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L41../L61.. SERIES  
THERMOSTAT (AQUASTAT)  
PRODUCTION HANDBOOK  
APPLICATION  
The L41../L61.. series aquastats are primarily designed for  
application on water filled heating systems and systems for hot  
water supply, mainly domestic use.  
Contents  
General  
page  
Description of device functions ......................................... 2  
Description ........................................................................ 3  
Overview/selection guide ................................................. 4  
Features ............................................................................ 5  
Aquastat series  
L4188 - L6188 .................................................................. 6  
L4189 - L6189 .................................................................. 8  
L6190 ............................................................................. 10  
L4191 - L6191 ................................................................ 12  
L6188A 2044 Tradeline .................................................. 14  
Performance .................................................................... 16  
Construction .................................................................... 17  
Various  
Accessories and spare parts ........................................... 18  
Quality assurance statement ........................................... 20  
Standards and approvals ................................................ 20  
Ordering information ........................................................ 21  
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DESCRIPTION OF DEVICE FUNCTIONS  
Aquastats thermostats  
The Micro Switch mechanism is intended to control electrically  
a burner, a relay, etc. in dependency of the temperature  
changes in a heating system.  
On choice the Micro Switch mechanism can be delivered with  
the following contact arrangements:  
Honeywell manufactures a coprehensive range of water  
temperature thermostats (trade name Aquastat) for controlling  
and limiting boiler water temperature in hydronic heating  
systems.  
These sensitive, fast response devices are available in either  
direct, panel or surface mount versions.  
 Single Pole Single Throw,  
C-1 breaks on temperature rise  
Single Pole Double Throw,  
C-1 breaks on temperature rise.  
C-2 makes on temperature rise.  
Sensing element  
The liquid filled sensing element, including well or sensor  
assembly, responds to temperature changes of water in a  
heating system.  
The contacts are connected to 6.3 mm terminals which are  
extending from the outside of the Aquastat housing.  
The sensor element has a diaphragm type power head  
connected to a tube type capsule, through a small bore  
capillary.  
Expansion of the liquid, which completely fills the sensing  
element, is the means of motion of the diaphragm.  
The sensor assembly, used on the surface mounted aquastat,  
envelopes the sensing capsule by means of an aluminium  
heat shield for better heat conduction, an insulator of  
glasswool and a mounting bracket.  
Cover and conduit entries  
The housing(s) of the Aquastat can be provided with conduit  
boxes which are provided with holes to fit Pg 13.5 conduits.  
To obtain easy wiring possibilities these boxes can be  
mounted or disconnect without the use of tools (hook in  
approach).  
The conduit box is locked with the front cover, which is  
fastened by means of an M3 thread forming screw. Also the  
top cover is locked by the front cover.  
Control mechanism  
The control mechanism is mounted into the thermoplastic  
housing. The mechanism transfers the motion of the  
diaphragm to a snap action switch (Micro Switch) and also  
provides the facility to adjust the temperature level on which  
the Micro Switch has to operate.  
The mechasnism consists of a two piece lever with calibration  
screw, a plastic actuator for the switch, a cam and shaft for the  
set-point adjustment, a loading spring for cam and levers and  
a pad with pushplate to transfer the diaphragm motion to the  
lever.  
Set-point stops  
On request, the Aquastat can be delivered with a high and low  
limit stop. The purpose of these stops is to provide the user  
with the facility to choose a maximum and/or minimum setting  
on the scale.  
The stop is situated on the rear side of the setting knob.  
Adjustment is only possible after removal of the knob.  
Manual or tool reset  
On request, the Aquastat can be delivered with a manual reset  
or a tool reset feature.  
The tool reset feature is covered by the front cover.  
Operating of the reset button is only possible after removal of  
the front cover.  
Knob with scale and index  
The plastic knob with scale and index enables the user to  
adjust the Aquastat on a selected temperature setting within  
its range. The knob fits on the cam and stays on it due to the  
force of the spring on the nave of the knob.  
This spring force enables the installer to pull the knob from the  
cam without the use of tools.  
The hole in the knob and the shaft of the cam are provided  
with a flat side which allows mounting of the knob only in one  
position in order to maintain the calibration.  
The plastic index will be fastened by means of two M4 thread  
forming screws on the housing.  
The manual reset button potrudes the front cover of the  
Aquastat and resetting can be done without the use of a tool.  
Adjustable differential  
On request, it is possible to deliver the Aquastat with an  
adjustable switch differential.  
The adjustable switch differential feature consists of a plastic  
adjusting dial with pointer, which is connected to a moveable  
contact.  
Turning of the dial changes the contact gap of the Micro  
Switch and thus the differential.  
The dial is situated under the front cover or behind the panel.  
Adjustable differential feature is only applicable on controllers  
and recycling limit controls  
Micro Switch  
The Micro Switch mechanism is also mounted into the plastic  
housing. the mechanism consists of a snap action spring type  
PL with contacts and a moveable or a fixed and a stationary  
contact bracket.  
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DESCRIPTION  
The L41../L61.. series aquastats can be divided in the  
following main types:  
The L41../L61.. series aquastats are sensitive water tempera-  
ture control, which are provided with a liquid filled sensing sys-  
tem.  
Controller  
Controls the water temperature in accordance with the  
setting of an external knob (TÜV-type TR)  
The following main types are available:  
Single, panel mount immersion  
Aquastat with remote bulb to select the most favourable  
position on a boiler or vessel.  
Single, direct mounted immersion  
Aquastat with insulating cover to protect against accidential  
touching of live parts.  
 Recycling limit control  
Limits the water temperature below or above an adjusted  
level and resets automatically. This type has a greater  
differential and no external knob (TÜV-type TW).  
 Thermal cut-out with external reset button  
(manual reset)  
Limits the water temperature on a maximum adjusted level.  
This type does not reset automatically and it does not have  
an external knob.  
Dual, direct mounted immersion  
Dual Aquastat and consisting of two basic single units,  
which are mounted together and protected by one common  
cover and using one well for the two sensors.  
 Thermal cut-out with internal reset button (tool reset)  
Limits the water temperature on a maximum adjusted level.  
This type does not reset automatically and it does not have  
an external knob.  
Single, surface mounted  
The sensor of this type is to be mounted directly on the  
surface of a boiler or pipe in a heating system. The  
Aquastat mechanism is directly attached to this sensor.  
The L41../L61.. series aquastats are primarily designed for  
application on water filled heating systems and systems for hot  
water supply, mainly domestic use.  
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OVERVIEW/SELECTION GUIDE  
Application  
Single Aquastat thermostats  
Controller or limiter thermostat  
Dual Aquastat thermostats  
Controller and limiter thermostat with standard  
sensing element  
Direct mount (immersion)  
L4188A, B, C  
L6188A, B, C  
L4191A, B and L6191A, B  
25 ... 95°C  
2
4
7
5 ... 95°C  
0 ... 110°C  
0 ... 140°C  
25 ... 95°C  
40 ... 110°C  
70 ... 140°C  
50 ... 95°C  
40 ... 110°C  
7
0 ... 140°C  
Panel mount (immersion)  
L4189A, B, C 25 ...  
L6189A, B, C  
25 ... 95°C  
9
1
5°C 40 ... 110°C  
10 ... 230°F  
40 ... 110°C  
7
1
0 ... 140°C  
10 ... 230°F  
Surface mount  
with mounting strap)  
(
L6190A, B, C  
5 ... 95°C  
2
Replacement aquastat (immersion)  
L6188A 2044  
0 ... 110°C  
4
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FEATURES  
6.3 mm quick connect terminals for receptacles  
Mounting either in a horizontal or vertical position.  
Housing is provided with two mounting holes which are  
suitable for M4 thread forming screws, for mounting on a  
control panel.  
Cable entry in the conduit box is suitable for Pg 13.5  
conduit or is provided with a plastic grommet (at choice).  
The high and low setpoint stops are field adjustabe with  
steps of 2.5°C.  
Capillary available in 350 mm (optional), 1000 mm  
(standard), 1500 mm (optional) and 2000 mm (optional)  
length.  
Surface mounted Aquastat can be mounted on  
cylinders of 300 ... 460 mm diameter as well on pipes  
from 40 ... 150 mm diameter.  
Wide range of well assemblies available.  
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L4188 - L6188 SINGLE AQUASTAT - DIRECT IMMERSION  
APPLICATIONS AND ORDERING INFORMATION  
Application  
L4188 and L6188 are sensitive, immersion-type water  
temperature thermostats for controlling and limiting boiler  
water temperature in hydronic heating systems.  
The thermostat has a liquid-filled sensing element which fits  
into an immersion well (order separately) for direct mounting  
into a boiler, tank or other vessel.  
Ordering information  
O.S. number  
Application  
Temperature  
range  
Switch  
differential (K)  
Switch type  
Setting means  
Remarks  
(see notes)  
L4188A 2015  
L4188A 2023  
L4188A 2031  
L4188B 2005  
L4188B 2013  
Controller  
Controller  
Controller  
Controller  
Controller  
25 ... 95°C  
40 ... 110°C  
25 ... 95°C  
40 ... 110°C  
25 ... 95°C  
4
4
4
4
4
SPST  
SPST  
SPST  
SPST  
SPST  
External knob  
External knob  
External knob  
Internal screw  
Internal screw  
-
5
5
4 - 5  
4 - 5  
4
... 10  
L6188A 2002  
L6188A 2010  
L6188A 2028  
L6188A 2036  
Controller  
Controller  
Controller  
Controller  
25 ... 95°C  
40 ... 110°C  
25 ... 95°C  
70 ... 140°C  
SPDT  
SPDT  
SPDT  
SPDT  
External knob  
External knob  
External knob  
External knob  
6
6
3
6
(
adjustable)  
4
... 10  
(
adjustable)  
4
... 10  
(
adjustable)  
4
... 10  
(
adjustable)  
4
... 10  
L6188A 2044  
L6188B 2000  
L6188B 2018  
Controller  
Controller  
Controller  
40 ... 110°C  
25 ... 95°C  
70 ... 140°C  
SPDT  
SPDT  
SPDT  
External knob  
Internal screw  
Internal screw  
Tradeline 1 - 7  
(
adjustable)  
4
4
4
... 10  
3 - 7  
(
4
(
adjustable)  
... 10  
adjustable)  
... 10  
adjustable)  
L6188B 2026  
L6188B 2034  
Controller  
Controller  
40 ... 110°C  
25 ... 95°C  
SPDT  
SPDT  
Internal screw  
Internal screw  
4
(
6 - 7  
L6188B 2042  
L6188C 2008  
L6188C 2016  
Controller  
Limiter  
Limiter  
25 ... 95°C  
70 ... 140°C  
25 ... 95°C  
4
SPDT  
SPDT  
SPDT  
Internal screw  
Internal screw  
Internal screw  
Manual reset  
Manual reset  
7
6 - 7  
1
= High limit stop  
= High limit stop at 60°C  
2
3
4
5
6
7
= Capilliary length 1500 mm and mounting bracket  
= Without cover and conduit box  
= Quick connect terminals only  
= With well assembly  
= With push-in plug  
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L4188 - L6188 SINGLE AQUASTAT - DIRECT IMMERSION  
Specifications  
Ambient temperature limits  
... 70°C  
Immersion wells, see page 18  
0
C
1
2 C 1  
Electrical connection  
.3 mm spade terminals  
6
+
+
Enclosure  
IP40  
Electrical rating  
SPST  
SPDT  
10 A at 250 Vac, resistive load  
2.5 A at 250 Vac, inductive load  
15 A at 250 Vac, locked motor  
250 mA at 30 mVdc (special option)  
Fig. 1. Internal schematics L4188/L6188  
Terminal data  
C-1 breaks on temperature rise (SPDT and SPST)  
C-2 makes on temperature rise (SPDT only)  
Accessories  
1
4.6  
1
1.5  
5
4
8
4
7.1  
8
5
3
2
2
1
C
9
7
2
3
0
1
4.4  
14  
4
21  
Pg 13.5  
4
8
4
8
Fig. 2. Dimensional drawing L4188/L6188  
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L4189 - L6189 SINGLE AQUASTAT - PANEL MOUNTING (IMMERSION)  
APPLICATIONS AND ORDERING INFORMATION  
Application  
L4189 and L6189 are sensitive, immersion-type water  
temperature thermostats for controlling and limiting boiler  
water temperature in hydronic heating systems.  
These thermostats are designed for panel mounting and are  
supplied with a remote bulb and a liquid-filled sensing element  
which fits into an immersion well (order separately) for  
mounting into a boiler, tank or other vessel.  
Ordering information  
O.S. number  
Application  
Temperature  
range  
Switch  
differential (K)  
Switch type  
Setting means Capillary  
Remarks  
length (mm) (see notes)  
L4189A 2006  
L4189A 2014  
L4189A 2089  
L4189A 2097  
L4189A 2105  
L4189B 2012  
L6189A 2001  
L6189A 2019  
Controller  
Controller  
Controller  
Controller  
Controller  
Controller  
Controller  
Controller  
25 ... 95°C  
25 ... 95°C  
25 ... 95°C  
25 ... 95°C  
25 ... 95°C  
100 ... 230°F  
25 ... 95°C  
25 ... 95°C  
4
4
4
4
4
4
8
4
SPST  
SPST  
SPST  
SPST  
SPST  
SPST  
SPDT  
SPDT  
External knob  
External knob  
External knob  
External knob  
External knob  
Internal screw  
External knob  
External knob  
1000  
1500  
1000  
1000  
350  
1000  
1500  
1500  
2
-
1 - 4 - 5  
5
1 - 6  
3
2
-
4
... 10  
L6189A 2043  
L6189A 2068  
L6189A 2092  
L6189A 2118  
L6189A 2134  
L6189A 2142  
L6189A 2159  
Controller  
Controller  
Controller  
Controller  
Controller  
Controller  
Controller  
40 ... 110°C  
25 ... 95°C  
SPDT  
SPDT  
SPDT  
SPDT  
SPDT  
SPDT  
SPDT  
External knob  
External knob  
External knob  
External knob  
External knob  
External knob  
External knob  
1500  
1000  
1500  
1500  
1500  
2000  
2000  
-
(
adjustable)  
4
7
2
1
1
1
1
1
... 18°F  
110 ... 230°F  
110 ... 230°F  
110 ... 230°F  
110 ... 230°F  
110 ... 230°F  
(
adjustable)  
15°F  
7
... 18°F  
(
adjustable)  
15°F  
7
... 18°F  
(
adjustable)  
L6189B 2009  
L6189B 2025  
L6189B 2041  
L6189C 2007  
L6189C 2023  
L6189C 2031  
Controller  
Controller  
Controller  
Limiter  
Limiter  
Limiter  
25 ... 95°C  
25 ... 95°C  
40 ... 110°C  
40 ... 110°C  
110 ... 230°F  
110 ... 230°F  
4
4
8
SPDT  
SPDT  
SPDT  
SPDT  
SPDT  
SPDT  
Internal screw  
Internal screw  
Internal screw  
Internal screw  
External knob  
External knob  
1000  
1000  
1500  
1500  
1500  
2000  
-
2, Tradeline  
-
-
-
-
Manual reset  
Manual reset  
Manual reset  
1
= High limit stop  
2
3
4
5
6
= Without knob and index  
= With mounting bracket  
= With conduit box  
= With cable connector  
= Low limit stop  
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L4189 - L6189 SINGLE AQUASTAT - PANEL MOUNTING (IMMERSION)  
SPECIFICATIONS AND DIMENSIONS  
Specifications  
Ambient temperature limits  
... 70°C  
Accessories  
Immersion wells, see page 18  
0
Electrical connections  
.3 mm spade terminals  
C
1
2 C 1  
6
+
+
Enclosure  
IP40  
Electrical rating  
10 A at 250 Vac, resistive load  
2,5 A at 250 Vac, inductive load  
15 A at 250 Vac, locked motor  
250 mA at 30 mVdc (special option)  
SPST  
SPDT  
Fig. 3. Internal schematics L4189/L6189  
Terminal data  
C-1 breaks on temperature rise (SPDT and SPST)  
C-2 makes on temperature rise (SPDT only)  
Capilliary length  
350 mm, 1000 mm, 1500 mm and 2000 mm  
Mounting hole (2) for M4x20  
tread forming screw  
1
7
48  
mm max  
3
2
2
1
6
6
0
4
7.1  
4
8
1
8
3
2
2
1
C
Panel  
Hole ( 4 min.) in  
panel for tool reset  
2
8.5  
85  
1
4.4 14  
30.5  
4
8
5
Fig. 4. Dimensional drawing L4189/L6189  
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L6190 SINGLE AQUASTAT - SURFACE MOUNTING  
APPLICATION AND ORDERING INFORMATION  
Application  
The L6190 is a sensitive water temperature thermostat  
designed for surface mounting on domestic hot water cylinders  
or pipe work. The SPDT switching action is accomplished by a  
snap-action microswitch actuated by the temperature sensing  
element.  
The L6190 is supplied complete with mounting strap for rapid  
and easy installation. Draining of the system or tapping of the  
cylinder or pipe work is not required. The required temperature  
control point is easily set using a screw driver.  
Ordering information  
O.S. number  
Application  
Temperature  
range  
Switch  
differential (K)  
Switch type  
Setting means  
Strap length  
(mm)  
L6190A 2016  
L6190B 2006  
L6190B 2014  
L6190B 2022  
Surface mounting  
Surface mounting  
Surface mounting  
Surface mounting  
25 ... 95°C  
25 ... 95°C  
25 ... 95°C  
25 ... 95°C  
8
8
12  
4
SPDT  
SPDT  
SPDT  
SPDT  
External knob  
External setting  
External setting  
External setting  
250  
2000  
2000  
2000  
4
... 10  
L6190B 2030  
Surface mounting  
25 ... 95°C  
SPDT  
Internal setting  
250  
(
adjustable)  
L6190C 2004  
L6190C 2012  
Surface mounting  
Surface mounting  
25 ... 95°C  
25 ... 95°C  
Manual reset  
Manual reset  
SPDT  
SPDT  
Internal setting  
Internal setting  
2000  
2000  
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L6190 SINGLE AQUASTAT - SURFACE MOUNTING  
SPECIFICATIONS AND DIMENSIONS  
Specifications  
Ambient temperature limits  
... 70°C  
Capilliary length  
55 mm  
0
Electrical connection  
.3 mm spade terminals or screw terminals  
2
C 1  
6
+
Enclosure  
IP40  
Electrical rating  
10 A at 250 Vac, resistive load  
2,5 A at 250 Vac, inductive load  
15 A at 250 Vac, locked motor  
SPDT  
Fig. 5. Internal schematic L6190  
Terminal data  
C-1 breaks and C-2 makes on temperature rise  
4
8
2
4
2
6.5  
6
1
7
2
2
1
00  
9
2
9
3
0
5
1
2
4
Fig. 6. Dimensional drawing L6190  
1
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L4191 - L6191 DUAL AQUASTAT - DIRECT IMMERSION  
APPLICATION AND ORDERING INFORMATION  
Application  
L4191 and L6191 are dual units in which two independently  
working water temperature thermostats are housed in one  
cover. Each thermostat has a separate liquid filled sensing  
element which fits into a common immersion well for direct  
mounting into a boiler, tank or other vessel. One thermostat,  
with external temperature setting dial, acts as a controller  
while the other, with internal setting dial, acts as a high limit  
control.  
Two main types are available, one with controller and auto  
recycling high limit and the other with controller and high limit  
with manual reset.  
Ordering information L4191  
O.S. number  
Application  
Temperature  
range  
Switch  
differential (K)  
Switch type  
Setting means  
Remarks  
(see notes)  
Controller  
Limiter  
Controller  
Limiter  
Controller  
Limiter  
Controller  
Limiter  
25 ... 95°C  
25 ... 95°C  
25 ... 95°C  
25 ... 95°C  
70 ... 140°C  
70 ... 140°C  
25 ... 95°C  
25 ... 95°C  
4
4
4
4
SPST  
SPST  
SPST  
SPST  
SPST  
SPDT  
SPST  
SPDT  
External knob  
Internal screw  
External knob  
Internal screw  
External knob  
Internal screw  
External knob  
Internal screw  
9
9
L4191A 2002  
L4191A 2010  
L4191B 2018  
L4191B 2042  
7 - 9 - 10  
9
6
1
5 - 9 - 10  
9 - 10  
4
Manual reset  
4
Manual reset  
1
2
3
4
5
6
=Gold contacts for thermocouple applications, without jumper  
=High limit stop at 80°C/low limit stop at 60°C  
=High limit stop at 82°C  
7 =With well assembly  
8 =High limit stop  
9 =With jumper  
=Low limit stop at 95°C  
10 =With push-in plug  
11 =Without knob and index  
=Isolated neutral terminal  
=High limit stop at 95°C  
Ordering information L6191  
O.S. number  
Application  
Temperature  
Switch  
differential (K)  
... 10  
adjustable)  
Switch type  
Setting means  
Remarks  
(see notes)  
range  
4
(
Controller  
40 ... 110°C  
SPDT  
External knob  
6 - 7 - 9  
L6191A 2007  
Limiter  
Controller  
Limiter  
Controller  
Limiter  
Controller  
Limiter  
40 ... 110°C  
25 ... 95°C  
101°C fixed  
50 ... 95°C  
101°C fixed  
25 ... 95°C  
40 ... 110°C  
40 ... 110°C  
40 ... 110°C  
4
4
4
4
4
4
SPDT  
SPDT  
SPST  
SPDT  
SPST  
SPDT  
SPDT  
SPDT  
SPDT  
Internal screw  
External knob  
Internal setting  
External knob  
Internal screw  
External knob  
Internal screw  
External knob  
Internal screw  
9
3
1
3
L6191A 2015  
L6191A 2023  
L6191B 2005  
L6191B 2013  
1
7 - 9 - 10  
9
5 - 6 - 7 - 9  
9
Manual reset  
4
Manual reset  
Controller  
Limiter  
4
... 10  
Controller  
Limiter  
70 ... 140°C  
70 ... 140°C  
70 ... 140°C  
SPDT  
SPDT  
SPDT  
External knob  
Internal screw  
External knob  
4 - 7 - 9  
9
L6191B 2021  
(adjustable)  
Manual reset  
4
(adjustable)  
Manual reset  
4
... 10  
Controller  
4 - 7 - 9 - 11  
L6191B 2047  
L6191B 2054  
Limiter  
Controller  
Limiter  
70 ... 140°C  
25 ... 95°C  
50 ... 95°C  
SPDT  
SPDT  
SPDT  
Internal screw  
External knob  
Internal screw  
9
7 - 10  
Manual reset  
1
2
3
4
5
6
=Gold contacts for thermocouple applications, without jumper  
=High limit stop at 80°C/low limit stop at 60°C  
=High limit stop at 82°C  
7 = With well assembly  
8 = High limit stop  
9 = With jumper  
= Low limit stop at 95°C  
10 =With push-in plug  
11 = Without knob and index  
= Isolated neutral terminal  
= High limit stop at 95°C  
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L4191 - L6191 DUAL AQUASTAT - DIRECT IMMERSION  
SPECIFICATIONS AND DIMENSIONS  
Specifications  
Ambient temperature limits  
... 70°C  
0
C
1
C
1
C
1
2 C 1  
Electrical connection  
.3 mm spade terminals  
6
+
+
+
+
Enclosure  
IP40  
Electrical rating:  
SPST SPST  
Control Limit  
SPST  
Control  
SPDT  
Limit  
10 A at 250 Vac, resistive load  
2,5 A at 250 Vac, inductive load  
15 A at 250 Vac, locked motor  
250 mA at 30 mVdc (special option)  
2
C
1
C
1
2
C
1
2 C 1  
Terminal data  
C-1 breaks on temperature rise  
C-2 makes on temperature rise  
+
+
+
+
Accessories  
Immersion wells, see page 18  
SPDT SPDT  
Control Limit  
SPDT  
Control  
SPDT  
Control  
Fig. 7. Internal schematics  
1
4.6  
1
1.5  
ϕ 5  
ϕ 47.1  
8
5
7
2
3
0
ϕ 21  
Pg 13.5  
4
8
4
4
8
Fig. 8. Dimensional drawing L4191/L6191  
1
3
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L6188A 2044 TRADELINE SINGLE AQUASTAT - DIRECT IMMERSION  
APPLICATIONS AND ORDERING INFORMATION  
Application  
L6188A 2044 Tradeline Aquastat is a sensitive immersion-type  
water temperature thermostat for regulating and limiting boiler  
water temperature in hydronic heating systems.  
The Honeywell Tradeline technique of using adapters enables  
the L6188A 2044 Aquatat thermostat to field replace  
Honeywell Aquastat thermostats as well as many competitive  
devices (using the existing well*). No draining of the system is  
needed. Ideal for service organisations to stock since only one  
Aquastat is needed for most calls.  
*
If a new immersion well is needed order separately.  
Ordering information L6188A 2044  
O.S. number  
Application  
Temperature  
range  
Switch  
differential (K)  
... 10  
adjustable)  
Switch type  
Setting means  
Remarks  
(see notes)  
4
(
L6188A 2044  
Controller  
40 ... 110°C  
SPDT  
External knob  
1
1
= High limit stop at 95°C/low limit stop at 50°C  
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L6188A 2044 TRADELINE SINGLE AQUASTAT - DIRECT IMMERSION  
SPECIFICATIONS AND DIMENSIONS  
Specifications  
Temperature range  
Accessories  
Immersion wells, see page 18  
40 ... 110°C  
Differential  
... 10 (adjustable)  
2
C 1  
4
+
Limit stops:  
Low limit: adjustable, factory set at 50°C  
High limit: adjustable, factory set at 95°C  
Ambient temperature limits  
... 70°C  
0
SPDT  
Electrical connection  
.3 mm spade terninals  
Fig. 9. Internal schematic  
6
Enclosure  
IP40  
Electrical rating  
10 A at 250 Vac, resistive load  
2,5 A at 250 Vac, inductive load  
15 A at 250 Vac, locked motor  
Terminal data  
C-1 breaks on temperature rise  
C-2 makes on temperature rise  
1
4.6  
1
1.5  
5
4
8
4
7.1  
8
5
3
2
2
1
C
9
7
2
3
0
1
4.4  
14  
4
21  
Pg 13.5  
4
8
4
8
Fig. 10. Dimensional drawing L6188A 2044  
1
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PERFORMANCE  
Fixed switch differential  
Ambient temperature error  
On controls and recycling limits a fixed differential of:  
Ratio of ambient error  
With capilliary lenth of 1000 mm  
With capilliary lenth of 50 mm  
Max. setting Min. setting  
4
1
± 1.5°C, 8 ± 3°C or  
2 ± 3°C is supllied as a standard.  
1 : 5.5  
1 : 12  
1 : 8.5  
1 : 25  
Optional are:  
Example:  
7 ± 2.7°F,  
14 ± 5.4°F  
15 ± 5.4°F  
An ambient error ratio of 1 : 6 means that an ambient  
change of 6°C will cause a setpoint shift of the Aquastat of  
1°C.  
Adjustable switch differential  
On controllers and recycling limiters an adjustable differential  
of:  
Time constant  
 With well  
4
7
± 1.5°C ... 10 ± 3°C or  
± 2.7°F ... 18 ± 5.4°F can be supllied.  
τ ≤ 30 s for panel mounted, single direct mounted, dual  
direct mounted and triple direct mounted Aquastats.  
Without well  
Manual or tool reset switch differential  
τ ≤ 4 s  
On the thermal cut-out versions (manual or tool reset) of the  
panel mounted, the single direct mounted and the dual direct  
mounted Aquastats the maximum reset differential might be  
With sensor assy (Surface mounted Aquastat)  
τ ± 50 s  
3
0°C  
Setpoint accuracy  
0/-8°C for thermal cut-outs  
+
NOTE: The differential (thermal) is dependant on the rate of  
change of the temperature in the heating system.  
The given differential datas are valid for a rate of1°C  
per minute.  
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CONSTRUCTION  
All aquastats have the following common parts  
Dual direct mounted Aquastat needs the following extra parts  
Thermoplastic housing of mainly rectangular form. This  
housing is the carrier of the Micro Switch mechanism, the  
 Two single thermoplastic conduit boxes (a right and a left  
one) with cable entry.  
6
.3 mm quick connect terminals, the lever mechanism and  
A dual thermoplastic front cover to protect against touching  
of live parts.  
A thermoplastic top cover for covering of units with internal  
setting.  
An adjustable dial for the Micro Switch differential (if  
applicable).  
A bracket on the rear side of the Aquastat to connect both  
basic units together and which fits into a dual well.  
the adjusting mechanism.  
Thermoplastic switch cover, which protects the switch  
mechanism and which fits in the above mentioned housing.  
Auxiliary parts to make it possible to use the quick connect  
terminals also for screw connection.  
External circular setting knob with scale and an index or  
internal setting with scale.  
Liquid filled sensing element with or without a remote bulb.  
This element is via a mounting plate connected to the rear  
side of the thermoplastic housing  
Surface mounted Aquastat needs the following extra parts  
A thermoplastic conduit box with a cable entry  
A thermoplastic front cover to protect against touching of  
live parts.  
A thermoplastic top cover with scale for covering of unit with  
internal setting.  
A fastening strap with fastener, to mount the Aquastat on  
the surface of boiler or pipe.  
Well assembly in which the bulb of the sensing elements  
fits. For the dual direct mount aquastat and triple direct  
mount aquastat the well is enable to contain two resp. three  
bulbs.  
NOTE: The surface mounted Aquastat does not have a  
well, but the bulb is enveloped by a sensor  
assembly of mainly rectangular form which is  
mounted on the rear side of the thermoplastic  
housing.  
Triple direct mounted Aquastat needs the following extra parts  
A reset button for the switch mechanism, manual or tool  
reset, with exception of the surface mounted Aquastat,  
which does not have such a button.  
 Three single thermoplastic conduit boxes with a cable entry.  
A dual and a single thermoplastic front cover.  
Two thermoplastic top covers for covering of units with  
internal setting.  
Single direct mounted Aquastat needs the following extra parts  
An adjustable dial for the Micro Switch differential (if  
applicable).  
Two brackets on the rear side of the Aquastat to connect  
the three basic units together and which fits into a triple  
well.  
A thermoplastic conduit box with a cable entry.  
A thermoplastic front cover to protect against touching of  
live parts.  
A thermoplastic top cover for covering of units with internal  
setting.  
An adjustable dial for the Micro Switch differential (if  
applicable).  
1
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ACCESSORIES AND SPARE PARTS  
Single well assembly  
Description  
Ordernumber  
Packing qty  
pcs)  
40  
(
1
Spud thread: /  BSPT  
45.900.409-003  
2
Maximum insertion length (including thread): 105 mm  
Suitable for Ø 5 mm sensor  
1
Spud thread: /  BSPT  
45.900.409-006  
100  
2
Maximum insertion length (including thread): 170 mm  
Suitable for Ø 5 mm sensor  
Dual well assembly  
Description  
Ordernumber  
Packing qty  
(
20  
pcs)  
1
Spud thread: /  BSPT  
45.900.409-007  
2
Maximum insertion length (including thread): 105 mm  
Suitable for two Ø 5 mm sensors.  
1
Spud thread: /  BSPT  
45.900.409-008  
20  
2
Maximum insertion length (including thread): 105 mm  
Suitable for two Ø 5 mm sensors when used with spring.  
Without spring suitable for three or four Ø 5 mm sensors.  
Supplied with spring  
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Miscellaneous  
Description  
Ordernumber  
Packing qty (pcs)  
Knob assembly  
4
4
4
5.900.427-002  
5.900.427-003  
5.900.443-001  
200  
Scale range: 110 ... 230°F, high limit stop: 180°F  
Knob assembly  
Scale range: 40 ... 110°C, high limit stop: 82°C  
Strap set for L6190 surface mounted aqustat  
Strap length: 2000 mm  
200  
50  
Key  
Description  
Part number  
number  
1
2
Fixing screw for front covers of single and dual aquastats  
Knob  
45.002.700-001  
Scale range  
Low limit stop  
High limit stop  
4
7
2
4
7
4
2
4
2
7
2
1
5
4
2
8
1
1
1
1
0 ... 110°C  
0 ... 140°C  
5 ... 95°C  
0 ... 110°C  
0 ... 140°C  
0 ... 110°C  
5 ... 95°C  
0 ... 110°C  
5 ... 95°C  
0 ... 140°C  
5 ... 95°C  
... 7 (40 ... 110°C)  
0 ... 95°C  
0 ... 110°C  
5 ... 95°C  
0 ... 100°F  
10 ... 230°F  
60 ... 280°F  
10 ... 230°F  
10 ... 230°F  
-
-
-
-
-
-
-
45.002.823-001  
45.002.823-002  
45.002.823-003  
45.002.823-004  
45.002.823-005  
45.002.823-006  
45.002.823-007  
45.002.823-008  
45.002.823-010  
45.002.823-011  
45.002.823-013  
45.002.823-014  
45.002.823-015  
45.002.823-017  
45.002.823-019  
45.004.213-001  
45.004.213-002  
45.004.213-003  
45.004.213-004  
45.004.213-005  
45.002.547-002  
45.000.219-015  
45.002.797-001  
45.002.540-001  
45.002.802-001  
95°C  
-
95°C  
50°C  
-
-
-
-
60°C  
-
-
-
95°C  
82°C  
100°C  
60°C  
95°C  
80°C  
85°C  
82°C  
82°C  
80°C  
-
40°C  
-
-
-
-
-
-
-
200°F  
180°F  
3
4
5
6
7
Cover for single Aquastat  
Screw  
Wire clamp  
Conduit box  
Push in plug  
1
9
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QUALITY ASSURANCE STATEMENT  
Products are manufactured under an ISO 9001 (1994) based  
and certified Quality System.  
Assembly processes are guided by work instructions. Patrol  
inspections form part of the assembly processes.  
The quality system is described in the Honeywell Combustion  
Controls Center Quality Assurance Programme and its related  
operational procedures and instructions.  
At the end of the assembly phase, all aqustats are leakage  
and performance tested/adjusted.  
Assembly inspection is performed by employees of the quality  
control department, using their own equipment.  
The quality system is approved by Gastec against certificate  
number 9.302/2.  
All inspections (incoming and assembly) are performed by  
trained personel and according inspection procedures.  
The quality organisation is responsible for defining,  
maintaining, improving and verification of the quality systems  
in the field of design, production process and field quality  
service.  
STANDARDS AND APPROVALS  
Standards  
Approvals  
The L41../L61.. series Aquastats have been designed  
according the Low Voltage Directive 73/23/EEC.  
An additional approval is obtained from DIN in Germany  
according to DIN 3440 as thermostat (TR) or temperature  
limiter (TW).  
This Low Voltage Directive is covered by approvals in  
Denmark, Finland, Norway, Sweden and Switserland.  
In North-America approvals have been obtained from UL,  
AGA and CSA.  
EMC Directive 89/336/EEC:  
The snap action switch ensures in most cases a switching  
action in less than 10 ms, which satisfies EMC-Directive  
without further measures.  
The exception is a highly inductive low current load combined  
with slow rate of temperature change, which requires  
additional suppression means. For this reason compliance  
with the EMC-Directive cannot be claimed.  
Europen countries accept above certificates as basis for  
appliance approval.  
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ORDERING INFORMATION  
When ordering specify  
Setting point(control and limit if necessary)  
Type of contact (SPDT/SPST/ electrical rating)  
Number of sensing point (single/dual)  
Type of mounting (direct immersion/panel/surface)  
Differential (adjustable/fixed/manual reset)  
Capillary length  
Ordering Specification number  
L 4 1 X X A 9999  
L: Aquastat  
Specification number  
Control contact:  
4
:
SPST  
6
:
SPDT  
A: Single: knob setting  
Dual: automatic reset limiter  
B: Single: internal setting (screw)  
Dual: manual reset limiter  
C: Single: manual reset  
1
:
Family  
8
8
9
9
9
8: Single aquastat, direct immersion  
9: Single aquastat, panel mounting  
0: Single aquastat, surface mounting  
1: Dual aquastat, direct mounting  
2: Triple aquastat, direct mounting  
Fig. 11. Model number chart  
2
1
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Home and Building Control  
Combustion Control Center Europe  
Honeywell BV  
Phileas Foggstraat 7  
7
821 AJ Emmen  
The Netherlands  
Tel.: +31 (-)591 695911  
Fax: +31 (-) 591 695200  
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