Checkout; Calibration; Cooling; Emergency Heat/Fan/Thermometer - Honeywell T874R Installation Instructions Manual

CHECKOUT

Heating
M o ve th e system sw itch o n th e Q 674 Subbase to H EA T.
M o ve th e setp o in t lever o n th e T874 Therm ostat ab o u t
10° F (6° C) above ro o m tem p eratu re. B o th stages o f
h eatin g and th e fan sho uld start. M o ve th e setp o in t lever
ab o u t 10° F (6° C) b elo w ro o m tem p eratu re. H eatin g an d
fan sho u ld shu t o ff.
N OTE: To p reven t com pressor sh o rt cyclin g , som e
m anufacturer eq uip m ent includes a m in im u m -o ff
tim e r to p ro vid e a five-m in u te tim e delay b efo re
tu rn in g o n th e com pressor after th e th erm o stat
last tu rn ed o ff th e com pressor, o r after th e
system first received p o w er. This delay p ro tects
th e com pressor.

Cooling

A CAUTION
D o n o t operate co o lin g if th e o u td o o r tem p eratu re
is b elo w 50° F (10° C). R efer to m an u factu rer
recom m end ations.
M o ve th e system sw itch o n th e Q 674 Subbase to COOL.
M o ve th e setp o in t lever o n th e T874 Therm ostat ab o u t
10° F (6° C) b elo w ro o m tem p eratu re. C o o ling and fa n
should start (see N OTE above). M o ve th e setp o in t lever
ab o u t 10° F (6° C) above ro o m tem p eratu re. C o o ling and
fan sho u ld sto p .
Emergency Heat
M o ve th e system sw itch to EM .H T. The EM .H T. LED
should com e o n . M o ve th e setp o in t lever ab o u t 10° F
(6° C) above ro o m tem p eratu re. The electric strip h eater(s)
should com e o n . M o ve th e setp o in t lever ab o u t 10° F
(6° C) b elo w ro o m tem p eratu re. The electric strip h eater
should de-energize. The EM .H T. LED rem ains o n u n til
system sw itch is m o ved to ano ther p o sitio n .
Fan
M o ve th e subbase system sw itch to OFF and th e fan
sw itch to O N . The fan should ru n co n tin u o u sly. W hen th e
fan sw itch is in th e AUTO p o sitio n , fan o p eratio n is con­
tro lle d b y th e h eatin g o r co o lin g system .
T874R THERMOSTATS AND Q674L SUBBASES

CALIBRATION

Thermostat
T874 Therm ostats are accurately calib rated at th e facto ry.
There is no provision fo r field calibration.
Thermometer
The th erm o m eter in th e th erm o stat has been accurately
calib rated at th e facto ry. The th erm o m eter sho u ld n eed
ad justm ent o nly if it was d ro p p ed o r sh ifted due to
m ish an d lin g .
If th e setp o in t lever and th e th erm o m eter read in g d o n o t
ag ree:
1 . Rem ove th e th erm o stat cover b y p u llin g o u t fro m th e
b o tto m o f cover u n til it clears th e m o u n tin g slo ts.
2. Set th e th erm o stat cover o n a tab le near an
accurate th erm o m eter.
3. A llo w 1 0 o r 1 5 m inutes fo r cover th erm o m eter to
sense area tem p eratu re; com pare th e read ing s. B e
carefu l n o t to to u ch th erm o m eter o r b reath e o n it .
4. If th e read ings are th e sam e, replace cover and p u t
th e system in to o p eratio n .
5. If th e read ings are d iffe re n t, in sert a sm all screw ­
d river in to th e th erm o m eter and tu rn it u n til th e
th erm o m eters have th e sam e read in g . See Fig . 1 5 .
6. Replace th erm o stat cover and p u t th e system in to
o p eratio n .
N OTE: R adiant h eat fro m hands o ffsets th e th erm o m eter
read in g . A fter m akin g each ad ju stm en t, w ait 1 0
o r 1 5 m in u tes fo r th e th erm o m eter to stab ilize
b efo re co m p arin g .
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