Question:
Need quickie help, as I am having my final pre-construction meeting today
before building a 3000 sq ft ranch home in Tampa FL (customized higher-
end tract builder), with a split floorplan. The base A/C system
provided is a 10 SEER 5 ton Carrier Weathermate, with 2 zones (Master
BR, LR, DR on one, other bedrooms and remainder in 2nd zone). Aside
from the issue of possibly upgrading to 12 SEER ($2000 option), my main
concern is whether I really should have TWO compressors, rather than
two zones. The HVAC contractor says the floorplan was originally
designed with a 2nd 1.5 ton unit, but in their opinion the single 5 ton
compressor with 2 zones will be sufficient
Answer:
I have heard that people use two air conditioners in a house because it is a
cost effective way to get a two zone HVAC system. Not because they need the
extra capacity. Two air conditioners are typically used in two story houses.
The first floor is one zone and the second floor with all of the bedrooms is
the second zone. Then one can use a prgramable thermostat to only cool the
first floor in the daytime and evenings and a second programable thermostat to
only cool the second floor bedrooms during sleeping hours. I don't have access
to the cost of the components in a HVAC system but I suspect you are paying
more for a one air conditioner two zone system than you would for a two air
conditioner two zone system. If it is not to late I suggest you get a bid from
another HVAC contractor for a two air conditioner two zone HVAC system for your
house.
If you do go to a one air conditioner two zone system I suggest you put all of
the bedrooms and bathrooms on one zone and the rest of the house in the other
zone. Two air conditioners will be more reliable than one. When one is down
for repair you can keep cool in the rooms cooled by your other air conditioner.
As I understand it manufacturers have done a good job designing multiple zone
air conditioning system so they can efficiently cool a house and run
efficiently. They have overcome a lot of the problems that are created when a
home owner closes the registers in all rooms except one and then uses a 5 ton
air conditioner to cool one bedroom.
