Just had installed a 3.5 ton am. std. heat pump with variable speed
air handler (13 SEER), 15K backup and 4" Honeywell media filter.
System seems to move more air than old 10+ SEER York system (3.5 ton
w/ 4 air handler) at standard speed (400 cfm) and am. std. setup says
setting for emergency heat mode to be 1600 cfm (450 cfm/ton). At 1600
cfm it's not only a bit noisy but seems to blow out old dust (possibly
settled in supply ducts or possibly sucked into return line, though
return line is in conditioned space except when passing between
basement and first floor through open web floor trusses. Increasing
return size is not an option due to space). Questions are:
1) any problem dropping standard setting back to 350 cfm/ton in
2) should 400 cfm/ton be sufficient for emergency heat mode, which
should rarely kick in more than 1st stage since balance point around
3) any recommended tests for locating possible duct leaks, other than
blocking all returns which could stress motor?
They (AM STD) Must have really changed their equipment in the last few
years. I have a 5 ton with variable speed air handler. I had choices on the
driver board with some dip switches. Was pretty simple to choose the program
I wanted. Been running great for 8 years. For cooling I choose, ramp up to
30% hold for a minute, then ramp up to 80% hold for a minute, then release
it to what ever it needs. Rarely runs at 100% and yes at 100 it is a tad
noisy. Shut down it the reverse. I choose this because I wanted more
humidity control. Works, every time the motor goes to 80% the condensate
pump cycles pushing 2 quarts of water out.
4" filter? How did you fit that in the bottom of the air handler. Mine will
not except anything other than a 1 inch thick filter.
No. Sounds about the same. I easily can program the dip switches but
wondering if adverse consequences to certain program settings. I know
that 350 cfm/ton is option for humid areas for better dehumidification
but wondering if any disadvantage to that setting in heat mode (such
as possibly causing auxilliary heat to kick in at higher outside
I had a 5" Honeywell media air cleaner (similar to Trane "Perfect
Fit" w/ media filter) installed with system to minimize air
resistance/static pressure. Same case as Honeywell electronic but
didn't want to deal w/ electronic cleaner (could fit one in later if
Also, is there a setting to keep auxilliary resistance heat from
kicking in until heat pump is unable to achieve or maintain temp on
its own (i.e. lock out "toaster mode" above the balance point) or is
it necessary to add an outside thermostat and guess at outside balance
point temp setting?
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