Boiler wont fire up after draining

[guinness]

Hi,

I have a Vaillant VCW 242E combi which is refusing to fire up since I drained the CH system today to move a radiator.

I re-filled and pressurized to about 1.3 bar, bleeding rads as I went. There is one at the top of the house I haven't been able to bleed yet as bleed screws are seized, but otherwise went well.

I now have no CH or DHW. When running DHW, I can see the spring-loaded actuator move and activate the microswitch. The boiler makes all the right noises (fan starts/pump runs) but it never ignites.

The first few times I ran the DHW, the flame failure kicked in, and I reset it maybe 2 or 3 times. Since then, it has not triggered again, but no change in the actual problem. As advised in the Vaillant manual, I have bled the main heat exchanger and pump. Opened auto-air valve at top right.

I have read various posts suggesting I might need to re-pressurize the expansion vessel (0.7 - 0.9bar), and even the manual makes reference to this - "access from underneath" - but I'm confused as I can't work out where it is the expansion vessel might need re-pressurizing from (diagram is not clear).

On the bottom-right of the boiler, there is a mini expansion vessel, about the size of a cricket ball with a schraeder (car-type) valve on top. This doesn't appear to be what the manual is referring to though? I cannot see any other similar valves underneath. See here:

http://i8.photobucket.com/albums/a39/autobot12345/PA140040.jpg

Any help appreciated.

 

[villa_tom]

Your pressure is on zero mate I'd try that first.

Are you GSR though?

 

[guinness]

Thanks, but that's not my boiler -it's just a picture I stole off Google images to show the mini expansion vessel I was referring to. Mine is definitely pressurized to 1.3bar as we speak.

No I'm not GSR but I'm technically orientated and keen to understand the problem even if I don't go at it myself. I know when I'm out of my depth and have a Vaillant engineer I can call on next week, but obviously being Sunday tmw, if it's something I can easily sort out myself, that would be good.

 

[mickie]

is the power on ? and the pilot light ?

see that black box behind the pump ? press it, thats a reset

 

[RoryD]

Expansion vessel won't be an issue for initial lighting if you do have 1.3bar. Fan runs = great, is there a spark??... If not, you'll have to call a GSR PROFESSIONAL If you're not registered then I won't give you the solution

 

[jase158]

Sounds to me like a component in your boiler. Any gas engineer can fix it at a relatively low cost. It isnt something you can do your self though. Be very careful about touching the inside of that boiler, anything goes wrong with it and you can be looking at a very long time behind bars. Vaillant may even come and fix it for free, if its still under warranty.

 

[mickie]

under warranty ? haha the things probably 25 yr old

 

[SafeGasInstall]

took one off back in feb ,good thing was two of us !

 

[mickie]

i took one off on me own, almost broke my back, the pcbs were gone and they cost a bomb, so just fitted a new boiler

 

[SafeGasInstall]

the one I took was the balanced flue one and god was heavy ! but I had some one to help

 

[tamz]

Stan i thought you would have been passed out on the highland park by now lol

 

[SafeGasInstall]

ohh is lovely here ,been out said seeing and had some of the local lamb shoulder in the cooker with cold beer then walk out again to see more and now just chiling with wife listening to some music ,weather has got bad here ! but i still like it and will be coming back to give it a go as here is so much going on
surprising li ! still not had any high land whisky -went to the brewery today to fined they sell some whisky for 4k ,end up not buying anything from there as
the basic 12y old was £6 more then local tesco ! will be picking a bottle tomorrow ! where is scotland r u tom ?

 

[tamz]

Told you it would be nice. Looks a bit weird without trees to begin with lol. Don't worry about the rain. At least it is warm rain lol Forecast is for rain tomorrow and drying for monday.
The Highland park distillery is too geared up for the cruise ships. It is a rip off.
If you are driving back from aberdeen and have a few hours to spare take the Speyside whisky trail.
Map of Scotch Whisky distilleries, single malt, whiskies, whiskey, distillery visits, distillery tours, scotland, whisky tours
The Glenfiddich one is a good visit.

I am in central Scotland just between Glasgow and Edinburgh but i work all over as far up as Golspie and West to Fort William and from Stranraer to Berwick upon England. I just go with the flow Stan and follow the cash.

 

[Kimou]

Make sure you purge the air out of the boiler before the diverter. This is a problem with Vaillants.

 

[guinness]

Thanks for the replies. There is no spark (no pilot as it's electronic ignition).

 

[diamondgas]

Guinness it has nothing to do with pressure. This boiler came out B4 they thought about putting pressure switch's on!

If it worked fine before hand then it'll be most likely something you've done/introduced. Hydraulics/Air is the main instigator of no ignition but to go to reset indicates something entirely different! There a bit of a pain these to work on coz you've got to have the hex front case on for them to fire up, if my memory serves me right, and there's a lot of mechanical switching to be achieved before ignition! Saying that you really want to consider getting someone in... Someone who's worked on a few will help for sure!!! 🙂

 

[Billy Bob Bob]

your aav has jammed,main heat exchangers full of air IMHO

 

[guinness]

Thanks all. Sorted it this afternoon. Drained and re-filled - this time with the air valve open as it should have been in the first place (last supposedly GSR engineer didn't spot this on service). Loads of air hissing out as it re-filled and ignited first time after reassembling. Cheers

 

[villa_tom]

Thanks all. Sorted it this afternoon. Drained and re-filled - this time with the air valve open as it should have been in the first place (last supposedly GSR engineer didn't spot this on service). Loads of air hissing out as it re-filled and ignited first time after reassembling. Cheers

Glad its sorted now mate! Enjoy your Sunday evening and get yourself ready for the fun to begin again tomorrow! 🙂

 

[boblydon]

The mini vessel you mention has nothing to do with the heating, that allows for expansion on the cold water main when the boiler fires on hot water.

The big red vessel at the back is the heating expansion vessel, for some reason that i can never understand, these never get checked during servicing or if they do, they never get checked correctly.

I would say that at least 80% of combi's i repair there is never any air pressure in the vessel it's full of water......on the other hand i have seen so many so called heating engineers check the pressure vessels without draining down the boiler/system ( on cold water booster sets ).

bob

 

[guinness]

Thanks bob - useful info there, cheers.

 

[Bartdude]

It's not uncommon for that AAV to start leaking too.Might be a good idea to check it over the next couple of days.

 

[AWheating]

had one like this a while back, tinker with air vent and away it went.