Sabre 24 combi boiler...help

[adeenuf]

hi i've got a problem with the above boiler, had problem losing pressure and having to top it up quite often checked all radiator pipe fittings (push fit) but they are all ok then found out that when the heating is on water trickles from the overflow, then when the system cools down i have to top it up again, any ideas, and can it be an easy fix with a replcement part, thanks in advance, mark

 

[diamondgas]

Sounds like your expansion vessel has lost its charge Mark. Does the pipe stop dripping when the heating cools off? Reason I ask is that once they drip they rarely re-sit water tight and may also need replacing.

 

[adeenuf]

when the heating is off the water stops dripping. expansion vessel, can they be changed and how easy ? or is it new boiler time

 

[diamondgas]

It doesn't necessarily need changing. It may be that it's just lost its charge in which case it will need re-pressurising! Takes about an hour max to do if the vessel is accessible

 

[adeenuf]

any idea on what sort of cost ???

 

[Blackcatgas]

Just for a recharge £50, new vessel if rechargeing doesnt work, If the boiler vessel isnt easily accessable ie you have to dismount the boiler then fit a remote vessel, £160 labour, £80 parts so £240 all in, also what youl probaly find is that your blow off valve will need replacing so add another £30.

 

[diamondgas]

A hour of your prefered engineers time

It all depends on whether the expansion vessel is still intact too! They can be expensive to replace and can sometimes be better to fit a replacement external if the instalation allows for it!

 

[adeenuf]

my mate said it could be the pressure relief valve !!! is this a possibility or is he just confusing me now......

 

[Hardy1]

check your expansion vessel for the correct charged pressure of air, and also check your PRV is not stuck a little bit open-have come across a few of these after checking the expansion vessel is fine- it just gets stuck and just needs maually re-setting. butt make sure you get a gas safe engineer in.

 

[adeenuf]

does anyone know the pressure of the expansion vessell ? looked in the manual i have but it doesnt say, i have a digital pressue gauge and can get to the valve, was going to check the pressue, but no good if i dont know what it should be... thanks, mark

 

[diamondgas]

0.5Bar is the norm Mark ... make sure the system is 'open' when you're charging the vessel though! That is, have a drain hose attached or prv open when you pump up the vessel

 

[adeenuf]

ok i found the service manual and filled expansion vessel to 1bar as it said but no change still losing pressure after a few days.... does this mean a new expansion vessel ??

 

[diamondgas]

Best thing to do is watch the gauge from cold to hot on central heating .... If you see it rise a great deal from its start position cold then you have issues with your EV. However if it doesn't move a great deal then the EV is okay and you have a leak somewhere.

 

[adeenuf]

yes i does, if i set it at about 1 1/4 bar when cold it rises to about 2 bar when hot, but after a while ( few days ) the pressure drops so much that the boiler wont restart ie: below 1 bar, but there are definately no leaks.

 

[adeenuf]

forgot to ask the system only has 4 rads on it what size of stand alone expansion vessel would i need ( looking at the ones in toolstation ) thanks, mark

 

[diamondgas]

1 1/4 to 2 isn't much of a rise Mark so I'd say your EV is okay ... Next is to look out for water leaks ... tie a plastic bag around the pressure relief valve pipe outside, if you can, and see if it's collecting anything. You have a small system so water escaping will show up pretty quickly .... And if you're only looking for 1/4bar loss then that may only be a pint or two, over a few days that's a small weep I'd say

Hold back on fitting an external EV till you know for sure that's at fault IMO

 

[adeenuf]

ok xmas an new year out the way back to building.....expansion vessel is shot, when the air valve is pressed water comes out, so i got an external one, realy silly question but what way up does it go, does the air valve go to the top or bottom ? seen pictures of it both ways..!!!

 

[Billy Bob Bob]

ok xmas an new year out the way back to building.....expansion vessel is shot, when the air valve is pressed water comes out, so i got an external one, realy silly question but what way up does it go, does the air valve go to the top or bottom ? seen pictures of it both ways..!!!

it can go either way round but try to connect it to the return

 

[adeenuf]

was just gonna connect the old pipe of the internal (broke) expansion vessel and connect it to the new (stand alone) EV, the pipe is already connected, just gonna disconnect one and attach another...

 

[Billy Bob Bob]

was just gonna connect the old pipe of the internal (broke) expansion vessel and connect it to the new (stand alone) EV, the pipe is already connected, just gonna disconnect one and attach another...

unless its 8 or 10mm you might find it hard to connect,you dont need to remove the old EV

 

[Riley]

I would guess it's probably been fixed from three years ago mate

 

[Dotty]

Closed.