Below is a link explaining how heat pumps work. It should give you some general knowledge. There a some heat pump experts on this forum who can answer additional questions.

This sentence does not make sense:

"The house will have an 80% electric furnace(110 BTU) and 13 SEER 3-ton heat pump with air conditioner."

The heat pump will need an auxiliary heat source for cold days when the heat pump cannot keep up with the heat demand. Usually these would be electric heat strips providing about 20K BTU.

I don't understand why you would need an electric furnace rated for 110,000 BTU for a house that is 1300 sq. ft. I also don't understand what is an "80% electric furnace". Are you sure it is an electric furnace and not propane?

Here is a link that might be useful: How heat pumps work

Mike, the information I sent is directly from my builders spec sheet. The 80% refers to the furnace efficiency and no, there is no gas from any source in this little subdivision. The original developer did not include it, and he went bankrupt. Also, propane is not allowed. Thanks for the link.

electric is 100%
minimal efficiency gas is 80%.
this 80% refers to afue of furnace
anual fuel utilization ...something.
spec sheet of builder has misprint or
is addressing both elec/heat pump & gas
furnace. my spec sheet lists both also,
just defines what is heat pump & what
is gas efficiency ratings.

heat pumps heating side is heating seasonal
performance factor HSPF
a/c side of heat pump and all a/c is SEER
seasonal energy efficiency ratio

13 SEER like 80AFUE furnace are both minimal
efficiency. since you have no access to gas
you'd want to pick up the efficiency of the heat pump.

heat pump efficiencies high end are 20 SEER 9.5 HSPF
I find these efficiencies to be not as cost effecient
as mid seer ranges. I'd price something in 15-17
SEER 8.5 HSPF.
you'll want more info on auto defrost for heat pump,
and possibly to stage the heat strips so that only
half comes on and then the other half..if needed.
electric heat strip is the most costly to heat
a house. so you want some control over how
much is used. as this is emergency/backup heat
staging the strips will save you money, but
still allow for all of the strips when needed.

what brands are you looking at?
keep in mind that name brands like trane
have 'sister' companies american standard.
same basic equipment, just different name.
some have less bells and whistles than others.

one thing I've learned..if you are talking to
trane dealer..get trane price from him.
then go to phone book & find am st dealer
& get price from that company.

shop wisely for hvac company, ask friends
neighbors & people you know who they recommend.
don't be afraid to bring in different hvac company
as builders chose by lowest price, and move to next
build. it isn't always a good choice for the homeowner.

also instead of sizing by sq ft..400-500 sq ft
per ton..is not how your hvac system should be
sized. invest in a load calculation to size the
unit for the house.
variable speed air handler units are an upcharge
but allow the heat/cool to vary when used.
instead of hot/cold blast you have an even
temp all the time.
3 tons a/c for 1300 sq ft is a lot. unit
will not run long enough to remove humidity
in summer months. cost more to operate and
have a lesser useful life than correctly sized
unit.

keep asking questions. we'll be happy to
answer all that we can.hvac is an important part
of your build that will effect comfort & cost
to operate for life of unit.

best of luck

Setting a heat pump back by that amount will cause the auxiliary heat ($) to come on. May want to cut that setback to 2-3 degrees. Depending on the thermostat used, it may still call for auxiliary heat with the smaller setback.

V