CH. Air noises driving me mad. Vented system.

[friendlyaviator]

Hi there, I really hope someone here can help me.

I have an open vented central heating system. Back in Dec 2011 I drained the CH system down, flushed it with clean water, fitted a new radiator to the living room and refilled with cleaner. Around a week later I drained the cleaner out, fitted TRVs on all but one radiator and refilled with inhibitor.

Ever since then I have been getting gurgling, trapped air noises while the CH pump runs when the CH is on. All radiators are filled with water and don't need anymore bleeding since I refilled the system. The pump also trickles water from the centre bleed screw when I undo it. I cannot find any other bleed vents on the system.

I am having no other symptons, all radiators get hot, the boiler cycles fine it's just this trapped air issue. I do not believe it is sucking in air as the radiators never need bleeding and as such I don't think the volume of air in the system is increasing.

I really hope you can help as the noise wakes my Mrs every morning!

Thanks,

Dean

 

[TBServices]

Sounds like your pump could be dragging in air.

 

[friendlyaviator]

Sounds like your pump could be dragging in air.

Thanks for the rapid reply.

I did wonder this but that air never reaches the radiators, therefore the air volume does not appear to be increasing. The bleed screw is tight and no leaks showing. It is a little noisy on low speed though. Could it still be the pump?

 

[TBServices]

Thanks for the rapid reply.

I did wonder this but that air never reaches the radiators, therefore the air volume does not appear to be increasing. The bleed screw is tight and no leaks showing. It is a little noisy on low speed though. Could it still be the pump?

In the op you said it weeps?

 

[friendlyaviator]

In the op you said it weeps?

You are correct. I meant when I undo it to bleed the pump. Sorry!

 

[DirksPlumbing]

You are correct. I meant when I undo it to bleed the pump. Sorry!

The air noise barely comes from the radiators except some design rads have to be filled in a certain way to overcome potential air traps.
Is it a sealed system? In this case bleed at low pressure and then increase the pressure again.

 

[friendlyaviator]

The air noise barely comes from the radiators except some design rads have to be filled in a certain way to overcome potential air traps.
Is it a sealed system? In this case bleed at low pressure and then increase the pressure again.

No it's an open vented system. F + E tank in loft. This is clean, has water in it and level reduces and tops up when I reinstalled the radiator.

I and still thinking trapped air rather than air ingestion based on the fact it never reaches the radiators, doesn't seem to be air entering if you get what I mean.

 

[DirksPlumbing]

Any specific location where the noise is dominant?

 

[friendlyaviator]

Any specific location where the noise is dominant?

Mainly upstairs but sometimes I can hear it in the downstairs radiator but when the noise comes there it sounds more of a gritty noise through the pipes instead of a bubbling.

One other thing to note is there was two capped off pipes in the kitchen at the ceiling level that used to feed a radiator. I changed these caps for two valves with the intention of adding a radiator in the future. Could this somehow contribute to my problem?

Boiler and pump situated in kitchen on ground floor.

 

[zzzjim]

What brand TRV and is the radiator without one nice and queit ?

 

[friendlyaviator]

What brand TRV and is the radiator without one nice and queit ?

They are cheap screw fix ones. The noise is bubbling water in the pipes. Not at the TRV. I've tried removing the TRV cap so the valve is fully open, this makes no difference to the noises

I've also looped the two pipes that were blanked off in case that was the issue. Can't really tell until the system cools and starts again.

 

[acecharly]

Can you describe how you refilled the system ie which radiators did you bleed first was pump running whilst you were filling were lock sheilds open or shut when you refilled..

 

[friendlyaviator]

Can you describe how you refilled the system ie which radiators did you bleed first was pump running whilst you were filling were lock sheilds open or shut when you refilled..

Your help is appreciated. Especially on a fri night!

I closed all valves on all rads. Turned on the header tank supply, opened the only downstairs rad TRV and bled until water came out. Then did upstairs. I can't remember if I left lock shields open or closed...

I have a two speed pump running just 4 radiators. Could this be too fast? I opened all lockshields to try and bleed the air out. Will them being wide open cause the pump to push water around so fast on such a small system and create my noise problem? Vacuum somehow?

 

[acecharly]

Was the header tank empty when you started? Did you clear any debris from the bottom of the tank first to stop it going into the system?

Follow these instructions:-

Make sure pump is not running and boiler is off.
Turn of all upstairs radiators. When turning of lockshields note the amount of turns to make sure your system stays balanced.
Start with the one downstairs radiator.
Keep the return pipe valve closed and fill until bleed vent drips then close bleed valve.
Now close the flow valve so this rad is isolated in effect and move upstairs to the next and repeat until the furthest rad is refilled last.

Making sure all bleed valves are closed, open the radiator valves one at a time starting with the first radiator on the system – remembering to open the lockshield valves by the same number of turns used to close them.

Can you do this and then report back how you got on

Cheers
Ace

 

[zzzjim]

Sounds like your pump could be dragging in air.

I do like TB services diagnosis , if the noise is worst when the system is cold , and has been stood for a while , Pump may be temporarily drawing air in , making lots of noise ( then rather miraculously air vents its self )

Check water level in F & E tank , rule out any strange behaviour there when in Cold and stood condition and pump is first started

 

[friendlyaviator]

Wow, this forum has lots of expert advice. Thanks for replies so far.

Was the header tank empty when you started? Did you clear any debris from the bottom of the tank first to stop it going into the system?

The header tank was dirty but I made sure it was very clean before I started all this. I am meticulous about this kind of thing. There was very little chance of sedement getting into the pipework as the cold feed to the boiler was around an inch off the bottom and way above the debris in the bottom.

Follow these instructions:-

Make sure pump is not running and boiler is off.
Turn of all upstairs radiators. When turning of lockshields note the amount of turns to make sure your system stays balanced.
Start with the one downstairs radiator.
Keep the return pipe valve closed and fill until bleed vent drips then close bleed valve.
Now close the flow valve so this rad is isolated in effect and move upstairs to the next and repeat until the furthest rad is refilled last.

Making sure all bleed valves are closed, open the radiator valves one at a time starting with the first radiator on the system – remembering to open the lockshield valves by the same number of turns used to close them.

Can you do this and then report back how you got on

Cheers
Ace

I did the above, for once I have managed to get air from the bathroom radiator (immediately above the boiler and below the expansion tank)

I turned the heating back on and not even the hint of a gurgle. It's too early to tell but the lack of noise coupled with the appearance of air from bleeding the bathroom radiator I think you have made some progress here Ace. The ultimate test will be in the morning after it has cooled overnight.

Once again, thank you all for your replies and I will report back tomorrow sometime.

The system does need balancing but for now I have put the lockshields around halfway...this is ok isn't it? All rads heat up well including the one furthest from the boiler.

 

[MRDrip]

I really hope you can help as the noise wakes my Mrs every morning!


Only option left if not working now get the the Mrs a job delivering the post.

​

 

[friendlyaviator]

I really hope you can help as the noise wakes my Mrs every morning!


Only option left if not working now get the the Mrs a job delivering the post.

​

Or doing the bins? Do you think she'll need to retrain or will she pick it up as she goes along?

 

[friendlyaviator]

Ace,

I do as you said but still have air trapped in pipes somewhere. It makes terrible noises in the bedroom radiator. It's either resonating or actually in the pipes near the rad. Any other ideas?

 

[Dannyparty92]

Perhaps vent pipe is in wrong place? a picture of your pump might help?

 

[friendlyaviator]

Just a little update...

I decided to try and do a little back-fill with a hose and mains pressure and to my surprise, when I applied mains pressure, water spurted out of the drain where the gnurled bit is.

I will try to show in this pic:



I tightened this to stop the flow of water. Could this have been sucking air in without leaking?

Your thoughts?

 

[zzzjim]

Wondering when you first started how dirty / sludgy things were , this may have moved about and settled somewhere else , making filling more problematic

 

[zzzjim]

Could this have been sucking air in without leaking?

Your thoughts?

Drain off point should be low down on system , hence plenty of water pressure to resist air entering , ( unless its near sucking side of pump )

 

[friendlyaviator]

Wondering when you first started how dirty / sludgy things were , this may have moved about and settled somewhere else , making filling more problematic

I removed all rads and hosed them out, cleaned out the sediment in the header tank, then ran water through until clear. Then ran cleaner, then refilled with inhibitor.

The cleaning cycle didn't produce any noises. The only thing I did after cleaning cycle and before refilling was fit TRVs, new lockshield valves and put the check valves in place of the blanking caps in the kitchen.

I used new olives for all replacements.

 

[Baxiboy]

Put in some Fernox boiler noise reducer, does what it says, great at getting rid of gurgling noisy systems