Air locking shower

[Hugh Jaleak]

Puzzled, could do with some other opinions please.

Shower is a Triton 'Altair' bar mixer type. Fed from conventional gravity supplies, cold from cistern in loft, hot via a Surrey flange on cylinder, both in 15mm to shower. Pipework drops, runs under floor then back up to shower.

If a bath is run (hot supply to bath is 22mm) then the hot supply to the shower seems to air lock. (Some hot water gets through, but at nowhere near the same rate as the cold.) Removing the shower head from the riser rail and leaving it dangling in the tray with shower temp control turned to full hot leads to a lot of gurgling and air being released from the shower head with the water, until eventually the gurgling ceases, the hot supply then achieves about the same rate as the cold. The shower temp control can then be set to mid way and a comfortable showering temp is achieved.

Have upgraded cold feed from cistern to cylinder to 28mm, fitted a single check valve in hot supply to shower and it's still air locking on the hot supply after a bath has been run. Running out of ideas, any advice gratefully received.

 

[petertheplumber12]

Best guess is the pipe to shower comes out of the surrey fitting from wrong outlet, Usually the outlet for the shower is the horizontal out tapping, is yours like that?

 

[JimCrow]

blank off the Surrey flange and cut in an essex flange into the side of the cyl. that should cure it,
is the cwsc running dry?.

 

[Hugh Jaleak]

Thanks Gents. Peter, shower connection is from the side tapping, top is to vent/hot feed to taps.

Jim, CWS is a 40/25, not checked it after shower has been used to see what the level is, but unlikely i'd have thought to be empty. (Shower is gravity feeds, not pumped.) If the Surrey flange is still allowing air in to the shower feed surely an Essex flange wouldn't make much difference?

 

[seco services]

It's a long shot but is the dip tube still on the surrey flange.
Seen them removed/come apart before.

Or the air vent in the dip tube stuck shut.

 

[Hugh Jaleak]

I'll take the Flange out and inspect it, hopefully tomorrow. Will report back. Thanks Seco.

 

[Hugh Jaleak]

To update, finally got round to looking at it.... Dip tube still in situ, cant see an air vent for the dip tube, it bends 90 ° then exits via the side tapping. Appeared to be a slight backfall in the pipework from top exit of the flange to vent/DHW to taps, so realigned that to give slight incline as required. See what happens now.....