Rads going cold after about a week of being hot

[Daniel Howden]

I guess this is going to be an airlock problem but I have tried to deal with it and I am getting nowhere.

I have two rads at the end of the heating run and they get cold when others around the house are hot. Even though we live in a bungalow we do have a loft conversion with two rads upstairs. It is a pressurised system, oil boiler.

If I run water from the bleed valve on the end rad until it comes through hot it will remain hot for about a week but then stop running hot until I run some water out again and so it continues. I have tried running water out past the point when it runs hot to see if any air comes out but nothing.

If this is air, how do I get it out of the system?

Thanks, Daniel.

 

[SimonG]

Is the system balanced?

 

[king of pipes]

Are there any air vents on the high points in the loft? Kop

 

[Brambles]

Turn off all the radiators in the bungalow except one of the ones in the attic. Open both the valve and the lockshield on that radiator to their fully open position. If you can, set the pump to its highest setting then do so and turn on the heating.

If the radiator gets hot, bleed it, then open up the second radiator in the attic in the same way (including bleeding) and progressively work around the bungalow. Thereafter balance the system

If the radiator does not get hot, you possibly have a vent valve in the attic above the level of the attic radiators that needs venting - see KOP posting above - try to trace the pipework to find it - often in loft conversions, the vents have been boxed in in the area between the eaves and the internal partition and can be a but of a puzzle to find. Start by looking in the area above where the pipework breaks through the ceiling.

It that fails get back to us

 

[Daniel Howden]

Are there any air vents on the high points in the loft? Kop

Yes there is a bleed vent in the loft near the hot water tank. I do check it regularly and there is often air in there although a tiny amount.

Is the system balanced?

Sorry, I don't understand how to tell about that.

Turn off all the radiators in the bungalow except one of the ones in the attic. Open both the valve and the lockshield on that radiator to their fully open position. If you can, set the pump to its highest setting then do so and turn on the heating.

If the radiator gets hot, bleed it, then open up the second radiator in the attic in the same way (including bleeding) and progressively work around the bungalow. Thereafter balance the system

If the radiator does not get hot, you possibly have a vent valve in the attic above the level of the attic radiators that needs venting - see KOP posting above - try to trace the pipework to find it - often in loft conversions, the vents have been boxed in in the area between the eaves and the internal partition and can be a but of a puzzle to find. Start by looking in the area above where the pipework breaks through the ceiling.

It that fails get back to us

I'll give that a go.

 

[Daniel Howden]

Wanted to come back here to say the problem has been fixed. I was a balancing problem after all so thanks to SimonG for pointing that out.

I confess I had no idea how or what balancing a heating system was all about but I googled it and watched a YouTube video.

This evening all rads are boiling hot, the best performance we have had for years so thank you very much for the input.

Daniel.