Microbore Taps?

[Alan51]

Ultimate plan is to update all rads and pipework but as an immediate job I'm putting a new rad on the landing and a towel rad in bathroom which currently has no heating.
Photo shows the connection to existing landing rad, would it be reasonable to remove the narrow pipe and connect new probably plastic 15mm to feed the new rads. The outlet from the valve is 15mm that immediately narrows to what looks like 10mm.
Also how do you drain a system that doesn't appear to have any drain off points. Some of the old rads have just one valve others have two.
Thanks

 

[Madrab]

You have 2 gate valves there and yes it looks like it's reduced to 10mm small bore. No reason to not up it to 15mm. In fact it would be advised to run 2 rads albeit the towel warmer will be a low output. You may want to see how free those valves are as they would isolate the hall section and allow the new rads to be fitted without draining down.

Find the lowest connection point of the central heating system and drain from there if needed.