Gurgling and air in central heating

[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?

 

[John.g]

Yes, maybe through the leaking NRV but very unlikely.

The most likely place for air ingress one might think would be at at attic rads even though these should still have ample positive pressure even if boiler pressure was =<1.5bar.
If you vent them with pump running does water definitely flow out after a burst of air? and does the same apply to all the other rads?

 

[jim843]

Yes, maybe through the leaking NRV but very unlikely.

The most likely place for air ingress one might think would be at at attic rads even though these should still have ample positive pressure even if boiler pressure was =<1.5bar.
If you vent them with pump running does water definitely flow out after a burst of air? and does the same apply to all the other rads?

The attic rads never have any air in them. They only had air in them before the bathroom was fitted. After the bathroom was fitted, air appeared in the bathroom towel rail instead.

I can always cap off the upstairs rads on the second floor and run the system for a bit to see if the air stops?

If the attic rads are pulling in air, why would it end up one floor down?

 

[John.g]

Its a mystery to me why any air is getting in!, does the towel rad vent water??.

 

[jim843]

Its a mystery to me why any air is getting in!, does the towel rad vent water??.

Yep, it vents water.

There’s some air. Then water.

I can repeat this every day.

 

[jim843]

Its a mystery to me why any air is getting in!, does the towel rad vent water??.

I re-read your previous comment: did you say vent with the pump running? I always vent when the pump is off.

Also, air only appears in the towel rail when the heating system has been on. In summer there’s no air in the towel rail. This might be expected, I don’t know.