Lennox 51M37 - Manuals

Page 5 51M37 SERIES 5/2 HOLD − Using Temperature Hold Modes When HOLD is displayed at the HOME screen, the ther-mostat is in a temperature hold condition. This means thatthe temperature program data is ignored and the thermo-stat functions much like a non−programmable thermostat. Adjusting Temperatu...

Page 6 505050M 5/1/05 5. Repeat steps 2 through 4 for periods B, C, and D.6. Repeat steps 1 through 5 for the 2−day program. NOTE − This thermostat will NOT automatically switchfrom heating to cooling, or vice versa; operator involve-ment is required. At the change of seasons, or to accomo-date abno...

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 thethermostat, balance point adjustment is available. The bal-ance point feature allows the measured outdoor tempera-ture to go...

Page 8 505050M 5/1/05 Default Thermostat Settings Default thermostat settings are shown in table 2 and thedefault program is shown in table 3. Table 2 Default Thermostat Settings Mode Heat (Permanent HoldMode) Setpoint 70°F (or 21°C) Fan Auto Filter Reminder OFF Maintenance Reminder OFF Equipment Pr...

Page 10 505050M 5/1/05 Thermostat Output Table Table 5 depicts the 51M37 thermostat output states for var-ious input conditions. The following notes described termsused in the table. NOTES: S X = output is activated with 24VAC. S BBP: outdoor temperature is below balance point S ABP: outdoor tempera...

05/05 505,049M *2P0505* *P505049M* Page 1 E 2005 Lennox Industries Inc. Dallas, Texas, USA RETAIN THESE INSTRUCTIONS FOR FUTURE REFERENCE 51M35 Merit ® Series Thermostat The Lennox Merit ® Series 5/2 day programmable electronic thermostat 51M35 provides excellenttemperature control and a large, easy...

Page 6 505049M 5/1/05 Service Indicator When abnormal equipment operation is detected, theSERVICE indicator will flash on the screen (see figure 17).This indicates that the equipment requires service from aqualified service technician. I0:i4 PROG A B C D HOLD 79 Service Indicator Flashing Figure 17 ...

Page 7 51M35 SERIES 5/2 Technical Specifications Thermostat Type Electronic programmable thermostat for 2−Stage (gas orelectric) Heat/2-Stage Cool, non−heat pump, non−powerrobbing applications. Power Supply Range 18VAC − 30VAC (24VAC nominal), 60Hz CAUTION 24VAC is present on the terminals of the th...

Page 8 505049M 5/1/05 Maintenance Reminder Settings of Off, 6 or 12 (months of chronological time) areavailable. When programmed time has elapsed, a mainte-nance indicator MAINT" is displayed. Service Reminder The SERVICE indicator is displayed only under the follow-ing conditions: S if the ther...

Page 8 505048M 5/1/05 Maintenance Reminder Settings of Off, 6 or 12 (months of chronological time) areavailable. When programmed time has elapsed, a mainte-nance indicator MAINT" is displayed. Service Reminder The SERVICE indicator is displayed only under the follow-ing conditions: S if the ther...

07/05 505,068M *2P0705* *P505068M* Page 1 E 2005 Lennox Industries Inc. Dallas, Texas, USA RETAIN THESE INSTRUCTIONS FOR FUTURE REFERENCE 51M39 Merit ® Series Thermostat The Lennox Merit ® Series 7 day programmable electronic thermostat 51M39 provides excellent temperature controland a large, easy-t...

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 minuteof initialization time, the actual room temperature will bedisplayed. NOTE − Tables 2 and 3 on page 7 show all system andprogramming defaults. COOL OFF AUTO EMG. HEA...

Page 5 51M39 SERIES 5/2 Figure 11 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 SATURDAY PROGRAM: 72° 68° 64° SUNDAY PROGRAM: 72° 68° 64° FRIDAY PROGRAM: 72° 68° 64° THURSDAY PROGRAM: 72° 68° 64° WEDNESDAY PROGRAM: 72° 68° 64° TUESDAY PROGRAM: 72°...

Page 6 505068M 07/05 Displaying Outside Temperature Pressing the ENTER (Outside) button at the HOMEscreen displays the outside temperature (see figure 15) forseveral seconds, then returns to room temperature. Check Outside Temperature Figure 15 88 Fan Settings Hold Enter (Outside) SETTINGS − Filter/...

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 snaps), then lift up to remove. To install it, first position th...

Page 9 51M39 SERIES 5/2 NOTE − All protection timers (except the compressor OFFtimer) can be over−ridden if a heating or cooling demand isinitiated or terminated using the UP, DOWN, HEAT, orCOOL buttons. Equipment Protection Override Both the minimum compressor OFF timer and the mini-mum equipment c...

Page 3 51M42 SERIES 5/2 HEAT − Using the Heat Mode Normal Heat Mode In normal heat mode, both the heat pump and the backupheat source are used to provide heat. If the thermostat de-tects that the heat pump is not able to provide enough heat(as may be the case in very cold weather), then the backuphe...

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 asdesired. If the thermostat is in heat or off mode, cool modeis enabled when the COOL button is pressed. This is indi-cated by COOL on the right side of the display (s...

Page 5 51M42 SERIES 5/2 Temporary (2-Hour) Hold At any time the program is running, from the HOMEscreen, set a temporary 2-hour hold by pressing the Up/Down arrow buttons until the desired setpoint is displayed;HOLD" flashes (see figure 12). This overrides the pro-gram for 2 hours from the last ...

Page 5 51M38 SERIES 5/2 1. Press and release the PROG button. "MO" (Monday), "AM 6:00", period "A", "COOL SETPOINT 78", and"HEAT SETPOINT 70" are displayed. "AM 6" flashes. 2. Use the Up/Down arrow buttons to select the desired hour; press the PROG but...