Replacing the 2nd floor original equipment 10SEER Split System 3.5T Carrier HP
Full Brick House 3900Sq-Ft. Black Roof. R-15 Wall / R-30 Ceiling, Vented Crawl.
SW Facing House in Profile Picture. Lots of windows on Front of house (SW) Side.
Old system had inadequate supply duct required 1400CFM and the supply duct provided 1170 CFM (16” & 10” Flex supply).
Performed an accurate load calc with HVAC-Calc program. Design Cond: 95 °F/75°F
33947 BTUH (97% design)
I’ve been wrestling with what tonnage unit to replace the 3.5T Carrier HP. In my opinion a 3.5T 2-Stage unit would be the best unit to install, however Goodman does not make a 2-stage unit. I have eliminated the 3.5T SS and am trying to decide between the 3.0T and the 4.0T units.
HVAC Load Calcs 3/3.5/4.0Ton
Link to Spreadsheets:
https://onedrive.live.com/redir?resid=e09e569762e7184f!115&authkey=!AFgpzH_F83NOa1I&ithint=album,
The 4.0 Ton operating in stage-1 would produce 31490 BTUH / 4700 BTUH St-2 so the system would remain in stage-1 most of the time unless the thermostat is turned up >2
I created operating envelope using HVAC-Calc program to get an idea of how the systems would perform under a variety of operating conditions (See Charts)
New Equipment Choices:
1.) Goodman DSZC 160361 3.0T/16SEER 2-stage HP with Variable Speed Blower and Communicating Thermostat
2.) Goodman DSZC 160481 4.0T/16SEER 2-stage HP with Variable Speed Blower and Communicating Thermostat
3) Goodman SSZ 14042 3.5T/14SEER Single Stage HP
Concerns
3.0T Not large enough (old3.5T sometimes had problems cooling)
4.0 T Short cycle in 2nd Stage
THOUGHTS?
Full Brick House 3900Sq-Ft. Black Roof. R-15 Wall / R-30 Ceiling, Vented Crawl.
SW Facing House in Profile Picture. Lots of windows on Front of house (SW) Side.
Old system had inadequate supply duct required 1400CFM and the supply duct provided 1170 CFM (16” & 10” Flex supply).
Performed an accurate load calc with HVAC-Calc program. Design Cond: 95 °F/75°F
33947 BTUH (97% design)
I’ve been wrestling with what tonnage unit to replace the 3.5T Carrier HP. In my opinion a 3.5T 2-Stage unit would be the best unit to install, however Goodman does not make a 2-stage unit. I have eliminated the 3.5T SS and am trying to decide between the 3.0T and the 4.0T units.
HVAC Load Calcs 3/3.5/4.0Ton
Link to Spreadsheets:
https://onedrive.live.com/redir?resid=e09e569762e7184f!115&authkey=!AFgpzH_F83NOa1I&ithint=album,
The 4.0 Ton operating in stage-1 would produce 31490 BTUH / 4700 BTUH St-2 so the system would remain in stage-1 most of the time unless the thermostat is turned up >2
I created operating envelope using HVAC-Calc program to get an idea of how the systems would perform under a variety of operating conditions (See Charts)
New Equipment Choices:
1.) Goodman DSZC 160361 3.0T/16SEER 2-stage HP with Variable Speed Blower and Communicating Thermostat
2.) Goodman DSZC 160481 4.0T/16SEER 2-stage HP with Variable Speed Blower and Communicating Thermostat
3) Goodman SSZ 14042 3.5T/14SEER Single Stage HP
Concerns
3.0T Not large enough (old3.5T sometimes had problems cooling)
4.0 T Short cycle in 2nd Stage
THOUGHTS?
