PLEASE HELP ME - AIR NEAR MY CENTRAL HEATING PUMP

[RSC]

I have a 20 year old boiler which I have been informed works efficiently. My pump is situated upstairs next to the hot water tank. In an adjoining vertical pipe there is a brass valve on the top to bleed air. There is no air in the radiators, and the little that accumulates in one is bleed frequently. They heat up well.

When either the hot water or the central heating is on there is a gurgling sound of air either in or very close to the vertical pipe with the valve. An engineer had to be called because air had got into the pump and it stopped working. He got it going. Following his departure the gurgling continued for three months until the pump stopped again. I have now had a new Grundfos pump installed and it is set to the maximum which is 45 rpm.

Unfortunately the gurgling air noise continues BUT there is rarely any air in the vertical pipe with the valve, which remains hot throughout, either whilst the system is running or when the system is turned off.

There is no valve on this new pump to release air, and I need advice on how to rectify this matter and release the air. As I mentioned it occurs even when the hot water alone is on.

 

[Rob Foster]

I have a 20 year old boiler which I have been informed works efficiently. My pump is situated upstairs next to the hot water tank. In an adjoining vertical pipe there is a brass valve on the top to bleed air. There is no air in the radiators, and the little that accumulates in one is bleed frequently. They heat up well.

When either the hot water or the central heating is on there is a gurgling sound of air either in or very close to the vertical pipe with the valve. An engineer had to be called because air had got into the pump and it stopped working. He got it going. Following his departure the gurgling continued for three months until the pump stopped again. I have now had a new Grundfos pump installed and it is set to the maximum which is 45 rpm.

Unfortunately the gurgling air noise continues BUT there is rarely any air in the vertical pipe with the valve, which remains hot throughout, either whilst the system is running or when the system is turned off.

There is no valve on this new pump to release air, and I need advice on how to rectify this matter and release the air. As I mentioned it occurs even when the hot water alone is on.

photo of pump plse, even use a mirror if it tucked away
I am going out now but others will help in meantime
centralheatking

 

[Millsy 82]

Have you got tanks in the roof space? Partial blockage of cold feed? So sucking air down the vent.

 

[chris watkins]

It is difficult for us to understand what you have got from your description so photos would be a great help.
Couple of things I can pick out.
1. It is not normal for air to have to be removed from heating systems so there is a fault which needs rectifying. The oxygen in the air being drawn in combined with the water & steel will lead to heavy rusting & fouling.
2. Almost certainly the new pump does not need to be set to maximum (not 45rpm that was the old records ). How big is the system how any rads are there?

 

[John.g]

Could you post the full model description of your Grundfos Pump.

 

[RSC]

Thank you to everybody who is trying to help me. Rob, Millsey, Chris and John . It might be helpful if I say that my central heating system is 20 years old and I feel sure that there is plenty of debris in it. I have 11 radiators. I have had 3 pumps during this time and even on a new system the pump had to be set on full. I regret my camera is on the blink but the new Grundfos is an ALPHA 2 model and has a LED screen which shows the speed setting. It has been installed the correct way up.The previous pump of course exhibited the same symptoms in the vicinity of it, but only during the last year of its life.

In reply - I do indeed have a water feed from a tank in the roof space almost above the pump.

What I cannot understand is that all the gurgling comes so close to the vertical pipe with the brass valve, but I rarely can get any air out of it. I wish I could get the air bubble to move into it.

 

[John.g]

I would first establish if you have a 6M, 5M or 4M pump,if the label on the pump states something like ....15-60 130 it means that its max head is 6M (60), ....15-50 130 refers to a 5m head and ....15-40 130 refers to a 4M head. Also see whether the label says Alpha 2 or Alpha 2 L.
A 6M pump running at full speed (3) can IMO lead to air ingress in a vented system.
I read somewhere that some models of the Alpha 2 have a air chamber with a tapping point for a air vent (not supplied).

 

[John.g]

You possibly have the pump as shown in the attachment, if so and if it is a 6M pump I would suggest changing it to a PP3 (proportional) setting which modulates from a max head of 4.5M, if gurgling still persists try it on PP2 (3M head). I have a A rated (Wilo) pump set to 4M proportional setting, if I run it in 6M max constant speed mode it gets very noisy and air will slowly build up in my upstairs rad(s). I also have a vented (42 year old) system.
Also make a note of the watts & flow rate before and after change over.

 

[RSC]

Many thanks John for your time - I have learnt a lot from your comments.

 

[Riley]

Again over complicating things with the all singing all dancing pumps, systems worked perfectly well for years and years and years with old school pumps with one two or three settings let alone variable speed and modulation. Something will have changed on the system, either works have been carried out, a pipe is blocked or simply pipes have moved from their original location. It could be as simple as your radiators have reached the stage where they have corroded past the point of no return and Are just producing gases. The other question is has the system ever worked properly??

 

[chris watkins]

My best guess RSC is that you have a heavy restriction in the pipe work around the point where the cold feed & open vent are connected to the main flow pipe this is quite common in older open vented systems like yours. If the noise doesn't stop when you turn down the pump speed /setting but still have a working heating system then the next step would be to have a heating engineer in to cut out this section, check & replace as required.
Still not sure what the "vertical pipe with the brass valve" is what type of valve is the brass bit? possible an air vent or does it isolate ?

PS don't listen to the bear the pumps are fine it the system.

 

[RSC]

Riley - In reply to you. Yes this system worked well for 19 years. But there has always been a little air in one radiator and not too much has changed on that front.
Chris - the valve is a small brass thing that is finger tight . It has one pinhead sized hole on the side.

I am now coming round to the point of view that I need to have the whole system power flushed, and get a new boiler with some kind of sealed system. Mine is 20 years old. Any comments would be very welcome.

 

[Riley]

No saying that you couldn’t deal tour exiating system after a good clean

 

[chris watkins]

Riley - In reply to you. Yes this system worked well for 19 years. But there has always been a little air in one radiator and not too much has changed on that front.
Chris - the valve is a small brass thing that is finger tight . It has one pinhead sized hole on the side.

I am now coming round to the point of view that I need to have the whole system power flushed, and get a new boiler with some kind of sealed system. Mine is 20 years old. Any comments would be very welcome.

Sounds like an automatic air vent, if it is the cap should be left loose to allow the air out but you have to ask how is it getting into the system in the first place.
Sealed system - yes but get them to cut out the old section with the tee's to the F&E tank in the loft even power flushing will not always remove the deposits.

 

[John.g]

Or simply T in the cold feed to the vent (combined cold feed&vent, like mine) and blank off the other end of the cold feed.

 

[RSC]

Thank you John and Chris. I have noted both suggestions and will discuss both. This is most helpful.

 

[Millsy 82]

Track from your f&e tank you should have a 22 and a 15 pipe coming from them they should join the system on the negative side of the pump (ideally just in front of the pump) get a magnet and see it it sticks where these pipes join the system. If so you could have a blockage there get someone to clean it out or replace it, I wouldnt do it your self as you will have a tank full of water come down on you if its fully blocked and it's usually filthy water. Then a good flush wouldn't hurt.

Personally I wouldnt put it into a combined cold feed and vent they have there place but separate feed and vents are better.

The other thing is have you got an air separator fitted (looks like a miniature cylinder about 4" high) if so have that beast cut out as they are shocking and break down inside.

 

[RSC]

Thank you Milley. I have printed out everything you have to say. Much appreciated.

 

[John.g]

Track from your f&e tank you should have a 22 and a 15 pipe coming from them they should join the system on the negative side of the pump (ideally just in front of the pump) get a magnet and see it it sticks where these pipes join the system. If so you could have a blockage there get someone to clean it out or replace it, I wouldnt do it your self as you will have a tank full of water come down on you if its fully blocked and it's usually filthy water. Then a good flush wouldn't hurt.

Personally I wouldnt put it into a combined cold feed and vent they have there place but separate feed and vents are better.

The other thing is have you got an air separator fitted (looks like a miniature cylinder about 4" high) if so have that beast cut out as they are shocking and break down inside.

Could a blockage be checked by draining down say 10 litres of water and observing if the F&E Tank ball cock starts to make up rapidly??

 

[Millsy 82]

Thank you Milley. I have printed out everything you have to say. Much appreciated.

If you want me to autograph it that will cost you.

 

[Millsy 82]

Could a blockage be checked by draining down say 10 litres of water and observing if the F&E Tank ball cock starts to make up rapidly??

You could do wouldnt telk you where the blockage is though.

 

[John.g]

What I was trying to say (badly) is if the make up is rapid then it would point possibly to no blockage and problem possibly elsewhere, will be interesting to see if reduced pump head helps to alleviate noise problem, OP said in first post that all rads are heating up ok.