this is my basement in floor heat zone on my system switched on and off by a wall thermostat and it’s own zone valve. The rear of the system works fine and also runs on zone valves. In trouble shooting l, I tuned off all other zones and just let this zone call for heat. I closed all 6 loops and opened one at a time (5-10) minutes until hot water was entering and warm water was returning). All loops did this although a couple took longer than others which I will assume means a longer loop. Problem is if I crack open all 6, the system has trouble keeping up. Hints, tips, suggestions? Thanks!