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Greentech Engineering Heating & Air Conditioning

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Greentech Engineering Heating & Air Conditioning

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Your trusted HVAC experts in DFW—delivering exceptional service to keep your home comfortable

10/14/2026

When an HVAC proposal says “3.5 ton,” should the certified capacity always be exactly 42,000 BTUH?

Not necessarily.

For this McKinney, TX 75070 project, the homeowner reported that the home was not cooling. The approved replacement included:

✅ nominal 3.5-ton Daikin R-32 straight-cool A/C
✅ matched horizontal evaporator coil
✅ 80,000-BTU-input, 80% AFUE gas furnace
✅ AHRI 214856170: 39,000 BTUH, 15.2 SEER2 and 12.0 EER2
✅ written installation scope and labor-warranty terms

“Nominal 3.5 ton” describes the equipment class. The exact certified performance belongs to the complete condenser, coil and furnace/blower combination.

The homeowner received the equipment information, AHRI reference, included work and warranty terms before approving the replacement. That documentation gives homeowners a clearer basis for comparing proposals than brand or tonnage alone.

Read the full McKinney case study:
https://www.greentechdfw.com/blog/mckinney-75070-daikin-hvac-replacement

10/06/2026

Is your HVAC quote too high—or simply too unclear to evaluate?

Do not compare two totals until both contractors are pricing the same outcome. Ask:

What condition was diagnosed?

What measurement, photo, error code or other evidence supports it?

What exact part or equipment is proposed?

Which work is required, and which is an optional upgrade?

What labor, materials, related work, setup and testing are included?

What is the total authorized price, and what is excluded?

What parts and labor warranties apply?

Were repair, monitoring and replacement alternatives explained?

An online part price and a complete installed-service price are not the same thing. At the same time, homeowners should be able to understand what they are authorizing.

Greentech uses written, itemized, scope-specific estimates so homeowners can review the selected work and total price before approval.

Read the full DFW guide and save the checklist: https://www.greentechdfw.com/blog/how-to-compare-hvac-repair-quotes-dfw

09/25/2026

What determines whether a replacement commercial RTU will work with an existing roof opening?

Nominal tonnage is only one part of the decision. The existing curb, new-unit footprint, supply and return openings, equipment support, service access and utility connections also need review.

For this Dallas 75229 project, we installed a nominal 5-ton Daikin R-32 straight-cool packaged rooftop unit with:

20 kW electric heat

Economizer

Programmable controls

Custom curb adapter

Coordinated professional crane service

The custom adapter created the planned transition between the existing roof interface and the replacement-unit configuration.

Daikin’s published table lists 57,500 BTU/h, 13.7 SEER2 and 11.8 EER2 for the base model. Those figures are manufacturer-published values; no project-specific AHRI reference was supplied.

Read the complete Dallas commercial RTU case: https://www.greentechdfw.com/blog/dallas-75229-commercial-daikin-r32-rtu-curb-adapter-replacement

09/24/2026

An upstairs-only HVAC replacement in Dallas 75287: Lennox R-410A to Daikin R-32.

This project replaced only the system serving the upstairs of a two-level home—not the entire home and not both HVAC systems.

The new matched combination includes:

Daikin nominal 4-ton R-32 cooling-only A/C

Horizontal evaporator coil

80% AFUE gas furnace

AHRI reference 214856292 rates the exact combination at 45,500 BTU/h, 14.5 SEER2 and 11.7 EER2.

One distinction matters when comparing proposals: “nominal 4 tons” is an equipment class, while 45,500 BTU/h is the certified cooling capacity of this specific indoor/outdoor match.

The available record does not establish a Manual J conclusion, Oncor incentive, measured commissioning result or before-and-after energy or comfort outcome, so none is claimed.

Read the documented equipment transition and installation record:https://www.greentechdfw.com/blog/dallas-75287-upstairs-lennox-to-daikin-hvac-replacement

09/15/2026

If an older A/C only provides cooling, can it be replaced with a heat pump that also provides heating?

Sometimes—but this is more than an outdoor-unit swap.

For this Fort Worth 76102 home, we converted legacy Lennox R-22 straight-cool equipment to a Daikin FIT R-32 variable-speed heat pump and communicating air handler. The heat pump can provide cooling and compressor-driven heating, with auxiliary electric heat available when the controls call for it.

AHRI 215415502 rates the exact combination at:

17,100 BTU/h cooling

17,400 BTU/h heating at 47°F

19.0 SEER2

12.0 EER2

8.8 HSPF2 Region IV

The project also integrated Daikin One Touch control, a replacement insulated supply plenum, MERV 11 media filtration and voltage/surge protection.

One important limitation: the change from nominal 2-ton equipment to 1.5-ton equipment is not presented as proven right-sizing. That conclusion requires project-specific load and selection records.

Read the documented Fort Worth case:https://www.greentechdfw.com/blog/fort-worth-76102-daikin-fit-heat-pump-conversion

09/08/2026

Should every old 4-ton heat pump be replaced with another 4-ton system? No—and Manual J does not always point to something smaller.

At this 3,661-square-foot home in Fort Worth 76131, the previous Lennox heat pump and air handler were in the nominal 4-ton class.

Before installation, we completed a project-specific Manual J calculation and used it during equipment selection. The calculation reported a total cooling load of 52,790 BTUH at a 99°F outdoor design condition.

The replacement is a nominal 5-ton Daikin R-32 heat pump paired with a Daikin variable-speed ECM air handler in an upflow closet configuration. Its exact AHRI-certified combination provides 56,500 BTUH of cooling at the 95°F rating condition.

Those two figures use different outdoor temperatures, so we do not call them a perfect or exact match. A complete selection also considers Manual S, expanded manufacturer performance data and airflow.

The lesson is not that every 4-ton system should become 5 tons. It is that neither copying the old label nor assuming “Manual J always means downsizing” is a reliable shortcut.

Before choosing replacement tonnage, would you ask to see both the load calculation and the matched-system performance data?

Read the full case study: https://www.greentechdfw.com/blog/fort-worth-76131-4-ton-to-5-ton-heat-pump-manual-j

08/28/2026

Can a cooling-only A/C system with electric heat be replaced by a heat pump?

Sometimes—but the project involves more than changing the outdoor unit.

At this Irving home, the older R-22 outdoor equipment provided cooling only, while the indoor equipment supplied electric resistance heat. We replaced that configuration with a nominal 1.5-ton Daikin R-32 heat pump and a First Co. ceiling air handler.

The new heat pump supplies both cooling and primary heating. Auxiliary electric heat remains available when the thermostat and equipment controls call for it.

This was equipment replacement and a change in system function. The old R-22 condenser was not retrofitted or converted to use R-32.

For this specific project, Greentech applied the anticipated $1,600 Oncor incentive as an immediate invoice discount before installation and before submitting the incentive application. We then handled the application, and Oncor later approved the project incentive.

Eligibility, equipment requirements, funding, approval and amounts vary by project and program rules. This completed project’s $1,600 discount does not promise that another installation will qualify for the same amount.

Replacing a straight-cool A/C with electric heat? Compare the complete indoor-and-outdoor match, controls, auxiliary-heat design and written incentive terms—not only the outdoor-unit size.

Read the complete Irving case study: https://www.greentechdfw.com/blog/irving-daikin-r32-heat-pump-upgrade

08/26/2026

How many repairs are too many for an older upstairs HVAC system?

There is no single answer for every home.

At this two-level Frisco home, the homeowner reported that the approximately 16-year-old upstairs system had become less efficient, required frequent repairs and was costing more to maintain. This project replaced the upstairs system only; the home’s other HVAC system was not part of the work.

The new matched equipment included:

A nominal 3-ton Daikin R-32 air conditioner

A horizontal Daikin evaporator coil

An 80% AFUE Daikin gas furnace

The exact combination is AHRI-certified at 34,400 BTUH, 15.2 SEER2 and 12.0 EER2.

An older system should not be replaced just because of its age. Before approving another repair, compare its condition, repair history, equipment compatibility and continued maintenance cost.

See the full before-and-after Frisco case study:
https://www.greentechdfw.com/blog/frisco-upstairs-hvac-replacement-daikin-r32

08/21/2026

Should a new HVAC system automatically match the tonnage printed on the old equipment?

No. The old size is useful background information, but it should not become the new specification without looking at the home’s calculated load, the proposed equipment match and the connected ductwork.

At this Coppell home, the previous systems were nominally rated at 5 tons downstairs and 3 tons upstairs. Separate load calculations and matched-equipment data supported nominal 4- and 2-ton Daikin FIT replacements.

The comparisons were:

• Downstairs: 39,638 BTU/h calculated cooling load and 45,500 BTU/h of certified matched-system capacity
• Upstairs: 18,504 BTU/h calculated cooling load and 23,200 BTU/h of certified matched-system capacity

The project scope also addressed return, supply, branch-duct and plenum changes. Replacing the boxes without considering how air moves through the home would leave out an important part of the system.

This does not mean every 5-ton unit should become a 4-ton unit or every 3-ton unit should become a 2-ton unit. It shows why each home—and each served area—needs its own evidence.

Read the complete Coppell case:

https://www.greentechdfw.com/blog/frisco-5-ton-daikin-ac-gas-furnace-replacement

08/12/2026

Should your new HVAC equipment automatically have the same tonnage as the old system?

Not necessarily.

At this McKinney home, the previous equipment was nominally rated at 3.5 tons. A confirmed Manual J calculation and the documented performance of the proposed equipment match supported installing a nominal 3-ton Daikin FIT system instead.

Here is the important distinction:

• Nominal tonnage is an equipment-size category.
• Manual J estimates the home’s design heating and cooling loads.
• AHRI-certified capacity describes the tested performance of a specific equipment combination.

For this installation, the matched combination has a certified cooling capacity of 33,600 BTU/h. That number is not the home’s Manual J load or a field measurement.

The project also received a confirmed $1,500 Oncor incentive. That amount was project-specific; eligibility, funding and incentive amounts vary.

This case does not mean every 3.5-ton system should be replaced with a 3-ton system. It shows why homeowners should ask what calculation and equipment data support a replacement recommendation.

Read the complete McKinney case:
https://www.greentechdfw.com/blog/mckinney-3-5-ton-to-3-ton-daikin-fit-manual-j

Address

1536 Hutton Drive Suite 110
Carrollton, TX
75006

Opening Hours

Monday	8am - 10:30pm
Tuesday	8am - 10:30pm
Wednesday	8am - 10:30pm
Thursday	8am - 10:30pm
Friday	8am - 10:30pm
Saturday	8am - 10:30pm
Sunday	8am - 10:30pm

Website

https://www.greentechdfw.com/

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