Are deaerators a necessity with combi boiler?

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I'm shortly going to be getting a new combi boiler fitted and one of the options the installer has offered is to fit a deareator. I'd never even heard of such a thing before but with Google's help I do at least have a vague idea what one does now.

What I'm not sure about is whether it's a necessity or just a bit of a nice to have? If it's a straight forward boiler swap (same location, same pipes, etc) and includes a system flush, is it a sensible thing to add in? Or not worth it?

Plus it seems like it's something that could be retro-fitted at a later date if necessary...is that right?
 
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Not a necessity.
However, system water quality is very important to boiler health, over time, and the majority of people don't give this any thought, let alone maintenance.
So, products such as magnetic filters and deaerators exist to counter this.
 
As Dean says, not a necessity but will definitely help to prevent corrosion in your system
 
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What dearators work on a combi? I haven't fitted a boiler in years, except my own. I wasn't aware of a combi one. It presumably incorporates an AARV?
 
I've got one of those Spirovents on our system. Works ok initially to get air out as you fill and bleed a system, however once the system is full I don't think it works so well - I constantly got air in the upstairs radiators, especially the bathroom one which is physically the highest. Most of this was gas coming from the old boiler internally rotting, however the Spirovent didn't seem to counter that much.
 
I have a sealed heat only system. When I had a new boiler fitted just over a year ago, I kept hearing small air bubbles peculating in the pipes, especially around the pump area. After advice on here, I fitted a Spirovent RV2 and the system is the quietest its ever been. Absolutely perfect - not so much as a single bubble can be heard now.
 
They already have an AAV fitted.

Exactly !!!! Why would you need a deaerator as well.

I have never seen or fitted one on a sealed system.

On open vent I fitted a Myson Aerjec every time......With 22mm feed and vent to prevent blockages.
 
Couple of things here. A deaerator is a good thing to have on any system, and the sooner its fitted the better so at install is proffered.

An AAV (auto air vent) doesnt actual vent a lot of gas from a system as there only used for purging air from the pump to allow circulation, most of the rest of the gas in a system will just pump clean past them, a proper deaerator works by encouraging microbubles to collect on a mesh in them in an area where there is a low flow velocity to assist in venting of dissolved gasses as well as circulating gas.

I've got one of those Spirovents on our system. Works ok initially to get air out as you fill and bleed a system, however once the system is full I don't think it works so well - I constantly got air in the upstairs radiators, especially the bathroom one which is physically the highest. Most of this was gas coming from the old boiler internally rotting, however the Spirovent didn't seem to counter that much.

What you have is a rotting system and needs different treatment, simply venting off some of the hydrogen thats being produced by your system doesnt stop formation of it, which will form in the boiler and in the radiators so wont all actually pass the Spirovent as its being produced after it.
 
Why would you need a dearator on a pressurised system FFS .??
To remove the air, oddly. Deaerators will remove the microbubbles of air suspended in the water which are the main cause of corrosion. These are not captured and released by cheap auto air vents
 
Interestingly, our new boiler (Intergas Xclusive 36) doesn't have an AAV - it has a manual bleed valve in its place.

What you have is a rotting system and needs different treatment, simply venting off some of the hydrogen thats being produced by your system doesnt stop formation of it, which will form in the boiler and in the radiators so wont all actually pass the Spirovent as its being produced after it.

Yep - the heat exchanger on the old boiler was on its last legs, and the bathroom radiator was was in a mess. I've now replaced all but 2 radiators and the boiler has just been replaced. The remaining 2 radiators appear to be pretty new and in decent condition. I'm optimistic I won't see any further build up of gas.
 
Deareator , made my rads quieter my combi system. Used to hear occasional pebble sound in rads. With regards to corrosion it will remove some dissolved from the first fill but nothing more for it to do,
 

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