help maintain system reliability and customer warranties1.
"Following manufacturer guidelines, alongside our condensate pipe installation guide, provides maximum protection against pipe freezing."
The guidance also encourages engineers to inspect systems carefully, confirm adherence to updated regulations, and advise homeowners on any necessary upgrades that could boost efficiency and resilience during the winter1. The report does not give a figure for how many boilers are affected by frozen condensate pipes in a typical winter, and no cost for insulation or a condensate pump is stated1.
Why it matters for households
A condensing boiler produces acidic water as a by-product of combustion, and that water has to leave the property through a condensate pipe. If the pipe freezes, the boiler can lock out and stop delivering heating and hot water, often at the point in the year when a household most depends on it1. The HHIC guidance treats the routing of the pipe as the first line of defence: an internal connection to a soil stack or waste pipe keeps the condensate inside the thermal envelope, where it is far less likely to freeze1. Where the pipe must run outside, the specified 13mm minimum of UV-resistant, waterproof insulation, sealed joints and a 45-degree termination are intended to limit heat loss and stop water sitting in the pipe where it can freeze1. For a household, the practical effect is that the reliability of heating and hot water in cold weather depends partly on how the condensate pipe was installed and whether it has been checked since. The guidance sits alongside the wider design and balancing of a heating system, covered in the site's heating system design, balancing and water treatment pages, and the boilers and heating hub carries related material.
What happens next
The guidance is described as released ahead of winter, with engineers encouraged to inspect systems and advise homeowners on upgrades1. No further dated steps, deadlines or enforcement dates are given in the report1.