Case Study: Replacing a 3-Ton and a 3.5-Ton System With One 5-Ton Carrier Infinity Dual Fuel System With Three Zones in League City

Installed May 20 and 21, 2026 · League City, TX 77573

In plain words. The homeowner's story. The homeowner lives near the coast and has a generator and solar power on the home, and wanted a simple way to connect the HVAC to those systems. The homeowner also wanted a company that could design a long-term solution for the home. The homeowner likes the primary bedroom at 68 degrees at night, but running the whole house that cold would waste energy, and 68 is too cold for other family members. So the homeowner wanted better temperature control in different areas of the home. The solar and generator connect to the home's main electrical panel, so the new system works with both without a separate hookup.

In plain words. Short answer. We replaced a 3-ton and a 3.5-ton system in this Marina Bay Park, League City home (Houston area) with one 5-ton Carrier Infinity dual fuel system with three zones. The upstairs system was not working. The ACCA Manual J calculation for the 3,608 sq ft house gives a total cooling load of 50,028 BTU/h, about 4.2 tons. The two old systems totaled 6.5 nominal tons. The Manual S report lists 52,234 BTU/h of total cooling capacity for the selected 5-ton Carrier match, 104% of the cooling load and inside the Manual S range of 90 to 130% for variable speed equipment. A modulating furnace lets the system serve small zones while reusing most of the existing ductwork.

Key facts

In plain words. Here are the home, equipment and project details.

The problem: two older systems, one of them down

In plain words. The homeowner had two older systems, and one of them, the upstairs system, was down. They were single-stage gas systems in the attic, a 3-ton and a 3.5-ton, and together they added up to 6.5 tons, which is more than the load calculation says this house needs. So we recommended replacing both old systems with one new 5-ton Carrier Infinity system with zoning. The result is one system serving the whole house instead of two old ones.

The homeowner had two older single-stage gas systems in the attic, a 3-ton upstairs and a 3.5-ton downstairs, and wanted to replace them with one Carrier Infinity system with zoning. The upstairs system was not working. What we found at the survey:

• Aging equipment. The Ruud condensers were made in February 2008 (UAPL-036JAZ, 3 tons, upstairs) and July 2010 (UAPM-042JEZ, 3.5 tons, downstairs), and both use R-410A.
• Two systems for one house. Together they added up to 6.5 nominal tons, compared with the Manual J cooling load of 50,028 BTU/h, about 4.2 tons.
• Window heat gain. The Manual J models 204 sq ft of windows and assigns them 9,684 BTU/h of cooling load. Window orientation and construction affect how much heat enters the home.
• Old 80% furnaces. We went from 80% furnaces to a 97.3% AFUE modulating furnace. The new furnace needs a PVC flue, so we replaced the flue with a new PVC flue through the roof.

What the homeowner wanted, and the result

In plain words. As described at the top of this page, the homeowner wanted better temperature control in different areas of the home. Specifically, the homeowner wanted one Carrier Infinity system with separate temperatures for different people, including the primary bedroom at 68 degrees at night, a return in every bedroom, and better indoor air quality. To get there, we installed one 5-ton system with three zones, four new 8 inch returns, a Carrier Infinity Air Purifier and a REME HALO LED. The table below shows each request, what we did and how it turned out, in the homeowner's own words where the review covers it.

How the size was chosen

In plain words. The two old systems added up to 6.5 nominal tons. The Manual J gives the whole 3,608 sq ft home a cooling load of 50,028 BTU/h, about 4.2 tons. The Manual S report lists 52,234 BTU/h of total cooling capacity for the selected 5-ton Carrier match, or 104% of that load. That is inside the Manual S range of 90 to 130% for variable speed equipment. The new system is smaller than the two it replaced.

The ACCA Manual J 8th Edition report uses Houston, Ellington Field AP weather data. It separates sensible cooling, the heat removed to lower temperature, from latent cooling, the heat removed with moisture. These are calculated design loads, not measured system output. The Manual J was run with an R-44 ceiling and a radiant barrier, because the software has no R-49 option. Window inputs are the report's model inputs.

Why this 5-ton match. The capacity check uses the total cooling capacity listed in the Manual S report, not the nominal 60,000 BTU/h size or the AHRI standard rated capacity. The 52,234 BTU/h result lands inside the Manual S total cooling range, and the latent capacity meets the Manual S latent check. The Manual S report does not list a separate sensible capacity. Carrier lists the 27VNA060A003 compressor with a capacity range of 20 to 100%, so on mild days it can run below full size, while zoning directs air to the areas calling for it.

Why we chose a modulating furnace for a zoned system

In plain words. When we design an Infinity zoning system, we check the furnace's minimum heating airflow against the smallest zone, not just the whole house cooling airflow. If we had designed this house for cooling alone, the primary bedroom would not have needed any additional supply ductwork. The most common Infinity furnace in South Texas is the two stage 80% Carrier 58TN0B. When only one zone calls for heat, the zone board runs it in first stage, and the size we would have used here moves about 1,445 CFM in first stage. The smallest zone, the primary bedroom, is good for an estimated 710 CFM, so if it called alone we believe that furnace could overheat, lock out and shut itself off. The fix was the Carrier 59MN7 modulating furnace, which can turn down to 645 CFM. It isn't stocked in South Texas, so Carrier brought it in from a northern region just for this job. Even with the modulating furnace, the primary zone was still too small, so we upsized one of its supplies. The outcome is a zoned system on mostly existing ductwork, and choosing the modulating furnace kept the ductwork down, which lowered the cost of the job and fit the homeowner's budget.

When we design an Infinity zoning system, we check the furnace's minimum heating airflow against the smallest zone, not just the whole house cooling airflow. If we had designed this house for cooling alone, the primary bedroom would not have needed any additional supply ductwork.

The most common Infinity furnace in South Texas is the Carrier 58TN0B, a two stage 80% furnace. Small zones are where it runs into trouble. When only one zone calls for heat, the zone board runs the furnace in first stage. The 58TN0B090C21 we would have used here if the home were not zoned moves about 1,445 CFM in first stage. The smallest zone in this house, the primary bedroom, is good for an estimated 710 CFM. If that zone were the only one calling for furnace heat, we believe the furnace could overheat, go into lockout and turn itself off to protect itself.

The fix was the Carrier 59MN7 modulating furnace. Carrier's product data lists 645 CFM minimum heating airflow at rated static pressure, with 40,000 BTU/h minimum input on this 100,000 BTU/h model, so it can turn down far enough for a small zone. Modulating furnaces aren't stocked in South Texas, so Carrier brought this one in from a northern region just for this project. The Manual J reports 1,072 CFM of heating airflow and 1,844 CFM of cooling airflow for the whole house. Those design airflow figures are separate from the furnace's minimum operating airflow when only one zone calls. On the cooling side the heat pump can drop to about 20%, about 1 ton.

Why the two stage furnace is the South Texas standard. We don't use our furnaces much during the winter here. A two stage 80% furnace costs less, and since it isn't used much for heating, the cheaper, less efficient furnace usually makes the most practical sense. That is why high efficiency modulating furnaces aren't stocked in South Texas.

Even with the modulating furnace, the primary zone was still too small, so we added supply air to it by upsizing one 8 inch supply to a 10 inch. Without that, we believe the furnace could overheat, go into lockout and turn off if only the primary zone called for heat and the furnace was being used, or called for defrost mode or emergency heat.

Choosing the modulating furnace kept the ductwork to a minimum, which lowered the overall cost of the job and fit the homeowner's budget. The same reasoning is why we chose the variable speed Greenspeed heat pump. A system that can slow down can serve one small zone without forcing too much air through that zone's ducts.

Zoning and ductwork

In plain words. The house already had ductwork for the two old systems, and we reused most of it, for the reasons given in why we reused most of the ductwork. The existing ducts could serve one new system once we divided the house into three zones: downstairs, upstairs and the primary bedroom. We made two changes. We added a new 8 inch return in the primary bedroom, in a family member's bedroom and in each of two guest bedrooms, so each zone has its own returns, and the added return air allows the system to better control each zone's environment, optimizing temperature and humidity for each zone. We also upsized one primary bedroom supply from 8 inch to 10 inch. Even with the modulating furnace, that zone was still too small for the airflow the furnace needs in heating, defrost or emergency heat, and we believe the furnace could overheat and shut off if only that zone called.

The table below gives the supply takeoff for each of the three zones next to the Infinity airflow limits as installed.

The Manual J also breaks the load into the three zones. These are calculated design loads and design airflow, separate from the duct chart estimates and the Infinity airflow limits above.

Zone sensible cooling values include the report's AED excursion adjustment, so they add up to 41,155 BTU/h rather than the 40,843 BTU/h summary figure.

The Manual J lists 1,013 CFM of cooling airflow for the downstairs zone. The chart estimate for the existing downstairs supply is 965 CFM. Those downstairs ducts run in a chase going downstairs, so they could not be reached to upsize. Whole-house supply is still above the load, at an estimated 2,670 CFM versus the 1,844 CFM the Manual J requires.

Zone dampers and zone control

In plain words. The old systems had no zone board and no dampers. A zone damper is a door inside a duct that opens and closes so air goes where it is needed. We added four round dampers, one Infinity zone board and two smart zone sensors, so each of the three zones has its own temperature setting. The Infinity control holds an airflow limit for each zone, shown in the table above. The homeowner's review describes setting the bedroom to 68 degrees while a family member in another zone sleeps at her own setting.

• Upstairs zone (upstairs hall and three bedrooms). A 16 inch Infinity damper feeds a distribution box with three 9 inch supplies (one to each of the three bedrooms) and two 8 inch supplies (the upstairs common area). This ductwork is existing and was reused. We added one 8 inch return in each of the three bedrooms.
• Primary bedroom zone. A 14 inch damper feeds a distribution box with two 10 inch bedroom supplies and one 7 inch primary bathroom supply. Before, the bedroom was fed by one 10 inch and one 8 inch supply. The 8 inch bedroom supply was upsized to a 10 inch so the furnace gets enough airflow in heating, defrost and emergency heat when only that zone calls. We added one 8 inch return in the primary bedroom.
• Downstairs zone. Two dampers are wired as one zone. A 14 inch damper feeds a distribution box with 10, 8 and 8 inch supplies, and a 12 inch damper feeds a distribution box with 6, 8 and 7 inch supplies. Both boxes are existing and were reused.
• Returns. The four new 8 inch returns (one in the primary bedroom, one in a family member's bedroom and one in each of two guest bedrooms) connect directly to the return plenum, and they mean each zone has its own returns. The added return air allows the system to better control each zone's environment, optimizing temperature and humidity for each zone. The existing 16 inch return serves downstairs and the existing 14 inch return serves the upstairs common hallway.
• Dampers. Four round zone dampers sit in the trunks: 16 inch for the upstairs zone, 14 inch for the primary bedroom zone, and a 14 inch and a 12 inch for the downstairs zone.
• Plenums and furnace. Two new metal plenums, assembled at the warehouse for this job: a 19.5 by 19.75 by 48 inch supply plenum and a 21 by 23 by 36 inch return plenum. The furnace is installed horizontally, with the coil mounted to the furnace and then the supply plenum.

Supply airflow

In plain words. The supply ducts carry the cooled or heated air to each room, and we kept the existing ones. We counted every supply run and used chart estimates for flex duct, which are not measured airflow. The three zones add up to 2,670 CFM, above the 1,844 CFM the load calculation requires, so the existing supply ducts could work with the new system as a whole. The downstairs zone is an estimated 965 CFM by the chart, below the Manual J figure of 1,013 CFM of downstairs cooling airflow. Those ducts run in a chase going downstairs, so they could not be reached to upsize. The one change was the primary bedroom, where an 8 inch supply became a 10 inch, about 140 CFM more by the chart. The smallest zone must accommodate the furnace's operating airflow in heating, defrost or emergency heat, and even with the modulating furnace the primary zone needed more supply capacity. Without the change, we believe the furnace could overheat and shut off if only that zone called.

Our supply airflow takeoff uses the NCI Field Duct Sizing Chart flex duct values: 5 inch 50 CFM, 6 inch 75, 7 inch 110, 8 inch 160, 9 inch 225, 10 inch 300, 14 inch 700 and 16 inch 1,000. They are chart estimates that assume flex duct, not measured airflow.

Returns

In plain words. The house had two existing returns, a 16 inch and a 14 inch. By our chart estimates they carry about 1,700 CFM, which is below the 1,844 CFM the load requires. We added a new 8 inch return in the primary bedroom, in a family member's bedroom and in each of two guest bedrooms, so each zone has its own returns. The added return air allows the system to better control each zone's environment, optimizing temperature and humidity for each zone. That brings the total to about 2,340 CFM, above what the load requires. The new returns connect directly to the return plenum. The existing 16 inch return serves downstairs and the existing 14 inch return serves the upstairs common hallway. The homeowner's review also mentions the four new upstairs return ducts.

Our return takeoff, with the same chart estimates for flex duct, puts the two existing returns, a 16 inch at 1,000 CFM and a 14 inch at 700 CFM, at 1,700 CFM. The four new 8 inch returns add 160 CFM each, 640 CFM, for a 2,340 CFM total. The existing returns alone are below the 1,844 CFM the load requires, and both the 2,670 CFM supply total and the 2,340 CFM return total are above it.

Why we reused most of the ductwork

In plain words. We reused most of the ductwork on purpose, for the reasons listed below. We changed only what the new zoning needed: the four new returns and the larger primary bedroom supply, which gives that zone enough airflow for the furnace in heating, defrost or emergency heat. The outcome is a zoned system on mostly existing ducts.

• The homeowner had a budget, and replacing all of the ductwork would have put the job over budget.
• Most of the ductwork was not accessible. The downstairs ducts run in a chase going downstairs, so they could not be reached to upsize.
• The homeowner had no airflow complaints and no hot or cold spot complaints.
• The homeowner wanted to control the primary bedroom independently, running it at 68 degrees at night, and it does not make sense to run the whole house at that temperature. So we made a zone for just that room and upsized the 8 inch supply to a 10 inch so the furnace gets enough airflow in heating, defrost and emergency heat when only that zone calls.

What was installed

In plain words. Both old condensers, both single-stage furnaces and the old Nest thermostat were replaced. In their place went one 5-ton Carrier Infinity variable speed heat pump, a cased coil, one modulating furnace, an Infinity control, a zone board, two smart zone sensors, four zone dampers, a Carrier Infinity Air Purifier and a REME HALO LED. We went from 80% furnaces to a 97.3% AFUE modulating furnace, which needs a PVC flue, so we replaced the flue with a new PVC flue through the roof. We reused the existing line set. The new matched system is rated 18.5 SEER2, 9 EER2 and 9 HSPF2, and it is listed as ENERGY STAR certified.

The matched system is listed under AHRI 215677063 as the 27VNA060A003 heat pump, CVAMA6021XMA coil and 59MN7C100C21 furnace: 18.5 SEER2, 9 EER2, 9 HSPF2 and 56,500 BTU/h of cooling capacity. The same combination is on the ENERGY STAR certified heat pump list (ENERGY STAR ID 3971544, certified January 30, 2025), where heating capacity is 56,000 BTU/h at 17°F and 45,000 BTU/h at 5°F. The Carrier 59MN7 is rated at 97.3% AFUE for this size in an upflow or horizontal position (Carrier 59MN7 product data).

How the install went

In plain words. Two older systems came out and one new system went in over two days, May 20 and 21, 2026. The crew removed both old systems and worked on the ductwork and returns on the first day. On the second day they set the new equipment, finished the ductwork, pressure tested the system with nitrogen and evacuated it before startup. The system was started that day.

The crew installed the system over two days, May 20 and 21, 2026. Fredi, Pablo, Israel and Adonis installed it. Atlas AC Repair operates under Texas ACR license TACLB00153401E, held by Timothy Carpenter, and the job was done under a city permit.

• May 20. The crew started at 7:37 AM, took out both old systems and worked on the ductwork and returns, while the plenums were assembled at the warehouse. A section of fence was removed to get the equipment in and the old equipment out.
• May 21. The crew started at 8:09 AM, set the new outdoor and indoor equipment and finished the ductwork. The system was pressure tested with nitrogen and evacuated before startup, and the job closed out at 9:52 PM.

Line set

In plain words. The house had an existing 7/8 by 3/8 line set, the refrigerant lines between the indoor and outdoor units. We were able to reuse it after a pressure test and an RX11 flush. The pressure test checks the lines for leaks, and the RX11 flush cleans them out. The outcome is that the new system runs on the existing lines.

We were able to reuse the existing 7/8 by 3/8 line set after a pressure test and an RX11 flush.

Inspection: failed once, then passed

In plain words. The city inspection did not pass the first time. The condenser was not anchored down. Our tech fixed it on June 2, 2026, and the reinspection passed on June 10, 2026.

The first city inspection, scheduled June 1, 2026, failed because the condenser was not anchored down. Our tech fixed it on June 2, 2026, and the reinspection passed on June 10, 2026.

Cost

In plain words. The final installed price was $34,308.82 after the Carrier CoolCash discounts, paid through GoodLeap financing. The price covers the 5-ton Carrier Infinity heat pump, modulating furnace and coil, the three zone Infinity zoning with two smart sensors and four dampers, new metal plenums, low voltage wiring, the ductwork changes with the new 8 inch returns and the upsized primary bedroom supply, the new PVC flue through the roof, the Carrier Infinity Air Purifier and the REME HALO LED, and the permit. The invoice shows Carrier CoolCash discounts of $1,700 and $200, and the $34,308.82 price is after those discounts. For typical ranges, see our Carrier Infinity cost guide and 5-ton HVAC unit cost guide. This price is above those ranges, and it covers two systems replaced by one, three zones, new returns, a new flue and two air treatment products. Learn about our HVAC financing options.

Warranty

In plain words. The Carrier registration of May 27, 2026 lists an enhanced parts warranty through May 21, 2036 on the heat pump, coil, furnace, Infinity control, zone board and air purifier, and primary and secondary furnace heat exchanger coverage through May 21, 2066. The REME HALO LED is registered with RGF through May 19, 2033. Our invoice includes 2 years of labor coverage.

Warranty visit

In plain words. After the install, the control showed error alerts on June 8 and 9 for an open fuse and lost power at the condenser. Our tech visited on June 10, 2026 and found the indoor blower running and the condenser not running. He pulled the disconnect and reinstalled the condenser fuses, and the system started working again. He then talked with the homeowner about the zone temperature settings. The visit was covered at $0 to the homeowner. The homeowner has had no other issues to date.

What the homeowner said

In plain words. Here is how Jim described the work and the results.

“Freddi's thorough duct survey in the attic ensured our custom plenums and the four newly added upstairs return ducts would easily handle the required airflow.”

“The results are nothing short of life-changing for our family, and the Carrier Infinity zoning capabilities are phenomenal.”

“Last night, for the first time ever, … were able to set our bedroom thermostat to 68 degrees. Normally, my live-in mom cannot tolerate it being that cool, but because our rooms are now zoned separately, she can sleep comfortably at her own desired temperature.”

“Furthermore, our investment in indoor air quality has made a massive difference. Atlas installed a 5-inch Carrier Air Purifier paired with a REME HALO LED. For the first time in the four years we've lived in this home, I woke up without a stuffy nose!”

Jim M, League City · 5-star Google review, May 22, 2026. Excerpts quoted word for word, with omissions marked.

Related pages

In plain words. These pages cover equipment, costs and other case studies.

• HVAC replacement cost guide
• HVAC contractor serving the Houston area
• AC installation in the Houston area
• Carrier Infinity cost guide
• Carrier Infinity guide
• Ductwork replacement cost guide
• Case study: sizing a 2,000 sq ft house with a heat load calculation
• Case study: 4-ton Carrier Infinity replacement in San Antonio
• Indoor air quality
• Carrier HVAC guide
• AC replacement
• Better Air Bundle
• All Atlas AC Repair case studies

Common questions

In plain words. These answers explain the equipment, sizing and project details.

Why replace a 3-ton and a 3.5-ton system with one 5-ton system?

In plain words. The ACCA Manual J calculation gives the whole 3,608 sq ft home a total cooling load of 50,028 BTU/h, about 4.2 tons. The old systems totaled 6.5 nominal tons, and the upstairs system was not working. The Manual S report lists 52,234 BTU/h of total cooling capacity for the selected 5-ton 27VNA060A003 match, 104% of the load and inside the Manual S variable speed range of 90 to 130%. The Manual J lists 1,844 CFM of cooling airflow. Zoning splits the house into three areas.

Is a 5-ton system too big for a house that is zoned?

In plain words. The Manual S report lists 52,234 BTU/h of total cooling capacity for the selected 5-ton match, not its nominal 60,000 BTU/h size. Dividing that by the Manual J cooling load of 50,028 BTU/h gives 104%, inside the Manual S variable speed range of 90 to 130%. The 27VNA060A003 compressor has a capacity range of 20 to 100%, so on mild days it can run below full size, while Infinity zoning directs air to the zones calling for it.

Why a modulating furnace for a zoned system?

In plain words. The most common Infinity furnace in South Texas is the two stage 80% Carrier 58TN0B, because furnaces get little use here and the cheaper furnace usually makes the most practical sense. In a zoned house, when only one zone calls for heat, the zone board runs it in first stage, and the 58TN0B090C21 we would have used moves about 1,445 CFM there. This home's smallest zone, the primary bedroom, is good for an estimated 710 CFM, so we believe that furnace could overheat, lock out and shut off if that zone called alone. The Carrier 59MN7 modulating furnace turns down to 645 CFM, which fixes that. It isn't stocked in South Texas, so Carrier brought it in from a northern region for this job. The modulating furnace also kept the ductwork down, which lowered the cost of the job to fit the homeowner's budget.

How does the zoning work in this house?

In plain words. Three zones (downstairs, upstairs and the primary bedroom, which is also upstairs) each have their own temperature setting, run by the Carrier Infinity control, an Infinity zone board (SYSTXCC4ZC01), two smart zone sensors (SYSTXZNSMS01) and four round zone dampers. Each zone has its own returns, and the dampers open and close in the attic trunks so air goes where it is needed.

Were the ducts replaced?

In plain words. No. Most of the ductwork was reused. The upstairs and downstairs distribution boxes and their supplies are existing, and the 8 inch supply to the primary bedroom was upsized to a 10 inch. The downstairs ducts run in a chase going downstairs, so they could not be reached to upsize. A new 8 inch return was added in the primary bedroom, in a family member's bedroom and in each of two guest bedrooms.

Why was most of the ductwork reused?

In plain words. Most of the ductwork was reused for four reasons. The homeowner had a budget, and replacing all of the ductwork would have put the job over budget. Most of the ductwork was not accessible, and the downstairs ducts run in a chase going downstairs, so they could not be reached to upsize. The homeowner had no airflow complaints and no hot or cold spot complaints. The homeowner also wanted to control the primary bedroom independently, running it at 68 degrees at night, and it does not make sense to run the whole house at that temperature. So we made a zone for just that room and upsized the 8 inch supply to a 10 inch so the furnace gets enough airflow in heating, defrost and emergency heat when only that zone calls.

Why were new returns added?

In plain words. We added four new 8 inch returns, one in the primary bedroom, one in a family member's bedroom and one in each of two guest bedrooms, so each zone has its own returns. The new returns connect directly to the return plenum. The existing 16 inch return serves downstairs and the existing 14 inch return serves the upstairs common hallway. Our return takeoff, using chart estimates for flex duct, puts the two existing returns (16 inch and 14 inch) at 1,700 CFM, below the 1,844 CFM the load requires, and the total at 2,340 CFM with the four new 8 inch returns.

How much airflow do the supply and return ducts carry?

In plain words. Both carry more than the 1,844 CFM the load requires: 2,670 CFM of supply and 2,340 CFM of return, by chart estimate. These are chart estimates from the NCI Field Duct Sizing Chart, which assume flex duct, not measured airflow. Supply: the upstairs zone is 995 CFM (three 9 inch bedroom supplies and two 8 inch common area supplies), the primary bedroom zone is 710 CFM (two 10 inch bedroom supplies and one 7 inch bathroom supply) and the downstairs zone is 965 CFM (620 CFM from the 10, 8 and 8 inch box and 345 CFM from the 6, 8 and 7 inch box). The Manual J lists 1,013 CFM of cooling airflow for the downstairs zone. Those downstairs ducts run in a chase going downstairs, so they could not be reached to upsize. Returns: the existing 16 inch (1,000 CFM) and 14 inch (700 CFM) returns total 1,700 CFM, and the four new 8 inch returns add 640 CFM.

Does window glass affect the cooling load?

In plain words. Yes. The Manual J models 204 sq ft of windows and assigns them 9,684 BTU/h of cooling load. The report models single pane, aluminum frame windows with a U-value of 1.13 and an SHGC of 0.52. These are the report's inputs, not an independent window inspection.

What size AC does a 3,600 sq ft home need?

In plain words. For this 3,608 sq ft League City home, the Manual J total cooling load is 50,028 BTU/h, about 4.2 tons, made up of 40,843 sensible and 9,185 latent. The heating load is 56,576 BTU/h. The Manual S report lists 52,234 BTU/h of total cooling capacity for the selected 5-ton Carrier match, 104% of the cooling load and within the Manual S variable speed range. These numbers depend on this home's construction, windows, insulation and air leakage, not square footage alone.

How efficient is the new system?

In plain words. The matched Carrier system is rated 18.5 SEER2, 9 EER2 and 9 HSPF2, with 56,500 BTU/h of cooling capacity and 56,000 BTU/h of heating capacity at 17°F (AHRI 215677063). It is listed as ENERGY STAR certified. The Carrier 59MN7 furnace is rated at 97.3% AFUE for this size in an upflow or horizontal position.

How much does a 5-ton Carrier Infinity zoned system cost?

In plain words. $34,308.82 installed in League City in May 2026, after the Carrier CoolCash discounts of $1,700 and $200, paid through GoodLeap financing. That covered one 5-ton Carrier Infinity dual fuel system with three zones, a modulating gas furnace, an upsized primary bedroom supply, new 8 inch returns, a MERV 15 air purifier and a REME HALO LED.

Did the install pass inspection?

In plain words. No, not the first time. The first inspection for the city permit failed because the condenser was not anchored down. Our tech fixed it on June 2, 2026, and the reinspection passed on June 10, 2026.

How long did the install take?

In plain words. Two days. The crew started at 7:37 AM on May 20, 2026 and took out both old systems and worked on the ductwork and returns. On May 21 they set the new equipment, finished the ductwork, pressure tested, evacuated and started the system. Fredi, Pablo, Israel and Adonis installed it.

What indoor air quality equipment was added?

In plain words. A Carrier Infinity Air Purifier (DGAPAXX2025, MERV 15) and an RGF REME HALO LED in the duct system. The homeowner wanted to explore a media filter, a dehumidifier and UV light, and the homeowner's review says they woke up without a stuffy nose for the first time in four years in the home.

Does the new system need a separate hookup for the solar and the generator?

In plain words. No. The solar and generator connect to the home's main electrical panel, so the new system works with both without a separate hookup.

Has there been any problem since the install?

In plain words. On June 10, 2026 our tech visited after the control showed error alerts on June 8 and 9 for an open fuse and lost power at the condenser. The condenser was not running. The tech pulled the disconnect, reinstalled the fuses and the system started working again. It was covered at $0 to the homeowner. The homeowner has had no other issues to date.

Proof and sources

In plain words. These records support the project details and calculations.

• ACCA Manual J 8th Edition load calculation; ACCA Manual S equipment selection report; survey findings and photos; install photos; invoice; Carrier registration (May 27, 2026); permit and inspection record; warranty visit record.
• Carrier product data: 27VNA060A003 product page and product data; 59MN7 product page and product data; CVAMA product data and spec sheet; SYSTXCCITC01-C and control product data; SYSTXCC4ZC01; SYSTXZNSMS01; zone board and damper installation instructions; zone damper product data; Infinity Air Purifier DGAPAXX2025; RGF HALO LED.
• NCI Field Duct Sizing Chart (flex duct values used for the supply and return takeoffs).
• AHRI 215677063, AHRI Directory listing; ENERGY STAR certified heat pump list.
• TDLR license search for TACLB00153401E, the license Atlas AC Repair operates under.