Gurgling and air in central heating

[jim843]

@johntheo while I was looking I noticed this.

Also some of the copper pipes into the boiler have this.

Anything to worry about?

 

[John.g]

Will see if there are isolating valves behind.

The pressure only drops/rises when the pump goes on/off. Not during heating.

Haven’t checked when using hot water but will check tomorrow.

That is the filling loop with a non return valve where shown and a isolating valve where shown on the other end, ensure the isolation valve is closed "across (at right angles to) the pipe" then just slacken the flexible hose where attached to the NR valve but do not remove it, when slackened a few turns water should only dribble out for a few seconds and then stop.
There may be another isolation valve on top of the NR valve but I don't think so, if there is, shut it as well

 

[John.g]

@johntheo while I was looking I noticed this.

Also some of the copper pipes into the boiler have this.

Anything to worry about?

I dont't think so, these look like isolating valves for the boiler flow/return.

 

[jim843]

That is the filling loop with a non return valve where shown and a isolating valve where shown on the other end, ensure the isolation valve is closed "across (at right angles to) the pipe" then just slacken the flexible hose where attached to the NR valve but do not remove it, when slackened a few turns water should only dribble out for a few seconds and then stop.
There may be another isolation valve on top of the NR valve but I don't think so, if there is, shut it as well

Ok, I’ll try this tomorrow along with the hydrogen check!

Do you think air could be somehow being pulled into the system here?

If so, would it be the loop or the NRV?

 

[John.g]

No, I think it highly unlikely because even if the flexible hose is perished/holed then with a sealed system the pressure should still keep the NR valve shut. I also find it difficult to imagine that you are pulling in air anywhere in the volumes that you are getting especially if the boiler pressure is normally 1bar or higher. Lets hope in one way that its hydrogen!.

 

[jim843]

No, I think it highly unlikely because even if the flexible hose is perished/holed then with a sealed system the pressure should still keep the NR valve shut. I also find it difficult to imagine that you are pulling in air anywhere in the volumes that you are getting especially if the boiler pressure is normally 1bar or higher. Lets hope in one way that its hydrogen!.

I’ll take a video of the amount of air/hydrogen coming out so it’s easier to see.

Is it worth doing the bleed when the system is cold? And by cold, how long should the system be off for?

 

[John.g]

I've only had to vent some air from my open vented system after a complete drain down and refill, I would stop the circ pump/boiler and then vent when hot. Hot or/& cold better IMO to vent with pump off.

 

[jim843]

I vented the bathroom towel rail today. Heating was turned off. System was still a bit warm.

I got about 7 seconds worth of air with a quarter turn of the bleed valve.

Here is the pressure before bleeding:

And pressure after bleeding:

Thing is, the pressure gauge usually varies a bit.

From earlier in the week:

@jim843 I tried the hydrogen test. There was no pop.

@John.g do you still think it's worth removing the filling loop?

@johntheo I turned on the hot water and the pressure does drop. It went from about 2.4 to about 2. Is this a problem?

Thank you all for your help. It's been very useful for me to vent (no pun intended?!) and discuss this.

 

[John.g]

Yes, definitely remove (after first slackening) that filling loop, it's only hand tightened at the connection to the NRV, obviously ensure that the isolaton valve is shut, as it appears to be, then post back.

 

[jim843]

Yes, definitely remove (after first slackening) that filling loop, it's only hand tightened at the connection to the NRV, obviously ensure that the isolaton valve is shut, as it appears to be, then post back.

Ok. Just so I'm clear, remove loop and leave it a couple days and see if there's any air in the system?

 

[John.g]

Correct, but let us know when you do disconnect it if there is any dribble of water from it just now.

 

[jim843]

Correct, but let us know when you do disconnect it if there is any dribble of water from it just now.

Ok, just slackened it and yes there was a dribble of water.

I've left a container underneath to see if it keeps leaking...

 

[John.g]

Now remove it completely and if its still dribbling from the hose then that's your problem.

 

[jim843]

Now remove it completely and if its still dribbling from the hose then that's your problem.

I don't think it's leaking from the hose but the NRV appears to be leaking:

I watched it and I can see the water filling up and then leaking.

Could this be the issue?

 

[John.g]

I would't have thought so as difficult to see how this would pull in air so as one would expect the pressure to slowly decay with time, just leave the hose disconnected and see what happens to the pressure.

 

[jim843]

I would't have thought as difficult to see how this would pull in air so as one would expect the pressure to slowly decay with time, just leave the hose disconnected and see what happens to the pressure.

Ok, will do.

 

[jim843]

I would't have thought so as difficult to see how this would pull in air so as one would expect the pressure to slowly decay with time, just leave the hose disconnected and see what happens to the pressure.

So filling loop has been off since about 1400 (5 hours or so).

Pressure was at 2.5 a while ago. I heard some bubbling sound in bathroom rad. So bled rad again - few seconds of air - and now pressure is 2.4.

Still confused why the pressure drops when the pump comes on…

 

[Deleted member 123817]

The expansion vessel is normally teed into the pump suction so will rise by the generated pump head when it starts so if connected to the pump discharge will fall but when when off should return to the original pressure if water temp doesn't change,
Can you bring on the hot water very briefly say for 10 secs and then switch off and see if pressure returns to its original.

 

[jim843]

The expansion vessel is normally teed into the pump suction so will rise by the generated pump head when it starts so if connected to the pump discharge will fall but when when off should return to the original pressure if water temp doesn't change,
Can you bring on the hot water very briefly say for 10 secs and then switch off and see if pressure returns to its original.

Ok. Pressure drops slightly when hot water comes on.

I waited about 30seconds and then the pressure goes (more or less) back to what it was before.

 

[Deleted member 123817]

Was the new E.vessel installed internally in the boiler or is it external where you can see it!.