combi boiler - fill loop not filling

ThisIsWeird

grumpycrab said:

They seem ok to me.  The screws follow the handles - full 90o -  LH is stiff and RH one is not stiff - while not loose it doesn't feel like its moving anything.   I'm going to slacken the end collars.

Hmm, perhaps the shaft has sheared inside.

When you remove the two collars and loop pipe - assuming no continuous leak - then you can try slowly turning that RH tap back 'open' - you should be able to see its internals through the end. It's essentially a shiny SS ball with a hole through t'middle - when the hole is aligned with the pipe, water flows through.

So, I'm hoping you can remove that loop completely, and can peer down the opening. Both should show the shiny metal surface of a ball. If you turn the LH valve, you'll get wet. So don't. Or, you could try turning it a teeny bit until water begins to squirt, just to confirm it's working fine.

The RH one, it'll be interesting to see if that ball does rotate.

If it doesn't, the valve is knackered.

When you call up your plumber, tell them the make and model, and that the RH filling loop valve is broken - he should then come prepared with the part.

This is really exciting...

grumpycrab

ThisIsWeird said:...

When you remove the two collars and loop pipe...

I'm not tackling this with any great urgency -can you tell?  The collars came off after a bit of brute force. Now what?  Should the loop pull out?  (aware of where the stop !!!!!! is)

nofoollikeold

1. Unscrew the two black plastic handles and turn the spindles with a spanner / grips.  Eliminates one possibility.
2. What is the current pressure reading?  If the pressure is equal to or greater than the mains pressure, no water will enter the system.  

FreeBear

grumpycrab said:

ThisIsWeird said:...

When you remove the two collars and loop pipe...

I'm not tackling this with any great urgency -can you tell?  The collars came off after a bit of brute force. Now what?  Should the loop pull out?  (aware of where the stop !!!!!! is)

You just need to slacken one collar off just to see if any water comes out under pressure. If you take the loop off completely and open a valve, you'll get water gushing out

And yes, if you want to remove the filling loop completely, it should just pull out. There might be a thin smear of sealant applied when it was first assembled which could require a small amount of force to break the seal. But there is unlikely to be any blockage in the pipe, so it shouldn't need removing.

grumpycrab

FreeBear said:...You just need to slacken one collar off just to see if any water comes out under pressure. If you take the loop off completely and open a valve, you'll get water gushing out

Unscrewed both isolation valve handles and the spindles are fine (only 3 years old, used a couple of times).  Pressure is 0.75bar (cold)  so I'm not panicking (yet). Water pressure is high.  There's no red bottom line on this combi but I guess if the pressure is too low the CH will not work. 
Plucking up courage to pull the loop out; removing both collars and -with care- openning the valves resulted in no water, not even a drop, but I guess there's a good seal.

grumpycrab

drum roll... the answer appears to be - LH valve blocked/knackered.  Nothing comes out of this with valve open.  BUT opened the RH (CH) slowly and got squirted at. I thought this was supposed  to be a N-R valve!?
Pic is LH valve.  (RH valve just shows ball bearing).

EDIT. guessing the knackered LH valve is the N-R valve (there's an arrow on the side of it) when we were expecting the RH valve to be the N-R valve.

FreeBear

grumpycrab said:

drum roll... the answer appears to be - LH valve blocked/knackered.  Nothing comes out of this with valve open.  BUT opened the RH (CH) slowly and got squirted at.

Time to call Viessmann and ask them to fix under warranty. Say nothing about removing the filling loop lest they claim you have invalidated the warranty. Just say you tried filling to bring the pressure up, but nothing happened.

ThisIsWeird

grumpycrab said:

drum roll... the answer appears to be - LH valve blocked/knackered.  Nothing comes out of this with valve open.  BUT opened the RH (CH) slowly and got squirted at. I thought this was supposed  to be a N-R valve!?
Pic is LH valve.  (RH valve just shows ball bearing).

EDIT. guessing the knackered LH valve is the N-R valve (there's an arrow on the side of it) when we were expecting the RH valve to be the N-R valve.

The royal 'we' :-) Very gracious of you to take some responsibility.

ThisIsWeird

Have you tried tapping the side of the LH valve body?! With it turned half open...

grumpycrab

ThisIsWeird said:

Have you tried tapping the side of the LH valve body?! With it turned half open...

Yes, will try that later. Sorry about the NR assumption I made. But I have learnt what an arrow on the side of a valve means and that you can get valves which are combination isolation (I assume that's what's the tap is for) and NR. Cheers!