Boilers fail in a surprisingly small number of ways. The same handful of faults account for most winter callouts, and each announces itself with symptoms specific enough that a household can usually tell which one has arrived before anyone opens the casing.
R M Burn & Son Plumbing & Heating Engineers repairs boilers across Clevedon, and this is the field guide to the faults that repeat.
Pressure loss, the most common of all
A sealed system holds its pressure. When the gauge sags toward zero the boiler locks out to protect itself, and topping up through the filling loop restores service in minutes. That part is a householder job and it fixes a great many mornings.
The fault is not the low pressure but the reason for it. Water leaves a sealed system through a weep on the circuit, a relief valve passing to its outside discharge, or an expansion vessel that has lost its charge and is forcing water out through that valve. A system needing topping up weekly is reporting one of those three, and every top-up adds fresh oxygenated water that accelerates internal corrosion.
- Top up once; log it if it returns.
- Weekly top-ups mean a weep, a passing valve or a flat expansion vessel.
- Fresh water repeatedly added is corrosion fuel.
Ignition failure and the flame that will not prove
A boiler that tries, fails and locks out is failing to prove a flame. The causes cluster around gas supply, ignition electrodes and the sensing that confirms the flame exists, and they are all behind the casing, which makes this an engineer's fault rather than a householder's.
What helps the visit is the pattern: whether it fails from cold, only under heavy demand, or intermittently. That description narrows the search before any panel comes off, and often means the right part travels on the van.
- Repeated attempts then lockout means no proven flame.
- Note whether it fails cold, hot, or at random.
- Everything behind the casing is engineer territory.
Winter's speciality: the frozen condensate
Modern boilers produce condensate that drains away through a plastic pipe, and where that pipe runs outside it can freeze in a cold snap and lock the boiler out. It is the single most common avoidable breakdown of any British winter.
Thawing the external section with warm, never boiling, water and resetting usually restores it. If it happens every cold spell, the pipe wants rerouting internally or upsizing and insulating properly, which is a small planned job rather than an annual emergency.
Hot water only, heating only, or neither
Which service failed is itself a diagnosis. Hot water working while heating does not, or the reverse, points at the diverter arrangement or the controls rather than at the boiler's core. Both failing together points at ignition, pressure or the appliance itself.
Everything lukewarm rather than absent is a circulation story: a tired pump, air in the system, or sludge restricting flow. R M Burn & Son Plumbing & Heating Engineers checks that distinction first, because it decides whether the visit is a boiler repair or a system repair wearing boiler clothes.
Related pages
Questions customers ask
How often should I have to top up boiler pressure?
Once or twice a year is unremarkable. Weekly or monthly means water is escaping and the cause should be found before it damages more than it already has.
Why does my boiler only break down in freezing weather?
Almost always the external condensate pipe icing up. Thawing restores it, and rerouting or insulating the pipe ends the annual repeat.
Is it a boiler fault if the radiators are only lukewarm?
Often not. Lukewarm everything usually points at circulation: pump, air or sludge restricting flow. That is a system repair rather than a boiler one.
Note which service failed, whether pressure is holding, and what the weather is doing. Those three observations identify most boiler faults before an engineer arrives.
R M Burn & Son Plumbing & Heating Engineers covers boiler repair across Clevedon. The contact page takes the symptoms.
