Valliant Ecotec 418 - periodic ignition mis-start

[silverfox2019]

My 12-year-old Valliant Ecotec plus 418 system boiler (i.e. old school with HW tank) works perfectly when providing hot water only, but now I’ve switched on central heating for autumn, every few days it fails to ignite properly and error code F62 shows. When this happens I press Reset and the main burner powers up for a minute then stops and error code F22 shows. If I then press Reset again, the main burner ignites and the whole system works perfectly for the whole day or several days before the same problem recurs upon morning start up. I’m guessing the main PCB needs replacing – or a new boiler. I guess ageing capacitors could be and issue but I understand regulations don't allow me to check them. Is there anything obvious I could check before biting the bullet?

 

[CountryFan]

Nothing obvious to check other than if f22 is genuine (loss of water/dry fire). Apart from that, sounds like pcb/gas valve issue. Local engineer or Vaillant fixed prixe repair

 

[fixitflav]

Nothing obvious to check other than if f22 is genuine (loss of water/dry fire). Apart from that, sounds like pcb/gas valve issue. Local engineer or Vaillant fixed prixe repair

I had a similar problem a few weeks ago. Turned out the gas pressure at the burner was below spec. Increased it and been fine since. Easy enough to do, but if you don't want to tackle it it might be worth asking the engineer to check it.

F

Thread 'Boiler intermittent fault'

16 Oct 2026

I have an old Ideal SE50 which has an intermittent fault.

The burner sometimes fails to light, though the fan is running. I turn the control-stat down to minimum then back up, and it then fires, each time it's happened so far. It seems to be more likely to happen when calling for HW (it's a W-plan) though I can't see why that would make a difference.

I'm inclined to suspect dirty contacts in the control-stat. Can anybody please comment or think of any other explanation?

• fixitflav
• Replies: 8
• Forum: Plumbing and Central Heating

 

[CountryFan]

I had a similar problem a few weeks ago. Turned out the gas pressure at the burner was below spec. Increased it and been fine since. Easy enough to do, but if you don't want to tackle it it might be worth asking the engineer to check it.

F

Thread 'Boiler intermittent fault'

16 Oct 2026

I have an old Ideal SE50 which has an intermittent fault.

The burner sometimes fails to light, though the fan is running. I turn the control-stat down to minimum then back up, and it then fires, each time it's happened so far. It seems to be more likely to happen when calling for HW (it's a W-plan) though I can't see why that would make a difference.

I'm inclined to suspect dirty contacts in the control-stat. Can anybody please comment or think of any other explanation?

• fixitflav
• Replies: 8
• Forum: Plumbing and Central Heating

At 12 Years old it won't be burner pressure, nor should we be encouraging gas work to random public

 

[fixitflav]

At 12 Years old it won't be burner pressure, nor should we be encouraging gas work to random public

OK, it's a modulating burner so maybe different. The manual just says 17 - 25 mbar at the test point. might be worth the engineer checking that, unless he can put his finger on the problem immediately.