Tribune Unvented hot water cylinder Water Overflow dripping

[BallyK]

Hi All - I have a fairly old Tribune unvented hot water cylinder direct unit with a Varem expansion tank. Today, I noticed the outside overflow pipe was dripping water - quite a lot of water. The presure gauge between the tank cylinder and tank was showing 3.5 bars - the immersion heater was on at the time. When I left the presure reducing valve open for a few minutes, the pressure fell to 3 bars and the overflow pipe stopped dripping. It looks like the pressure is still rising and I expect it to start dripping again shortly. Does anyone have any ideas on what might be the cause and what I can do to fix. Thanks in advance for any help you can provide.

 

[entreri911]

does it drip constanly or just when the hotwater has fired if so the expansion vessle may need charging. if its 24 hrs a day then you may need a new flow limiter.

hope this helps

 

[BallyK]

Thank. It seems to be just when the hot water has fired. Can you let me know how I "charge" the expansion vessle?

 

[Terry7556]

read the FAQs /sticky at the top of the plumbing/ ch page

 

[simond]

Once the expansion vessel has lost the air charge, it can only be permanently fixed by changing it. Pumping it up is a very temporary respite, it has a leak and will continue to cause problems.

 

[BallyK]

Apologies for my ignorance but is this the sticky post about recharging?
http://www.youtube.com/watch?v=sKvxlQI0fH4&feature=player_embedded

I see another one (link below) but this one seems to be for boiler systems. Does the same apply to my unvented water cylinder?
//www.diynot.com/forums/viewtopic.php?p=251090#251090

 

[Terry7556]

not the one im referring to. click forum
click plumbing/central heating
look at the first 3/4 lines one of which says sticky boilers/central heating FAQs
it contains a list of common questions about boilers, one of which is how to recharge your expansion vessel