Condensing vs Non-Condensing Boiler Checker
Pick a type to see matching UK models, efficiency ratings, and whether a replacement could cut your bills. New installs must be condensing. Older non-condensing boilers are the ones ECO4 often replaces for free.
Up to about 98% efficient. Recovers heat from flue gases.
Required for almost all new UK gas boiler installs since 2005.
Look for a white plastic condensate pipe to an outside drain.
Often 60% to 80% efficient. Waste heat goes straight out the flue.
Common on older homes. Higher bills and more carbon.
A broken or inefficient unit can qualify for a free ECO4 swap.
Common questions
How do I tell if my boiler is condensing or non-condensing?
Condensing boilers have a plastic condensate pipe, usually white, running to an outside drain. They also have a larger flue. Non-condensing boilers are typically older, vent heat through a metal flue, and sit below about 80% efficiency.
Why are condensing boilers more efficient?
They recover heat from waste flue gases that older boilers dump outside. That extra heat warms the returning water, so less fuel is burned for the same room temperature.
Are non-condensing boilers still legal?
You can keep an existing non-condensing boiler running. New gas boiler installs in the UK must be condensing, except in rare cases where a competent person documents that a condensing unit cannot be fitted.
Can I get a free condensing boiler through ECO4?
If you receive a qualifying benefit, your home has a low EPC rating, and the current boiler is broken or inefficient, you may qualify for a free A-rated condensing boiler. Use the eligibility checker to find out.