Allen 75002 Daikin A/C and Furnace Replacement With Plenum and R-8 Duct

Greentech Engineering Heating & Air Conditioning — DFW HVAC completed this Allen, TX 75002 replacement on September 8, 2026. The project paired a nominal 4-ton Daikin DC4SEA4810-series R-32 cooling-only A/C with a CHPTA4830C3 horizontal coil and a DR80SN0805CX-series, 80,000-BTU-input, 80% AFUE gas furnace. AHRI reference 214856292 rates the combination at 45,500 BTU/h, 14.5 SEER2 and 11.7 EER2. The scope also included one replacement return plenum and one insulated R-8 flex duct run.

The street address, homeowner identity, equipment serial numbers and other identifying information are excluded from this case study.

Project at a glance

• Location: Allen, TX 75002; single-family house
• Existing outdoor equipment: Legacy Trane R-22 condenser; exact model, capacity and age not verified for publication
• Existing furnace: Legacy Borg-Warner gas furnace; exact model and age not verified for publication
• New outdoor unit: Daikin DC4SEA4810 series; nominal 4-ton; single-stage; R-32; cooling-only
• New indoor coil: Daikin CHPTA4830C3 horizontal cased coil
• New furnace: Daikin DR80SN0805CX series; installed label DR80SN0805CXAA
• Furnace rating: 80,000 BTU/h input; 64,000 BTU/h output; 80% AFUE
• AHRI reference: 214856292
• Certified cooling performance: 45,500 BTU/h; 14.5 SEER2; 11.7 EER2
• Indoor orientation: Horizontal attic installation
• Duct scope: One replacement return plenum and one insulated R-8 flex duct run
• Completion date: September 8, 2026

What was replaced in this Allen home?

The project replaced a legacy Trane R-22 outdoor condenser, an older Borg-Warner gas furnace and the indoor evaporator coil. The available records support the equipment identities, but not a precise public claim about the old system’s model, capacity, manufacture date or service age.

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The indoor equipment was installed horizontally in the attic. This case study does not add an unverified homeowner complaint, failure diagnosis, repair history or before-and-after utility analysis.

What Daikin equipment was installed?

The installed cooling system consists of a nominal 4-ton Daikin DC4SEA4810-series, single-stage R-32 air conditioner and a Daikin CHPTA4830C3 horizontal cased evaporator coil. The outdoor unit provides cooling only; it is not a heat pump.

The matched indoor furnace is a Daikin DR80SN0805CX-series model. Its installed label identifies the full model as DR80SN0805CXAA and lists:

• 80,000 BTU/h gas input
• 64,000 BTU/h output
• 80% AFUE

A gas furnace should not be called a “5-ton furnace.” Furnace heat is described by input and output BTU/h and AFUE. Cooling tonnage describes the nominal A/C class and compatible blower application, not the furnace’s gas-heating output.

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What does AHRI reference 214856292 verify?

AHRI reference 214856292 verifies the standardized rated performance of the listed outdoor unit, indoor coil and furnace/blower combination:

• 45,500 BTU/h certified cooling capacity
• 14.5 SEER2
• 11.7 EER2

The reference establishes the certified rating for this exact equipment match. It does not certify the home’s cooling load, duct design or installation workmanship.

No Manual J, Manual S or Manual D report was supplied for this project. The article therefore does not claim that the system was “right-sized” or selected through a documented load calculation. For an example focused specifically on load calculations, see this separate Allen Manual J sizing case.

Why is a nominal 4-ton system rated at 45,500 BTU/h?

Nominal tonnage identifies an equipment class; it is not always the certified capacity of a specific combination. Four nominal tons are commonly associated with 48,000 BTU/h, while AHRI lists 45,500 BTU/h for the exact condenser, coil and furnace/blower combination used here.

The AHRI certificate is dated September 10, 2026, two days after the September 8 installation. It verifies the listed combination and is not represented as a pre-installation document.

Why was a return plenum included in the replacement?

The return plenum connects the return-air system to the furnace or air handler. When replacement equipment has different cabinet dimensions or connection requirements, the transition may need to be rebuilt so the equipment and return path can be properly connected and sealed.

This project included one replacement return plenum. Accessible equipment and duct connections were sealed with HVAC-rated materials. This work addressed the new equipment’s connection to the air path, but no before-and-after airflow or static-pressure measurements were supplied. The article therefore does not claim that the plenum corrected a measured airflow problem.

Homeowners can learn more about duct design and airflow evaluation in Allen.

What does R-8 mean on the new flex duct?

R-8 is the flex duct’s insulation rating; it is not an airflow-capacity rating. Airflow also depends on duct diameter, length, bends, compression, support, sealing, available static pressure and system balancing.

The verified scope is one insulated R-8 flex duct run, including its collar, boot, hanging support, tape and duct sealant. The available record does not conclusively identify the run as supply or return or verify its diameter, so those details are not stated.

What installation work was documented?

The project scope included:

• Removal and disposal of the old condenser, coil and furnace
• Recovery of the old refrigerant through the documented service process
• Installation of the Daikin condenser on a new equipment pad
• Horizontal attic installation of the cased coil and gas furnace
• Connection and support at the supply and return plenums
• One replacement return plenum and one insulated R-8 flex duct run
• Sealing of accessible equipment and duct connections
• A gas sediment trap, Safe-T condensate switch, drain-line insulation and drain pan
• Condensate-drain cleaning and required trap, vent or routing modifications
• Required gas-line and furnace-vent modifications
• Preparation of the existing refrigerant line set using RX-11 and dry nitrogen
• Line-set modifications and connections brazed using 15% silver brazing alloy
• Startup and operational testing after installation

The written scope specified a dry-nitrogen pressure test at 250 psi for at least 15 minutes and evacuation below 500 microns before charging. Because achieved readings were not supplied for publication, these values are documented requirements—not claimed final measurements.

Does R-32 or 14.5 SEER2 guarantee energy savings?

No. R-32 is an equipment-compatibility and service-procedure fact, and SEER2 is a standardized seasonal efficiency rating. Neither guarantees a specific utility-bill reduction.

Actual energy use depends on the building load, weather, thermostat settings, airflow, ducts, installation, maintenance, utility rates and occupant behavior. Read what homeowners should know about R-32 for broader refrigerant information.

What warranty applies to this project?

Greentech provided a complimentary three-year, or 1,095-day, labor warranty for qualifying labor on the installed Daikin system. The labor warranty is non-transferable and remains subject to the written coverage, claim, exclusion and ownership-change terms.

Parts and equipment are governed separately by the applicable manufacturer warranty. No project-specific manufacturer duration is stated because registration and final written coverage were not supplied for publication.

What was the documented result?

Greentech completed the A/C, coil, gas-furnace, return-plenum and flex-duct scope on September 8, 2026. Project photographs document the installed outdoor and attic equipment, while AHRI reference 214856292 verifies the standardized performance of the listed match.

No measured energy savings, humidity change, sound reduction, airflow improvement, room-temperature change or homeowner review was supplied. None is claimed here.

Frequently asked questions

What was installed in this Allen 75002 HVAC replacement?

A nominal 4-ton Daikin R-32 cooling-only A/C, horizontal cased coil and 80,000-BTU-input, 80% AFUE gas furnace were installed. The scope also included one replacement return plenum and one insulated R-8 flex duct run.

What does AHRI reference 214856292 verify?

It verifies 45,500 BTU/h of certified cooling capacity, 14.5 SEER2 and 11.7 EER2 for the listed condenser, coil and furnace/blower combination. It does not certify the home’s load, duct design or installation workmanship.

Is an 80,000-BTU gas furnace a “5-ton furnace”?

No. Gas-furnace heating is described by input and output BTU/h and AFUE. Cooling tonnage describes the A/C class and compatible blower application.

Why might a return plenum be replaced with the equipment?

The return transition may need to be rebuilt when new equipment has different cabinet dimensions or connection requirements. This project included one replacement return plenum, but no measured airflow-improvement claim is made.

What does R-8 mean on flex duct?

R-8 is the duct insulation rating, not its airflow capacity. Duct dimensions, routing, support, sealing and available pressure also influence airflow.

Does 14.5 SEER2 guarantee lower utility bills?

No. It is a standardized equipment rating. Actual energy use depends on the home, weather, controls, duct system, installation, maintenance, utility rates and occupant behavior.

Schedule an Allen A/C and furnace replacement evaluation

If you are considering an A/C and gas-furnace replacement, Greentech can evaluate the equipment match, return path, duct connections, drainage, refrigerant lines and installation options for your home.

Call (469) 551-6806, visit the A/C replacement service page for Allen, or explore HVAC services in Allen.

About the author

Siwei (Lucas) Chen
Chief Technology Officer | Greentech Engineering Heating & Air Conditioning — DFW HVAC

Siwei (Lucas) Chen applies an engineering-based, data-first approach to residential HVAC system design, diagnostics, airflow measurement, equipment selection and duct-system optimization across Dallas–Fort Worth. He holds a B.S. in Mechanical Engineering from Virginia Tech.

Lucas completed ACCA’s Residential Design for Quality Installation Course, which covers residential design procedures associated with ACCA Manuals J, S, T and D. He is also an NCI Certified Residential Air Balancer and NCI Certified Duct System Optimization Specialist.

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