Re-pressure expansion vessel / glow-worm fuelsaver

[dogbiscuit]

Hi folks,
I bled a radiator, then checked the pressure gauge on the expansion vessel and it reads empty. I've no idea how to top it up as I can't find any taps on the pipes or boiler. Does it also need air pumped in?
I've attached a photo of the system. If someone could advise what to do I'd be very greatful.
Please note my knowledge of heating systems is extremely limited! Thank you

 

[Mike Jackson]

There should be a filling loop somewhere on the system. It is normally two chrome taps and a silver braided hose that connects the two. Possibly adjacent to the hot water cylinder.

 

[Dotty]

But has been known to be hidden behind a panel by vindictive or brain dead kitchen fitters.

 

[dogbiscuit]

Aha ok. I found something like this in the utility cupboard by the cylinder and washing machine. There appears to be just one black tap. Is this the one? It's out of sight of the expansion vessel so won't be able to see the pressure guage! Also does the expansion vessel require air, and if so how would I go about that?
I've attached a picture again.

 

[Simon F]

yes the flexi hose with the black tap is the one.
dont be tempted to open the red tap which was a hot water feed to a previous washing machine, it should really be cut out.
the expansion vessel will only need air adding if it is lower than it should be.
just top up the water, get someone else to look at the dial and shout when its up to 1 bar, then close.

 

[dogbiscuit]

yes the flexi hose with the black tap is the one.
dont be tempted to open the red tap which was a hot water feed to a previous washing machine, it should really be cut out.
the expansion vessel will only need air adding if it is lower than it should be.
just top up the water, get someone else to look at the dial and shout when its up to 1 bar, then close.

Ok thanks. Well I just pressed the air valve under the expansion vessel and air came out with a bit of water. And the pressure guage reads zero. So is it right to assume it needs air first? And if so, how much? The only thing at my disposal is a cheap bicycle pump!

 

[Deleted member 32524]

was the system loosing pressure? When did you last have it serviced? If it has been a few years then get someone to service it and they will deal with the expansion vessel.

 

[dogbiscuit]

was the system loosing pressure? When did you last have it serviced? If it has been a few years then get someone to service it and they will deal with the expansion vessel.

No it just went down when I bled the radiator yesterday. I don't think it was too long ago since last serviced but it seems to have been workng fine.

 

[happyflyer]

If water has got onto the bottom side of the vessel it indicates that the rubber membrane may have become porous, it would be a good idea to take the vessel out of circuit and check it before you top up the system, it would be better as some as already suggested you get someone to do it for , it will only take 10 mins, it all depends how much water has got into the nitrogen side, yes N2 is what it was originally charged with, I hate it when someone puts the fill loop where you cant see the gauge, pretty stupid, unless it is just the other side of the boiler, your photo doesn't make it clear.

 

[dogbiscuit]

If water has got onto the bottom side of the vessel it indicates that the rubber membrane may have become porous, it would be a good idea to take the vessel out of circuit and check it before you top up the system, it would be better as some as already suggested you get someone to do it for , it will only take 10 mins, it all depends how much water has got into the nitrogen side, yes N2 is what it was originally charged with, I hate it when someone puts the fill loop where you cant see the gauge, pretty stupid, unless it is just the other side of the boiler, your photo doesn't make it clear.

Ok, I was trying to avoid getting my landlord invloved as he's not the most pro-active and the weather has got cold! But guess it's worth getting checked out.
Yeh the fill loop is in a different cupboard in the opposite corner of the room. Does seem a bit stupid!
Anyway, thanks for your help everyone. Much appreciated. I guess it's sensible to get a plumber to check it.

 

[happyflyer]

Maybe if the plumber comes around you could ask him to put another pressure gauge next to the loop and then you can see what the pressure is as you fill, can't see the LL paying for it can you, how do these people get away with it.

You need to tell your LL there are some safely issue here too, tell him to get a grip!

Good Luck

 

[Dotty]

As long as you only gave the schraeder a quick blip it should be ok.

Don't get too het up on the expansion vessel as it causes similar problems when over charged and under charged.....

 

[happyflyer]

Good tool to have around about £5 Halford

 

[dogbiscuit]

As long as you only gave the schraeder a quick blip it should be ok.

Don't get too het up on the expansion vessel as it causes similar problems when over charged and under charged.....

Yeh it was just 2 or 3 quick blips and each time some drips of water ran out. You think it might be ok?

 

[oz-plumber]

Generally when water comes out of the expansion tank through the schraeder valve, it menas the membrane has been broken.
That size of expansion tank 8 /10 litres, from your photos, are not expensive.
Get someone to replace it and your problems will be sorted.
As stated, it will take about 10 minutes to replace.

 

[happyflyer]

Like Oz says you don't know how much water has gone over onto the dry gas side, you can only tell if you unscrew the vessel from the upper brass fitting and feel the weigh of it, shack it and if you can feel lots of water moving around, its had it. Like we say the plumber should be in there for no more than 30 minutes, it will take longer to vent the system than fit a new vessel.

 

[dogbiscuit]

Ok, I'm definitely gonna get a plumber.
One last question guys. It's soo cold! In the meantime, do you think I can get away with using the heating a little if I top up the system with water?

 

[happyflyer]

You only lost the water because you were venting, that's what you said, the worst that could happen is the SV could blow out water when it heats up.

 

[dogbiscuit]

You only lost the water because you were venting, that's what you said, the worst that could happen is the SV could blow out water when it heats up.

Yeh that's right. What's an SV?

 

[Crinkmeister]

Safety Valve

 

[happyflyer]

Dogbiscuit,

Your another one who didn't say where you live, there could be help just around the corner and you would never know it, hey well. Sounds like your Landlord is as much use as an ashtray on a motorbike, I take it you have told him what's wrong.

 

[dogbiscuit]

Dogbiscuit,

Your another one who didn't say where you live, there could be help just around the corner and you would never know it, hey well. Sounds like your Landlord is as much use as an ashtray on a motorbike, I take it you have told him what's wrong.

I live in Edinburgh. I'm seeing my landlord today so will tell him to get it serviced. This morning I topped up the system with water and ran the heating for a short time and it was ok.