Strange air noise and “whooshing” near pump in an otherwise efficient central heating system

[Johntheo5]

Sadly not Andy, can’t see any anywhere. The only option to bleed the system is at the rads… which are all bled!

What mode/setting is the pump on?

 

[Plumbingnovice101]

is the F&E vent pipe going over the header tank in the loft on your system like this?

View attachment 362502

No, it’s a combined feed and vent.

 

[Plumbingnovice101]

What mode/setting is the pump on?

2. 1 is too slow for the boiler, and I’m concerned about using speed 3 on the old pipework.

 

[andyr123]

No, it’s a combined feed and vent.

Odd , not seen that combined F&E before done that way - the only combined F&E I have seen is the pic I posted above , where the vent pipe hangs over the top of the header tank

And older systems fed and vented like this:

 

[Plumbingnovice101]

Odd , the only combined F&E I have seen is the pic I posted above , where the vent pipe hangs over the top of the header tank.

And older systems vented like this:
View attachment 362511

Yeah had a few comments about it in the past. It’s only possible with 22mm pipe.

 

[andyr123]

Yeah had a few comments about it in the past. It’s only possible with 22mm pipe.

are your copper pipes going to your boiler 22mm or 28mm ? - fully pumped or gravity or gravity/pumped?

 

[Plumbingnovice101]

are your copper pipes going to your boiler 22mm or 28mm ? - fully pumped or gravity or gravity/pumped?

It’s 22mm throughout but does manifold off into microbore. All the rads are microbore. The heating is pumped with an F&E tank.

Thanks to John, I am fairly confident that the aerjec is the cause of the problem. It’s definitely piped incorrectly for a combined feed and vent. The boiler flow is supposed to go into the top valve inlet and then drop into the bottom valve outlet, with the cold feed inlet capped off (because it’s part of the vent pipe)… but instead the boiler flow is going through both inlets and going straight back out the outlet… so nothing can aerate. This must be why air is getting trapped.

 

[Johntheo5]

On the basis there is no separate cold feed, I think it’s fair to assume I just need the “aeration” setup only… and therefore it has been plumbed incorrectly!

Where will the cold feed be?. if you are installing it as a deaerator only?

 

[Plumbingnovice101]

Where will the cold feed be?. if you are installing it as a deaerator only?

The cold feed will be the vent pipe! Combined feed and vent.

If it makes it easier to understand… my F&E tank doesn’t have a vent pipe over the top of it. There’s nothing there.

It simply vents through the 22mm feed pipe. More info here:

Combined cold feed and vent......

I have just been told by British Gas that the answer to my central heating problems is to have Combined cold feed and vent fitted. As I understand, all I need to do is to cap the cold feed pipe off and divert it through the 22mm feed pipe. Is this correct? Also, how does it work and are...

www.diynot.com

 

[andyr123]

this is how I understand feed and vent (this is not combined F&E) to work , it acts as one way valve so it wont suck air in through the vent pipe - but it will expand when it needs to and release into tank if boiler overheats:

 

[Johntheo5]

The cold feed will be the vent pipe! Combined feed and vent.

If it makes it easier to understand… my F&E tank doesn’t have a vent pipe over the top of it. There’s nothing there.

It simply vents through the 22mm feed pipe. More info here:

Combined cold feed and vent......

I have just been told by British Gas that the answer to my central heating problems is to have Combined cold feed and vent fitted. As I understand, all I need to do is to cap the cold feed pipe off and divert it through the 22mm feed pipe. Is this correct? Also, how does it work and are...

www.diynot.com

Well, one of us is confused, you suggested using the aerjec as a deaerator only, and you posted the attached schematic, item 5, it shows the cold feed as a separate item, doesn't it? or are you going to install it as originally designed, item 4?.

 

[Johntheo5]

this is how I understand feed and vent (this is not combined F&E) to work , it acts as one way valve so it wont suck air in through the vent pipe - but it will expand when it needs to and release into tank if boiler overheats:

View attachment 362526

Thats the much vaunted VCP system where, from the boiler, you have the Vent, Cold Feed (no more than 150mm away) and Pump, these systems have also given problems and were "cured" by converting to my system, schematic shown in post #11, above.

 

[Plumbingnovice101]

Well, one of us is confused, you suggested using the aerjec as a deaerator only, and you posted the attached schematic, item 5, it shows the cold feed as a separate item, doesn't it? or are you going to install it as originally designed, item 4?.

I assumed as it was a separate pipe, it could just be disregarded, as it doesn’t exist on my system!?

 

[Plumbingnovice101]

this is how I understand feed and vent (this is not combined F&E) to work , it acts as one way valve so it wont suck air in through the vent pipe - but it will expand when it needs to and release into tank if boiler overheats:

View attachment 362526


View attachment 362528

Yeah, I don’t have that.

 

[Plumbingnovice101]

This is my current aerjec. The pipe you see leading out the top of it is the combined feed and vent. This is the pipe that goes into the bottom of the F&E tank.

There is no other vent pipe or indeed any pipe that goes into the loft, except the cold main, to refill the tank.