Replacing a Grundfos 15-50 pump

[steve0209]

Hi there, i have just joined to see if i can get some help.
Firstly the pilot wouldnt stay alight on the boiler and couldnt afford to get fixed, so it stayed unfixed for around a year.
Now its fixed, the heating wouldnt come on, checked the pump and it wasnt circulating.
so i have bought a new pump and put it on.
The problem im having now is that it seems there is no water getting to the pump. What have i done wrong?
Many thanks for any help.

 

[kay-jay]

probably an airlock! is the pump working? can you feel it vibrate when its energised. did you bleed the pump? did you reopen any pump union lockshields?

 

[steve0209]

Hi yes the pump is vibrating, and i bled the pump, i also bled the radiators. Could the airlock be in the header tank? Do i need to flush the radiators? Thanks for your response.

 

[kay-jay]

is pump fitted in the right direction?

have you opened the motorized valves to allow the full circuit to fill?

 

[fuzzy]

blocked feed?

 

[steve0209]

Ok first of all i fitted it exactly the same as th one i took off, but then when it wouldnt work i changed it, but have now turned it back to the original position. What is the motorized valve you mentioned please? I have checked the header tank, all seems ok up there. Sorry for all the questions, thought i could fix this myself without having to pay a fortune.

 

[kay-jay]

motorised valve = 2 port valve or 3 port

 

[WHPES]

Is the water actually flowing from the header tank? Sometimes the feed pipe gets blocked where it tees into the circuit.

 

[kay-jay]

Is the water actually flowing from the header tank? Sometimes the feed pipe gets blocked where it tees into the circuit.

this can be checked with a magnet on the tee as a blockage here will be magnetic from radiator corrosion

 

[fuzzy]

ive had this before many many times, blocked feed is often the issue, hence will not fill. as kay jay says use a magnet or drain down cut out anyway

 

[steve0209]

Hi i have checked the tee with a magnet and yes it is magnetic. So one more question please, how do i clear the blockage? Thanks for your help

 

[WHPES]

Cut the pipes at about 8" from the tee, get a screwdriver, poke all the dross out until perfectly clean, check the part of the feed pipe above for blockages and fit back ideally with solder fittings.

 

[fuzzy]

Hi i have checked the tee with a magnet and yes it is magnetic. So one more question please, how do i clear the blockage? Thanks for your help

dont try to, cut it out and replace its easier

 

[steve0209]

Hi i would just like to say thankyou to all that contributed to my post. I now have the central heating fully working, I couldnt have done it without your expert help and you have saved me a fortune.