Central Heating Problem - please help!

[angelic]

Hi guys,
I have a glow worm space saver II boiler, im not sure what kind of system it is, its really old and has been in the house long before i moved in, but i know its just for the central heating - my hot water is from a seperate boiler and is still working fine.
The other morning, it started making a really loud noise, which i can hear through the pipes in every room. I switched it off and went to work, and when i came home i bled the radiators then switched it back on. None of the radiators are getting hot, and its still making the noise.

The boiler seems to be working fine, the pilot light is lit and its getting hot, the pipe that comes down from it swan-necks over to where the pump is, and its getting warm up until the first bend, then its stone cold. (its a Grundfos 15-60 pump if that makes a difference)
My dad seems to think its a problem with the pump, but when i switch the heating on, i can hear the pump and feel it vibrating, and when i switch the speed up and down the vibrations change speed, so the motor at least is still working.
I have tried bleeding the pump also, clean water was coming out, but still no joy.
Any help you could give me before i call a plumber would be most gratefully appeciated, as i would like to have a rough idea of the problem before i get someone in!
Many thanks in advance, Jo x

 

[kevindgas]

try taking the screw out of the pump the one used to bleed and with a small flat screwdriver you should be able to turn the pump manually see if it turns freely if it is stiff - its a new pump sorry! if it turns freely then the problem is water circulation or lack of by the sound of it
any air vents above the pump? or where does the pipe go next?

 

[angelic]

I cant see any air vents, and the pipe just disappears into the floorboards. Just been up and tried to turn the pump, and it doesnt seem to be turning so it looks like a new one is needed!!

Thanks for the help kevindgas, its much appreciated!

 

[kevindgas]

when u put the new one in and have turned the valves back on give the pump a couple of turns each way to get air out before powering up

 

[tommygas]

check the pressure in the system. On some old boilers the burner may light on low pressure. The pressure should be about 1 bar

 

[angelic]

Will do that, thank you both for the help and advice!