hard sell for combi

[dilalio]

Maybe I'm missing something here. I assume an air separator is a canister with water in and out, and a gas vent at the top. I can see that could be better at venting gas than a simple tee on the pipe, but after commissioning there shouldn't be a significant quantity of gas. But I can't see why it would be better in a low head situation.

By gas, I assume you mean 'air'?
An air separator is something that used to be installed a lot, on old systems. They are a magnet for blockages. If you're putting a new boiler on an old gravity system that catches a lot of 'air', then they can be useful... as can Aladdin radiator air vents

 

[fixitflav]

By gas, I assume you mean 'air'?

Air is a gas! I meant gas in general, air and any other gas that might be released, possibly some hydrogen if inhibitor is inadequate.

An air separator is something that used to be installed a lot, on old systems. They are a magnet for blockages. If you're putting a new boiler on an old gravity system that catches a lot of 'air', then they can be useful... as can Aladdin radiator air vents

I can see an air separator would collect solids, as the flow velocity falls and allows it to settle. I suppose if there is a drain connection collection/removal of muck is a good thing.
But I still don't see how it helps on a low-static system.

 

[dilalio]

Air is a gas! I meant gas in general

Don't need to use the word gas when air would suffice, especially when you're asking about an "air' separator. On this forum, gas automatically suggests natural gas to most.

I have only fitted two air separarors in a standard domestic setting. Most of the time, I'm ripping them out.

 

[hard-work]

IIRC, separator has flow from boiler into the side and the flow again out of the side. The cold feed from the f&e tank into the bottom via a loop 'U', and out of the top with the vent over the f&e tank. At the bottom of the loop a tap could be fitted to empty any debris. But not needed if a filter is on the boiler return

Ideal had the drawing in their installation manuals. The level of the bottom of the tank could be just about the same level as the top of the boiler. It worked.

 

[Dan Robinson]

An air separator will have an area of non laminar Flow to help the micro air bubbles settle out of the system, helped by an hour or so if "baking".

I can't seem to open my ideal manuals at the moment, but assume the "separator" in there is just an Aerjec thing. These are not the same.

 

[fixitflav]

Don't need to use the word gas when air would suffice, especially when you're asking about an "air' separator. On this forum, gas automatically suggests natural gas to most.

I have only fitted two air separarors in a standard domestic setting. Most of the time, I'm ripping them out.

OK but if there were mains gas in the circulating water there'd be something funny going on!

 

[hard-work]

An air separator will have an area of non laminar Flow to help the micro air bubbles settle out of the system, helped by an hour or so if "baking".

I can't seem to open my ideal manuals at the moment, but assume the "separator" in there is just an Aerjec thing. These are not the same.

As I described. 4 connections.

 

[fixitflav]

An air separator will have an area of non laminar Flow

Did you mean "An air separator will have an area of laminar flow"? The separator is about the only place there is laminar flow, which helps separate air (and solids). In a 22mm pipe at a conservative 1m/s Reynolds number is > 20000. Higher at higher velocity.

 

[Dan Robinson]

I should have said "laminar no flow".

Caleffi are great for this kind of information.

 

[John D v2.0]

Also radiators have the same conditions especially when the system is idle, but unfortunately only the air can be removed easily.

 

[fixitflav]

Also radiators have the same conditions especially when the system is idle, but unfortunately only the air can be removed easily.

Yes, that's a good point. Specially when the system is idle!!