The T87F Universal Thermostat provides tempera-
ture control for 24 to 30 Vac residential heating, cooling
or heating-cooling systems. For heating systems, the
T87F mounts on the wallplate provided. For cooling
only, or heating-cooling, order the 137421A (198170A
if textured designer model) Heating-Cooling Wallplate
with remote switching, or the Q539 Subbase, which
provides switching at the thermostat location.
The spdt switch makes one set of contacts on a tem-
perature fall to operate the heating system. The other set
of contacts make on a temperature rise to operate the
cooling system when the T87F is used to control cool-
Heat anticipation is adjustable, 0.1 to 1.2A.
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
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 Inc. at 1-
Installation and Setting
WHEN INSTALLING THIS PRODUCT...
1. Read these instructions carefully. Failure to fol-
low them could cause a hazardous condition.
2. Check the ratings given in the instructions and on
the product to make sure the product is suitable for your
3. Installer must be a trained, experienced service
4. After installation is complete, check out product
operation as provided in these instructions.
®U.S. Registered Trademark
Copyright © 2002 Honeywell •
Installation Instructions for the Trained Service Technician.
• All Rights Reserved
1. Disconnect power supply to prevent electri-
cal shock or equipment damage.
2. To prevent interference with the thermostat
linkage, keep wire length to a minimum and
run wires as close as possible to the subbase.
3. Do not overtighten thermostat captive mount-
ing screws because damage to subbase threads
4. Do not short across coil terminals on relay.
This can burn out the thermostat heat antici-
IMPORTANT: An incorrectly leveled thermostat will
cause the temperature control to deviate from set
Install the thermostat about 5 ft [1.5m] above the
floor in an area with good air circulation at average
Do not install the thermostat where it may be affected
— drafts, or dead spots behind doors and in corners.
— hot or cold air from ducts.
— radiant heat from sun or appliances.
— concealed pipes and chimneys.
— unheated (uncooled) areas such as an outside wall
behind the thermostat.
This thermostat is a precision instrument and was
carefully adjusted at the factory. Handle it carefully.
MOUNTING WALLPLATE OR SUBBASE (Fig. 2)
1. Use a spirit level to accurately level the wallplate
or subbase as in Fig. 1. Inaccurate leveling may
cause thermostat control deviation.
2. When using the T87F with a Q539 Subbase, follow
the mounting and wiring instructions included with
1. Place the wallplate on the wall at the desired loca-
tion. Pull the thermostat cable through the entrance hole.
2. Fasten wallplate. Do not tighten the screws.
3. Level according to Fig. 1 then tighten screws.
4. After wiring wallplate, plug hole to prevent drafts
from affecting thermostat.
NOTE: To mount T87 Thermostat on an outlet box,
order 129044A Adapter Ring Assembly.