Vaillant boiler behaving erratically...

[kevster310]

Hi there,

I have a Vaillant EcoMax 8000 series combi boiler.

It's probably 2-3 years old and has worked flawlessly up until now. Recently, it keeps locking out with error code F28. Read the manual and it says it's failing to ignite, possibly having something to do with the gas supply.

Funny thing is if I shut off the boiler and reset, it'll ignite perfectly and work like a charm. However, it doesn't stay that way and after a period of time, it'll lock out again with F28.

I had a heating man around and his suggestion is to just replace everything having to do with the F28 code, which is quite a few parts and quite a few quid...

Just want to see if you guys had any ideas?

Tanks!!

 

[GQuigley67]

better getting someone who specialises in boiler repairs and knows about vaillants as that guy doesnt sound like he knows what hes doing, he probably only does installs.

 

[rab250]

like GQuigley67 says you need to find a better breakdown engineer who knows how to test the related components anyone can fix a boiler if they throw parts at em but by the time they finish you may aswell put a new one on the wall.

 

[wards]

last f28 i had turned out to be the gas valve.

 

[CombiDog246]

I had F28 problems regularly on a Combimax (Vaillant aquablock) supplied with bottled gas. Turned out to be the gas pressure regulator and not the boiler but the fault found by measuring the gas pressures at rest and on demand. At rest the gas supply was at correct pressure and the boiler was happy. On demand the pressure slowly dropped to the point where the F28 fault come on. Sometimes it took minutes other times hours to go to fault but it always reset after turning the boiler on/off because the faulty regulator had time to recover. Get the supply pressures measured before and after the gas valve before throwing away cash on spare parts. The replacement regulator cost me a fiver.

 

[GQuigley67]

the F28 code narrows down the components for the engineer to test to make it easier to find the fault, it doesnt mean you need to replace all of them and hope for the best ! get someone in who knows what hes doing

 

[Daleroader]

Double check the flue is not obstructed in some way. I had same fault code few weeks ago and that was the problem.

 

[MatthewHurt]

I had an F28 on a job a few weeks ago, turned out a bird or something had knocked the flue terminal slightly as it went through the roof, and this has stoped the boiler drawing in enough air to burn the gas properly.
I also seem to remember this fault code coming up when an ignition probe had warped and the spark wasn't able to fire across the two probes properly.

If it is either of these two problems it will hopefully only cost you a couple of peanuts =)
Hope this helps

 

[fagsanbooz]

check all pressures including at meter whilst appliance is running and at appliance inlet. if pressure is fluctuating it maybe meter regulator or pipework, or faulty gas valve or blocked flue.

 

[pobsdad]

F28 narrows it down to only a million possibilities!Start with the easy/cheap options.Gas supply ok?Check meter regulator(not so easy,but you could get it changed easily),then rectification electrodes.AP switch dropping out can give similar faults on some boilers.Gas valve may be faulty,or even pcb,but now you're talking serious money to try new (non returnable) parts.Intermittent faults are horrible,and expensive!