Why one radiator needs bleeding a lot?

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CluelessDIYer1

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I'm just wondering why one radiator in our house would keep air locking & requires bleeding much more than any other. We have 9 radiators in the house but the one in the 3rd bedroom is terrible. The others are fine but this one keeps air locking.



While i'm on the topic of radiators, if you pressurised the system & had to bleed them all in sequence, what sequence would you do mine in?

The layout of our house is as the pic shows:



Downstairs on left
Upstairs on right

The combi boiler is located in bedroom 2 on the wall that separates it (bedroom 2) & the bathroom.

Someone told me you do nearest first working to the furthest, but it's debatable whether bedroom 2 or the bathroom is nearest as the bathroom one is also quite close. I've been doing....

bedroom2
master bedroom
bedroom 3
Hall
Living room (the one closest to the diner)
Diner
Kitchen
Living room (the one up against the window which would be at the top of the photo)
bathroom

I'm sure i have that sequence wrong, but how wrong? Very probably lol.
 
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Bleed sequence doesn't matter (balancing sequence is what you seem to be referring too). You should be bleeding with the system cold and not running.

Usual to find that the highest rad on the system is the one that collects any gas.

If you are having to bleed the radiators often then it suggests that you may have a problem with the system especially as you have sealed system.

How often are you bleeding and how much gas are you releasing?
 
Constant bleeding is damaging to a system if the inhibitor is not replenished. Air in a sealed system is usually hydrogen associated with system corrosion. Air cannot be drawn into a system which is pressurised.
 
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3DGuy said:
Do you by any chance have a Chrome/Towel rail in the bathroom?
Click to expand...
What makes you say that? Yes I do btw. How would this effect the radiator in the opposite room?

& I'm not ignoring the other 2. Thanks for your posts. I'm just on a quick break at work now.
 
CluelessDIYer1 said:
3DGuy said:
Do you by any chance have a Chrome/Towel rail in the bathroom?
Click to expand...
What makes you say that? Yes I do btw. How would this effect the radiator in the opposite room?

& I'm not ignoring the other 2. Thanks for your posts. I'm just on a quick break at work now.
Click to expand...

Our plumbers when installing a full system for us, told me when we were looking at towel rails to avoid the cheap ones. I cant remember the materials but apparently some cheaper ones use ally inside and chrome plate, or another material. He said the better ones are Brass then Chrome plated. Also shows why there are more expensive ones also (within reason). He said we should avoid the one we were looking at and use a better branded one not a DIY store type. They installed a system a year or two ago and had a lot of issues with it. They tried replacing all rads, and I believe it was air in the system causing issues. It was just by chance they didn't change the Towel rail he said and focused don the other rads. After countless issues they called the boiler company out to check and the inspector took 1 look at the towel rail and he said that was the issue before looking at anything else. They changed it to a better branded one and zero issues followed.

Just thought it might be worth a mentioned because you seem to have a continuing problem similar to the problem he described they had in the past.

Effects wise possibly generating gas mentioned and it being carried towards the other room. Might be some design setup in the system that means that's where it pools.
 
I would try adding a litre of Fernox to the heating header tank before the next bleed so as to get some into the circuit. This should increase the alkalinity of the water and reduce oxidation, which is what's making the hydrogen.
 
Ok, time for chemistry lesson.....

The 'gas' is hydrogen. Its created like this....

Water is H2O. The radiators are made of steel which is based on iron (Fe).

When water comes into contact with iron in free air it produces rust (Fe4O). When this process happens inside a radiator there is a lack of air but the oxidization still happens ... the iron breaks down the water into its constituent parts because iron is more active than hydrogen & is able to break the molecular bonds. The iron combines with the oxygen from the water to form Fe3O (one less oxygen atom than in free air). Fe3O is the black sludge that you find in the system. Fe3O is ferrous and so makes it way to places like the pump. The fact that its ferrous is also why the magnet-on-the-pipe method works for detecting its presence. Once the water has been stripped of its oxygen then only the hydrogen remains - this is what you are bleeding off.

The presence of the hydrogen is indicating that your system is rusting - from the inside out! This may well be exasperated by the presence of other metals in the system which are creating oxidisation by electrolytic action.

To stop this you need to make the water inert by adding the correct amount of corrosion inhibitor PDQ!
 
Whoa there's some rubbish advice as usual. Excessive trapped air in a particular rad is often down to a leak on the system This is a Worcester Greenstar Junior/Si so there's no header tank. And yes it's sealed but that means zilch....air can still enter the system.

Bleed off the air into and upturned vessel, then use a taper to check if the gas is indeed hydrogen but the chances are it's plain old air.

Go round and have a very thorough check of all the radiator bleed and blanking plugs, the valves each end (take off the TRV heads and wheelhead caps...check the spindles), check the pipework connections...you have microbore so more chance of leakage. Towel rails are notorious for having junk valves...check the spindles and the tails where they screw into the rail.

Given you gave the pump a hard time the seals could have failed on that drawing in air. The system pressure has been dropped many times and the auto air vent may be leaking. Also check the pressure relief valve pipe through the wall for drips.
 
Gasguru said:
*This is a Worcester Greenstar Junior/Si
*you have microbore so more chance of leakage.
Click to expand...

More than anything I'd love to know how you know the boiler and pipes? Or have I totally missed that on this thread :) haha!

Also what was the junk info? Just out of curiosity really as I'm probably being a doughnut!
 
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