Honeywell T991A Installation Guide
I
T991A REMOTE BULB
TEMPERATURE CONTROLLER
APPLICATION
The T991A Remote
used to sense water and air temperatures, and provides proportional control of a Series 90 (Modutrol*)
motor. Typically, Series SO motors are used with
linkages to operate valves or dampers in air cmditiming systems.
The TSSlA cm be used to replace the controliers
listed below:
INSTALLATION
NOTE:
by a quaiiCied service mm. Follov instruciions lunished by heating or cooling system manufacturer, if
available.
(ion on a blat surface where the ambient temper&e
does not exceed 125 F. When mounting on a hoi or
cold surface. mount the case on a wood board or
other insulating material. The 5-fool capillary tube
provides for remote mounting.
or FOR REPLACEMENT section.
FOR NEW INSTALLATION:
MOUNTTHE CONTHOLLER CASEmark three screw hole locations on mountinz surface,
then punch or drill holes.
the mounting screws furnished.
TO INSTALL SENSING BULB IN AIR DUCT:
temperature can circulate freely around ii. Avoid
mounting the bulb close to hot pipes, cooling coils,
and other places where air temperatures are not
representative.
No. 107324A (supplied).
Installation and service should be made only
Proceed lo Ihe FORK NEW INSTALLATION section
1. Remove cover. Using the case as a templa.te,
2. Fasten TSSlAsecurely lo mounting surfacewith
Locale
To support the bulb in Lhe duct, use Bulb Hoider
the sensing bulb where duct air of average
Bulb Temperature Controller is
TSSIA temperature settings sa,me
See
Table
1 for corresponding T9SlA
-
shown in Fig. 2.
to hold sensing bulb in freely circulaiing air, away
from duck wail. Neatly coil any excess capillary
tubing at controller case or at bulb holder.
Fig. 2Shortening Ihe bulb holder.
4. Place capillary tubing in bulb holder channel,
and pinch topedges of holder together aleach segment:
Fig. 3--Securing the bulb to the holder
NOTE:
Holder should be long enough
Fig. l-Bulb Holder,
1. Drill a 3/4-inch hole in the duct wall to admit
the sensing bulb and the holder.
2.
Using
holes for bulb holder mounting screws (see Fig. 4).
3.
*Trademark
3-64 R.T.
the holder as a template, mark and drill
Break off bulb holder to desired length, as
5. Insert bulb and holder into controlled area
through hole prepared in Step 1.
Fig. 4-Insertion into duct.
3
6. Fasten bulb holder to duct wall with screws 4. Fit bulb retaining clamp over immersion well
furnished.
flange and capillary tubing, and tighten screw, as
slhown in Fie. 7.
Neatly coil excess capillary tubing at T991A case.
8”s RETAlNlNG CLAMP pMERSI”N WELL
\
FOR REPLACEMENT:
Remove old controller. Moluit T991A in same lo-
cation if ihis meek the requirements in LOCATION,
FigI 5-Fastening bulb holder to duck wail above.
Use old sensing bulb hole, bulb holder, immersion
TO INSTALL SENSING BULB IN TANKS OR BOIL- well, or compression iitting if these are suitable;
ERS - otherwise, follow applicable instructions for new in-
The T991A sensing bulb may be inserted directly stallaiion, above.
into a tank or boiler tapping by “si”g a No. 7617M See Table 1 in SETTINGS AND ADJUSTMENTS.
(M-inch NPT) or 76172 (3kinch NPT) Compression
Fitting (order separately); or the element may be
inscried into a No. 112622AA (&‘-inch NPT) or
WIRING
112G30AA (3/4-inch NPT) Immersion Well (order All wiring must comply with local electrical codes.
separately) which is screwed into ihe ianlr or boiler.
CAUTION: Disconnect power supply.
Two knockouts are provided ai top and boliom of
Installing Compression Fitiing (not i”rnished)- ca.se for U-inch conduit. Follow any wiring instruc-
iions furnished with heaiing or cooling system. In
replacemenis, make certain the T991A is wired in the
system to operate the same way as old control.
Fig. 8-Typical hookup for T991A
SEtTTINGS AND ADJUSTMENTS
L
PPiCKlNGNUT
Fig. B-Exploded view of compression fitting,
1. Drain system. Screw boiler plug into properly Porportional range adjustmen-The T991A may be
sized and threaded boiler or pipe tapping.
2. Place packing nut 011 T99iA capillary lube.
3. Slide sensing bulb compieieiy tko”gh boiler adjustment wheel (marked 3, 5, 10, 20, 30) until de-
p,i,g.
4. Place composilion disc and the 4 slotted brass
washers
on
tubing in the order shown in Fig. 6.
5. Slide the assembly into the boiler plug, and medium is to be maintained ai 130 F, and propor-
tighte” the packing nul.
6. ReIill the sysiem and check for leaks. Neatly
coil cxccss capillary tubing at T991A case. inclicaior to 130 F and the proportional range adjust-
Inslalling Immersion Well (not furnished)-
1. Drain system. Screw the well into properly
sized and threaded boiler tappiq or pipe Eiiiing.
2. Refill the syShn and check for leaks.
3. Insert sensing b”ib into well wlil it bottoms. WHEN REPLACING A T915C-See Table 1.
,OiS~,~i
Temperaiure sel point-Turn knob on front of case
until pokier indicates temperaiure which is io be
maintained in the controlled medium This is the
center point Of the proportional range.
adjusted to vary the iemperaturc range within which
action
proporlionai
is desired. With cover off, lurn
sired value is aligned wiih p~inier on frame.
EXAMPLE: If the temperature of the controlled
tional action from 125 F to 135 F (a range of 10 degrees) is desired-turn ihe iemperature set point
ment wheel to 10.
WHEN REPLACBIG A T915A-
Set the T991A temperature set point to same seiiing
as Oid control (from 55 io 140 F). Set T991A propor-
tional range adjustmeni wheel to 3.
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