Always lots of air in our CH system

[Alucard]

Hi to John.g.
You recommend ...Try and look into the small feed and expansion tank in the Attic and see if water is flowing out of the vent pipe or drawing air into it, you will have to hold a "glass" full of water...

I can do this test, as my CH system that has a similar issue, but only at the bathroom radiator.
Please can you enlighten me on what the outcome proves and what the solution would be?
As I have noticed the copper pipe that runs upto the expansion tank gets warm /hot. would this draw air the the system as it cools down?

Best regards

 

[John.g]

Hi to John.g.
You recommend ...Try and look into the small feed and expansion tank in the Attic and see if water is flowing out of the vent pipe or drawing air into it, you will have to hold a "glass" full of water...

I can do this test, as my CH system that has a similar issue, but only at the bathroom radiator.
Please can you enlighten me on what the outcome proves and what the solution would be?
As I have noticed the copper pipe that runs upto the expansion tank gets warm /hot. would this draw air the the system as it cools down?

Best regards

Have you the same vent/cold feed arrangemant as Richtop8 above or something similar without the "dome",
depending on what arrangement you've got you may have to cut out a section and throw away the dome (think its called a Airjec or something like that, as sludge builds up in it)

Before doing anything look at your pump and check its mode & setting, if it has LEDs and you are unsure what they show, just post a close up photo of them wthe pump/boiler running. It may be set too high.

How mant rads??.

 

[Alucard]

Hi good afternoon l
My CH system has 10 rads.

I do not have a "dome" arrangement, the expansion goes via 25mm copper pipe to the expansion header tank. It has a bend downwards and an air gate to the surface of the liquid.

The Pump is a Grundfos type: UPS2 15-50/60. It has 3 pump settings low, medium and high.
On the low settings I get less air than on the medium and most air on the high setting.

It is presumed to be air as it is not flammable gas.

About 5 years ago I flushed out the CH system by taking out the Grundfos pump to get access to the connections for the circulating pump instalation. There were no leaks during the circulation cleaning period. So I presumed all fittings were sound and leak free.

Do you have any observations on what causes the air ingress and how to fix it?

Thanks

 

[Alucard]

Hi good afternoon l
My CH system has 10 rads.

I do not have a "dome" arrangement, the expansion goes via 25mm copper pipe to the expansion header tank. It has a bend downwards and an air gate to the surface of the liquid.

The Pump is a Grundfos type: UPS2 15-50/60. It has 3 pump settings low, medium and high.
On the low settings I get less air than on the medium and most air on the high setting.

It is presumed to be air as it is not flammable gas.

About 5 years ago I flushed out the CH system by taking out the Grundfos pump to get access to the connections for the circulating pump instalation. There were no leaks during the circulation cleaning period. So I presumed all fittings were sound and leak free.

Do you have any observations on what causes the air ingress and how to fix it?

Thanks

 

[Alucard]

Hi apologies
The expansion copper pipe is 15mm not 25mm...finger trouble

 

[John.g]

Hi apologies
The expansion copper pipe is 15mm not 25mm...finger trouble

The vent pipe is/should be 22mm and the cold feed is 15mm, are you sure its not the cold feed you are looking at.
Is the pump located upstairs in the hot press and the boiler downstairs, if so, and if you have zoned CH and HW then you will have at least two motorized valves fairly close to the pump, they may be located above the pump or below it, between the pump and these you might see something like the above arrangement (without the air jec).
Also go to the attic and have a look at your small cistern (Feed & expansion or F&E cistern for short) and see where the vent goes up and over it and also the cold feed which will come from the side or end of this cistern, you can then follow it and see where it is teed into the system.

Might look something like this: (This pump is pumping downwards)

 

[Alucard]

Apologies for the delay in replying.
F&E tank photo attached plus images of:
Grundfos pump set at lowest speed
2-way Motorised valve and controller also shows 15mm F&E feed.

Do you recomend the "glass" of water test on the 22mm vent pipe.

I presume that if the water is sucked into the vent that is where the air gets in.

Any other thoughts?
Thanks

 

[Alucard]

For clarification
15mm F&E pipe
22mm vent pipe
Gas boiler is downstairs, pump upstairs in the hot press.
Zoned CH and HW with a 2-way Motorised pump and controller.

Thanks again.

 

[John.g]

That Drayton 3 way mid position valve installation doesn't look right to me, can you check that the direction (up or down) the pump is pumping, there should be a arrow on the pump body, also there may be AB stamped on one the valve body ports and maybe a A & a B on the other two, B should go to the cylinder heating coil inlet (top) and A should go the the rads.

 

[Alucard]

Hi good afternoon ,
I'm having trouble sending my reply with the attached images. I will try later.

Thanks