HI forum I recently purchased a Screwfix external expansion vessel for my Vailant Turbomax Combi boiler because the internal vessel diaphragm has perished and water splutters when the schrader valve is depressed. My question is regarding the new vessel, it seems there's a black rubber bung halfway down the neck of the vessel and I'm not sure if I'm supposed to remove this before installation. Sorry if this is a dumb question....
Glad its Friday, thanks for your reply. I have fitted it to the system 'as-is' and currently I'm running Sentinel X400 cleaner around for a few days. I didn't put an isolating valve on the vessel (dooh) so I need to drain it all before I can take a photo but I will do asap. I don't actually know if the vessel is doing anything at all. When looking down the neck of expansion vessels would you normally expect to see straight through to the diaphragm ? I have emailed Screwfix but their reply said they don't know the answer and gave me a phone number for the bracket manufacturer, not the vessel manufacturer! Many Thanks
Boris, it doesn't make sense for there to be a 'bung' there. What do you mean by the 'neck'? The water side or the 'air' side? If 'air', then surely what you are looking at is the Shraeder valve? Have you tested the air pressure? A normal car tyre pump will do, but really the water side should be depressurised first, so perhaps wait until you drain your system after the chemicals have done their job (do you have a magnetic filter fitted? Worth it...) Anyhoo, it should be pretty obvious if the vessel is doing it's job - what's your system pressure doing?
Sorry for not being clearer, the "bung thingy" is in the water side, its a brand new and pre-pressurised vessel. The system pressure is actually very constant, I keep it about 1.25 bar cold and it doesn't go up that much when hot. "Magnetic Filter" I'll have to google that one .. Thanks again.
I've just run a test. The gauge shows 1.25 bar when cold and 1.85 bar when blisteringly hot. Within the green sector of the gauge so I guess it's working ok? Phew it's hot in here!
Sounds fine, Boris. Yes, it's not unusual to find some fluctuation in the working pressure betwixt hot and cold, and as long as it's within the 'ok' sector not a problem. If your exp vessel wasn't working, then your pressure would shoot up to over the max 3bar, opening the safety valve. That bung still sounds weird, tho'! I guess it must has had a hole in it somewhere? If you had wanted to remove that bung, how would have managed it - would it have been easy? Unless it's a clever design where it's there to prevent dirt getting in, and is simply blown in to the vessel when the water side is pressurised, safely out of the way? Was there a cap of some sort over the actual threaded end of that fitting that you had to remove?
Hi Dev' I was thinking a cork screw might get it! No there was no cap on it but I've subsequently found the hotdesk email address of the manufacturer and asked them the question. They are in Germany so I can only hope they comprehend me. They're called Reflex & the item in question is a 'Reflex N 12 grey Expansion Vessel'. By the way the magnetic filter looks a handy gadget, think I'll start saving up. Fingers crossed & thanks for your help.
Sounds like it is working ok Boris, not worth draining down to have a look, but see what the manufacturer comes back with though. Don't put an isolation valve in-line with the vessel, it may get turned off at some point and cause you grief.
Aaah good point, I was looking for the easy option. Will leave the isolator out. If I get a reply from Reflex I'll post it here, it might help somebody else. I will post a photo as soon as I can. Thanks all
Received a reply from the manufacturers as follows: Good Morning Boris, At first many thanks for your E-Mail. Please let the plug inside the vessel at the installation. The plug prevent and protect the diaphragm to not come out of the water connection and maybe destroy than J Have a nice day and best wishes from Ahlen. Ha - my interpretation is .. leave the plug in! I'm going to drain out the cleaner next tuesday - will post a photo then. Thx
Ah, so you speak Pidgin-German? I think the drift is that it stops the diaphragm inside from being possibly damaged by being pushed oot the wee hole by the air pressure inside before its fitted? The only Q now - and it's a real biggie - is what they mean by 'let'... ("Please let the plug inside the vessel at the installation") Is it 'let' the plug in - ie press it right inside the chamber? Or 'let' the plug stay where it is - in the nozzle. The wrong decision could have dire consequences... (walks away whistling...)
Having actually read the Sentinel instructions I realised I could leave the cleaner in for a couple of weeks at least, so I gave it another week. I also went back to the manufacturers, explained that I'm an idiot and that I didn't understand their reply. They came back with .... "Yes right, leave it there inside. Because it is an fixed plastic plug. That plastic plug protect the bladder to not come out of the nitrogen prepressure. Make it sense? When the plug is not inside the water connection maybe the nitrogen pressure can be pulled the bladder out and this is not very good for material of bladder. The bladder can be destroy…. " Well hmmmm - that might mean leave it in there - so I have. I've attached a photo Thanks - Boris
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