Problem with One Radiator which keeps filling up with Air

[SWE]

I have got a problem with only 1 Radiator. It keeps filling up with Air and needs to be bleed. Its the radiator which is nearest to the airing cupboard. In the airing cupboard there is 2 2 port valves, pump and By pass Valve and Cylinder. Anyone got any idea's what could be causing the problem. The system is open vented.

 

[Whyme]

its usually due to vent configuration or pumping over aerating the water..Do you ever hear water trickling in the loft when the boilers running?

 

[SimonG]

Sure its air and not hydrogen? Hydrogen would signify corrosion.

 

[PlumbBobBob]

Sure its air and not hydrogen? Hydrogen would signify corrosion.

+1 for it being possibly hydrogen

 

[SWE]

its usually due to vent configuration or pumping over aerating the water..Do you ever hear water trickling in the loft when the boilers running?

I will go into the loft when the boiler is running and check it out.

 

[SWE]

+1 for it being possibly hydrogen

All the radiators on the 1st floor were fitted at the same time. If it was corrosion surely there would be more than 1 rad filling up with Hyrogen. Advice appreciated.

 

[MC_Bob]

Not if that rad has the corrosion occuring.
Someone may correct me but I think you can hold a cup upside down over the vent as you bleed it. Light a match and put it under into the cup and if it squeeks its hydrogen.

More than likely though its the first rad on the htg circuit and its drawing air from the loft.

 

[PlumbBobBob]

Someone may correct me but I think you can hold a cup upside down over the vent as you bleed it. Light a match and put it under into the cup and if it squeeks its hydrogen.

yes just like that

 

[helpsy]

Watch out for the curtains!

 

[happyflyer]

+1 for it being possibly hydrogen

Only one way to find out, take 2 mins and burnt finger and thumb

 

[happyflyer]

Watch out for the curtains!

Some one else fell into the trap

 

[SWE]

Not if that rad has the corrosion occuring.
Someone may correct me but I think you can hold a cup upside down over the vent as you bleed it. Light a match and put it under into the cup and if it squeeks its hydrogen.

More than likely though its the first rad on the htg circuit and its drawing air from the loft.

Thanks for the replies. If its drawing air from the loft. What could be the cause of drawing air from the loft and how do you go about fixing the problem.

 

[Best]

Even on a well designed open heating system, there will be air released somewhere.
When water is heated up it will create micro bubbles of air at heat source (boiler) & these air bubbles tend to travel around the system until they hit a low pressure point, usually the first radiator, typically upstairs, or a towel rail. When the system cools down again, it absorbs air again from the expansion tank & vent & feed pipe & so the cycle continues. An auto vent on the boiler will not remove the air bubbles as they are in movement & suspended in the water.
Best solution if you have gas or oil heating is to get it changed to a sealed system if the system is decent order & no weeps. It can't absorb & release air because it is not open to atmosphere.
Do check you do not have auto vents letting air suck into system.
There is also air grabbing devices such as Flamco air vent which catches the air & then auto vents it. It is simply a wide vessel, which in itself grabs air plus it has lots of tiny cylindrical stainless steel bits to catch micro bubbles & then an auto vent on top.

 

[SWE]

Even on a well designed open heating system, there will be air released somewhere.
When water is heated up it will create micro bubbles of air at heat source (boiler) & these air bubbles tend to travel around the system until they hit a low pressure point, usually the first radiator, typically upstairs, or a towel rail. When the system cools down again, it absorbs air again from the expansion tank & vent & feed pipe & so the cycle continues. An auto vent on the boiler will not remove the air bubbles as they are in movement & suspended in the water.
Best solution if you have gas or oil heating is to get it changed to a sealed system if the system is decent order & no weeps. It can't absorb & release air because it is not open to atmosphere.
Do check you do not have auto vents letting air suck into system.
There is also air grabbing devices such as Flamco air vent which catches the air & then auto vents it. It is simply a wide vessel, which in itself grabs air plus it has lots of tiny cylindrical stainless steel bits to catch micro bubbles & then an auto vent on top.

Thanks for the info. I dont really want to seal the system. The pipework is 30 years old and I dont want to put extra pressure on the pipework. I might look at a air grabbing device.

 

[Best]

Thanks for the info. I dont really want to seal the system. The pipework is 30 years old and I dont want to put extra pressure on the pipework. I might look at a air grabbing device.

Pipework at 30 year old shouldn't be any problem if it was done right. I know many systems that age & more that are like new inside. The joints on system need to be perfect - soldered joints should be ever lasting if soldered properly. Any brass joints need to have no weeps & rad valves need good quality. It's the rads generally I worry about if badly corroded, but that depends on if the system has had inhibitor over the years & if it was designed to not pump over or draw air somehow. Pressure is not enormous on a sealed system.

 

[helpsy]

Some one else fell into the trap

Not yet!