Hot in the Pews

Jay Martin

We recently purchased a 25 year old church and are having overheating problems.
The one wing has three zone loops piped to baseboard fintube radiation. (Basement, first and second floor).
The returns from all three floors are connected to a common return main at the basement ceiling.
When the basement zone is running, hot water circulates from the return main up through the return risers to the fintube on the first & second floor causing overheating. (first and second floor zone pumps are off).

The fintube units only have an isolation valve and a circuit setter (no control valves).
The fintube returns connect at serveral location along the return main as it raps around the exterior wall.

Is there an easy fix for this with out putting check valves at each riser? (About 15 sections of radiation on the common return)

Partial diagraph attached.
Thanks Jay