Gotcha. Seeing as they're on the upper level, I would definitely recommend some sort of air removal device. If your boiler loop pump is big enough, you should be easily able to crack the valve or whatever you decide to put up there to bleed. That's how I always do them, but in previous discussions here, others mostly prefer to add valving to force domestic water through the system which also shoves the air back to the boiler. This also works well, but you also introduce new oxygenated water to your system and lose a bit of inhibitor from the overflow resulting from the new added domestic water. If your pump and piping can't support the head pressure to burp the air via a valve on top, the domestic purge is really the only option. All new installs I do, get a bleeder on the high point which allows any air trapped in the high point to be burped using the supply pressure from the boiler pump. This has always served me well, but I always size my pump accordingly too. Also, I do not recommend the bullhead tee you have drawn into the supply line under the convectors. Better would be to put the tee in the vertical and split it that way. It will take a couple extra 90s but will eliminate turbulence in the bullhead. With either setup, you'll want some sort of balancing valve on each unit to equalize flow between the two convectors. One ball valve on each supply or each return will accomplish this. Balancing valves are more ideal, but ball valves do work just fine