Vokera 730 Linea - New Expansion Vessel - help please

[StingStiz]

Hi hope someone can help. The expansion vessel (EV) seems to be knackered as water comes out of the schreader valve (car tyre valve) when pressed. The pressure valve is also leaking (water out of overflow pipe outside) and small drip inside, again more signs that the pressure has increased at some point and is not seating after being disturbed. I want to fit an external expansion vessel (12 litres as we have 11 radiators). Due to space (no room under or to side of boiler) I wanted to disconnect the old pancake expansion vessel and connect the flexible pipe which went to it , via an isolation valve and copper pipe to a new external expansion vessel. There is room above boiler for external EV and space for the copper pipe to fit up the back of the boiler.
Can someone tell me fittings I need (sizes) so I can get all the bits in one go. I assume I just close flow and return valves on CH under boiler (quarter turn to close ???) ,catch water from old EV and connect new one up and do the normal checks (1 bar air in EV with 0 system pressure etc).

One last thing, I have heard the isolation valves leak if disturbed, is it better to jst drain the CH system (I have new Sentinel inhibitor to go in anyway).

Martin.

 

[McCombi]

If the pressure relief valve is passing I would replace that also, then you can use the old one to drain the boiler first also.
Sometimes you get lots of condensation in the vessels, are you sure it's burst and not just that in the vessel? You can check by keeping prv open and use a footpump to pump up original vessel to 1 bar, if it is burst, is there not sufficient room to remove old one and refit similar? Or is it rear exiting flue?

 

[StingStiz]

If the pressure relief valve is passing I would replace that also, then you can use the old one to drain the boiler first also.
Sometimes you get lots of condensation in the vessels, are you sure it's burst and not just that in the vessel? You can check by keeping prv open and use a footpump to pump up original vessel to 1 bar, if it is burst, is there not sufficient room to remove old one and refit similar? Or is it rear exiting flue?

Hi, thanks for the quick reply, the EV has been pressuried with a pump (1 bar) but a few days later when the valve was pressed in, just a little water dribbles out , no air and water (droplets/mist). You can get the old EV out (just 4 screws which I can see) as there is plenty room above but I would have to disturb the flue section, it seems easy to remove the bend/straight section of the flue just above as it looks like it is two collars (like big jublee clips) holding the flue section together just above the boiler. This would easily allow the removal of the EV, but if the seals ripped could you get new ones or is it a new flue ?. Its funny as the pressure on the boiler is steady now (at around 1 bar) and never goes past 1.5 bar even when heating on. It does drop down to approx 0.5 bar over a week or so as the PR Valve is weaping still (I have a new one but didnt want to fit it until the EV has been fixed/changed).

Martin.

 

[McCombi]

No don't disturb the flue at all. It may not look difficult but its very easy to damage the seals and can be dangerous.

When you pumped the vessel did you have the prv open at the same time? If not do it that way again. Lots of vessels are replaced when they don't need to be.

If its holding pressure like that, probably just the prv needing replaced.

 

[StingStiz]

No don't disturb the flue at all. It may not look difficult but its very easy to damage the seals and can be dangerous.

When you pumped the vessel did you have the prv open at the same time? If not do it that way again. Lots of vessels are replaced when they don't need to be.

If its holding pressure like that, probably just the prv needing replaced.

Hi, there was zero pressure in the system at the time when the EV was pumped up. I will try one more time tonight just in case but the EV valve didnt even hiss as soon as I pressed it in, just clear water dribbled out (too much for just condensation I think ?).

I think maybe now with me pumping 1 bar of air into the EV (if its leaking it would go into the CH system ? ) there may just be enough air in the CH system that it is behaving like a mini EV now. The problem originally started when I bled the towel radiator in the bathroom upstairs (its also the highest point radiator). About 30 mins later the pressure dropped (PRV leaking), assume because the 'air' had been removed ?.

Is it possible to just fit a copper pipe , isolation valve and external EV (12 litre with a guage) to the existing flexible pipe that used to go to the boiler EV ?. Note - I can't replace the flexible pipe (to EV) with copper entirely as it connects on the other end to a plastic looking push fit joint secured with a pull clip. There is very little room under the boiler to join to the return flow copper pipe.

 

[StingStiz]

No don't disturb the flue at all. It may not look difficult but its very easy to damage the seals and can be dangerous.

When you pumped the vessel did you have the prv open at the same time? If not do it that way again. Lots of vessels are replaced when they don't need to be.

If its holding pressure like that, probably just the prv needing replaced.

Hi, there was zero pressure in the system at the time when the EV was pumped up. I will try one more time tonight just in case but the EV valve didnt even hiss as soon as I pressed it in, just clear water dribbled out (too much for just condensation I think ?).

I think maybe now with me pumping 1 bar of air into the EV (if its leaking it would go into the CH system ? ) there may just be enough air in the CH system that it is behaving like a mini EV now. The problem originally started when I bled the towel radiator in the bathroom upstairs (its also the highest point radiator). About 30 mins later the pressure dropped (PRV leaking), assume because the 'air' had been removed and now pressure built up as no air to cushion the water expansion ?.

Is it possible to just fit a copper pipe , isolation valve and external EV (12 litre with a guage) to the existing flexible pipe that used to go to the boiler EV ?. Note - I can't replace the flexible pipe (to EV) with copper entirely as it connects on the other end to a plastic looking push fit joint secured with a pull clip. There is very little room under the boiler to join to the return flow copper pipe.

See Fig 40 pg 26 in the manual :
http://cdn0.vokera.co.uk/wp-content...a_installation_and_servicing_instructions.pdf

 

[StingStiz]

No don't disturb the flue at all. It may not look difficult but its very easy to damage the seals and can be dangerous.

When you pumped the vessel did you have the prv open at the same time? If not do it that way again. Lots of vessels are replaced when they don't need to be.

If its holding pressure like that, probably just the prv needing replaced.

The expansion 'tyre' valve is just letting water out, so looks like the membrane is knackered. Is it possible to just connect a 12 litre external expansion tank to the flexible pipe that went and screwed to the original EV ?

 

[ianmcd]

There is nothing wrong with your EV you are just not charging it correctly, YOU MUST have a drain point open when you try to charge it, there is no other way

 

[StingStiz]

There is nothing wrong with your EV you are just not charging it correctly, YOU MUST have a drain point open when you try to charge it, there is no other way

Hi, but there was no pressure in the system (zero on front guage) when i charged it. Also if the membrane inside the EV is like an innertube, how can so much water get in if it is not punctured ?.

 

[ianmcd]

The guage shows the pressure of the water in your system not the pressure of the air in the expansion vessel, you need a car foot pump or similar with a guage attached to read what you have recharged the EV to

 

[nickso]

There is nothing wrong with your EV you are just not charging it correctly, YOU MUST have a drain point open when you try to charge it, there is no other way

Hi, but there was no pressure in the system (zero on front guage) when i charged it. Also if the membrane inside the EV is like an innertube, how can so much water get in if it is not punctured ?.

Condensation.

Remove the schraeder valve from the vessel, put a tube on the shraeder and refill the boiler to get the condensation out. If it is burst then water will obviously continue to come out.

Put a new schraeder back in and WITH AN OPEN OUTLET ON HEATING SYSTEM pump the vessel back up. Job done.