Vaillant VCW 221H hot water and now heating problem.

[archyM]

Over the last couple of weeks have noticed the hot water sometimes not working. Recently hot water has stopped completely. A couple of days ago i decided to try switching the heating to constant and then opened hot water tap and the hot water started to work.
I tried to have a look after speaking to a few people and trying the internet to understand more. I was told to check the microswitch which might need replacing.
I have checked the microswitch by manually pressing and this time round not even the heating is working.
When i opened the hot water tap the switch was being made as the piston/arm from the servo was pressing against the micsroswitch.
I have noticed there to be a slight leak as looking underneath past the microswitch, could these be seals that would need replacing.

Here are a few more things that might help;
Pressure is fine and sometimes needs topping up to just over the 1 bar, say we top up about 3-4 times a year.
Pilot light is always on.
Initially jets were firing up when heating was switched on, but not anymore. The hot water only operated if heating was on, but doesn't happen anymore as the heating is no longer working.

I have read quite a lot into this and have been told as the boiler is 13 years old the engineers i have spoke to are advising on changing the boiler, but are reluctant to come out to do repair job as they feel this can lead to many other jobs, but they do not mind advising. They will gladly come out to change the boiler.

Please can someone help on this. Much appreciated. [/quote]

 

[weareleeds]

Most likely cause is diverter valve it will want a diaphragm & clean also possibly microswitches

 

[archyM]

So will more than likely be changing the diverter valve and diaphragm and possibly even the microswitch. By clean do you mean give the boiler a service type clean.

By changing the diaphragm this would eliminate the leak. I was thinking might the problem be electrical if the burners are not firing up.

 

[Gasguru]

Phone around until you find someone willing to repair it. These boilers are complicated and most will want to replace it since its beyond their knowledge.

The leak is probably from the stuffing box on top of the water section.

As the hot tap is opened the pin rises from thw water section. This activates the microswitch to put the boiler in DHW mode. It also rotates the cam operating the servo valve. This sets the correct hydraulic pressure differential on the diverter valve diaphragm. The diverter valve then operates actuating its own set of microswitches. Unfortunately there are many many items to stop the boiler from operating.

Have you tried Vaillant - they may have someone on their "books"

 

[DP]

Regret the problem (I feel) are due to boiler neglect.

I fail to see how hot water will be available if CH is on. The diverter valve sits idle to move right for hot water and left for CH.

This boiler is overengineered, complicated and bomb proof. Someone who wants to replace this workhorse sure suggests he is not a heating engineer.

Get someone who is a VCW hugger, you boiler will work again. Do not try to understand it, it is not for the faint hearted.

 

[namsag]

DP would you agree as opposed to the divertor being faulty mostly it is the servo valve at fault although fault finding charts lead you to divertor. Sounds like the stuffing box is leaking this can stop the water section pin moving in and out freely thus affecting how the servo cam works .

 

[DP]

Cannot imagine the diverter being defective.

My money would be on the water section and mechanism above it.

 

[namsag]

Been a few year since i have worked on them in great numbers but i have never seen a divertor fail on one. And as you first thing i would do is strip water section clean pin, new stuffing box and diaphragm. Then servo valve on top of water section. Valiants of this age an older must have had the best pcb`s ever made very reliable and rarely broke.. although many people ordered them they where rarely needed.

 

[werewolf]

Will be stuffing box on top of water valve.Have changed loads of them.

The servo valve and tubes could be cleaned out while your at it.

Never have dv`s failing completely only the diaphragm inside it which can tear.

Paul

 

[archyM]

Hi thanks for all the replies.

The hot water is still not working on its own, the heating is working again it must just have happenned that one day when i was checking it. Again hot water will only come on after i have turned on the heating for a few minutes. So in order for me to have hot water i first have to switch on the heating and while it is running i then proceed to open any hot water tap and there i have my hot water.

I have opened the front panel of the boiler and watched and checked the servo, actuator and microswitch when opening hot water tap and all process is working fine the switch is made and a clicking sound is heard.

I hope i am not being confusing. I still would like to understand more and if someone could give a final verdict before i decide on what to do next.

I do not understand why the servo microswitch etc are problematic if switch is being made all the time. I can understand changing the stuffing box eliminating any leaks. but pin cannot be stuck if the switch is being made.

I am a bit confused at present and hope someone can help. Any info. needed please ask.

Again thanks for the previous replies.

 

[archyM]

I have read that it could be the diaphragm at the bottom of the water assembly(housing) which could be worn out. Firstly can someone tell me where the water assembly is exactly and also if repalcing diaphragm to this does not work what should i be looking for next.

Thankyou.

 

[werewolf]

When switch on servo makes do the 2 microswitches attached to the end of the dv ( right hand side of boiler) move out to the right?

 

[archyM]

I have not checked that and will get back to you. If it does move to the right what would be the next step. If it does not move to the right then what would be the next step.

Thanks

 

[archyM]

Does anybody know where i can get the manual for this Vaillant VCW 211H boiler?

 

[archyM]

Hello all,

I have stripped the water section cleaned and greased the pin and also changed the stuffing box put all back together. Heating and hot water working fine.

About 10 minutes later boiler is not firing up for hot water or heating.

Pressure is 1.5 bars the radiators are fully blead, pilot is on and all radiator valves are fully opened.

Please advise.