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HVAC and Plumbing Distributor
Steven Simmons

Steven Simmons

Technical Services Manager
Southwest District

Using a Standard Thermostat with a Communicating System for Emergency Operation

On rare occasions the infinity wall controllers fail. Sometimes, this failure is after hours and the supply house is closed. Periodically, homeowners do not want to purchase another wall controller due to cost and they researched their unit on the web and read that a “regular or standard” thermostat will work their Infinity system.

I have to say first, that it is highly recommended that Infinity series equipment be used with an Infinity wall control; this way all the features of the unit the customer initially bought can be utilized and when there is a malfunction it is communicated to all the equipment to better protect against further damage. The installation manual provided from Carrier for the FE4A/FE5A does NOT show an option for wiring a standard Thermostat nor Thermidistat to the fan coil, only an Infinity wall controller. Furthermore, ALL the manuals for outdoor Infinity equipment state that an Infinity wall controller MUST be used.  All manuals do say however that a standard thermostat can be used to control the unit’s control boards using emergency operation modes. There is NO guarantee that it will work indefinitely because the terminals that will be used to wire the board are intended to be outputs for a non-communicating outdoor unit not inputs from a thermostat. If the unit is being ran in emergency operation with a standard thermostat then there will be no control of humidity, no air flow staging, and the unit will not provide the level of efficiency nor comfort that they were receiving with the Infinity wall controller. Carrier states in the FE4A/FE5A manual “(Emergency mode) should only be activated when User Interface cannot be replaced immediately”.

If through troubleshooting it is found that the wall controller is faulty and must be replaced, the wall controller should be changed and replaced with a newer model. If it happens to be after hours, on the weekend, a holiday, or the wall controller is not available, then the indoor and outdoor control boards will allow emergency heating and cooling operations using a standard thermostat. If the FE4A/FE5A control board does not have communication with a wall controller for a period exceeding two minutes then the unit will flash a code 16, system communication fault.

To utilize this emergency operation modes the thermostat, fan coil, and outdoor unit must be unwired from the ABCD terminals and be rewired for R, G, W, Y, O, C. When the unit is wired appropriately, the two-minute time period has lapsed, and the indoor is flashing a code 16 on the status LED the unit will start responding to the emergency inputs. If the indoor control board retains the tonnage of the outdoor equipment, then the indoor will provide the air flow of 350 CFM times the tonnage of the outdoor. If the indoor control board does retain the information of the outdoor equipment then the indoor board will provide 350 CFM per ton for the highest possible matched outdoor unit for each indoor unit size:

002: 1050 CFM;             003/004: 1225 CFM;      005:1400 CFM;             006:1750 CFM;

Thermostat HVAC Supply House
Thermostat HVAC Supply House
Thermostat HVAC Supply House
Thermostat HVAC Supply House

The thermostat should be programmed for either 2H/2C or 3H/2C depending on your outdoor equipment. Use the chart to wire the thermostat and follow from left to right to see where each wire will be terminated according to which model outdoor unit you have. The chart represents the latest models found in Carrier’s Catalog.

 

Thermostat

Fan coil

Heat Pumps

3H/2C

FE4A

25HNAB6/9

25VNA8

25VNA0

25VNA4

R

R

 

R

 

 

C

C

C

C

C

C

O

O

O

O

O

O

Y1

Y

Y1

Y1

Y

Y1

Y2

 

Y2

Y2

 

Y2

G*

G*

 

 

 

 

W2/AUX

W

W

W

 

W

*not all indoor control boards have a G terminal

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Alabama Locations

Anniston (256) 241-3026 105 E D St, Anniston, AL 36201
Auburn (334) 734-8011 2295 1st Ave, Opelika, AL 36801
Birmingham (205) 250-7714 516 31st St N, Birmingham, AL 35203
Dothan (334) 836-1035 205 Wedgewood Dr, Dothan, AL 36303
Gulf Shores (251) 968-2660 820 Commerce Dr, Gulf Shores, AL 36542
Huntsville (256) 859-2691 391 Nick Fitcheard Rd NW, Huntsville, AL 35806
Loxley (251) 964-2707 30020 Co Rd 49, Loxley, AL 36551
Mobile (251) 476-2220 5522 W Commerce Blvd West, Mobile, AL 36619
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Georgia Locations

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Athens(706) 548-2563105 Whitetail Way, Bogart, GA 30622
Atlanta(404) 875-77551290 Tacoma Dr NW, Atlanta, GA 30318
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Brunswick(912) 265-5193275 Rose Dr, Brunswick, GA 31520
Columbus(706) 322-38706201 W Hamilton Park Rd, Columbus, GA 31909
Conyers(770) 918-9132335 Gees Mill Business Pkwy NE, Conyers, GA 30013
Forest Park(404) 361-24745158-C Kennedy Rd, Forest Park, GA 30297
Gainesville(770) 297-93352472 Hilton Dr, Gainesville, GA 30501
Lawrenceville(678) 442-10602111 Cedars Rd SE, Lawrenceville, GA 30043
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Macon(478) 474-85445527 Thomaston Rd, Macon, GA 31220
Marietta(770) 426-05511060 Triad Ct, Marietta, GA 30062
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Valdosta(229) 245-8200363 Connell Rd, Valdosta, GA 31602
Warner Robins(478) 953-3727110 Byrd Way, Warner Robins, GA 31088

South Carolina Locations

Hilton Head(843) 689-34043715, 21 Hunter Rd, Hilton Head Island, SC 29926

Florida Locations

Fort Walton Beach(850) 244-201776 Beal Pkwy SW, Fort Walton Beach, FL 32548
Panama City(850) 913-05853012 Lisenby Ave, Panama City, FL 32405
Pensacola(850) 438-10054405 N. Palafox Street, Pensacola FL 32505

Mississippi Locations

Hattiesburg(601) 579-96701851 Lincoln Rd, Hattiesburg, MS 39402
Ocean Springs(228) 497-5090Sunplex Industrial Park, 5717 Suntec Drive, Ocean Springs, MS 39564

Commercial Sales

Norcross – North Georgia Hub
(800) 282-4911

Birmingham – North Alabama Hub
(205) 250-7714

Macon – Southwest Hub
(800) 342-9250

Loxley – Gulf Coast Hub
(800) 239-7419

Savannah – Southeast Hub
(800) 822-7617

Commercial Parts

 CompanyWeb AddressDescription
Airzonewww.airzoneinc.comCustom and Underfloor Air Handlers
Aladdin Metal Productswww.aladdinmetalproducts.comCurb Adapters and Roof Curbs
Aprilairewww.aprilaire.comIndoor Air Quality Products
Autaniwww.autani.comBuilding Automation and Controls
Bardwww.bardhvac.comHeat Pumps,Gas/Electric, and Wall Mounted Air Conditioners
Bryantwww.bryant.comCommercial, Industrial, Residential Heating & A/C Products and Controls
Carrierwww.commercial.carrier.comCommercial and Residential Heating & A/C Products
Data Airewww.dataaire.comPrecision Air Control for Data Processing Centers
 DXairwww.dxair.comPool dehumidification systems
 First Companywww.firstco.comFan Coil Units
Global Plasma Solutionswww.gpshvac.comAir Purification and Bi-Polar Ionization
 Greewww.greeusa.comPTACs
 Hayes Fluid Controlswww.haysfluidcontrols.comHose Kits and Control Valves
 iAirewww.myiaire.comCommercial Air Purification using ionization with energy savings
 IslandAirewww.islandaire.comPTACs, Vertical Units, Water Source Heat Pumps
 i-Vuwww.commercial.carrier.comBuilding Automation and Controls
 Magic Airewww.magicaire.comFan Coil Units
 Micro Metlwww.micrometl.comRoof Curbs, RTU Accessories, & ERVs
 Modinewww.modine.comGas-Fired Unit Heaters, Duct, Furnaces, Hot Water Cabinet Unit Heaters, Makeup Air, and Dedicated Outdoor Air Systems
 Network Thermostatwww.networkthermostat.comInternet Thermostats, Wifi Themostats, Ethernet Thermostats
Paynewww.payne.comResidential Heating & A/C Products
Rawal Deviceswww.rawal.comContinuous Capacity Modulation and Dehumidification for DX Systems
Renew Airewww.renewaire.comFixed-Plate ERVs
Totalinewww.totaline.comCompressors, Parts, and Supplies
United CoolAirwww.unitedcoolair.comModular All-Indoor HVAC Systems
 Warren Technologywww.warrenhvac.comElectric Heaters
 Wilo Pumpswww.wilo-usa.comPump Systems for HVAC and Water Supply and Sewage