I need to replace my Air Separator, but have come across an issue…

[Rapidonset]

My air separator (Tower AIR22CF with cold feed) is blocked with magnetite, not an issue. A straightforward simple replacement along with some associated pipework to keep things new, shiny and clean, so I thought.

I was looking at the specs Tower provide and note they state a minimum distance of 1 metre between the bottom of the F&E tank to the air sep (see pic). On my existing system (and the other 200 odd fitted to all the houses on the development) the distance is around 300-400mm (see pic).

I’ve not become aware that this has caused issues for other residents over the past 15 years, so why do Tower state 1 metre?



PS, I could replace with a combined feed / vent or seal it up. But I want to keep the vented system for now due to cost and other reasons.

 

[footprints]

That is a very low head, in my view even a metre is cutting it fine, I suspect others on the estate will soon be suffering the same problem.

We used to have lots of council flats where that was done and they suffered problems with pumping over etc.

Assuming your boiler is suitable (most are these days) a pressure vessel and sealed system is the best way to go.

 

[Rapidonset]

That is a very low head, in my view even a metre is cutting it fine, I suspect others on the estate will soon be suffering the same problem.

We used to have lots of council flats where that was done and they suffered problems with pumping over etc.

Assuming your boiler is suitable (most are these days) a pressure vessel and sealed system is the best way to go.

Sealing up is not an option.

Mine only recently started to pump over since I drained the system and sucked all the sludge into the cold fill from the F&E. I cleaned and replaced some pipework which resolved much of the pumping over, but noted the air-sep was still partially blocked. Never had issues with pumping over prior to this or come across it with the other properties.

If I drop the air sep to get more head, the pump will also need dropping ( which is impossible in a one floor property). So, I have two choices. Replace the air-sep and hope it will last another 15 years, or cut out the air-sep and replace with a combined feed / vent. Would the latter work?

 

[footprints]

Problem is even with a combined feed and vent you will still get some interchange of water with the F&E tank, a short length of 22mm will heat up and rise into the expansion tank, as the system cools water level in the tank drops and water is drawn back into the system and so on . Each exchange of water with the open tank will allow oxygenated water back into the system. Blocking of a combined vent is possibly dangerous.
If you do not wish to update the system to sealed, replace the existing air separator like for like ignoring the Tower makers advice and simply buy yourself some more time.
At some point the boiler will need replacing, you can upgrade then.

 

[Rapidonset]

, replace the existing air separator like for like ignoring the Tower makers advice and simply buy yourself some more time.
At some point the boiler will need replacing, you can upgrade then.

That does seem the logical solution. And yes, any replacement boiler will need addressing before 2025, or when the Gov make their mind up (oil boiler). I'm looking into buying a replacement next year to store away ready to install when my current one finally dies.

 

[gas112]

You can only do a combined cold feed open vent if the installation instructions for the boiler say its allowed , they will also sometimes show what to do for a low head installation which involves putting a section of large diameter pipe in

 

[Rapidonset]

You can only do a combined cold feed open vent if the installation instructions for the boiler say its allowed , they will also sometimes show what to do for a low head installation which involves putting a section of large diameter pipe in

I've ripped out the air-sep and replaced much of the 22mm flow pipe and constructed a new close coupled cold feed / vent from two tees. I also removed all the elbows and replaced with pipe using radiused bends for better flow. Then I stuck mains water through the boiler via the short loop between the pump and filter. Finally, I extended the vent up a further 30cm. This was the cheapest option as I had the bits laying around. If this doesn't work, then I'll seal the bugger up. However, so far, so good

The air-sep was cacked up, but still enough room to allow flow. Although the soldering from the original install many years ago was abysmal. Will have to post some pics up lol

 

[Johntheo5]

I have seen installations like that, with close coupled Ts that still experienced problems with air ingress, normally vent pump over when the circ pump starts/stops but cured by a combined cold feed & vent where the the cold feed (increased to 22mm) is teed into the vent as close to the F&E tank as possible.

 

[Rapidonset]

So far, so good. No pump over (as yet). Although flow was still fairly good, the image shows the state of the Air-sep and associated pipework. Now all replaced.

 

[old duffer]

Once you remove it them turn it into jewellery https://rockchasing.com/how-much-is-magnetite-worth/