Valliant VCW GB240H cold from the taps ,hot centralheating

[Roadhog]

My central heating is working ok but the hot taps have gradually over about the last year become colder ,last week the central heating would not fire up due to low pressure so i represurised the system but since then the taps are refusing to run hot,they will sometimes start hot for about five seconds then revert to running almost cold.i have tried the flow rate adjuster ,Grey knob in pic 2 , all positions but no change.













upon seeing this next picture i noticed that the clear pipe was off ,i pushed it back on the tube but no diferance was made to the tap temperature.



the temp adjuster dial has had a slight leak for years, acasionally a slight drip.









Is there a simple fix for the taps not runing hot or do i need an expert , I suspect the latter.

 

[Bunnyman]

Not so much an expert as a priest! The gas has never bin set on it u still got the original seal over the adjuster! Also the model u show in the pic is a vcw 221 not a 240, lookin at the flame picture u need a reg engineer to check burner pressure

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• Bunnyman
• 26 Mar 2010
• 499

the knob u refer to is the isolation tap not the flow adjuster, the isolator needs to be fully opened ,the flow adjusting knob has obviously been snapped an lost at some point,as this is the brass coloured splines to the left of the grey knob point in toasted front of boiler

 

[Roadhog]

Are you saying that the burner flame is lower than it should be .

 

[Bunnyman]

U can't tell without puttin a gauge on it but it looks it also get a complete new water section fitted that leaks not from the flow adjuster but from the gland on top of section

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• Bunnyman
• 26 Mar 2010
• 499

 

[Roadhog]

So you advise that i change the whole brass contraption in picture 8 , Whats its tecnical parts name .
Is it listed at this site http://www.boilersparesdirect.co.uk...products.asp?id=3841&cat=Vaillant+VCW+GB+240H

 

[Bunnyman]

Vaillant part 011299 get support 086462 as well

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• Bunnyman
• 26 Mar 2010
• 499

 

[Roadhog]

Heres the manual with my heating system .




the reason i thought it was the 240 H is that it says 240 on the black plastic thing at the left of picture ,though all three models probably use the same parts.

 

[Bunnyman]

The 240/280 models r open flue ie with a chimney the 221 is balanced flue room sealed as in ur picture u have a front cover with a sight glass for ur pilot, the black plastic thing is the domestic hot water heat exchanger

 

[The831Bunny]

I'm with Bunnyman, looks like water section is/has been leaking and I very much doubt you will easily remove the screw that holds the water section to the support bracket. These can be drilled out, but a job for an expert.

Diaphragm gone or dhw microswitch faulty are the top of the list of faults causing your loss of dhw. I'd get a RGI to change the water section and support bracket to start with and go from there. He needs to check the working and operating gas pressures on ignition and full burner are correct too. This is important on this age of appliance given that the seal in the picture has never been off. The appliance is approx 18 years old.

Once repaired though boiler should be good for another 5 years if given some TLC.

Cheers

 

[Agile]

Presumably he could rotate the black plastic cam in the middle clockwise to simulate an operating diaphragm and see if/how it performs on DHW?

I do have to say seeing the black plastic HE on the left would make me suggest a replacement is the best option!

The last one I repaired was a nightmare! After sorting out the boiler following BG giving up, the owner having gone out for the evening and told me to just leave and pull door behind me, I discovered that he had double locked it!

Garden was a walled sunken type with no way out without a ladder. Front door lock was a six pin tumbler type and did not want to open by picking. Barrel would not come out with door closed so I was apparently stuck!

I called his mobile and very luckily he was still in the pub before going on to a club where the mobile would not be heard so he returned to let me out! I had already checked the food in fridge and the DVDs!

Tony

 

[Roadhog]

Turns out that a freind of a freind is a heating installer so we called him out ,he said that the hot water was going down the big pipe on the left instead of out the tap ,he told me to aquire a diaphram kit for the Diverter Valve and call him back to install it .




Diverter Valve with micro switches in clear plastic cover.
Dam it i forgot to invert this picture as i had the camera upside down when i took it ,diverter is at right side not left as in picy


Can someone edit the title to 221 model instead of 240

 

[Bunnyman]

Trust me mate getting a friend of a friend is not goin to b the cheapest option with this boiler u will b cheaper to get a specialist! U say the heating works so it's very unlikely to b the divertor diaphragm !

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• Bunnyman
• 26 Mar 2010
• 499

 

[Mikefromlondon]

Just out of interest. Its the same as mine VCW221. The clear plastic piupe that was left out and made no difference is a pipe leading to atmospehric pressure, so if this one comes out, it would not make any difference to heat output, but there are two, the other pipe then connects to the gas valve and modulates the output of the gas valve. If this was missing or slipped out, you won't get full burner pressure or heating output.

There is a diaghpram air pump behind the control box which uses an electro/mechanical viberating arm to push and pull on the air diagpram to generate air pressure to modulate the gas valve, yes 20 year old technology! No body would use that technique today to modulate the gas valve, stepper motors indeed controlled by processors!

IMPORTANT:
If the OP is still able to check this, get this boiler serviced and pay particular attention to the Heat Exchanger that sits around the burner, any punctures or sections burnt through by the flames in the thin copper skirting walls of this HE can lead to Co build up as some of the heat and flue gasses can escape from the side instead of all going out through the flue, can lead to the top plastic cover overheatring and melting with Co spilling inside the room! Thanks to my Co detector going off, this problem was arrested in good time!

 

[Bunnyman]

HI mark thread is 18 month old so he should have mended it by now, but it's similar to urs but not the same ie. No plastic top to melt an urs has the cooling jacket u mentioned his doesn't so none of that applies

 

[Mikefromlondon]

HI mark thread is 18 month old so he should have mended it by now, but it's similar to urs but not the same ie. No plastic top to melt an urs has the cooling jacket u mentioned his doesn't so none of that applies

Yes, no disrecpect, but I stumbled upon this thread through the bottom of every page called "Similar opics" and so I decided to check it out, though it is an old thread and I don't doubt that OP either had it fixed or even may be by now he may have had it freplaced altogether.

But if he hadn't, then I thought it is best to inform him of the weakness of this boiler, my plastic top cosmetic cover melted, and from the seams of the boiler on the top, heat started to escape directly into the room, as well as some of the combustion gasses, causing my Co detector to go off, thank God for that i bought it just 3 weeks before!

All these boilers are of similar base design, and share a lot in common. so even if OP's boiler is a bit different, it is worth getting them serviced more regularly as they age more.

I must say, I did not replace parts on mine myself, my original fitter who was at the time Corgi registered, installed it and since then he became a good friend, so he does mine for free, so what have I got to loose when he does mine for free, and I do lots of electrical work for him in return.

it was him who took me through each and every component of this boiler and showed me how that gas valve modulates burner pressure through air pump!