These T874A,D Zone Thermostats and Q674B,D,E Subbases provide 24 to 30 Vac temperature control in Honeywell Trol-A-Temp heating/cooling zone systems. See Table 1 for thermostat/subbase and system compatibil-ity; see Table 2 for thermostat specifications. For complete Honeywell Trol-A-Temp System specification and appli-cation information, refer to the system specification in-cluded with the control panel.
TABLE 1—THERMOSTAT/SUBBASE AND SYSTEM COMPATIBILITY.
Thermostat/ Subbase Model Numbera | Application | Stages | ||
Mini-Zone | Mabs II, Mabs II-L | Mabs XX | ||
T874A/Q674B | Zone 1; conventional heat-cool. | Zone 1; conventional heat-cool. | Any zone; conventional heat-cool. | Single-stage |
T874A/Q674D | Zones other than zone 1; conventional heat-cool. | Zones other than zone 1; conventional heat-cool. | Not applicable | Single-stage |
T874A/Q674E | Not applicable | Not applicable | Any zone; conventional heat-cool. | Single-stage |
T874D/Q674B | Not applicable | Zone 1; conventional heat-cool. | Any zone; conventional heat-cool. | Multistage |
T874D/Q674D | Not applicable | Zones other than zone 1; conventional heat-cool and heat pump. | Not applicable | Multistage |
T874D/Q674E | Not applicable | Not applicable | Any zone; conventional heat-cool. | Multistage |
Subbase not included with thermostat; order separately.
TABLE 2—THERMOSTAT/SUBBASE SPECIFICATIONS.
Thermostat/Subbase Order Numbera | Switching | Thermostat/ Subbase Color | Anticipator Range (A) | |||
Heating (Adj.) | Cooling (Fixed) | |||||
System | Fan | |||||
T874A1465/Q674B1471 | HEAT-OFF-COOL | ON-AUTO | White/Gray | Stg. 1— 0.1 to 1.2 | Stg. 1— 0 to 1.5 | |
T874A1465/Q674D1123 | None | None | White/Gray | |||
T874A1465/Q674E1379 | HEAT-OFF-COOL-AUTO | ON-AUTO | White/Gray | |||
T874D1801/Q674B1463 | HEAT-OFF-COOL | ON-AUTO | Beige/Brown | Stg. 1— 0.1 to 1.2; Stg. 2— 0.1 to 1.0. | Stg. 1— 0 to 1.2; Stg. 2— 0 to 1.0. | |
T874D1827/Q674B1471 | HEAT-OFF-COOL | ON-AUTO | White/Gray | |||
T874D1801/Q674D1115 | None | None | Beige/Brown | |||
T874D1827/Q674D1123 | None | None | White/Gray | |||
T874D1827/Q674E1379 | HEAT-OFF-COOL-AUTO | ON-AUTO | White/Gray |
Subbase not included with thermostat; order separately.
On a 2-heat thermostat, the two stages of heat make sequentially as the temperature drops. Make refers to the mercury switch initiating a call for heat or cool.
There are about 2° F [1° C] between stages so that the second stage makes only when the first stage cannot handle the load. This is the interstage differential.
Recycling Notice
This control contains mercury in a sealed tube. Do not place control in the trash at the end of its useful life.
If this control is replacing a control that contains mercury in a sealed tube, do not place your old control in the trash. Contact your local waste management authority for instructions regarding recycling and the proper disposal of this control, or of an old control containing mercury in a sealed tube. If you have questions, call Honeywell at 1-800-468-1502.
WHEN INSTALLING THIS PRODUCT…
CAUTION
IMPORTANT: Thermostats are calibrated at the factory by using subbases mounted at true level. Inaccurate sub-base leveling will cause thermostat control deviation.
Locate the subbase about 5 ft [1.5 m] above the floor in an area with good air circulation at average temperature.
Do not mount the subbase where the thermostat may be affected by:
MOUNTING THE SUBBASE
The thermostat subbase can be mounted on a horizontal outlet box or directly on the wall.
All wiring must comply with local electrical codes and ordinances. Follow equipment manufacturer wiring instructions when available. To wire subbase:
Fig. 6—Typical hookup for MM-2 Mini-zone
Control Panel with T874A Thermostat/Q674B,D Subbase in single-stage heating-cooling two-zone system.
Fig. 7—Typical hookup for MABS II and MABS II-L
Control Panels with T874A Thermostat/Q674B,D Subbases in single-stage heating-cooling zone system. MABS II Control Panel shown; MABS II-L Control Panel hookup is the same.
Fig. 8—Typical hookup for MABS II and MABS II-L
Control Panels with T874D Thermostat/Q674B,D Subbases in a multistage heating-cooling zone system. MABS II Control Panel shown; MABS II-L Control Panel hookup is the same.
Fig. 9—Typical hookup for MABS XX
Control Panel with T874A Thermostat/Q674B,E Subbases in a single-stage heating-cooling zone system.
Fig. 10-Typical hookup for MABS XX
Control Panel with T874O Thermostat/0674B,E Subbases in multistage heating-cooling zone system.
TEMPERA TlJRE SETTING
Move the heating and cooling set point levers (Fig. 13) to the desired comfort positions. One lever controls all stages of heating, and the other lever controls all stages of cooling. The minimum differential between the heating and cooling set point is 3° F [2° C].
SUBBASE SETTING (Q6748 AND E ONLY)
Refer to Tables 3 and 4 for descriptions of subbase switching positions
TABLE 3-SUBBASE SYSTEM SWITCHING POSITIONS
Switching Position | Mini-Zone, Mabs II, Mabs II-L System | Mabs XX System |
OFF | Both heating and cooling systems are off. If the fan is at AUTO position, the cooling fan is also off. | Zone thermostat will not call for heating or woling. |
HEAT | The system operates in heating m0<.Je. The cooling is off. | Zone thermostat calls for heating only. |
COOL | System operates in cooling mode. Heating is off. | Zone thermostat calls for cooling only. |
AUTO | Not applicable. | ‘.I.one thermostat calls for heating or cooling depending upon indoor temperature. |
TABLE 4—-SUBBASE FAN SWITCHING POSITIONS
Switching Po ition | Mini-Zone, Mabs II, Mabs ll-L System | Mabs XX System |
ON | Fan operates continuously. | Wilh any zone set to ON, fan will operate continuously. |
AUTO | In cooling, fan operates with cooling equipment; in heating. fan operates as controlled by the plenum fan control. | If all zones are set to AUTO, the fan operates as controlled by the plenum fan control in heating and with cooling equipment in cooling. If any zone is set to ON, the fan will operate continuously. |
To move the sub-base switches to the desired control pos1t10ns, use thumb and mdex finger to slide the lever. Stop the lever over the desired function indicator position for proper circuit operation. Before beginning checkout of thermostat operation, set switches on the control panel for the desired system operation. See the instructions provided with the control panel. To set up the system for thermostat checkout, adjust each thermostat setting as shown in Table 5.
TABLE 5—SYSTEM SET-UP FOR THERMOSTAT CHECKOUT.
Control Panel | Heating | Cooling | ||
Zone 1 | Zones Other Than Zone 1 | Zone 1 | Zones Other Than Zone 1 | |
Mini-zone MABS II MABS II-L | Set the thermostat system switch to HEAT; set fan switch to AUTO. Move the heating set point lever 10° F [6° C] below room temperature. | Move the heating set point lever 10° F [6° C] below room temperature. | Set the thermostat system switch to COOL; set fan switch to AUTO. Move the cooling set point lever 10° F [6° C] above room temperature. | Move the cooling set point lever 10° F [6° C] above room temperature. |
MABS XX | On all zone thermostats, set the system switch to HEAT; set the fan switch to AUTO. Move the heating set point lever 10° F [6° C] below room temperature.
NOTE: The control panel provides a three- minute time delay when 24V is applied to the control panel and at the end of each equipment cycle. The high-speed fan runs during this time delay. | On all zone thermostats, set the system switch to COOL; set the fan switch to AUTO. Move the cooling set point lever 10° F [6° C] above room temperature.
NOTE: The control panel provides a three- minute time delay when 24V is applied to the control panel and at the end of each equipment cycle. The high-speed fan runs during this time delay. |
NOTE: If a plenum fan control is used in the heating system, there will be a short delay on a call for heat to allow the furnace to heat the plenum. The fan starts immediately in electric heat systems. Allow 30 seconds for the damper to open or close completely.
Make sure all zone thermostats are set as instructed in the Heating column in Table 5. Check each zone thermo-stat as follows:
CAUTION Do not operate cooling equipment if outdoor temperature is below 50° F [10° C]. Refer to manufacturer recommendations. Make sure all zone thermostats are set as instructed in the Cooling column in Table 5. Check each zone thermo-stat as follows:
THERMOSTAT
T874 thermostats are accurately calibrated at the factory. They do not have provision for field calibration.
THERMOMETER
The thermometer in your thermostat has been accu-rately calibrated at the factory. The thermometer should only need adjustment if it has been dropped or shifted due to mishandling.
If the set point lever and the thermometer reading do not agree:
Home and Building Control Honeywell Inc.
1985 Douglas Drive North Golden Valley, Minnesota 55422
Printed in U.S.A.
Home and Building Control Honeywell Limited—Honeywell Limitée 740 Ellesmere Road
Scarborough, Ontario
M1P 2V9
Download Manual:
Honeywell T874A Zone Thermostat Installation Instruction
Johnson Controls T7000e LCD Digital Thermostat Johnson Controls T7000e LCD Digital Thermostat Installation Guide
Honeywell T8635L Microelectronic Communicating Programmable Thermostat Honeywell T8635L Microelectronic Communicating Programmable Thermostat USER’s GUIDE
Hetta HS01RF WIRELESS THERMOSTAT Kit PAIRING INSTRUCTIONS Insert batteries into the Thermostat. Ensure that the…
HEAT-MAT NGT-567-0010 Underfloor Heating Thermostat Menu Introduction The NGT thermostat can switch your underfloor heating…
Honeywell RLV450 PROGRAMMABLE THERMOSTAT READ BEFORE INSTALLING DESCRIPTION * LP appears only for the first…
Honeywell RLV431 Programmable Thermostat Description The RLV431 thermostat can be used to control an electric…