Instruction/ maintenance manual of the product 51M37 Lennox International Inc.
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05/05 505,050M *2P0505* *P505050M* Page 1 E 2005 Lennox Industries Inc. Dallas, T exas, USA RET AIN THESE INSTRUCTIONS FOR FUTURE REFERENCE 51M37 Merit ® Series Thermost at The Lennox Merit ® Series 5/2 day programmable electronic thermostat 51M37 provides excellent temperature control and a large, easy-to-read display .
Page 2 505050M 5/1/05 Within a few seconds, the Home Screen appears (see fig- ure 2) with default settings as shown. After about 1 minute of initialization time, the actual room temperature will be displayed. NOTE − T ables 2 and 3 on page 8 show all system and programming default s.
Page 3 51M37 SERIES 5/2 HEA T − Using the Heat Mode Normal Heat Mode In normal heat mode, both the heat pump and the backup heat source are used to provide heat. If the thermost at d e- tects that the heat pump is not able to provide enough heat (as may be the case in very cold weather), then the backup heat source is activated.
Page 4 505050M 5/1/05 COOL − Using the Cool Mode Enabling and Disabling Cool Mode Use the COOL button to enable or disable cool mode as desired. If the thermostat is in HEA T or OFF mode, cool mo d e is enabled when the COOL button is pressed. This is indicated by COOL in the SYSTEM box (s ee f i gu r e 9).
Page 5 51M37 SERIES 5/2 HOLD − Using T emperature Hold Modes When HOLD is displayed at the HOME screen, the ther- mos tat is in a temperature hold condition. This means that the temperature program data is ignored and the thermo- stat functions much like a non−programmable thermost at.
Page 6 505050M 5/1/05 5. Repeat step s 2 through 4 for periods B, C, and D. 6. Repeat step s 1 through 5 for the 2−day program. NOTE − This thermost at will NOT automatically switch from heating to cooling, or vice versa; operator involve- men t is required.
Page 7 51M37 SERIES 5/2 SETTINGS − Balance Point NOTE − The balance point is only available with the out- door sensor . If the optional outdoor sensor (X2658) is connected to the thermostat, balance point adjustment is available.
Page 8 505050M 5/1/05 Default Thermostat Settings Default thermostat settings are shown in table 2 and the default program is shown in table 3. T able 2 Default Thermostat Settings Mode Heat (Permanen.
Page 9 51M37 SERIES 5/2 Smart Setback Recovery (via DIP switch #6) Smart Setback Recovery (SSR) affects the way the ther- mo st at responds to program events. If SSR is disabled, th e thermostat will react to a program event at the time the event occurs.
Page 10 505050M 5/1/05 Thermostat Output T able T able 5 depicts the 51M37 thermostat output st ates for var- ious input conditions. The following notes described terms used in the t able.
05/05 505,049M *2P0505* *P505049M* Page 1 E 2005 Lennox Industries Inc. Dallas, T exas, USA RET AIN THESE INSTRUCTIONS FOR FUTURE REFERENCE 51M35 Merit ® Series Thermost at The Lennox Merit ® Series 5/2 day programmable electronic thermostat 51M35 provides excellent temperature control and a large, easy-to-read display .
Page 2 505049M 5/1/05 Within a few seconds, the Home Screen appears (see fig- ure 2) with default settings as shown. After about 1 minute of initialization time, the actual room temperature will be displayed. NOTE − T ables 2 and 3 on page 6 show all system and programming default s.
Page 3 51M35 SERIES 5/2 HEA T − Using the Heat Mode Enabling and Disabling Heat Mode The thermostat must be in the HEA T mode to control the heating equipment.
Page 4 505049M 5/1/05 HOLD − Using T emperature Hold Modes When HOLD is displayed at the HOME screen, the ther- mos tat is in a temperature hold condition. This means that the temperature program data is ignored and the thermo- stat functions much like a non−programmable thermost at.
Page 5 51M35 SERIES 5/2 NOTE − This thermost at will NOT automatically switch from heating to cooling, or vice versa; operator involve- men t is required. At the change of seasons, or to accomo- date abnormal seasonal temperature swings, you must manually select to the opposite conditioning (Heat or Cool) program.
Page 6 505049M 5/1/05 Service Indicator When abnormal equipment operation is detected, the SERVICE in d icator will flash on the screen (see figure 17).
Page 7 51M35 SERIES 5/2 T echnical S pecifications Thermostat T ype Electronic programmable thermostat for 2−S tage (gas or electric) Heat/2-S tage Cool, non−heat pump, non−power robbing applications. Power Supply Range 18V AC − 30V AC (24V AC nominal), 60Hz CAUTION 24V AC is present on the terminals of the thermost at bracket.
Page 8 505049M 5/1/05 Maintenance Reminder Settings of Of f, 6 or 12 (months of chronological time) are available. W hen programmed time has elap sed, a mainte- nance indicator MAINT" is displayed.
05/05 505,048M *2P0505* *P505048M* Page 1 E 2005 Lennox Industries Inc. Dallas, T exas, USA RET AIN THESE INSTRUCTIONS FOR FUTURE REFERENCE 51M34 Merit ® Series Thermost at The Lennox Merit ® Series 5/2 day programmable electronic thermostat 51M34 provides excellent temperature control and a large, easy-to-read display .
Page 2 505048M 5/1/05 Within a few seconds, the Home Screen appears (see fig- ure 2) with default settings as shown. After about 1 minute of initialization time, the actual room temperature will be displayed.
Page 3 51M34 SERIES 5/2 HEA T − Using the Heat Mode Enabling and Disabling Heat Mode The thermostat must be in the HEA T mode to control the heating equipment.
Page 4 505048M 5/1/05 HOLD − Using T emperature Hold Modes When HOLD is displayed at the HOME screen, the ther- mos tat is in a temperature hold condition. This means that the temperature program data is ignored and the thermo- stat functions much like a non−programmable thermost at.
Page 5 51M34 SERIES 5/2 NOTE − This thermost at will NOT automatically switch from heating to cooling, or vice versa; operator involve- men t is required. At the change of seasons, or to accomo- date abnormal seasonal temperature swings, you must manually select to the opposite conditioning (Heat or Cool) program.
Page 6 505048M 5/1/05 Service Indicator When abnormal equipment operation is detected, the SERVICE in d icator will flash on the screen (see figure 17).
Page 7 51M34 SERIES 5/2 T echnical S pecifications Thermostat T ype Electronic programmable thermostat for 1-S tage- Heat/1-S tage Cool, gas or electric heat, non−heat pump, non−power robbing applications. Power Supply Range 18V AC − 30V AC (24V AC nominal), 60Hz CAUTION 24V AC is present on the terminals of the thermost at bracket.
Page 8 505048M 5/1/05 Maintenance Reminder Settings of Of f, 6 or 12 (months of chronological time) are available. W hen programmed time has elap sed, a mainte- nance indicator MAINT" is displayed.
07/05 505,068M *2P0705* *P505068M* Page 1 E 2005 Lennox Industries Inc. Dallas, T exas, USA RET AIN THESE INSTRUCTIONS FOR FUTURE REFERENCE 51M39 Merit ® Series Thermost at The Lennox Merit ® Series 7 day programmable electronic thermostat 51M39 provides excellent temperature control and a large, easy-to-read display .
Page 2 505068M 07/05 Within a few seconds, the HOME screen appears (see fig- ure 2) with default settings as shown. After about 1 minute of initialization time, the actual room temperature will be displayed. NOTE − T ables 2 and 3 on page 7 show all system and programming default s.
Page 3 51M39 SERIES 5/2 HEA T − Using the Heat Mode Enabling and Disabling Heat Mode The thermostat must be in the heat mode to control the heating equipment.
Page 4 505068M 07/05 NOTE − If no buttons are pressed during a demand for cooling, t he equipment must operate for at least 4 minutes. Afte r a demand has been satisfied, cooling equipment op- eration is locked out for 5 minutes.
Page 5 51M39 SERIES 5/2 Figure 1 1 Program Example 6AM NOON 6PM MID 6AM NIGHT A B D A B D A B D A B D A B C D A B C D A B C D C C C C SA TURDA Y PROGRAM: 72° 68° 64° SUNDA Y PROGRAM: 72° 68° 64°.
Page 6 505068M 07/05 Displaying Outside T emperature Pressing the ENTER (Outside) button at the HOME screen di sp l ays the out side temperature (see figure 15) for several seconds, then returns to room temperature.
Page 7 51M39 SERIES 5/2 Removing and Installing Thermostat The thermostat hinges on tabs on the top of the subbase; no tool is needed to remove the thermostat from the sub- base. Pivot the bottom of the thermostat outward (releas- ing the snap s), then lif t up to remove.
Page 8 505068M 07/05 T echnical S pecifications Thermostat T ype Electronic programmable thermostat for 2−S tage (gas or electric) Heat/2-S tage Cool, non−heat pump, non−power robbing applications.
Page 9 51M39 SERIES 5/2 NOTE − All protection timers (except the compressor OFF timer) can be over−ridden if a heating or cooling demand is initiated or terminated using the UP , DOWN, HEA T , or COOL buttons.
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07/05 505,069M *2P0705* *P505069M* Page 1 E 2005 Lennox Industries Inc. Dallas, T exas, USA RET AIN THESE INSTRUCTIONS FOR FUTURE REFERENCE 51M42 Merit ® Series Thermost at The Lennox Merit ® Series 7−day programmable electronic thermostat 51M42 provides excellent temperature control and a large, easy-to-read display .
Page 2 505069M 07/05 Within a few seconds, the HOME screen appears (see fig- ure 2) with default settings as shown. After about 1 minute of initialization time, the actual room temperature will be displayed. NOTE − T ables 2 and 3 on page 8 show all system and programming default s.
Page 3 51M42 SERIES 5/2 HEA T − Using the Heat Mode Normal Heat Mode In normal heat mode, both the heat pump and the backup heat source are used to provide heat. If the thermost at d e- tects that the heat pump is not able to provide enough heat (as may be the case in very cold weather), then the backup heat source is activated.
Page 4 505069M 07/05 COOL − Using the Cool Mode Enabling and Disabling Cool Mode Use the COOL button to enable or disable cool mode as desired. If the thermosta t i s in heat or of f mode, cool mode is enabled when the COOL button is pressed. This is indi- cated by COOL on the r igh t si de of the disp lay (s e e fig u r e 9).
Page 5 51M42 SERIES 5/2 T emporary (2-Hour) Hold At any time the program is running, from the HOME screen, set a temporary 2-hour hold by pressing the Up/ Down arrow buttons until the desired setpoint is displayed; HOLD" flashes (see figure 12).
Page 6 505069M 07/05 F AN − Controlling the Fan Operation U s e the F AN button to select either continuous fan mode or auto fan mode. T o change from continuous to auto fan mode (or vice ver - sa), press the F AN button. Note whether a fan icon in the F AN b ox is present (indicating that the fan is running) or not (fan not running) .
Page 7 51M42 SERIES 5/2 COOL OFF AUTO EMG. HEAT I0:26 PROG A B C D HOLD F AN ON AUT O FIL TER S ER VICE MAINTENANCE 76 Reminders Figure 19 ROOM ° MO AM PM COOL OFF AUTO EMG.
Page 8 505069M 07/05 Default Thermostat Settings Default thermostat settings are shown in table 2 and the default program is shown in table 3. T able 2 Default Thermostat Settings Mode Heat (Perm.
Page 9 51M42 SERIES 5/2 T echnical S pecifications Thermostat T ype Electronic programmable thermostat for heat pump, 3-stage heat/2-st age cool. NOTE − 2 s t ages of heat pump heat and one st age of auxil- iary (gas or electric) backup heat are supported.
Page 10 505069M 07/05 T able 5 51M42 T erminal Designations T erm. Description B Reversing valve, heat active O Reversing valve, cool active R 24V AC Y1 First-stage cooling/heating, compressor energiz.
07/05 505,067M *2P0705* *P505067M* Page 1 E 2005 Lennox Industries Inc. Dallas, T exas, USA RET AIN THESE INSTRUCTIONS FOR FUTURE REFERENCE 51M38 Merit ® Series Thermost at The Lennox Merit ® Series 7 day programmable electronic thermostat 51M38 provides excellent temperature control and a large, easy-to-read display .
Page 2 505067M 7/13/05 Within a few seconds, the HOME screen appears (see fig- ure 2) with default settings as shown. After about 1 minute of initialization time, the actual room temperature will be displayed.
Page 3 51M38 SERIES 5/2 HEA T − Using the Heat Mode Enabling and Disabling Heat Mode The thermostat must be in the heat mode to control the heating equipment.
Page 4 505067M 7/13/05 HOLD − Using T emperature Hold Modes When HOLD is displayed at the HOME screen, the ther- mos tat is in a temperature hold condition. This means that the temperature program data is ignored and the thermo- stat functions much like a non−programmable thermost at.
Page 5 51M38 SERIES 5/2 1. Press and re lease the PROG button. "MO" (Monday), "AM 6:00", period "A", "COOL SETPOINT 78", and "HEA T SETPOINT 70" are displayed.
Page 6 505067M 7/13/05 The default setting for the reminders is OFF (disabled). Press Up/Down arrow buttons to select the desired re- minder intervals.
Page 7 51M38 SERIES 5/2 T able 3 Default Program Settings (Time & T emp.) Programs Time T emp. − Heat T emp. Cool All days − A 6:00am 70 _ F / 21 ° C 78 _ F / 26 ° C All days − B 8:00am 62.
Page 8 505067M 7/13/05 Smart Setback Recovery (via DIP switch #6) Smart Setback Recovery (SSR) affects the way the ther- mo st at responds to program events. If SSR is disabled, th e thermostat will react to a program event at the time the event occurs.
An important point after buying a device Lennox International Inc. 51M37 (or even before the purchase) is to read its user manual. We should do this for several simple reasons:
If you have not bought Lennox International Inc. 51M37 yet, this is a good time to familiarize yourself with the basic data on the product. First of all view first pages of the manual, you can find above. You should find there the most important technical data Lennox International Inc. 51M37 - thus you can check whether the hardware meets your expectations. When delving into next pages of the user manual, Lennox International Inc. 51M37 you will learn all the available features of the product, as well as information on its operation. The information that you get Lennox International Inc. 51M37 will certainly help you make a decision on the purchase.
If you already are a holder of Lennox International Inc. 51M37, but have not read the manual yet, you should do it for the reasons described above. You will learn then if you properly used the available features, and whether you have not made any mistakes, which can shorten the lifetime Lennox International Inc. 51M37.
However, one of the most important roles played by the user manual is to help in solving problems with Lennox International Inc. 51M37. Almost always you will find there Troubleshooting, which are the most frequently occurring failures and malfunctions of the device Lennox International Inc. 51M37 along with tips on how to solve them. Even if you fail to solve the problem, the manual will show you a further procedure – contact to the customer service center or the nearest service center
