Gurgling Noise From Rads When System Is Drained And F&E Empty And Boiler Empty

[JackK]

My heat only gas boiler is drained from the boiler drain valve - There is no water in the F&E tank. The hot water vented cylinder is removed. So far so good

Twice this evening I heard radiator gurgling noises which frightened the life out of me

I cant seem to reproduce the noise and I cant get to sleep thinking there will be one hell of a flood!

Boiler is off from mains fuse so pump will not run and yet I heard the gurglig noise twice from two different radiators

How can this be possible? Many articles link to airlock in a filled system but have not seen this being mentioned on an empty one!

 

[JackK]

Would an open hot water tap / open radiator bleed valve (with system empty) cause gurgling noises?! I cannot think of anything else

 

[HERTS P&D]

Your system is not empty yet. Water is moving around.

Andy

 

[JackK]

the drain valve at the boiler is open - However the radiators might not be all bleeded - Thats the only explanation I can think of!

 

[conny]

In that case, air is getting into the system and causing, what water remains to, slip past a section of the water.
The water will change temperature, albeit ever so slightly, and will therefore expand/contract at random. Similarly, the air temperature changes so you have two different things in contact with differing temperatures. If the water is near the lip of a bend, these changes will allow it to drop, and the air gets past.

 

[Johntheo5]

Open the rads bleed valves but close them before refilling and then bleed individually.