Carrier Programmable Dual Fuel Thermostats Installation, Start-up, And Operating Instructions Manual

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Programmable Dual Fuel ThermostatsInstallation, Start-Up, and Operating InstructionsNOTE: Read the entire instruction manual before starting theinstallation.This symbol → indicates a change since the last issue.SAFETY CONSIDERATIONSRead and follow manufacturer instructions carefully. Follow alllocal electrical codes during installation. All wiring must conformto local and national electrical codes. Improper wiring or installa-tion may damage thermostat.Recognize safety information. This is the safety-alert symbol .When you see this symbol on the equipment and in the instructionmanual, be alert to the potential for personal injury.Understand the signal words DANGER, WARNING, and CAU-TION. These words are used with the safety-alert symbol. DAN-GER identifies the most serious hazards which will result in severepersonal injury or death. WARNING signifies a hazard whichcould result in personal injury or death. CAUTION is used toidentify unsafe practices which would result in minor personalinjury or product and property damage.INTRODUCTIONCarrier’s 7-day programmable dual fuel thermostat is a wall-mounted, low-voltage thermostat which provides proper control ofa heat pump (HP) and furnace combination without using aHP/furnace interface kit. Separate heating and cooling setpoints,plus auto changeover allow setback programming for maximumenergy savings. Up to 4 time/temperature settings per 24 hourperiod for 7 independent days may be programmed. Batteries arenot required; during a power interruption, the internal memorystores programs for an unlimited time and the clock continues torun for at least 72 hrs.SYSTEM CONSIDERATIONSThe dual fuel thermostat is designed to be used only in HP/furnaceinstallations. It replaces a conventional 2-stage HP thermostat anda HP/furnace interface kit. An outdoor temperature sensor, PartNo. TSTATCCSEN01 MUST be used with this thermostat. It isnot supplied with thermostat.If HP is not already equipped with a high-pressure switch, onemust be added for dual fuel applications. It protects HP fromoverpressure which would occur if a failure resulted in bothHP and furnace operating at same time. Kit No.KSAHI0201HPS includes required switch and instructionsfor its proper installation.A HP/furnace installation has several special requirements. Fore-most is that furnace and HP must not be allowed to operate at sametime, except during HP defrost. A second is to have furnacecomplete a heating cycle once it is turned on. A third is the needto have HP not operate at all when outdoor temperatures are belowa certain value. Finally, HP and furnace must work togetherproperly to provide an efficient and comfortable defrost. Theserequirements are addressed by the dual fuel thermostat itself andan interface kit is NOT required.APPLICATIONThe dual fuel thermostat is designed for the following applications:1-stage cool, 2-stage heat: 1-speed HP with 1-stage furnace1-stage cool, 3-stage heat: 1-speed HP with 2-stage furnace2-stage cool, 3-stage heat: 2-speed HP with 1-stage furnace2-stage cool, 4-stage heat: 2-speed HP with 2-stage furnace**This combination must use furnace algorithm to control furnacestaging.As outdoor temperature decreases, heat loss increases and HPcapacity decreases. There is a temperature below which HP willnot be able to ″keep up″ and furnace will be required to maintaintemperature. This is the thermal balance point.There is also an economic balance point, determined by relativecosts of fuel and electricity, below which the furnace is the mostcost effective and above which the HP is the most cost effective.Finally there may be a comfort balance point below which leavingair temperature of HP is not comfortable, even if HP has sufficientcapacity to keep structure warm.Any of these balance points may be the determining factor in theselection of an outdoor temperature below which HP will be turnedoff and only furnace allowed to operate. This balance pointtemperature is entered into thermostat by installer. Outdoor tem-peratures from 15˚F to 55˚F may be selected. Instructions forentering this selection is covered in the section: BalancePoint—Value Selection.When outdoor temperature is below selected balance point tem-perature, furnace is used exclusively to supply heat.Fig. 1—Carrier Programmable ThermostatA94134®HEIGHT (IN.) WIDTH (IN.) DEPTH (IN.)4-1/4 7-1/2 1-3/8Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.Book 1 4Tab misc. misc. PC 101 Catalog No. 92-33TS-TA35C Printed in U.S.A. Form TSTAT-9SI Pg 1 2-96 Replaces: TSTAT-6SI