Our sink pipes have been singing when we flush toilet or water heats up, I’ve bled the rads (one in our bedroom was full of air), I’ve released the air out of the expansion vessel (I was told at the plumbing place to) but the pressure keeps dropping. I’ll post a picture of the expansion vessel and pressure gauge and see if anybody can help. Thank you
Pressure drop on expansion vessel (1)
- Thread starter Caren
- Start date
Sponsored Links
Could the diaphragm have failed?
PS, maybe better in the Central Heating forum?
Sponsored Links
Our sink pipes have been singing when we flush toilet or water heats up, I’ve bled the rads (one in our bedroom was full of air), I’ve released the air out of the expansion vessel (I was told at the plumbing place to) but the pressure keeps dropping. I’ll post a picture of the expansion vessel and pressure gauge and see if anybody can help. I haven’t a clue about heating or anything btw.
Thank you in advance
Read more: https://www.diynot.com/diy/threads/pressure-drop-on-expansion-vessel.562419/#ixzz6kNhcYFF5
Thank you in advance
Read more: https://www.diynot.com/diy/threads/pressure-drop-on-expansion-vessel.562419/#ixzz6kNhcYFF5
Attachments
Half of the 'tank' is water, half air. Between them is a rubber barrier- the diaphragm. When you pressure the system, the water you are adding presses against the rubber, and that pressure registers on the pressure gauge. If the water leaks through the rubber, the pressure keeps dropping. I THINK!, said not-a-pro.
Thank you for your reply there doesn’t seem to be any water leaking. It’s a fairly new boiler, we had it fitted over a year ago by British Gas and the system flushed but they’re not sending anybody out due to covid. I have the heating on and the pressure hasn’t fallen, it seems to be dropping when the heating is off, I’m so confused
there doesn’t seem to be any water leaking. It’s a fairly new boiler, we had it fitted over a year ago by British Gas and the system flushed but they’re not sending anybody out due to covid. I have the heating on and the pressure hasn’t fallen, it seems to be dropping when the heating is off, I’m so confused 
Releasing air from your expansion vessel is not good advice at all, which will be why you’re experiencing the pressure dropping. Do you have an open vented system (hot water cylinder)?
Oh really? I’m not sure, I don’t know anything about central heating or plumbing, I was just doing what I was told to do. When the heating is on, the pressure stays but drops when the heating is off. The guy said if air comes out of the valve on your expansion vessel then that’s good so I let all the air out
That’s incorrect advice and proves nothing. You’ll need to have the expansion vessel pumped back up. You can have the heating on when pressurised, but the pressure will rise too much and discharge via safety discharge pipe.Oh The guy said if air comes out of the valve on your expansion vessel then that’s good so I let all the air out
Unfortunately your sink pipes have nothing to do with the red expansion vessel your have pictured. That expansion vessel is for your central heating pipework that supplies your radiators. Don't let the air out of that red vessel, it needs air in it to work properly. If you find that the pressure on that gauge rises closer to the 3 when the central heating is on, then the vessel need to be pressurised properly. Time for an engineer.
Do you have an unvented hot water cylinder? If you can post a picture of that if possible.
Do you have an unvented hot water cylinder? If you can post a picture of that if possible.
It may be ok very short term, depends how long you’ve been doing it for. Every time you re-pressurise the system, you’re adding oxygenated water, which can cause corrosion. Also do you have hot water cylinder?
The guy at the plumbers store said to reduce all the air out the vessel and that should stop the noise as there will be air in the pipes. I did see on YouTube that you can pump air back into the vessel but I have no idea what I’m doing as I don’t know anything about plumbing or heating. Is this the water cylinder? Please excuse the mess
Attachments
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
