A reverse return system with mixed heat emitters

jay in NY

I am splitting a single zone monoflow T system into two separate zones. For the sake of simplicity I plan to leave the monoflow system in place for the second floor. The first floor is to be re-piped with a reverse return system. This floor has six CI rads ranging in BTUs from 4000 to 15,300. Also on the first floor is 9 feet of tube baseboard, and a kick space heater. Can I mix these different types and still have a balanced system that heats well? The baseboard heats a small bathroom, and the kick heater is in the kitchen.

Timco

The kick space & BB needs to be separate zone from CI rads. The KS heater will not heat the kit when the CI rads are done, nor will the BB do it's job. Those will always be colder than CI rad rooms.

Tim

Brad White_202

Also

Tim has it right as usual.

I would also add that reverse-return works well when all emitters have about the same pressure drop. CI rads are very low in resistance and fin tube is higher, especially if the fins are hydraulically bonded. Kick-space heaters have relatively high resistances.

Point being, if the notion of "self-balancing" is sought, you will not achieve it with mixed emitters.

Normally flow is pretty forgiving, but in this case, CI radiators have so little resistance that, unless constricted by TRVs or balancing valves, they will hog the flow.

The small-tube emitters (FTR and KSHs of the world) would then have flows drop low enough to fall into the laminar flow region, which reduces output.

As Tim suggests, split off those high PD devices on their own circuit for heat emission compatibility and independent control. I just gave you one more reason to do so.


My $0.02

Brad