How to recharge an expansion vessel in a combi boiler

To check if the expansion vessel requires re-charging please watch this video-

[profhindsight]

Fantastic! If all plumbers were as honest as you there wouldn't be any hesitation to call in a plumber. I've had three plumbers all tell me my Ariston boiler (2011) needs replacing at £1750 when a simple repressure cured a four year problem. Just brilliant!

[nightowl]

Just like to say, that thanks to this excellent video. I have sorted, which both 24/7 home rescue and BRITISH GAS, failed to do during their annual boiler service. prior to me fixing it. the boiler pressure was 1.6 in standby, but would shoot to over 3.0 in use. I bled a radiator to get the pressure down to 0. I then switched boiler (Valliant Ecotec Plus 831) off. removed the cover and attached my bicycle stand pump with pressure gauge to the expansion vessel. and the pressure in vessel was 0 (Zero) so I pumped it up to 0.9 bar. replaced the cover and switched boiler back on. refilled using the filling loop to 1.5 bar and now the pressure tops out at around 2.0 bar when in use. needless to say. I would not have done anything to the gas side of it, But I was confident of doing the recharge side. Isn't the expansion vessel pressure supposed to be checked during an annual service ????

[RichardKingADI]

From the point where my wife complained about the boiler and I found this on YouTube - to the point where I had successfully put some pressure back into the expansion vessel must have taken me all of five minutes!! many thanks - problem solved!

[gedheaton]

47 represent nails it 7 yrs ago below, you need to clear the ex vessel of ALL water (even standing) to get a accurate reading, correct way is to close F&R valves release pressure in boiler using boiler drain off NOT PRV (asking for trouble there), leave drain open and pump up pressure in vessel, the water left and there will be quite a bit will be forced out of the vessel, when empty and you'll know cos the last bit will be filthy, then re pressurise vessel to what MI state, open F&R valves and repressurise system.

[jimmyboy]

Thanks for this! Started having issues with my Immergas Combi (again) after having a new expansion vessel installed 18 months ago. Been fine since. System now losing pressure again (assume over pressure and PRV releasing it up). I will check air pressure in the expansion vessel. Thanks.

[Oneofakind]

May I say thanks a million in advance!

I'm pretty competent at having a go at plumbing, but being a boiler i've not wanted to mess with anything. Not being a gas engineer.

I was unaware of the expansion vessels purpose or the fact it required periodic maintenance. I.E recharging.
Your video has helped me cure a problem i've been dealing with for over a year!
I'm ecstatic, that hasn't cost me anything to fix.

Many Thanks!

Cracking tutorial, saved myself a fortune by repressuring the vessel today. Thanks for taking the time to make these videos

[yerlock]

I owe you one. 2 months after a service my boiler started losing water venting outside via the overflow pipe. Checked out your video & found water passed out of the E/V valve, so I re-pressurised it to the correct pressure after which only air vented. I assume there is a bladder inside which as luck would have it was only deflated as the boiler has ran for weeks with no water loss. I can't thank you enough.

[pavlouplumbers]

As mentioned previously in the comments some expansion vessels on some boilers (mainly newer boilers) are in the air tight area which should only be accessed if you are gas safe registered. If the expansion vessel is at the back of the boiler then you would need to release the pressure from the central heating system either as mentioned in the video or by using the drain off on the boiler and you would need to leave the drain valve open while you are re-pressurising the expansion vessel. This way you will be pushing the water out of the expansion vessel while pumping it up then pressurising the expansion vessel to the correct amount.

[shakeeloniel]

Excellent video mate solved my 3 year misery pressure kept shooting to 3 bar... service engineer not once checked the vessel pressure.

[wingaard]

Thanks for the Vid. My Ideal Combi is losing pressure on daily basis. The water is collecting in a catch bucket underneath overflow outside. I tried valve on Exp.vessel earlier and it seemed flat (ie no hissing) but luckily no water came out. Do these two symptoms tie in with each other or should I be looking at something else? Cheers

[ultimatehandyman]

+ Nunsweepit421 
It could be. I suggest you drain out some water from the system perhaps via the radiator drain off valve. Then re-charge the expansion vessel. After doing that you can re-pressurise the central heating and see if the problem is still there.

[Stringbean]

Just lately, the pressure gauge on my 5 year old boiler keeps going into the red when heating is on for about ten minutes so I have to quickly switch off. YouTube videos say that this problem is the expansion vessel. When I press the schrader valve on the vessel, no water comes out. Just air. Does this simply mean the vessel needs re-pressurising as shown in the video? Thanks.

[motivationformuslims]

Thank you so much for all these videos. May God bless you with true faith!

[davidbenson]

So once I have let some water out of the system and the pressure gauge gos to zero on the boiler do I leave the bleed valve open on the radiator while filling the expansion vessel thanks Dave

[kjhi]

great video mate, do you release the pressure to down to 0 on the pressure meter from the radiator bleed valve?many thanks

[flyerh]

Should you not isolate and drain the boiler before you recharge the bladder to prevent pushing against static water pressure?

[grahamtaylor]

Thanks ultimate handyman will now go ahead with the job thanks to your how to video and quick reply to my question

[SEuk]

Can you put a small amount of air in with no psi gauge and while there is water/pressure in the ev if it was 0.5 cold 3 bar hot
2 pumps then blead the rad as not to get air in the system
is there a air bleed on the 28 jnr

[rickful]

A very helpful video. I charged it to 0.8/9 bar and hey, ye its working great. The pressure gauge does not go up above 3 bar now and the house is very warm. Thanks . I do a lot of DIY, and would not recommend a novice trying to do this. ( it was at 0.3 bar on first test)