Air in heating syatem

[fixitflav]

We tried adjusting the radiator valves one at a time and it changes which radiators get the most noise, but nothing stops it completely. It's difficult to experiment with because it only happens first thing in the morning. After that it's quiet for the rest of the day.

I run mine 24/7 and I think it costs very little if any more than on a timer. If you did that the situation wouldn't arise, presumably.

 

[Johntheo5]

The pump is on its lowest setting. It isn't easy to get up to the tank.

Just post a photo anyway especially if it has LEDs, all modern circ pumps now have several modes of operation and even the lowest fixed speed setting can sometimes be too high but it may possible to change to a constant speed setting with a lower head.
Of course it might be due to some chemical reaction after adding the inhibitor but unlikely.

 

[Sally2000]

No LEDs anywher except on the Drayton control box. The pump has a three position switch and it's on the lowest setting.
Where is the air getting in? There are no water leaks anywhere.

We don't want to run the heating 24/7. As an experiment tonight we will set all the thermo valves to max and see what happens in the morning.

 

[fixitflav]

We don't want to run the heating 24/7

You could try that as an experiment too, and compare gas usage!

You say "It's definitely just air", but how do you know? Have you tried lighting it?

 

[Johntheo5]

No LEDs anywher except on the Drayton control box. The pump has a three position switch and it's on the lowest setting.
Where is the air getting in? There are no water leaks anywhere.

We don't want to run the heating 24/7. As an experiment tonight we will set all the thermo valves to max and see what happens in the morning.

I'm afraid you will/should have to get someone up to watch the vent, switch off the boiler while watching it and see if any spurt of water comes out the vent, you may have to wait for 2 to 3 mins for the pump to stop as it might have a overrun function, then restart the boiler/pump and again watch and see if any spurt of water from the vent, obviously watch for any vent dribbling with the pump running constantly.

 

[Sally2000]

It's definitely air. We read about the match test and tried it long ago.

If there is water coming out the vent, how is air getting in?

 

[fixitflav]

It's definitely air. We read about the match test and tried it long ago.

OK got it!

If there is water coming out the vent, how is air getting in?

That's the big question.
Interesting that it only started when the TRVs were fitted. Can we assume there were no others mods to the system, like pipework layout?
Must have been drained, at least partly, and maybe not topped up with inhibitor. Worth doing a bright wire nail test, costs nothing apart from a couple of nails, and a useful check anyway.

 

[Jurassicspark]

If there is water coming out the vent, how is air getting in?

if you have an aluminium heat exchanger it may be creating hydrogen only way would be to test the waters ph.

 

[Johntheo5]

It's definitely air. We read about the match test and tried it long ago.

If there is water coming out the vent, how is air getting in?

When the water (if) rises up the vent and then recedes back down it can draw in air each time.

 

[baldykev]

You said you have TRVs on all rads ,have you a by pass on the system?

 

[fixitflav]

if you have an aluminium heat exchanger it may be creating hydrogen only way would be to test the waters ph.

But why is it different since adding the TRVs? That's why I asked about any other mods.

 

[Sally2000]

OK got it!

That's the big question.
Interesting that it only started when the TRVs were fitted. Can we assume there were no others mods to the system, like pipework layout?
Must have been drained, at least partly, and maybe not topped up with inhibitor. Worth doing a bright wire nail test, costs nothing apart from a couple of nails, and a useful check anyway.

It had a full drain and flush. No changes except the TRVs fitted.
I know it had a full can of inhibitor because I saw the empty can.

There is one radiator in the utility room without a TRV, I think this had to be left for a bypass?
I don't know whether the exchanger is alumininium.

 

[fixitflav]

I know it had a full can of inhibitor because I saw the empty can.

I suppose it's too cynical to say that doesn't prove it went in, clutching at straws

Have you tried turning all the TRVs fully open, which should replicate the situation before they were fitted?

 

[Sally2000]

Last night we set all the TRVs to max temp. This morning all the air noise was in just one upstairs rad instead of all three. Tonight we'll close that one down and see what happens.
Must confess I find this quite interesting, a sort of detective story following clues to find who is guilty...

 

[fixitflav]

Last night we set all the TRVs to max temp. This morning all the air noise was in just one upstairs rad instead of all three. Tonight we'll close that one down and see what happens.
Must confess I find this quite interesting, a sort of detective story following clues to find who is guilty...

You be Miss Marple, I'll be Hercule Poirot!