Draining open indirect heating system.

[CURIOSITY]

I drained the system by moving each of the motorised valve levers to 'manual'. Then I filled up, adding inhibitor to the feeder tank. '
When I started, the pump was noisy unlike before I drained the system. I tried different speeds for pump, the noise did not disappear. I stopped the system after about 2 or 3 mts so as not to damage the pump

Then I swiched off, moved the lever to manual again and bled one of the downstairs radiators for about 2 or 3 mts, stopping the flow into the feeder tank. I noticed ;at about 12" down stream of the heating valve, the pipe was warm/hot.

I then closed the radiator valve, moved the motor- levers to 'auto' and started the system. No change to noise in the pump. I then checked for any bleeding device on the pump. There seems to be none. If there is one how does it look and how would I operate it.
Or have I done/missed something.
I did the same operation last year, the pump noise was there for a initial period of only 30-60secs and no more.

Any advice is much appreciated.
Thanks

 

[hi-spec plumbing heating]

in the centre of the pump is a screw, undo the screw hold a cloth under pump and it should release the air.
do that with heating switched off the replace screw and try.

sometimes you can shift the airlock by switching the pump speeds.

 

[dal5band]

You could try running the system "cold" - just turn the boiler thermostat to zero so the boiler dosn't fire up. Also ensure all valves are open by turning the thermostats high.

 

[grib]

Then I swiched off, moved the lever to manual again and bled one of the downstairs radiators for about 2 or 3 mts, stopping the flow into the feeder tank.

I don't quite understand what you mean about stopping the flow into the feeder tank? You shouldn't stop the tank filling while you bleed coz thats not bleeding thats just emptying .. maybe I'm just misunderstanding what you did.

You say you bled one downstairs radiator.... I assume you have bled all the others too?

It just sounds like the system isn't completely full.. make sure all radiators are bled and check around for any other air vents that you can see (often in airing cupboard)... and of course vent the pump as the previous guy explained.

 

[gas4you]

Check for an air vent next to the HW cylinder as well.

Worse case could be a blockage in the cold feed where it joins the heating system.

 

[CURIOSITY]

Thanks guys for your advice,
Re Hi-spec's advice I did open the pump screw, which I had to struggle to get it opened, but only a weep of water came but no air.

then I tried dal5band's method but still the pump noise persisted.
then I gave up for the day as I was too tired (75 with asthma/neuropathy) going up and down.

The next day I set the two diverter valves to 'manual' -fully opened , drained via lowest point, but it drained much quicker than before, suggesting that the diverter levers must have sprung back to 'auto'position.
I drained till the water level in the feeder tank was not lower than the highest point of discharge point, to prevent any air getting through.

Then I filled up and away it went- no problem so far.

Thanks.All your help is much appreciated