Vaillant Turbomax VUW 242 1/E intermittent fault

[TGS]

Hi Guys

I have an intermittent fault on my Vaillant Turbomax VUW GB 242 1/E. The fault occurs when the air temperature has dropped overnight and the first demand for hot water or heating is made in the morning. The sequence commences, pump, fan, ignition (burner lights) flame not detected so burner out. 10 second pause (as it should) then 2nd sequence commences, pump, fan, ignition (burner lights) flame not detected so red light lock out.

However, turn reset switch and the sequence will then complete successfully on first or 2nd cycle. All will then be ok unless there is a significant temp drop overnight then problem returns.

Had a local GS Engineer round twice who tested everything but could not identify any fault. The boiler works fine as soon as reset so he is pretty much waiting until the fault is permanent then identify the failed component.

I have followed the fault charts in the manual and replaced the PCBs (I have a qualified electrical background) but the problem persists. I need to sort this before winter so any experience of this fault or remedy would be greatly received.

 

[Razor900]

Is your meter inside or out? If you have any other gas appliances try running them first before you try the boiler in case it's a sticky governor

 

[TGS]

Thanks Razor900 I will try that on next air temp drop, hopefully tonight.

 

[TGS]

Oh, yes the gas meter is outside

 

[hertsboilers]

Is this boiler with a digital display? If yes what is the error code, F28?

 

[TGS]

hi, no its standard black plastic control panel face wth green knobs/controls

 

[AGAS]

you might want to take note off the LED'S sequence on front of boiler when faulting to help the engineer ( if any ) , but there could be few problems to choose from but at least you tried the expensive stuff first

 

[TGS]

Thanks AGAS, but I have set out the sequence of LEDs in the question posed above, which the GS engineer is fully aware of. He also contacted Vaillant technical but they couldn't help him - wait for it to fail completely was the basic answer. The fault chart said change the PCBs. The GS changed the flame sensor. Any ideas if you read the question again?

 

[Agile]

When you signed up for this site you agreed to abide by the rules.

One of the rules is that we are not allowed to give advice on DIY gas work.

Since Vaillant have a fixed price repair service I don't know why you decided to replace PCBs yourself when you knew they might not be the problem.

The definition of gas work in this context may be wider than you imagine. It includes all aspects of combustion including the flue, fan and the PCB.

The obvious advice is to get a competent engineer with diagnostic experience or call Vaillant.

Tony

 

[Agile]

Is your meter inside or out? If you have any other gas appliances try running them first before you try the boiler in case it's a sticky governor

Slightly more than that.

You need to run two hob gas burmers when the boiler is being started.

Sometimes the regulator at the meter sticks and prevents the boiler lighting.

But that does not seem to be your problem because you say the flame lights.

Tony

 

[Steelmasons]

You need to run two hob gas burmers when the boiler is being started.

Would that be two of the smaller hob burners or would one larger burner suffice??

 

[AGAS]

Thanks AGAS, but I have set out the sequence of LEDs in the question posed above, which the GS engineer is fully aware of. He also contacted Vaillant technical but they couldn't help him - wait for it to fail completely was the basic answer. The fault chart said change the PCBs. The GS changed the flame sensor. Any ideas if you read the question again?

was thinking different model ( regarding sequence ).
where did you get the board from ? which board was changed ? maybe check the earth as your a electrician . your engineer should see the problem when it is actually faulting .

 

[Aquaheat]

You need to run two hob gas burmers when the boiler is being started.

Would that be two of the smaller hob burners or would one larger burner suffice??

Depends Steel, If it's a range then just the middle one should be good? Will make a big difference if theres a pan on it though. I'd always test without a pan but a Wok is OK as the gas can get up and around the smooth sides.

 

[Bunnyman]

Why change pcbs?? Mental the cost of them (unless you bought recon) would cover a vaillant fixed price repair to cover anything. anyway forget the weather an temps an all that rubbish thats a red herring, nought on these old boilers is affected by this.. This will be a mechanical problem we cany help with as agas has indicated. We cant help more, get a vaillant specialist in