Refilling open bented CH system - Won't refill

[acrookston]

Apologies if this has been covered. I've searched, but not found anything.

I've been stung by this problem twice now! Different properties, both new.

I've removed a radiator, went through the usual process of draining down, tying up the ballcock in the header tank. When trying to refill the system, the header tank fills, but the system dosent. Nothing in rads.

The last time, a few years ago, a plumber friend of a friend called me and talked me through moving some switch thing under the HW tank. immediatley, water flowed into the system.

I cant find anything this time. I have a 3 way mid port valve thingy. Moving this has not effect.

Any help greatly appreciated.

 

[Nige F]

2 NEW houses.......... .like New built or new2you.........another lashed up heating system then........just backfill through a drain cock with an assistant watching the f+e tank so it don`t overfill ...I just love new houses

 

[acrookston]

Thanks Nige.

1 new build, this one 3 yr old. What's the f+e tank? Is this the small tank that has the mains/ballcock inlet?

If I connect a hose to the draincock, what will I see in the loft when the system is full? Will the system refill when I bleed the rads?

What causes this?

Cheers

Allan