Air trapped in open vented central heating system; unknown device...

[JamesElstone]

Hi All,

I have an air lock in my central heating. This is since rads were taken off for plastering and system drained. Have open vented gas CHS, with three way Y valve for CH/HW.

The air lock disappears after system has got to temp, but returns on next timed firing. Symptoms sounds like pipes From boiler are filling up, the "air" rushes through CHS pump. This repeats for about 30 mins, when on HW only, or about 10 mins on CH+HW. Noise coming from circuit between boiler and pump...

There is a device I don't recognise (can't show photos I have: inline you attachments are off and newbies can't post urls). It has both the pipe from the hot water expansion tank and the vent pipe (positioned over the HWET), and is inline with the hot return from the boiler and the CHS pump.

As we suffer from limescale here (also have water softener) could this device be beyond its life span, and if not where is bthe air coming from???? What his the device, what is it called and where could I get a replacement if it is knackered?

Can anyone shed some light or silence in my case please?

Kr,
James.

 

[solutions]

Sounds like an air seperator (ironically). Does it look like one of these.

If not pm me the pics and I will post them up which will speed up identifying the mystery item and whether or not it might be the cause of your air locking system.
Were any radiators relocated or pipework changed? Has pump speed been altered? Have you identified any automatic air vents or manual vents in airing cupboard perhaps on cylinder coil? Did you say the central heating system vent pipe was over the cold water storage cistern or over the f & e?
Did the system refill quickly from the f&e or did the f&e empty in to the system very slowly? Is the f&e ball valve moving freely and supplying water when depressed?

 

[JamesElstone]

Hi Solutions,

That is indeed the chap!

I have vents at the tank and above the boiler also. Vents in airing cupboard let out a little air and then water. Not tried the vents above the boiler - will give a go at the weekend. Will also check the hot water tank in loft.

CHS vent pipe goes to ubend above hot water feed tank - haven't check ball valve as it had water in but see where you are going with this.

No rads were relocated, just removed to plaster behind - could be a red herring.

What effect would the pump speed have? It is set to 3 (Max) at present....

James