problems with air in CH system after replacing pump

[tash]

I have an old Baxi Bermuda back boiler which I service regularly and the system was running fine until last weak when the CH failed (hot water was still OK). The pump was turning but no water flow, so I replaced it. The problem now is that the water is going through to the upstairs radiators.

I bleed the radiators downstairs and they had a bit of air but then water starting coming through. However on the upstairs RAds all I get is a bit of air escaping at first and then nothing no water. I subsequently trained the system from the lowest radiator and found that only a small amount of water came out. Now even the lowest radiator has hardly any water in it.

I am at a loss to figure out why the water is not flowing through the radiator when the CH is switched off (gravity should take care of that). I know that that air is being pushed around the system by the pump, but that's because no water is coming through to it (I checked).
Can anyone please help?

I have replaced the same pump a few years a go and I did not experience any problems like this!

Many thanks in advance

 

[breezer]

you may have put the pump in the wrong way round

 

[tash]

No, its definetly the correct way up I checked. I even disconnected it from the pipe above it to check for water flow and found no evidence of water in the above pipe or the pump itself!

 

[breezer]

wrong pump speed? have you bled the pump?

 

[tash]

Yes I have, but no water came through!

 

[oilman]

Sounds like the feed pipe from the tank is blocked, and water is not getting into the system.

 

[tash]

Thanks oilman,

The blocked pipe sounds reasonable, but How can I check that without dismantling the entire system and is there an easy way of unblocking it (feeding a hosepipe down it for example). I know this may sounds amateurish, but I don't want to do something that makes thinks worst. By the way, is that pipe the one that feeds in the top of the pump?

Also, Could it be that the valve has failed after the pump was replaced? How can I check?

Many Thanks

 

[masona]

Could it be that the valve has failed after the pump was replaced

Not normally but is the valves open correctly ?

 

[tash]

How can I tell?

 

[masona]

Most valve have a screwdriver slot to open/shut and that should line up with the pipe position, if it's across the pipe then that is shut.

 

[tash]

So, I guess it must be in the open position as it was working before I changed the pump and I did not change the setting on the valve.