Water Cylinder noise issue

Bendy_House

You are welcome.

A few other things, brought up by your latest comments! If the pressure drops to near-zero when cold, and rises by nearly a bar (~0.7) when hot, such a fluctuation is not ideal. There's a risk that, if you now start at 1.2b when cold, it could rise to nearly 2 bar when hot?

Your system - perhaps inside your boiler, perhaps external - has an Expansion Vessel. Its purpose is to accommodate the extra water created by expansion as the system heats up, so keeping the pressure pretty steady, and then to release it back when the system cools (and contracts) back down. Your EV doesn't appear to be operating as well as it should.

So, I'd repressurise the system to no more than 1 bar in your case, and then observe what happens to this pressure after you turn on the CH - take readings every 5 minutes or so over the next 45 minutes - until the rads are hot.

If it rises from 1 bar to over 2, then good chance your EV needs a little attention. If it rises but doesn't hit 2 bar, you can live with that

If it starts going into the high-2's, then there's a risk it'll blow open the safety discharge valve and dump excess water out the copper pipe that's on your outside wall.

Another thing that occurs; if your pressure is near-zero at the boiler's height - is this on a ground floor, for example? - then there is a possibility that in an upstairs rad it's fractionally below zero. If a rad valve gland is lightly loose, then it could actually draw in air to the inside of the rad! This is not common, but it can happen; the rubber gland is tight enough to prevent water escaping, but not to prevent air from seeping in from the potentially greater atmospheric pressure outside. 

As long as your system is at 1bar or so, this shouldn't happen - it should still be well above atmos upstairs.

malexicon

Thanks again... 1 bar it is then and I'll observe carefully as you suggest... Boiler is on the ground floor. Interestingly, when the ensuite reconfig work was done, the fitter re-pressured the boiler, it was still in the green on the dial, but more like 1.5bar cold or so, going to 2 (or more maybe) when on. I must admit, I didnt think much about it at the time other than it was higher than usual. Not long after the work was done we had the annual service from BG and the pressure was reduced a bit after that back to levels closer to those you suggest.

Bendy_House

How many floors do you have?

malexicon

...Just ground and first, modern (ish) build -  Bathroom / ensuite / cylinder are upstairs. Boiler downstairs in kitchen

coffeehound

Hi malexicon, would it be poss to see a photo of the top half of the hot water tank with the valves and expansion vessel, pls?

malexicon

Yes, of course. I'll get this tomorrow and pop it o  the site

Bendy_House

malexicon said:

...Just ground and first, modern (ish) build -  Bathroom / ensuite / cylinder are upstairs. Boiler downstairs in kitchen

Ok, so pressure drop on upper floor shouldn't be large (I thinks it's circa 0.1bar per metre?)
However, if 'ground' is genuinely at zero, then 1st could be 'below', and could seep in air from a slightly loose connection or fitting.
Once your pressure is restored and rad's bled, it should STAY fine, but if it drops to zero again then there's always the chance. 
I'm just citing it as 'possible', and not likely.

malexicon

Hi Coffeehound... as requested - hard to get in one shot..- all is bang on in terms of install according to the Gledhill installation manual and G3 saw no issues with set up (though he said he might have piped things slightly differently etc) which is good.

Thanks again Bendy...I'll keep a close eye on things as and when I sort out the boiler pressure / bleeding ... Covid has caught up with me unfortunately :-(     

If there are any issues with the seeping sounds like something BG can come and fix under my service plan...

malexicon

Hi Bendy, I was just reading back through the thread and your comment from 25/2 about air being released via a vent caught me eye. I read in my bolier manual (a Greenstar 24i system boiler) that this model does have an automatic air vent - excuse my obvious ignorance again on this score but is the purpose of this to try and remove some of the air that might be in the system loop? 

I am still to get around to the bleeding etc - but will in the next few days once I'm a bit better, but over the last couple of days the cylinder has still a bit of noise, though not as loud as previously so I am still trying to gauge things.  Am hoping if I can get the air out of the rads, and hence the system loop itself a bit, then it will calm the cylinder down further.

Also, on further conversation with the G3 who serviced recently they are now suggesting to contact the manufacturer if issues persist rather than doing a system drain (which you questioned). I may do this depending how it goes, but suspect if the noise persists after I try and get rid of the air that my next course will be to contact BG/Dyno who installed the thing and I have the repair and service plan with - that would take me back to where I started though sadly.

Thanks again for your help.

Bendy_House

Yes, the purpose of the auto air vent is just that - it automatically releases air from the sealed system.

It'll be inside the boiler, and is usually a reliable device. I can seize, tho', and the wee valve doesn't release the caught air as it should.

As for the system drain, I just can't see its purpose. There may be a good reason for it, but I can't figure it out.

If all you are trying to do is release trapped wind - barp - then a combi of rad bleed screws, the boiler's auto air vent, and the manual one we saw in front of your cylinder ought to do it.