Problems with Vaillant boiler not firing up

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  #1  
Old 11-09-06, 02:59 AM
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Red face Problems with Vaillant boiler not firing up

I've had a problem with my Vaillant Turbomax Plus 824/2 E for a while now where it will randomly (for an hour or so) fails to ignite the burner (so no hot water or central heating) with an error code of S.33 (Check air/flue system). I've checked the flue which is completely clear, so I can't work out where the problem is. And before you know it, it starts working again...random!

Any help would be hugely appreciated as its starting to get cold and couldn't have a shower this morning!?!
 
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  #2  
Old 11-09-06, 09:08 AM
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Some boilers had a black air pressure switch that was to be unreliable giving faults like you mention.

Look at the top of your boiler to the right and then look down the back You will see it clipped to the back of your boiler. If it black ( small black box ) it is one of the unreliable type. The new ones are now white and are better.

I would suggest get a CORGI man to come and check and replace if needed.

Andy
 
  #3  
Old 11-21-06, 05:50 AM
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problem with Valiant boiler

I've had the same problem and had engineers out 3 times and replaced 1 part at 100!! but still did not sort out problem. Eventually I trawlled the web and found this thread.

Is this component safe to fit myself or does it need an engineer?? It looks simple enough.

Thanks
 
  #4  
Old 11-21-06, 09:26 AM
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I would advise you get a CORGI man in so he could check the flue and make sure it is safe. The replacing of the air pressure switch is straight forward.

Andy.
 
  #5  
Old 04-06-08, 02:32 PM
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Lightbulb If in doubt fiddle with it first!

I had this problem ages ago switched the boiler off at the mains and went out for the day when i came back all resolved. Woke up this morning and shower just would not run hot.

Found this thread I checked the flue was clear and found

black air pressure switch that was to be unreliable giving faults like you mention.

Look at the top of your boiler to the right and then look down the back You will see it clipped to the back of your boiler. If it black ( small round black box ) it is one of the unreliable type
It is basically a switch with an internal diaphragm it has two wires and two little pipes. I figure from the s.33 check flue status code that its role is to check the flue and cutout if it is blocked.

When the fan kicks in air travels through flue (ie only if the flue is clear) it also moves through the little pipes inflates the internal diaphragm and joins the connections on the two wires. (this will not happen if the flue is blocked)

I disconnected and reconcted the two pipes in various orders as the boiler went through it ignition sequence. From this I could hear the switch clicking on and off even though the diagnostic display d.24 for the preasure switch did not move from 0 to 1 (see page 39 http://www.vaillant.co.uk/stepone2/data/downloads/90/42/00/turboMAX_plus_thermoCOMPACT_installation.pdf

So I took the blighter off (remember which way round the pipes go! The return on mine was marked "-" it was also a blue pipe and there was a blue sticker next to the corresponding pipe connector. ) attached a circuit tester and blow alternately through the flow and return. I could hear the switch was definitely working. But there was something wrong with the contacts. At first the nedle flickered I twidled with the sensitivity, the central white screw and finally after some fiddling the needle was went right over to green with a by blowing down the flow "+" side.

I reattached the little black thing and now when it started up the d.24 flicked over from 0 to 1 but now it was switching on and off and on and off again. I knew exactly what I had done for some reason during the fiddling I had tighten down the white screw thinking it would make a better connection in fact I was asking it to only switch with higher air flow (the flow through those pipes during the ignition sequence was barely a wisper so I wound it out to its most open ie most sensitive and the switch stayed closed).

Whoop whoop It sunday night with expected frosts and we have heat. Hope the tempremental little blighter continues to work and its saved me 50-100+

Now I recomend having a fiddle if you can be sure your flue is not blocked, as I have reduced the sensitivity of this switch if the flow is partially blocked it possible a build up of dangerous gas could occur. In any case we have a carbon monoxide alarm right next to the boiler and if you do do as I do please spend 20-30 of the money you save on a good one its worth having anyway.

all the best

JB
 
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