No heating, no hot water, and a fault code on the display.
The boiler was a Vaillant and the code was F22, which on a Vaillant is low water pressure. When the pressure in the heating drops that far the boiler stops, and it stops the heating and the hot water together. That is what had happened here, and it is why the radiators and the hot taps can both go cold at once with nothing in the house obviously broken.
Fault code F22
The first photograph is the boiler’s own display. The big figure is the pressure, 0.8 bar. Under it, in small figures, it reads 0.8 to 3.0, and the reading was sitting on the bottom one.
People type "what does F22 mean on a boiler" into Google, and the answer is the one on this job. Not enough water pressure in the system for the boiler to run.
The filling loop
The second photograph is the filling loop, the braided hose with a valve at each end, down among the copper under the boiler. It joins the mains cold water to the heating. Opened, it lets water into the system and the figure on the display climbs, and that is how this one was brought back up.
At 1.5 bar
The third photograph is the same display afterwards, reading 1.5 bar, which is the working pressure we wanted on this boiler. A sealed heating system runs with the water inside it under a little pressure, and the boiler checks that pressure before it will light. Too little and it shuts itself down and puts the code up rather than run without enough water round it, which is what a boiler ought to do, even if it never feels that way when the radiators are cold. Bringing it back to working pressure is a small job when the pressure is the whole problem, and on this visit the pressure is what we found and the pressure is what we put right. We are not going to dress it up as anything more. We are not claiming a leak, a faulty valve or a new part, because the three photographs show a low reading, the loop and a good reading, and that is the job. Both the heating and the hot water had stopped on that one figure.
If it drops again
A top up is the short term fix.
If the pressure falls again afterwards, water is leaving the system somewhere, through a leak on the pipework or through the pressure relief valve, and as our boiler page says, finding where it is going is the repair. That would be a different visit, and we would rather tell you so than guess at it now.
Ring 07546 185778 if your boiler is showing F22 or the pressure has dropped, and tell us what the display reads.
