Constant Flow

Paul Rohrs_2

I have been looking at Oventrop TRV based Unibox Plus and have been impressed with what we can do with room zoning and constant flow. I am considering this setup for a retirement home addition to accomodate their request for individual room control with infloor heating.

I have questions about the piping layout they show. If I pipe primary-secondary, (the secondary handling all of the heat load, primary handling boiler loop) How can I expect flow on this direct return system with TRV's? I believe I should be putting tube in each room and connecting back on a reverse return setup. Otherwise, I could put a pressure bypass differential on my supply loop (past the rooms) to give me enough head to push against to give flow as the TRV's "call" for heat. Am I overthinking this? I have a "wing of rooms", 7 on each side. I am considering this as opposed to zoning by circulator. This will be constant flow with outdoor reset, but will be my first job with TRV's and constant flow.

I know Mark Eatherton talked about this as his dream setup sometime ago, and the concept is simple, but I have to have adequate flow thru each room TRV.

PR