Glow-worm Error Code F.22

What Does F.22 Mean?

Error code F.22 indicates low water pressure in your Glow-worm boiler. This is a safety mechanism to prevent the boiler from running without enough water to circulate heat.

Common Causes

1. Natural pressure drop over time
2. Leaking radiator valves or pipework
3. Bleeding radiators without refilling the system
4. Faulty pressure sensor or expansion vessel

What You Can Do

Immediate Steps

1. Check the pressure gauge - ensure system pressure is between 1-1.5 bar
2. Repressurise the system using the filling loop
3. Inspect the system for any visible leaks
4. Reset the boiler once the pressure is restored

When to Call an Engineer

Contact a Gas Safe registered engineer if:

• The pressure drops again shortly after refilling
• You notice any leaks within the boiler itself
• The error persists despite the pressure being correct
• You're unsure how to use the filling loop

Prevention

• Regular system pressure checks
• Annual boiler servicing
• Ensure all radiator valves are secure and leak-free
• Consider a magnetic filter to keep the system clean