Glow-worm F22: low water pressure on an Ultracom or Betacom

Understanding a Glow-worm F22 shortage before you spend money

Refill with the boiler cold, using the external filling loop, up to the pressure figure printed on the appliance data badge, then fully close both loop valves. Where the fault returns within weeks, the search moves to the expansion vessel charge and then to slow leaks at radiator valves, pipe unions and the pressure relief valve seat, roughly in that order of likelihood.

A Glow-worm F22 shortage — the facts that change the job

• Refill cold, to the figure on the appliance data badge, not a guess
• Close both filling loop valves fully once the target is reached
• A vessel that has lost its charge causes very frequent top-ups
• Radiator valve unions are a common slow, hard-to-spot leak point
• The relief valve seat is checked where staining appears outside

Questions we get asked

What if I don't know the target pressure?

It is printed on the data badge inside or beside the appliance; if it is missing, an engineer can confirm the correct figure for your model.

Is it safe to run the boiler slightly under pressure?

Below the manufacturer's minimum the boiler will lock out to protect itself rather than run unsafely.

Where we deal with this

• Westbury (Wiltshire) (BA13) · 13 mi
• Twerton (BA2) · 7 mi
• Nailsea (BS48) · 14 mi
• Odd Down (BA2) · 8 mi
• Keynsham (BS31) · 9 mi