No water in pump!

[Rampage]

I've fixed a couple of leaks in my central heating.
Upon restarting the heating was only warming 2 downstairs radiators.
I've bled the system twice, but upon bleeding the pump there is no water coming out of the centre screw.

The pump sounds like it is turning.

I've connected the mains water via a hose pipe, it comes out of the overflow outside of the house, but made no difference.

Any ideas?

 

[JayJay1978]

Have you bled all the vent points in the airing cupboard?

It will be trapped air somewhere.

It takes a brave man to backfill his system untill it pours out of the F&E overflow!!

 

[tryitandsee]

If you've taken the screw out of the pump. you should be able to 'make sure' the pump is spinning. Either put a flat blade screw driver in and feel the thing spinning or your little finger

Once pump primed adjusting the speed fast then slow, sometimes shifts the 'mother of all air locks'

 

[gassafeman]

Air can cause so many problems.

It took me 30 minutes to shift and airlock (on a pressurised system) yesterday. The flow was not clipped properly and had 'fell' an inch. It was enough for air to gather. The boiler was a Micron in a loft with a big horizonal pipe run on the flow and returns.

Ive now re-clipped it and changed the manual vents in the loft to Autos and the system seems ok.

Paul.

 

[Rampage]

I don't think there are any bleed points in the airing cupboard.
The Boiler (CH & DHW) is downstairs, the hot water tank is upstairs, about 2 meters from being directly above it. The water tank is directly above this. Then the CH water tank is directly above that in the loft.

There is water coming down from the CH tank as I tested it. I did try removing the lower CH pipe that goes into the hot water tank (the coil), and water came out.

So, I'm out of idea's except connecting the hose to the other radiator pipe (not sure if I connected it to the flow or return earlier).

There is no valve on this system.
Where do the pipes that the pump is connected to go to? Straight to the radiators?

Chris

 

[Rampage]

I've taken pump off and their seems to be water there, so I don't know!
Is the pump normally on the flow or return?

Central heating still not working?

 

[tryitandsee]

Have you made sure the pump is spinning.

If all you did was fix a water leak prior to all this, it hopefully will just be an airlock.

 

[Rampage]

Yes, it's definately turning!

I've drained the CH a couple of times before and it's always been fine.

Does the pipe that the pump is in go straight to the radiators?

 

[tryitandsee]

Running out of suggestions.
No valve, (motorised valve) then is this a gravity fed hot water and pumped central heating. Not sure but you must be able to bleed the gravity side, I would have thought, somewhere near the cylinder, normally a small screw capped 15mm fitting.

 

[Rampage]

Yes, I believe it it.

Would it be on the pipe from the boiler to the coil in the hot water cylinder?

 

[tryitandsee]

Can only say what I have seen, but yes on the indirect coil circuit, normally tee'd off small length of vertical pipe with screw cap bleed cap (in the airing cupboard where the cylinder is).

 

[tryitandsee]

The hight of the bleed cap is higher than the top of the highest coil tapping, so you can let all the air out when filling.

 

[Rampage]

I don't think I've got one then!

My system is the same as this I think:

http://www.deals4homes.co.uk/images/centheat1.gif

Do you mean on the coil pipe where it runs through the hot water cylinder? As this is vented to the overflow in the CH expansion tank?

 

[tryitandsee]

OK so is the hot water working as normal and just the central heating not working.

The pump needs to be primed, in order to circulate, no gurgling sounds, no obvious noises of water when pumping, there must be some strange things happening

 

[Rampage]

Yes, hot water seems to be fine.

You can hear the pump because there is no water in there.

I'm wondering if moving the radiators has stirred up some detritus which has blocked a pipe.