Central Heating conundrum

Hey folks, I'm in need of some advice please.

I have a combi boiler, I have just drained the system, removed some of the rads to flush out the sludge and fitted TRVs to the rads also. One rad has remained off the wall to allow for some damp proofing behind it.

My boiler is on 1st floor, some if the rads on the ground floor have pipes coming directly from the ceiling and some the pipes that disappear into the wall.

There are three draining points off the system and two rads that need to be drained manually.(Seems like a bit of a mess?)

My question relates to the two rads in the living room. One of these is still off the wall to allow for the damp proofing the other now, does no get up to heat. The flow pipe is hot to the rad, the rad itself is luke warm towards the top and the return pipe is cold. I have balanced the other rads, flushed out the rad again, switched the actual rad with the now spare from the other side of the room and used different valves all to no effect.

So my conclusion/question is: is this rad is looped in with the rad that is still off the wall and as such will not have flow through it as it is capped off at the other end (where the other rad is still off the wall) Does this make sense? It is my first real dip into plumbing so any help appreciated.

Cheers
Phil

Standard bleeding turn off TRV and bleed, then turn back on and turn off lock shield and bleed, if the radiator is in series with another radiator is will not bleed on one side.

I am an electrician not a plumber, however as I understand it, with all TRV control, you need a by-pass valve, so if all close then by-pass opens so still circulation, not sure what happens when the TRV heads link to the wall thermostat, as one would hope if no TRV head open than thermostat would not ask boiler to run?

I found in old house the lock shield valve setting was critical. Open too much and temperature over shoots the mark, and closed too much and clearly room does not get warm. It is specially a problem if the TRV is on return, the problem is a TRV takes time to open or close, so unless balanced the room get hot before the valve can close.

If balanced also there is a flow on every radiator together when heating starts, without the balance all heat tends to go to one room until TRV starts to close, then next room and so on. More of a problem with modulating boilers and pumps, but even with old oil boiler still a problem.