Central Heating Nightmare - Air in System Daily

[Cellophaneskies]

I'm having continuous issues with my central heating. I've tried all sorts and there is no improvement so I'm reaching out online to see if anyone has an ideas or if anyone has experienced something similar.

To put it simply, there is always air in the system that I can never fully clear. Radiators while trickle and gurgle with air inside. Every day I need to turn off all rads aside from one or two, then bleed an upstairs radiator - It’s like I need to force the air out by focusing on a single radiator at a time.

Air that does come out seems to be in the water. I will get little 'whoosh' of air, instead, water will come out that fizzes, spits and hisses. This can be a nightmare to get to this stage, but when I do, you can almost feel the radiator and the water being expelled getting hotter.

Following this the radiators will all be screaming hot. The house will be tropical within a matter of minutes, but then the following day, I get little heat from the downstairs radiators and the process starts fresh.

In the process of troubleshooting (and normal upgrades) I have had
-new boiler (5 year old now, Baxi)
-all new radiators bar one (which is probably 10-15 years old).
- Most pipework replaced, just not the initial run out of the boiler. Backbone upgraded to 21mm from 15mm
-I’ve taken all rads off and flushed them through one by one with a hose
-Drained and refilled the system multiple times
-Balance by a heating company
-Turned off (lockshield and thermostat), one at a time, each upstairs radiator (including the oldest) to see if one radiator is causing the issue - no change

But the issue persists and I’m at my wits end as I need to spend half an hour+ a day fighting to get air out of the system before I can get some heat. It makes it pointless letting the system come on and off by thermostat as I until I mess with it, it will not heat rooms. I'm fighting with it daily, running it until I sweat, and the I leave it until I repeat the ordeal the next day.

Does anyone have any ideas? This is a 28Kw Baxi combi, closed system, eight radiators, most are Stelrad (6/8). Inhibitors is used and there is a magnetic grot collector on the return to the boiler (forget the name for it).

 

[Stuckinarut]

there is a magnetic grot collector on the return to the boiler (forget the name for it).

Magnetic filter.

Do you have any rads leaking? The stuff coming out could be hydrogen gas and could be tested I believe by attempting to ignite it.

 

[Cellophaneskies]

Magnetic filter.

Do you have any rads leaking? The stuff coming out could be hydrogen gas and could be tested I believe by attempting to ignite it.

Nothing leaking. No signs of leak on ceilings or on floors. Been under the floorboards multiple times and no signs of water dripping or leaks there either. Pressure never rises on its own and it doesn’t drop, until I bleed them.

Water that comes out is like an orange colour. The longer I leave in between bleeding, the more it gives off like a metallic sort of smell.

I haven’t tried the classic lighter hydrogen test but I’ve been meaning to.

 

[Stuckinarut]

Water that comes out is like an orange colour.

If it’s coming out orange, it suggests fresh rust imo, especially when adding fresh oxygenated water

 

[gas112]

First of all are you bleeding it with the boiler off .
For system to be filling with that much air in a day or so to stop it working suggests a leak but your pressure gauge should drop to indicate that

 

[trojanhawrs]

Do you have any obvious air traps in your pipework? Like an upside down U bend or similar.

 

[Cellophaneskies]

First of all are you bleeding it with the boiler off .
For system to be filling with that much air in a day or so to stop it working suggests a leak but your pressure gauge should drop to indicate that

If I bleed with it off I don’t get much out. And then the radiators don’t get hot.

Trial and error has shown that I need to do it while it is running. A downstairs radiator makes loads of gurgling and trickling noises. I have to leave this one on, all others off, and then bleed from an upstairs rad. This can vary- usually it’s bathroom but it can be another one.

It’s like the water needs to be flowing to bring the air up to the higher radiator.

 

[Cellophaneskies]

Do you have any obvious air traps in your pipework? Like an upside down U bend or similar.

No. It’s all quite simple. There used to be an upside down U bend which I suspected as contributing to the problem but I had that removed, and it has made no difference.

 

[Cellophaneskies]

If it’s coming out orange, it suggests fresh rust imo, especially when adding fresh oxygenated water

Yes I’m a bit suspicious of this. My last thought is to replace the final bit of pipework running up from the boiler. I suspect it wasn’t a professional job. Everything else has been replaced - aside from one rad - so I can’t see how the cause could be elsewhere.

 

[gas112]

If I bleed with it off I don’t get much out. And then the radiators don’t get hot.

Trial and error has shown that I need to do it while it is running. A downstairs radiator makes loads of gurgling and trickling noises. I have to leave this one on, all others off, and then bleed from an upstairs rad. This can vary- usually it’s bathroom but it can be another one.

It’s like the water needs to be flowing to bring the air up to the higher radiator.

dont bleed it with heating on you can suck air in, stick the pressure up to 2 and then bleed it repeating at each rad turn heating on for a bit and then back off and repeat

 

[Cellophaneskies]

dont bleed it with heating on you can suck air in, stick the pressure up to 2 and then bleed it repeating at each rad turn heating on for a bit and then back off and repeat

I’ll try this again to confirm. Experience has told me that I simply don’t get anywhere doing it with it off. I might get a tiny blip of air but I then never get the ‘air inside water’ fizzing and spitting happening.

If I don’t get that, nothing changes. When I get this fizzy air, I then get stonking hot radiators.

 

[gas112]

I’ll try this again to confirm. Experience has told me that I simply don’t get anywhere doing it with it off. I might get a tiny blip of air but I then never get the ‘air inside water’ fizzing and spitting happening.

If I don’t get that, nothing changes. When I get this fizzy air, I then get stonking hot radiators.

do you have designers column rads or standard rads

 

[Jurassicspark]

+ have you got any manual air vents?

 

[Cellophaneskies]

do you have designers column rads or standard rads

Standard dull white Stelrad. One of them is a vertical Stelrad. This has never really caused an issue.

When I wasn’t bleeding them regularly - or only letting out the initial blast of air and not getting fizzy water - one or two rads would be almost stone cold. The bottom of the rest would be cooler than the top.

During this period the radiators that were the worse would vary, and sometimes the vertical one was the issue.

Since I’ve been bleeding more thoroughly the vertical one is never a problem. It’s right next to the boiler along with another one on the other wise of the wall. Recently these have never posed any problem at all.


It’s as if air gets in the water and then ‘blocks’ or causes a bottleneck at the top of the system, and then the three radiators beyond that suffer the most.

Boiler downstairs with two rads within a metre. Pipes then go up to bathroom directly above. This then feeds to three bedrooms. Pipework drops down from the third bedroom in two separate drops - one to living room, one to extension. This are always the worst impacted rads and the nosiest too.

 

[Cellophaneskies]

+ have you got any manual air vents?

None