Vaillant VCW GB242EH - Any advice?

[obseen16]

Hi Fellas.

im going to have a second look at the above combi boiler, the DHW works perfectly but the CH is very temperamental. in CH mode the pump runs but the fan takes ages to start up (sometimes it takes a few mins, other times its more like 10 mins or not at all). im thinking that one of the capillary tubes has a small blockage in it which is delaying the 2nd micro switch to make contact, the trouble is the boiler is in a kitchen cupboard and i cant get access from the side to see well enough if that theory is correct.

I dont suppose anyone on here has had any similar experiences with this type of problem on this boiler?

also if anyone on here has stripped the capillary tubes are they a pain to put back in without getting a leak?

 

[Puddle]

Do not think tubes are blocked,think maybe the black rocker switch is not sitting back correctly once tap turned off or servo unit diagram worn maybe

 

[SimonJohns]

This boiler relies on the fan aps shutting correctly before it can relight. Multimeter time

 

[diamondgas]

They are a brilliant piece of machinery when working but a pain when not ....... Initial thoughts are mechanical so would tend towards the capiliatry tubes blocking as you've thought! Or the Servo as puddle mentions ... all hydraulic related! Rarely if ever a diaphragm. I may add I take it the diverter is slow to react yeh?

Maybe time for a new'in!

 

[obseen16]

this is the fisrt time i have had to repair one of these boilers. im thinking the servo might be at fault, should the black rocker switch (the one at the front with the spring on it) move when ch mode is selected? if it is supposed to move then this might be the fault as i dont remember seeing it move at all when on ch or dhw mode. ????

sadly i cant walk away from this job as its a piggin neighbour

 

[Puddle]

no,the rocker only moves forward when hot water turned on and must return and seat fully back for heating to work,it heating not working when you go back,push rocker back and see it heating comes on

If so,you will probably find metal rod on top of hw diaphragm valve,that activates rocker is maybe sticking in its plastic sleeve

 

[diamondgas]

Now your checking my brains ...........

I'm sure it moves when demanding water and at resr with heating ... best thing is to try it it out IMHO .. see if it moves either way! Eithe way it's purpose is to divert hydraulics in the diverter and thus change the direction of the water flow

 

[thereisawizza]

Last one of these I stripped the servo and took loads of crud out. Put back together, worked pukka! Lovely appliance.....

 

[Pssst]

The Vaillants of that era and earlier are things of beauty.

Well crafted and designed machines of some complexity but also very reliable.

I particularly liked the Sine 18..

 

[stevetheplumber]

probably told this story before but the vailant diaphram very rarely failing jogged my memory
when combis started to apper on the uk plumbing scene i went of and got trained by saunier duval vailants and a few others
i decided to carry some stock in the van and bought a selection of bits and ive still got the vailant sine thermocouple as ive never had one fail
these were boiler built to a standard not to a price

 

[bennygas]

obseen - if you're still stuck, i got a load of fault finding stuff for these if you want it. just too much to post as attachments on here.PM me if u want the docs.