Shower Pump - Vent Required?

[yeahdisk]

I'm in the process of installing a new shower, including new pump and pipework.

My plan is to site the pump next to the HWC, feeding hot from a dedicated essex flange and cold from a dedicated feed from the header tank in loft (about 3m directly above the pump).

I then plan to pump the water back up (about 3m) into the loft, across (about 2m) and then down (about 2m) into the bathroom.

Question: Will I need to install some kind of bleed / vent at the highest point, or not? Although the pipes will be up in the loft, they will not be any higher than the top of the header tank.

Thanks

(Pump: ST showermate twin 1.4bar positive head)[/img]

 

[seco services]

you need to be able to bleed the pipework.
as when you first install air will be in the pipework at the highest point
air won't go down hill so install them in the loft.

 

[doitall]

A positive head pump relies on a flow for the switch to work, in your case any air in the pipe and the pump won't work.

Change it to an negative head pump which works on pressure and it should be fine

 

[yeahdisk]

Thanks a lot for the help!

(PS I posted another question on how to install my essex flange here: //www.diynot.com/forums/viewtopic.php?t=124438 - if you could help me out there I'd be all set! thanks again)