Air in Combi CH System

[tommytibs]

Hi,

I’m hoping someone can shed some light. I have a Baxi Ecoblue 33 Combi with around 12 radiators. I seem to keep getting air in the system which needs blessing every 2/3 days. Pressure doesn’t drop until air is released. Checked all usual spots for leaks (including valves and under floor with no luck). Boiler’s expansion vessel is holding 1Bar. When heating is off, boiler shows around 1.3 bar, with heating on it rises to around 1.9 bar. For the life of me, I can’t figure out how air is getting in the system, and if it is leaking where that might be (because I can’t see anything). Radiators all warm up perfectly once bled (no sludge). Any ideas?

 

[Wayners]

Corrosion gas?
Any inhibitor in the system

 

[tommytibs]

Good question and thanks for the reply, tested the air using the cup/lighter method and it’s simply air (isn’t corrosion). I actually ran a cleaner for 2 weeks prior to filling up the system and adding 2 litres of Sentinel x100. I also have used a thermal camera to confirm no sludge as such on any heaters. Really confused!

 

[Wayners]

The expansion tank can cause air to get into a water system.
It will get worse whatever the fault so keep looking .

Not my area tbh. Get a heating engineer to look

 

[tommytibs]

No worries, there isn’t an expansion tank as such since it’s a Combi (sealed system). Had the last engineer take a look and he couldn’t figure it out, thought it may be a leak but can’t for the life of me see even a drip anywhere!

 

[fixitflav]

Hi,

I’m hoping someone can shed some light. I have a Baxi Ecoblue 33 Combi with around 12 radiators. I seem to keep getting air in the system which needs blessing every 2/3 days. Pressure doesn’t drop until air is released. Checked all usual spots for leaks (including valves and under floor with no luck). Boiler’s expansion vessel is holding 1Bar. When heating is off, boiler shows around 1.3 bar, with heating on it rises to around 1.9 bar. For the life of me, I can’t figure out how air is getting in the system, and if it is leaking where that might be (because I can’t see anything). Radiators all warm up perfectly once bled (no sludge). Any ideas?

Is it new build/new to you/new problem?

 

[Madrab]

If it's not corrosion gasses then air can only get in if water gets out. May be time to look for water getting out.

 

[opps]

No worries, there isn’t an expansion tank as such since it’s a Combi (sealed system). Had the last engineer take a look and he couldn’t figure it out, thought it may be a leak but can’t for the life of me see even a drip anywhere!

I am not a plumber, but surely there is an expansion vessel in the combi?

 

[fixitflav]

I am not a plumber, but surely there is an expansion vessel in the combi?

That's right, but it's not an open-topped tank in the loft, as in an open vented system.

 

[tommytibs]

Thanks for the replies. So it seems like it can only be due to a leak somewhere. But a leak where it takes me 4/5 seconds to remove air should be quite substantial and obvious which is the puzzling part! I’ll take another deeper look later and see if I can find anything else. Thanks for all the replies above. Defos helped guide me where I need to be looking

 

[Johntheo5]

Are you sure its air and not hydrogen due to corrosion & lack of inhibitor, theres some knack of holding a glass over the vent and seeing does it ignite if you try and light it to test for this.

 

[Madrab]

Are you sure its air and not hydrogen due to corrosion & lack of inhibitor, theres some knack of holding a glass over the vent and seeing does it ignite if you try and light it to test for this.

tested the air using the cup/lighter method and it’s simply air (isn’t corrosion). I actually ran a cleaner for 2 weeks prior to filling up the system and adding 2 litres of Sentinel x100.

 

[tommytibs]

Are you sure its air and not hydrogen due to corrosion & lack of inhibitor, theres some knack of holding a glass over the vent and seeing does it ignite if you try and light it to test for this.

Hi mate, I did try this but will happily give this a go again. I actually drained the system, ran 2 litres of Sentinelx400 (3 weeks) and then drained again and filled with 2 litres of Sentinelx100.

 

[Johntheo5]

If it is air only then no topping up required??,

 

[tommytibs]

I’ll monitor how much I do need to top up and when and will report back too. Currently the boiler is showing around 1.2 so will record how often I blead the radiators and how long it takes before it drops to 1 bar. Thanks for the pointer