FORM NO. X11-1117 REV. 7 Supersedes Form No. X11-1117 Rev. 6 ACCESSORY ITEMS FOSSIL FUEL KITS RXPF- SERIES Model RXPF-F01 Model RXPF-F02 IMPORTANT: The RXPF-F01 & RXPF-F02 are designed for use with Rheem manufactured equipment only. Use of any other equipment may void warranty and/or give undesired results. RXPF Fossil Fuel Kits The Rheem RXPF Fossil Fuel Kits are intended to be used where the heat pump may provide heat at a lower cost than oil, natural gas or L.P. gas within a certain outdoor temperature range. The kit permits the heat pump to operate at temperatures (usually from 30 F to 35 F and above) where the heat pump is most efficient. For the colder periods, the heating will be provided by a standard fossil fuel furnace which has approximately the same efficiency at all temperatures. The RXPF Fossil Fuel Kits are for use with Rheem Heat Pumps only and most fossil-fueled warm air furnaces. They operate by turning the heat pump off at a pre-determined outdoor temperature permitting the furnace to heat as demanded by the wall thermostat. When the outdoor temperature warms up, it will lock out the furnace and let the heat pump do the heating. A plenum switch is employed that will, during heat pump defrost, turn the furnace on as required to prevent cold drafts. The set point of the kit is adjustable. The recommended set point should be that temperature at which the heat pump will just provide 100% of the heating requirements. When used with a recommended thermostat, the emergency heat feature easily allows conversion to 100% fossil fuel heat should the heat pump fail, for any reason. Also, the heat pump-only switch on the kit allows 100% use of the heat pump if for any reason the fossil fuel heat should fail (such as component failure or lack of fossil fuel). RXPF-F01 Heat Pump Operation when Outdoor Air Temperature is above set point. Gas Furnace Operation when Outdoor Air Temperature is below set point. ( Heat Blower Speed) Indoor Thermostat set to Heat Outdoor Thermostat Set to Heat Pump Only, only the Heat Pump Operates. Indoor Thermostat Set to Emer, only the Furnace Operates on 1st Stage. Defrost, Furnace cycles on when supply air temp. drops to 95 F, Cycles Off when supply air temp. reaches 110 F. Blower runs in cooling speed. Contents for RXPF-F01: Plenum Switch Assy. (AS-52048-03) Outdoor Thermostat (41-20874-01) Wiring Diagram Thermostat (90-20873-03) Booklet Remote Heat Pump (92-21779-08) Installation Instructions (92-20871-23)
RXPF-F02 with Single-Stage Fossil-Fuel Furnace (For T.V.A.) Meets Tennessee Valley Authority (T.V.A.) requirements (No connection to E on Indoor Thermostat). 1st Stage, Heat Pump Operates. 2nd Stage, Furnace Operates, Heat Pump Shuts Off. Indoor Thermostat Set to Emer Furnace Operates on 1st Stage (Optional). Defrost, Furnace cycles on when supply air temp. drops to 95 F., cycles off when supply air temp. reaches 110 F. Blower in Cooling Speed (for TVA, in Defrost 2nd Stage On has no effect). Contents for RXPF-F02: Interface Wiring Board (62-24102-01) Plenum Switch Assy. (AS-52048-03) Outdoor Thermostat (41-20874-01) Wiring Diagram Thermostat (90-20873-03) Relay (42-101208-01) (For use with modulating furnaces only) Booklet Remote Heat Pump (92-21779-08) Installation Instructions (92-20871-23) Note: The relay (42-101208-01) in this kit is only for use with Rheem modulating gas furnaces. The relay is to be discarded for all other applications. To wire this relay, use field wiring with the terminals supplied in this kit. WHEN TO USE AN RXPF-F02 INSTEAD OF AN RXPF-F01: 1. WHEN UNDER THE TVA JURISDICTION (ALWAYS) 2. WHEN THERE IS A NEED TO HAVE FOSSIL FUEL ONLY FOR THE SECOND STAGE OF HEAT. (A TWO-STAGE HEAT PUMP THERMOSTAT MUST BE USED.) 3. WHEN THERE IS A NEED TO USE A MODULATING GAS FURNACE AS A SECONDARY HEAT SOURCE TO A HEAT PUMP. (A TWO-STAGE HEAT PUMP THERMOSTAT MUST BE USED.) As with the RXPF-F01, a plenum switch is provided to control heat in the defrost mode. This switch prevents the evaporator coil from overheating when gas heat is running in the defrost mode. Also, as with the RXPF-F01, the setpoint of the outdoor thermostat is adjustable allowing the installer to adjust the point at which the system will switch from heat pump to fossil heat. Unlike the RXPF-F01, The RXPF-F02 can be used with second-stage heat as the control of the RXPF-F02 turns off the Y signal to the IFC and the cooling contactor when second-stage heat is engaged. This makes the kit ready for use in the Tennessee Valley Authority region where the use of the emergency heat feature is not permitted. In this region, the use of W2 to turn on the fossil heat is the only permissible way that fossil heat can be used with a heat pump. The homeowner can not force the unit to use fossil heat by switching the system to Emergency heat. The only permissible ways to use fossil heat with a heat pump in the TVA region are: 1. When the heat pump can not provide enough heat (forcing the thermostat to call for second stage heat) or 2. When the outdoor temperature is sufficiently below the setpoint of the outdoor thermostat to force the system to engage fossil heat. IN THE REGION CONTROLLED BY THE TVA, THE HOMEOWNER CANNOT FORCE THE FOSSIL HEAT ON BY SWITCHING TO EMERGENCY HEAT. FOR THIS REASON AN RXPF- F02 KIT MUST BE USED WITH NO CONNECTION TO THE EMERGENCY HEAT ON THE THERMOSTAT. FOSSIL HEAT CONNECTIONS MUST BE MADE TO W2 ON THE THERMO- STAT AND NOT TO THE EMERGENCY HEAT TERMINAL. The RXPF-F02 can also be used with the Rheem modulating gas furnace to provide excellent temperature control during heating. When wired as shown in this document, the modulating furnace will provide minimal heat (40% gas or heat pump) in first stage and gas heat at 65% to 100% in second stage. This provides a comfort level exceeding that of a two-stage furnace while also yielding the cost benefits of both gas and heat pump. During transition between heat pump and gas furnace (directed by the Outdoor Thermostat set point or thermostat staging), blower is off. Furnace runs through normal sequence timings. CAUTION: Before installing any heat pump system with an existing furnace be sure that the duct system, blower and blower motor will provide the air required for the heat pump. The heat pump will not work satisfactorily with low air flows across the indoor coil. CONTENTS: Product Description & System Operation...Pages 14-15 Wiring Diagrams Table of Contents RXPF-F01 RXPF-F02 Time/temp defrost control, single phase condensor, R22 refrigerant...3 Demand-based defrost control, single phase condensor, R22 refrigerant....4 Time/temp defrost control, single phase condensor, R22 refrigerant...7 Demand-based defrost control, single phase condensor, R22 refrigerant....8 MODULATING FURNACE W/RXPF-F02 Demand-based defrost control, single phase condensor, R22 refrigerant...11 Demand-based defrost control, three phase condensor, R22 refrigerant...12 Demand-based defrost control, three phase condensor, R22 refrigerant...5 Demand-based defrost control, single phase condensor, R410A refrigerant...6 Demand-based defrost control, three phase condensor, R22 refrigerant...9 Demand-based defrost control, single phase condensor, R410A refrigerant...10 Demand-based defrost control, single phase condensor, R410A refrigerant...13 2 Rheem Manufacturing Company
RXPF-F01 WITH TIME/TEMPERATURE DEFROST CONTROL, SINGLE-PHASE CONDENSOR & R22 REFRIGERANT Rheem Manufacturing Company 3
RXPF-F01 WITH DEMAND-BASED DEFROST CONTROL, SINGLE-PHASE CONDENSOR & R22 REFRIGERANT 4 Rheem Manufacturing Company
RXPF-F01 WITH DEMAND-BASED DEFROST CONTROL, THREE-PHASE CONDENSOR & R22 REFRIGERANT Rheem Manufacturing Company 5
RXPF-F01 WITH DEMAND-BASED DEFROST CONTROL, SINGLE-PHASE CONDENSOR & R410A REFRIGERANT 6 Rheem Manufacturing Company
RXPF-F02 WITH TIME/TEMPERATURE DEFROST CONTROL, SINGLE-PHASE CONDENSOR & R22 REFRIGERANT (TVA COMPLIANT) Rheem Manufacturing Company 7
RXPF-F02 WITH DEMAND-BASED DEFROST CONTROL, SINGLE-PHASE CONDENSOR & R22 REFRIGERANT (TVA COMPLIANT) 8 Rheem Manufacturing Company
RXPF-F02 WITH DEMAND-BASED DEFROST CONTROL, THREE-PHASE CONDENSOR & R22 REFRIGERANT (TVA COMPLIANT) Rheem Manufacturing Company 9
RXPF-F02 WITH DEMAND-BASED DEFROST CONTROL, SINGLE-PHASE CONDENSOR & R410 REFRIGERANT (TVA COMPLIANT) 10 Rheem Manufacturing Company
RXPF-F02 WITH DEMAND-BASED DEFROST CONTROL, SINGLE-PHASE CONDENSOR & R22 REFRIGERANT WITH MODULATING (-)GFD & (-)GGD GAS FURNACES (TVA COMPLIANT) Rheem Manufacturing Company 11
RXPF-F02 WITH DEMAND-BASED DEFROST CONTROL,THREE-PHASE CONDENSOR, R22 REFRIGERANT WITH MODULATING (-)GFD & (-)GGD GAS FURNACES (TVA COMPLIANT) 12 Rheem Manufacturing Company
RXPF-F02 WITH DEMAND-BASED DEFROST CONTROL, SINGLE-PHASE CONDENSOR, R410A REFRIGERANT WITH MODULATING (-)GFD & (-)GGD GAS FURNACES (TVA COMPLIANT) Rheem Manufacturing Company 13
Fossil Fuel Kit Application FURNACE RGLK RGPK RGRA RGLH RGPL ROBD RGLJ RGPN ROPD RGLL RGPJ RGGD, RGFD 1.0 Product Description FOSSIL FUEL KIT RXPF-F01 OR RXPF-F02 (TVA OR TWO-STAGE) RXPF-F02 The Fossil Fuel Kit (FFK) Interface Wiring Board (IWB) provides a common low-voltage wiring terminal for a Heat Pump system which uses the Heat Pump as the primary heat source and a Gas Furnace for the secondary heat source (a.k.a. the Dual Fuel system). The IWB provides functional control of the system by routing low-voltage thermostat outputs to the desired input of the Heat Pump Outdoor Unit, the Integrated Furnace Control (IFC), and the Outdoor Thermostat and/or isolating inputs that are not desired. 2.0 Function Definitions 2.1 Emergency Heat Setting the indoor thermostat such that the gas furnace is the primary heat source and the heat pump is locked out. 2.2 Auxiliary Heat The secondary heat source is energized by the system controls when the primary heat source is not sufficient (the primary heat source is locked out). 2.3 Second-Stage Heat The secondary heat source is energized by second stage of a two-stage indoor thermostat (the primary heat source is locked out). For modulating furnaces, the primary heat source can be gas at 40% or heat pump. 2.4 Back-Up Heat The secondary heat source is energized by the outdoor thermostat or outdoor condensing unit control system. 2.5 Balance Point Outdoor temperature below which the secondary heat source is preferred over the primary heat source. (May be determined by heating capacity, comfort, efficiency and/or economy.) 2.6 Defrost A function of the Heat Pump Control System which causes the Heat Pump to temporarily function in the air conditioning mode during a heating cycle in order to pump heated refrigerant to the outdoor condensing unit; during this period, the operation of the Gas Furnace is controlled by the plenum sensor for backup heat to ensure warm airflow indoors. 3.0 Function Specifications 3.1 Emergency Heat Controlled by switch settings on the indoor thermostat. Wired to the E terminal (indoor thermostat) on the FFK IWB. 3.2 Auxiliary Heat Controlled by: (1) the indoor thermostat, (2) the outdoor thermostat, and/or (3) the Heat Pump control system. Wired to the three W2 terminals (indoor thermostat, outdoor thermostat, and heat pump outdoor unit) on the FFK IWB. 3.3 Second-Stage Heat Auxiliary Heat controlled by the indoor thermostat {3.2 (1)}. Wired to W2 on the indoor thermostat. 3.4 Back-Up Heat Auxiliary Heat controlled by the outdoor thermostat {3.2 (2)} or the heat pump outdoor unit control system {3.2 (3)}. Wired to W2 on the outdoor thermostat and W2 on the heat pump outdoor unit respectively. 3.5 Balance Point The temperature setting of the outdoor thermostat (Range: 10 F to +50 F). Above this setting, the heat pump is the primary heat source. Below this setting, the gas furnace is the primary heat source. The first-stage heat demand signal from the indoor thermostat in output through the OD terminal to the outdoor thermostat and the signal is routed back from the outdoor thermostat to either W2 (outdoor temperature is below the set point) or Y (outdoor temperature is above the set point). 3.6 Defrost The heat pump outdoor unit control system runs the outdoor unit in the air conditioning mode and outputs a signal for back-up heat through the W2 terminal. 4.0 System Operation 4.1 Call for Heat (1) The system receives a demand for heat from the indoor thermostat. ( Y and B ) B is energized when the indoor thermostat is set to HEAT Y is energized when the indoor thermostat first stage makes a demand for heat (2) B is routed directly to the outdoor unit for the heat pump heating control system (usually the reversing valve). (3) Y is routed through the outdoor thermostat: Y is energized above the outdoor thermostat set point. (to outdoor unit and IFC) W2 is energized below the outdoor thermostat set point. (to W on the IFC) 4.2 Call for Second-Stage Heat (1) The system receives a thermostat demand for second-stage heat. ( W2, Y and B ) (2) W2 is routed to the furnace control and the Y circuit is de-energized by the FFK IWB. 4.3 Call for Defrost (1) The system receives back-up heat demand from the outdoor unit control ( W2 and Y ) (2) The second-stage heat circuit from the indoor thermostat is de-energized by the FFK IWB. (3) D (sometimes W2) from the outdoor unit is routed through the Plenum Sensor to W on the IFC. (4) The Plenum Sensor energizes W on the IFC to provide back-up heat -OR- (5) The Plenum Sensor de-energizes W on the IFC to control the temperature of the indoor coil. (6) The Y circuit remains energized on the IFC. 4.4 Call for Emergency Heat (1) The indoor thermostat routes all heat demands to the IFC. ( E and W2 ) Note: This circuit connection is optional and this function is not allowed by some local codes. 4.5 Call for Cool (1) The system receives a demand for cooling from the indoor thermostat. ( O and Y -or- Y + G ) Y is energized (outdoor unit and IFC) when the indoor thermostat makes a demand for cool. O is energized when the indoor thermostat is set to COOL. (2) O is routed directly to the outdoor unit for the heat pump cooling control system (usually the Low-Ambient relay or alternate reversing valve control system). 4.6 Call for Fan-On (1) The system receives a demand for continuous fan from the indoor thermostat. ( G ) (2) The G circuit is energized on the IFC. 5.0 System Operation with Modulating Gas Furnace with RXPF-F02 NOTE: MODULATING CONTROL MUST BE RHEEM PART NUMBER 62-24174-01 REV. 03 OR NEWER. NOTE: BOTH DIP SWITCHES OF SW-2 OF THE MODULATING CONTROL (IFC) MUST BE IN THE ON POSITION (TIMED TWO-STAGE HEAT OPERA- TION). NOTE: THERMOSTAT MUST HAVE A W2 CONNECTION FOR SECOND-STAGE HEAT WHEN CONFIGURED FOR A MODULATING FURNACE. REFER TO THE WIRING DIAGRAM(S) ON PAGE 7 OF THIS DOCUMENT. 5.1 First-Stage Heat Call (Thermostat Y + B ) (1) The system receives a demand for heat from the indoor thermostat ( Y and B ) B is energized when the indoor thermostat is set to HEAT Y is energized when the indoor thermostat calls for heat. (2) B is routed directly to the outdoor unit for the heat pump heating control system. (Usually a reversing valve). 14 Rheem Manufacturing Company
(3) Y is routed to the outdoor thermostat: Condition 1: When the outdoor air temperature is above the setpoint of the outdoor thermostat and the indoor thermostat only senses a need for firststage heat, the operation is normal heat pump. Both the cooling contactor on the condenser and cooling speed fan on the control board (IFC) (via Y ) are energized at this point. Condition 2: When the outdoor air temperature is below the setpoint of the outdoor thermostat and the indoor thermostat only senses a need for firststage heat, heating control is switched directly to the modulating gas furnace by energizing W on the modulating control (IFC) alone. This will give 40% (low fire) gas heat until either a second-stage heat call is present or the thermostat heat call is satisfied. At this point, the thermostat has energized both Y and B, but the fossil fuel kit changes the Y signal into a W call to the modulating control. The cooling contactor is de-energized during this mode and the compressor and condenser fan are turned off. The reversing valve (via B ) is energized throughout Condition 1 or 2, but is ignored and has no consequence in Condition 2 since the compressor and condensing fan are not running in Condition 2. 5.2 Second-Stage Heat Call (Thermostat W2 + Y + B ) (1) When the system thermostat determines that the indoor air temperature is significantly below the setpoint of the thermostat, it will call for second-stage heat. Second-Stage heat with a modulating furnace as installed and wired per this document will be gas heat starting at 65% of full fire. W2, Y and B are simultaneously energized by the thermostat. W2 is routed to the modulating furnace control to energize both W and V/W2 on the modulating control board (IFC) (through the relay provided with the RXPF-F02). This turns on gas heat at 65% for seven minutes followed by 100% gas heat until the Second-Stage heat call is satisfied. Y is turned off by the FFK IWB (Fossil Fuel Kit Interface Wiring Board) so that the cooling contactor is NOT energized. Note: At this point, Y from the thermostat to the FFK IWB will be energized, however, neither Y between the FFK IWB and the cooling contactor nor Y between the FFK IWB and the modulating control (IFC) will be energized. The reversing valve (via B ) is energized during the Second-Stage heat call, but is ignored and has no consequence on the system since the compressor and condensing fan will not be running during Second-Stage Heat. 5.3 Defrost (Thermostat Y + B ) (Defrost Control W2 or D ) (1) The system receives a backup heat demand from the outdoor unit defrost control (Defrost Control W2 or D ) (2) When the defrost control determines there is a need to defrost the coil, the heating call is re-routed by the defrost control back to the FFK IWB. The Defrost control also forces the reversing valve to run the AC system in cooling. (3) The Defrost mode heat call from the outdoor unit is routed to the FFK IWB, through the Plenum Sensor and finally to W and V/W2 on the modulating control (IFC). The modulating furnace begins heating at 65% of full fire for seven minutes followed by 100% until the heat/defrost call is satisfied. (4) A plenum switch is provided to control heat in the defrost mode. This switch prevents the evaporator coil from overheating when gas heat is running in the defrost mode. (5) The Y (Cooling) circuit remains energized on the modulating control (IFC). This means that the furnace is running at either 65% or 100% of full fire heat with cooling speed blower. (6) The compressor and condensing fan of the cooling system will be running in the cooling direction during the Defrost mode to transfer heat to the condensing coil to melt away any frost or ice build-up on the condenser. The reversing valve (via B) is de-energized during the defrost cycle. During defrost mode, B from the thermostat through the FFK IWB and out to the defrost control will be energized, but the circuit from the defrost control to the reversing valve will NOT be energized as the defrost control forces the reversing valve into cooling. 5.3 Call for Emergency Heat (Thermostat E ) (1) In the Emergency Heat mode, the indoor thermostat routes all heat demands (first- and second-stage) to the modulating furnace so that, with an Emergency heat call from the thermostat, gas heat will turn on at 65% of full fire for seven minutes followed by 100% until the Emergency Heat call is satisfied. The reversing valve (via B ) is energized during the Emergency Heat call, but is ignored and has no consequence on the system since the compressor and condensing fan will not be running during Emergency Heat. 5.4 Call for Cooling (Thermostat O, Y & G or Y & G ) (1) In the cooling mode, the system receives a demand for cooling from the indoor thermostat. When the thermostat recognizes a need for cooling, Y is energized by the thermostat and the FFK IWB uses this signal to energize Y to the modulating control (IFC) and to the cooling contactor. In cooling, B is de-energized and O is energized. This sets the reversing valve for the cooling mode. (2) O is routed to the outdoor unit for the heat pump cooling control system (usually the Low-Ambient relay or alternate reversing valve control system.) 5.5 Call for Continuous Fan (Thermostat G ) (1) The system receives a demand from the indoor thermostat G. (2) The fan call is routed directly to the G terminal on the modulating control (IFC). Rheem Manufacturing Company 15
Before proceeding with installation, refer to installation instructions packaged with each model, as well as complying with all Federal, State, Provincial, and Local codes, regulations, and practices. RHEEM AIR CONDITIONING DIVISION 5600 Old Greenwood Road, Fort Smith, Arkansas 72908 In keeping with its policy of continuous progress and product improvement, Rheem reserves the right to make changes without notice. PRINTED IN U.S.A. 1-05 DC FORM NO. X11-1117 REV. 7 Supersedes Form No. X11-1117 Rev. 6