Vaillant TURBOmax Plus 824E Boiler LOCKOUT F28 Fault Code

[Lez359]

Hi, I have a the above boiler which is approximately 5 years old. I switched off system to change gas cooker. House has been empty for 12 months due to renovation and thus I never turned boiler on. Now, when I have come to do it the boiler will not ignite and comes up with F.28 fault code. The manual tells me this could be a lack of pressure, iginition, no gas??? There is plenty of gas there as cooker and fire works fine. When boiler turned on it "clicks" 3 times and nothing happens. When reset button pressed nothing happens. Two Gas Engineers baffled. Can anyone help and shed any light please? Thanks

 

[Happyplumber]

Two gas engineers baffled !!! I dont believe that for second or obviously they dont have clue how to repair boilers,combustion related issues have to be deal with Registered Gas Installer ,i suggest you find someone who is local and comes with recommendations

 

[Lez359]

Afraid so - wouldn't put it otherwise. Registered too!!!!!!!!! Still, no further forward

 

[gasinspect]

just come back from fixing one.

check green resister - should be 68ohms. If it isnt and, then the rectifier in the lead to the gas valve has gone and that has blown resister. quick fix, you need to change lead and pcb,

DONT change pcb without changing lead, or you will blow your new board.

 

[MarkRainbow]

I've just had an F28 error on this boiler.

Looked like a gas valve failure at first sight, but all coil resistances looked fine.

I called Vaillant Tech support and they confirmed that the coil resistances were all good. They got me to check the green resistor on the PCB, which was fine at 68 Ohms. They concluded that it must be thhe gas valve.

They then advised me not to change the valve without changing the lead as it has a diode, or some diodes in it.

I duely ordered both, but tried changing just the lead first. The valve was working fine. Glad I checked.

Is this Vaillant selling their very expensive valve unnecessarily? THe same Sigma 845 valve is fitted in Baxi's and cost £45 against £120 Parts Center quoted for the Vaillant version.

 

[SShar]

Hi Mark Rainbow and Lez 359,

As far as I was aware and f.28 code displaying is usually down to a frozen condensate pipe, it could have frozen during the cold weather and snow we had recently, i'd check that first before anything else

HTH

 

[Bunnyman]

Very old thread but may help someone. Sorry sha but the turbo is not a condenser, this is gas valve or if a later model 2003 onwards it could be low water pressure or pressure switch the early models 2000-2002 had the Honeywell gas valve with the diode in the lead this was a common problem .the later valves had the sit valve with different lead ,they also had 2 types of sit valve the early 2002 with a flange and 2002 onwards had 2 threaded ends.NEVER HAD A LEAD FAIL ON A SIT VALVE LOL! The early sit and Honeywell valves were interchangeable if you changed the lead and the jumper on the pcb to suit

 

[geoffgiltrap1]

Funningly enough I had same fault code this morning on a Turbo max plus I fitted in 2001.
The original installation manual states "boiler goes to lockout"
no gas
insufficient gas
incorrect gas pressure
All proved okay
fault code also says igniter or ignition lead- which I have ordered.
Vaillant tech support suggested i replace electrodes and leads (no mention of gas valve or lead)- I'll report back tomorrow

 

[Bunnyman]

Take the valve off connect up the power c if u can blow through it, was it sparking? If so forget the leads an electrodes😞 if no spark prob pcb if spark an no gas prob gas valve😄

 

[geoffgiltrap1]

I'll report back tomorrow .sometimes it fired up sometimes it locked out f28

 

[geoffgiltrap1]

Electrodes replaced today- all seems fine.I'll leave it a couple of days to be sure.

 

[Boilerman2]

I had fun & games with one of these a few years ago, intermittant lock out, ALWAYS fired first & every time I was there, however one morning I reset it, and no gas passed to the burner BINGO! new gas control valve and away it went! patience is essential

 

[ollski]

Ecotec plus this morning locking out on f28, it was lighting but not rectifying, electrodes and lead looked A-ok so I fitted a new board. New board didn't work but electrodes and lead did!

 

[geoffgiltrap1]

Phoned client today -no fault codes all okay.they should get invoice tomorrow morning.

 

[dingaling]

A more recent update and case....
I had the same as the OP. The F28 fault would not clear. It's a 2018 model (ish) and not condensing.
Water pressure was low because a radiator had been removed for decorating. Topped up and fault still there.
Eventually after hearing about pressure differential issues I bled some air from the autovent on the top of the pump. Next power cycle and all fine again.
Conclusion... Pump airlocked. Nothing to do with gas, condensate, leads, PCB etc.

Just fyi for DIY.