A question of design (circuit setters)

steamfitter

I am currently working on a large project as an installer with limited acces to design drawings of a 3-pipe hw/chilled water system using fan coil units in apartments (3rd pipe is cond. drain).

The buildings are 21 stories high with approx. 20 sets of risers ( each riser feeding one unit per floor). Each trane unit has a circuit setter on the return and shut-off valves on both supply & return)

The supply & return mains are 6 inch and supply chilled water in the summer and hot water in the winter from a central plant. The return riser runouts have a circuit setter.

The mains on the ground floor are run in reverse as a reverse return system. However, the risers (which were originally run as a reverse return when the building was built 50 years ago) are presently being run as a direct return system. So the 1st floor is now returned first as opposed to its original layout which had them returning last. There used to be a return main on the 21st floor which tied into a dead riser down to the first floor.

So my question is this:

For water balancing purposes, can this new modified system work properly and be balanced as the previous system was? Are the circuit setters on each return risers capable of doing the job without a reverse return riser set-up?

This new renovated system obviously saves money on installation due to the labor and material saving of a 6 inch riser and main on the top floor, but will it be easy to balance? Are the circuit setters capable of doing the balancing?

Thanks guys for any comments!

RJ_4

balancing

That sounds like a tough one, can you make a detailed piping drawing.  I worked on several changeover systems in the past and am familiar with the fan coil and mechanical room changeover process,  Usually direct return systems would have circut setters on the fan coils.

SWEI

It's, probably too late, but

This might be a good fit for a Taco LoadMatch system.



Too bad they ditched the reverse return.  I'm a huge fan of getting the hydraulics right before you start putting on band-aids.  Are there control valves on each zone?  A PICCV (or similar) might be an option.

hot_rod

Read this

it has a lot of good info about balancing.



Possibly a manual setter on the risers to adjust total flow, then PIB (pressure independant bypass) on every terminal unit.



http://www.caleffi.us/en_US/caleffi/Details/Magazines/pdf/idronics_8_us.pdf