Gurgling and air in central heating

[jim843]

How often have had to top it iup?

Never.

I bleed the air. That’s it.

 

[Deleted member 123817]

So after bleeding the air off each time the pressure returns to normal ?. I know it doesn't add up but could/can you remove the filling loop to absolutely rule it out.

 

[jim843]

So after bleeding the air off each time the pressure returns to normal ?. I know it doesn't add up but could/can you remove the filling loop to absolutely rule it out.

I’m not sure that the pressure rises. I will try and monitor.

It’s hard because it fluctuates a little bit. Baxi engineers said this is normal.

Not sure how to remove the filling loop exactly. Would I have to drain the system?

 

[Deleted member 123817]

There should be a flexible hose somewhere where it connects to the boiler return with isolating valves or can you post a photo of the isolation valve you described previously?

Do mean by PG fluctuations that it changes fairly rapidly while watching it and have you watched it for any unusual behaviour while using hot water?

 

[jim843]

There should be a flexible hose somewhere where it connects to the boiler return with isolating valves or can you post a photo of the isolation valve you described previously?

Do mean by PG fluctuations that it changes fairly rapidly while watching it and have you watched it for any unusual behaviour while using hot water?

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.

 

[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!.

 

[jim843]

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

Pretty sure it’s internal. The engineer took the cover off. There’s nothing outside the boiler as far as I know.

 

[John.g]

In the attachment is that a PRV on the filling system??.

It's also possible I suppose but very unlikely as I said above that the pump is pulling in a tiny amount of air through that leaking NRV each time it starts especially if the E.vessel is on the discharge side of the pump, the closer to the boiler the greater the chance, if the boiler is under warranty then that should be covered? its the only part that has direct communication to the atmosphere via the leak even though pressurized.

 

[jim843]

In the attachment is that a PRV on the filling system??.

It's also possible I suppose but very unlikely as I said above that the pump is pulling in a tiny amount of air through that leaking NRV each time it starts especially if the E.vessel is on the discharge side of the pump, the closer to the boiler the greater the chance, if the boiler is under warranty then that should be covered? its the only part that has direct communication to the atmosphere via the leak even though pressurized.

Maybe I’m mixing this up: the leak is on the valve that has an arrow on it.

The arrow you have drawn on the photo: do you mean a pressure release valve? I don’t know what that black thing is.

 

[jim843]

In the attachment is that a PRV on the filling system??.

It's also possible I suppose but very unlikely as I said above that the pump is pulling in a tiny amount of air through that leaking NRV each time it starts especially if the E.vessel is on the discharge side of the pump, the closer to the boiler the greater the chance, if the boiler is under warranty then that should be covered? its the only part that has direct communication to the atmosphere via the leak even though pressurized.

This is where the leak is (see attached).

Do you think it’s worth replacing that NRV?

 

[John.g]

Yes, I would replace it as every other possibility seems to have been reasonably exhausted. Maybe its under warranty?.

The valve thats leaking is a non return valve (NRV). the PRV I'm referring to is a pressure reducing valve called a PRV (as is the safety valve also called a PRV, a bit confusing) the pressure reducing valve above is/should be connected dirrectly to the filling hose?.

Forget my reference to that PRV, thats the isolating valve for the filling hose.

 

[John.g]

As a temporary measure you could attach another filling hose which has isolating valves at both ends, connect one end to the NRV and shut it.

 

[jim843]

Yes, I would replace it as every other possibility seems to have been reasonably exhausted. Maybe its under warranty?.

The valve thats leaking is a non return valve (NRV). the PRV I'm referring to is a pressure reducing valve called a PRV (as is the safety valve also called a PRV, a bit confusing) the pressure reducing valve above is/should be connected dirrectly to the filling hose?.

Forget my reference to that PRV, thats the isolating valve for the filling hose.

I seem to remember from a couple years back a Baxi engineer saying that this filling loop is old and should have been replaced when the boiler was replaced. Maybe I’m misremembering, though.

You’d think the boiler would be under warranty but the installer has moved and I’ve no idea where they live now. Considering the mess they made - leaking joints under the boiler, not fitting the soak away - I should probably get someone else in.

 

[jim843]

As a temporary measure you could attach another filling hose which has isolating valves at both ends, connect one end to the NRV and shut it.

Ok, I’ll have a look and see what screwfix have tomorrow.

 

[jim843]

As a temporary measure you could attach another filling hose which has isolating valves at both ends, connect one end to the NRV and shut it.

Something like R24 Filling Loop - https://www.NoLinkingToThis/p/r24-filling-loop/83905 with some pipe and compression fittings to connect to that new loop?

 

[jim843]

As a temporary measure you could attach another filling hose which has isolating valves at both ends, connect one end to the NRV and shut it.

Another thought: the isolation valve with the handle before the filling loop would stop the leak, if any, right?

Or are you thinking that the leaking NRV is somehow pulling air into the system even though the filling loop isolation valve is closed?