refilling vented CH system - trapped air??

[goodhallproj]

Hi, I'm refilling my vented system (5 hours in!) after changing a motorised valve body.

System info: feeder tank (and cold tank) in loft, Ht Cylinder, pump and valves etc plus some rads 1st floor, and on ground floor - just rads and boiler in kitchen.

Have been filling system under gravity (Elec supply off). Valves are both set to manual (both 2port).

Downstairs rads filled ok and have now shut bleed valves. bled downstairs rads first, then moved onto 1st floor rads, where things have now stopped! no hissing of air anymore, no water. Have bled pump, no obvious air or water. Bled additional vent in boiler cupboard (highest bleed valve in house). Now all upstairs bleeds open, but little happening.

So seems downstairs filled, upstairs not and everything stalled. Don't want to switch on power to pump, as pretty sure nothing there?

Any advice much appreciated!

 

[bryanpar]

check your headder tank is filling up in the loft!!

 

[dcawkwell]

Maybe you have strange piping.

If you know there is water at the pump and boiler turn on and allow it to
circulate. You might find that you will be able to bleed the radiators.

Another possibility is there is a blockage in the cold feed pipe.

 

[goodhallproj]

Thanks both,

Strange piping is a distinct possibility. Several inverted loops.

feeder tank in loft is full but with a slow and steady drip from ball valve, suggesting system continues to fill, but really slowly.

Could be blockage in the cold feed (is this pipe from the feeder tank suppling the system).

Any ideas how is this confirmed and fixed?

thanks again

GHP[/u]

 

[dcawkwell]

Thanks both,

Strange piping is a distinct possibility. Several inverted loops.

feeder tank in loft is full but with a slow and steady drip from ball valve, suggesting system continues to fill, but really slowly.

Could be blockage in the cold feed (is this pipe from the feeder tank suppling the system).

Any ideas how is this confirmed and fixed?

thanks again

GHP[/u]

Suggest leave it overnight. If there is a very slow flow it will refill overnight.

 

[cjb1971]

Start up the pump bleed air from it should start circulating the water whats allready in there and system should start filling up,in extreme cases where nothing will work conenct hose pipe to a drain point on a radiator downstairs,open drain point then turn on water suply to hose and it will backfill the system just make sure your overflow pipe is not blocked as water will need to come out of there when the system is filled up

 

[bryanpar]

Thanks both,

Strange piping is a distinct possibility. Several inverted loops.

feeder tank in loft is full but with a slow and steady drip from ball valve, suggesting system continues to fill, but really slowly.

Could be blockage in the cold feed (is this pipe from the feeder tank suppling the system).

Any ideas how is this confirmed and fixed?

thanks again

GHP[/u]

yeah leave it till morning see if its filled good luck

 

[Hugh Jaleak]

Cold feed is the pipe from the F&E tank into the system. They can and do block, especially if the cold feed loops down and back up where it joins the system. (First port of call to check for blockages if this is the case.) Otherwise use of a magnet along the pipe may indicate area of blockage if magnet attracts. Best solution is to cut out offending pipework and replace.

I'd be cautious running the pump if system is only half full, pump will cavitate like mad and this could damage it.