I've got some wild temp swings between an office, machine
room, and production room (and the bathroom is almost
always too cold 9 months out of 12). This part of the
building has its own separate 1.5 ton heatpump for these
areas, but it's on one thermostat in the office.

Active zoning should take care of those temp issues, and
the air-handler/heat exchanger is down below in a nice,
easy-access crawl space. All the ducting is simple to get
to as well.

The folks who do the retrofit bladder system for zoning
want a MINIMUM of $7K. It appears I can get a computer good
for four zones, four stats, and the various dampers for
probably around $700-800.

Seems simple enough, but I always approach such things with
caution.

Has anyone done this? Any overlooked "gotchas"? Any
suppliers/brands better than others?

Given that the tiny machine room will probably call for
cooling when nobody else does, there might be too much back
pressure on the fan, as the duct in that room probably
represents less than 5% of total system airflow capacity.
(I might put in a larger duct and vent.)

I still might also need a bypass damper. Are those
"passive" (too much pressure opens a spring- or weight-
loaded damper); or are there active ones controlled by the
computer?

I thought perhaps a variable speed blower might be the way
to go, but that means a new fan, and still a likely chance
for a coil freeze or overheat, unless the computer has the
added smarts to run the blower longer and the compressor
less.

It'd be nice if the system was smart enough to use
(recirculate) the waste heat from the machine room first,
before calling for heat from the heatpump.

A central computer where I could add functions or modify
standard heating/cooling "events" would good. For example,
I'd like to start the blower for a while first to
redistribute the air before switching on a compressor, or
perhaps periodically run the blower for all zones just to
recirculate the air. (I do that now manually. This alone
helps quite a bit.)

And, a central computer with a heatpump "anti-slump"
timeout would be good too.

If anyone's done their own zoning on a forced-air system,
I'd be interested in hearing your experiences, suggestions,
and recommended DIY-friendly HVAC suppliers.

Thanks in advance,

Frank
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