Why Your Boiler Loses Pressure in Winter (And How to Fix It)

A drop in boiler pressure is one of the most common callouts we get during cold snaps in South Wales. It usually happens when you turn your heating back on full blast after the summer.

What's Causing the Issue?

As temperatures drop, the metal in your pipes and radiators contracts. Tiny, previously unnoticeable leaks can suddenly start letting water escape. Alternatively, your boiler's pressure relief valve might be venting excess pressure if it's working too hard.

What This Means For You

When the pressure drops below 1 bar, your boiler will shut down for safety. This leaves you with no heating or hot water right when you need it most. Constantly topping it up dilutes the protective chemicals inside, leading to rust and expensive sludge buildup.

Practical Tip

Check your pressure gauge. If it's below 1 bar, use the filling loop underneath the boiler to top it up to 1.5 bar. If you have to do this more than once a month, you have a leak that needs fixing.