vaillant 221combi boiler

[shaggersan]

Hi
i have the above boiler and the spring has come off the pressures valve at front ,the problem at the moment is if i turn the boiler on at switches the system fires up and cam on the diverter valve go to the right but i have not got the hot water turned on so the burner soon stops but the pump still runs .i f i put the water on and manually move cam at back of pressure switch burners stay on and get hot water fine . if i turn the water off though i have to turn the valve all way to left to get the burner to stop .but as i manual move cam to the right we are back to square one with the burners firing up briefly.
for the ch to work i sure i read that both micro switches need to be made but the diverter goes to center when off and then to right soon as system turns on which says to me that it stuck in hot water mode.

so is the fault with the divert-er valve or this pressure valve i need to take the pressure valve off as cant get the spring back on in place no matter how much i shout at it.
i did have to have a new divert-er valve years ago and the guy at the time said he could give me hot water or central heating while he getting new valve any idea what he did as just like to get heating on at moment .

 

[The831Bunny]

The spring on the Servo Valve returns it to the heating position after DHW is drawn. If the spring is missing the cam will stay in the DHW position and keep the microswitch activated as you've found. Yes it is tricky refitting the spring with the valve in situ, but can be done. The spring threads through a hole on a small up stand on the metal support bracket and over a lip on the cam arm. Use long nose pliers to hold the spring loop and drop over the lip on the cam. It does NOT go through the small hole on the cam, just over the lip on the arm.

Failing that, the boiler needs to be drained and the Servo Valve removed. A good idea to replace it completely when its off as these often stiffen up and block up with crud. Part No. is 012646. Replace all the O rings when you do it, and label or take a pic of the hydraulic tubes before you dismantle it

 

[shaggersan]

Thanks for reply but i still have the problem of no ch even if i manually but the cam in the postion it would be if the spring had returned it?
does the fault still lie with this valve

regards shane

 

[The831Bunny]

Check to see if the pump is definitely running on heating demand. The cam may be stopped from dropping down by a leaking water section putting scale on the coupling piston. Take out the small screw that holds the Servo at its base, slide it to the right and pull gently forward, being careful of the copper tubes. You should be able to pull the piston up and see if it's wet and corroded. If so, you are getting deeper into the problem and that's a different discussion. You need to check with the Servo pulled forward if the heating now works, if not its odds on a Servo problem. It could be a DV problem, but unlikely if it's relatively new.

 

[shaggersan]

i taking the unit off to have a good look at it.
i did drain the water out just in case and blockages and can move the divert er valve manual one way or the other but it is harder to push in toward central heating .
but as soon as i turn system on via switch then it goes to hot water side .
servo valve does not move it stays fully closed .
if i understand things correctly the divert-er valve is told what position it should be in via the servo valve .
so it either that which is my first port of call or pos diaphragm on divert-er valve ?

regards shane

 

[The831Bunny]

Did you take the Servo off the tubes and check the ports of the Servo and the tube ends for blockages? A small screwdriver or stiff wire is handy to clear the debris. The DV is always stiff to push to heating position, and you can't 'pull' it to DHW position, you're just moving the switch cage, not the valve seating.

With the Servo off, use a length of tube to suck hard (by mouth) on both tubes going to the DV. You'll get a mouthful of water, but such is life! This will move the DV one way, then the other way depending on what tube you are using. This proves the diaphragm in the DV and you can then eliminate that and start looking at replacing the Servo.

 

[shaggersan]

thanks for help didn't have to strip to much down found the pin in the bottom was not returning so it was actually holding the cam in position for hot water easy to see when took off,
Put back on and when turned unit on nothing fired up good start ,
turned hot water on and system fired up as should but when turned water off the pilot gas turned off as well.
tried central heating and divert-er didn't move although system fired up so gave gental persuasion as may just been air blockage gas fired up ok .
i had it on 1 hour cycle for heating and seem ok at moment .
will try hot water again when it finished .
one small leak to do will get new seal for fitting but bucket under for now .
Once again cheers for all help.

Regards Shane

 

[Bunnyman]

The reason the pin stuck is coz the gland is leaking on the water section , u will need to change that

 

[Agile]

There is actually a special tool like a dental pick with a double hook for putting springs into difficult positions.

Tony

 

[Bunnyman]

Yea use ur fingers tony ffs

 

[Agile]

Untitled

• Agile
• 16 Oct 2014
• 1

Click to enlarge and see what it could do for you too!


Wow, that took me a long time to find it.

Absolutely the exact tool for things like placing that Vaillant spring!

Tony