Unvented cylinder pipework

[Johnsflat]

Hi all,
First time posting here.
I'm fitting a new direct unvented hot water cylinder well, a G3 guy will actually do this.
I will do the first fix pipe runs as I'm renovating the bathroom (and the whole flat).
So this is a flat with loft space and other dwellings below. I don't trust or want to use the two 15mm pipes buried in the screed delivering hot and cold water at the moment. Was an old Fortic cylinder with no pressure.

I propose to run 22mm speedfit up into the loft and down again.

So from the stopcock, up the wall through the loft (4m) and down to the cylinder, From the cylinder the hot and balanced cold in 22mm speed fit back the same way.

My question is, do I need any a way to remove air from the high point? Automatic vents?

This is a mains pressure system but I don't know if the pressure and flow will be enough to remove the air on its own.

Thanks for any advice.
John

 

[Exedon]

It's pressurized air will push out via taps no vents required.

 

[Johnsflat]

Thank you Exedon,
I wasn't sure about the 2.4m drops before the plumbing to the taps, especialy being 22mm (altough Speedfit has a smaller id than copper).
I was hoping to do the runs in continious lengths to avoid fittings in the loft.

 

[oldbutnotdead]

Speedfit are good quality, long as you use inserts and make sure you push the connections all the way home you'll be fine, no worry with couplers in the loft as long as you lag them to death- just make sure you can get at them if you ever need to. Bonus with using Pushfit- you should be fine long as the water pressure is good enough for unvented (2 bar dynamic at 24l/min). If you get problems it's a 5 minute job to stick some air vents at the top of the loops (use the cheap brass manual screw ones if you do have issues, you'll only need them when you fill the system)

 

[Johnsflat]

Thanks Oldbut, I will insulate the pipes very well, not only to protect from freezing but to help preserve the hot water temperature. I think my water pressure and flow is fine, it's very good at the kitchen sink and that's at the end of a 4 meter run in 15mm from the stopcock.
I was thinking of doing the whole lot in 15mm Speedfit but was worried about the small inside diameter, especialy at the inserts. So I decided on 22mm to avoid any flow rate problems. The taps will be run in 15mm T'd from the 22mm apart from the bath.
I get your point of it being easily to fit vents if I need them (hopefully not) but to put in a T with a vent on top should be easy in speed fit because it's flexable.
Well, I say flexable but I've got a coil of 22mm Layflat and it does not lay flat! it's realy quite stiff, oo-er!