Honeywell V8943CN Thermostat User Manual

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V4943/V8943B,C,N;  
V4944/V8944B,C,L,N  
Regulating Diaphragm Gas Valves  
PRODUCT DATA  
FEATURES  
Models are available for natural or liquid petroleum  
LP) gases.  
(
Valve models L, N are rapid opening (less than six  
seconds) and fast closing, and are available for LP and  
natural gases, respectively.  
Line voltage with two-wire thermostat or controller is  
used with V4943; V8943 is used with 24V thermostat or  
controller.  
V4944 is used with line voltage dual-stage thermostat  
or controller; V8944 is used with 24V dual-stage  
thermostat or controller.  
Slow opening B,C valve models are available for  
natural and LP gases respectively.  
Valve closes on power failure; recommended for final  
shutoff service.  
APPLICATION  
Valve closing time: 2 seconds maximum at 7 inches wc  
inlet pressure.  
The V4943/V8943B and N (single stage) and V4944/V8944B  
and N (two stage) are solenoid-operated diaphragm valves  
suitable for natural gas only. The V4943/V8943C and  
V4944/V8944C and L are solenoid-operated diaphragm  
valves suitable for Liquefied Petroleum (LP) gas only. These  
valves are used on boilers, unit heaters, duct furnaces,  
makeup air and rooftop heaters.  
Valves rated for 0.5 pound per square inch (psi) (3.4  
kPa).  
Leadwires and cover for electrical conduit connections  
are provided.  
Contents  
Application ........................................................................  
Features ...........................................................................  
Specifications ...................................................................  
Ordering Information ........................................................  
Installation ........................................................................  
Operation ..........................................................................  
1
1
2
2
6
9
Checkout and Troubleshooting ......................................... 10  
Service Information .......................................................... 12  
6
5-0214-08  
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V4943/V8943B,C,N; V4944/V8944B,C,L,N REGULATING DIAPHRAGM GAS VALVES  
SPECIFICATIONS  
Models:  
All models are solenoid-operated regulating diaphragm gas  
valves. Details are shown in Table 1.  
Table 1. Model Availability.  
Maximum  
Power  
Operating  
Voltage  
and  
Consumption  
(VA  
Opening  
Time  
Number  
Pressure  
Maximum  
Pipe Size Thread  
Pressure Type of of Lead-  
Model Frequency Current  
Maximum)  
(in.)  
Type  
psi kPa  
(sec.) Regulation  
Gas  
wires  
V4943B 120V 0.055A  
6.6  
1, 1-1/4,  
1-1/2, 2  
NPT  
0.5  
3.4  
3 to 25 Single  
stage  
a 2  
Natural  
(
-
6
+10%,  
15%),  
0 Hz  
V4943N  
1, 1-1/4,  
<6  
1-1/2  
V8943B 24V,(+10%, 0.363A  
15%)  
0/60 Hz  
9.0  
1, 1-1/4,  
1-1/2, 2  
3 to 25  
-
5
V8943C  
V8943N  
1, 1-1/4  
LP  
1, 1-1/4,  
<6  
Naturala  
1-1/2  
V4944B 120V  
0.077A  
9.0  
3 to 25 Two stage  
3
(
-
6
+10%,  
15%)  
0 Hz  
V4944C  
V4944L  
V4944N  
LP  
1-1/4  
<6  
1, 1-1/4,  
Naturala  
1-1/2, 2  
V8944B 24V  
0.470A  
11.3  
3 to 25  
(
-
5
+10%,  
15%)  
0/60 hz  
V8944C  
1, 1-1/4,  
LP  
1-1/2  
V8944L  
V8944N  
1, 1-1/4  
1, 1-1/4,  
1
<6  
Naturala  
-1/2, 2  
Includes natural gas, mixed air-natural gas, LP gas-air.  
Flow Capacity: See Table 2.  
Table 2. V4/8943 and V4/8944 Flow Capacity.  
a
Valve Pattern:Straight-through, non offset.  
Valve Body Material:Die-cast aluminum.  
CSA  
Regulation Capacities  
Electrical Terminations:1/4 in. (6 mm) spade terminals  
quick connects). Leadwires and cover for electrical conduit  
connections are provided.  
Certified  
1
Btuh per 0.64 sp gr Natural Gas  
.0 in. pd 1000 cfh  
Natural  
gas  
(
PipeSize Natural  
in.) Gas cfh  
Maximum Minimum  
cfh cfh  
(
Valve Closing Time: On power failure, a maximum of  
2
seconds at 7 in. wc inlet pressure.  
1
1
1
2
1,000  
1,000,000 1,000  
1,600,000 1,600  
2,300,000 2,300  
3,000,000 3,000  
300  
480  
780  
870  
-1/4  
-1/2  
1,600  
2,300  
3,000  
Ambient Temperature Ratings: -40°F to +150°F (-40°C to  
66°C).  
+
Maximum Fluid Temperatures: 150°F (66°C).  
ORDERING INFORMATION  
When purchasing replacement and modernization products from your TRADELINE® wholesaler or distributor, refer to the  
TRADELINE® Catalog or price sheets for complete ordering number. If you have additional questions, need further information,  
or would like to comment on our products or services, please write or phone:  
1
.
.
Your local Honeywell Environmental and Combustion Controls Sales Office (check white pages of your phone directory).  
Honeywell Customer Care  
2
1885 Douglas Drive North  
Minneapolis, Minnesota 55422-4386  
http://customer.honeywell.com or http://customer.honeywell.ca  
3.  
International Sales and Service Offices in all principal cities of the world. Manufacturing in Belgium, Canada, China, Czech  
Republic, Germany, Hungary, Italy, Mexico, Netherlands, United Kingdom, and United States.  
65-0214—08  
2
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V4943/V8943B,C,N; V4944/V8944B,C,L,N REGULATING DIAPHRAGM GAS VALVES  
Pressure Reference Port Vent: 5/16–24 UNF internal  
tapping.  
Weight:  
1 in., 1-1/4 in. valves: 4 lb (1.8 kg).  
1-1/2 in., 2 in. valves: 5 lb (2.3 kg).  
Standard Factory Settings: See Table 3.  
Dimensions: See Fig. 1.  
Table 3. Factory Settings and Regulation Ranges.  
Natural Gas (i.e. B, N models)  
LP Gas (i.e. C, L models)  
Factory Setting  
Adj. Rangeb  
Firing stagesa  
Factory Setting  
Adj. Rangeb  
Low Fire:  
Standard Models  
0.8” wc  
1.6” wc  
0.8” wc  
0.8” wc  
0.8” to 2” wc  
1.6” to 4.2” wc  
0.8” to 2” wc  
0.8” to 2” wc  
1.4” wc  
1.4” to 4.2” wc  
Special Models (Group 1)  
Special Models (Group 2)  
Special Models (Group 3)  
High Fire:  
Standard Models  
3.5” wc  
3.5” wc  
3.5” wc  
5” wc  
3” to 4.5” wc  
3” to 4.5” wc  
1.4” to 4.2” wc  
4.0” to 7” wc  
10” wc  
8.8” to 11.5” wc  
Special Models (Group 1)  
Special Models (Group 2)  
Special Models (Group 3)  
a
b
V4943 is a single-stage valve, please refer to “High Fire” for spring specifications.  
Do not adjust or operate valve outside of the specified ranges.  
CAUTION  
DO NOT adjust or operate valve outside of the  
specified ranges. Valve will not regulate or work  
properly.  
Special Models (Group 1): V4944B1075, V4944B1083, V4944B1091, V8944B1092, V8944B1100, V8944B1118  
Special Models (Group 2): V4944B1109, V4944B1125, V4944B1141, V4944B1166; V4943B1050, V4943B1068, V4943B1076,  
V4943B1084  
Special Models (Group 3): V4944B1117, V4944B1133, V4944B1158; V4943B1092, V4943B1100, V4943B1118  
Approvals:  
Underwriters Laboratories Listed: File Number MH1639  
CSA Certified: Report Number C2030020 (except those listed as Special Models Group 2 and Special Models Group 3)  
Commonwealth of Massachusetts Product Certification Number: G1-12-05-22  
Mounting Position:  
Standard Position: Upright (horizontal).  
Accessories:  
AT72D Transformer (40 VA) for all 24 Vac models.  
204480 Vent Pipe Adapter  
NOTE: V4944B1059, V4944N1052 and V4944N1060 can  
be mounted upright to 90 degrees from the  
upright on the horizontal axis with respect to the  
inlet connection.  
3
65-0214—08  
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V4943/V8943B,C,N; V4944/V8944B,C,L,N REGULATING DIAPHRAGM GAS VALVES  
SIDE VIEW  
TOP VIEW  
(152)  
6
6
-9/16 (167)  
FOR 1, 1-1/4  
6
152)  
PRESSURE  
REGULATOR  
ADJUSTMENT  
CAPS  
OR  
(
7
-3/8 (187)  
FOR 1-1/2, 2  
ATMOSPHERIC  
PRESSURE  
REFERENCE  
PORT WITH  
INTERNAL  
VENT LIMITER  
INLET  
PRESSURE  
TAP  
OUTLET  
PRESSURE  
TAP  
M23375  
Fig. 1. V4943/44 and V8943/44 dimensions in in. (mm).  
7
.
At the point of intersection of the vertical line and the  
curve, draw a horizontal line to intersect the flow  
(capacity) scale. The point of intersection indicates the  
capacity that can be obtained with the maximum  
pressure drop.  
Gas Valve Sizing  
1.  
Check the burner nameplate for:  
a. the type of gas used, and  
b. the gas flow capacity. The capacity will be listed in  
British thermal units per hour (Btuh) or in cubic feet  
per hour (cfh).  
Contact the local gas utility for information regarding:  
a. the specific gravity (sp gr) and  
b. the Btu per cubic foot (Btucf) for the type of gas used.  
Find the capacity in cf/h. If the capacity is listed in Btu,  
convert to cf/h using the following formula:  
8. If the capacity at the maximum pressure drop is  
insufficient, use the capacity vs. pressure drop curve for  
the next larger valve size and repeat steps 6 and 7.  
2
.
.
1
INCH V4/8944B/N REGULATION AREA  
3
100  
Capacity in cfh = Btuh (burner nameplate)  
Btu/cf (gas utility)  
10  
PO > 2 IN.  
ANY PO  
4.  
For gases with specific gravities other than 0.64, multiply  
the burner cf/h using the proper conversion factor in  
Table 4.  
Table 4. Gas Conversion Factors.  
Type of Gas  
sp gr (average)  
0.60  
Multiply cfh by  
0.968  
1
PO < 2.5 IN.  
Manufactured  
Mixed  
0.70  
1.53  
1.98  
1.046  
1.546  
1.759  
LP-Propane  
LP-Butane  
0
.1  
1
00  
1000  
10000  
M23376  
5.  
Use the corrected burner capacity in cfh when determin-  
ing the gas valve size in Figs. 2–9.  
FLOW NATURAL GAS (CFH)  
6.  
Determine the maximum pressure drop across the valve  
and draw a vertical line at this pressure in Figs. 2–9.  
Fig. 2. Capacity vs. pressure drop of Natural Gas  
curves for 1 in. valve.  
65-0214—08  
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V4943/V8943B,C,N; V4944/V8944B,C,L,N REGULATING DIAPHRAGM GAS VALVES  
1
.25 INCH V4/8944B/N REGULATION AREA  
2 INCH V4/8944B/N REGULATION AREA  
100  
100  
10  
10  
PO > 2 IN.  
ANY PO  
PO > 2 IN.  
ANY PO  
1
PO < 2.5 IN.  
1
0
.1  
0
.1  
1
00  
1000  
10000  
M23377  
1
00  
1000  
10000  
M23379  
FLOW NATURAL GAS (CFH)  
FLOW NATURAL GAS (CFH)  
Fig. 3. Capacity vs. pressure drop of Natural Gas  
curves for 1-1/4 in. valve.  
Fig. 5. Capacity vs. pressure drop of Natural Gas  
curves for 2 in. valve.  
1
.5 INCH V4/8944B/N REGULATION AREA  
1
INCH V4/8944C/L REGULATION AREA  
100  
100  
10  
PO > 2 IN.  
ANY PO  
10  
ANY PO  
PO < 2.5 IN.  
1
1
PO < 7 IN.  
0
.1  
1
00  
1000  
10000  
M23378  
0.1  
100  
1000  
10000  
M23380  
FLOW NATURAL GAS (CFH)  
FLOW LP GAS (CFH)  
Fig. 4. Capacity vs. pressure drop of Natural Gas  
curves for 1-1/2 in. valve.  
Fig. 6. Capacity vs. pressure drop of LP Gas  
curves for 1 in. valve.  
5
65-0214—08  
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V4943/V8943B,C,N; V4944/V8944B,C,L,N REGULATING DIAPHRAGM GAS VALVES  
1
.25 INCH V4/8944C/L REGULATION AREA  
2 INCH V4/8944C/L REGULATION AREA  
1
00  
100  
10  
1
1
0
ANY PO  
ANY PO  
PO < 5.5 IN.  
1
PO < 8 IN.  
0
.1  
0.1  
1
00  
1000  
10000  
M23381  
100  
1000  
10000  
M23383  
FLOW LP GAS (CFH)  
FLOW LP GAS (CFH)  
Fig. 9. Capacity vs. pressure drop of LP Gas  
curves for 2 in. valve.  
Fig. 7. Capacity vs. pressure drop of LP Gas  
curves for 1-1/4 in. valve.  
To size two identical valves piped in series:  
1. Find the cf/h for the type of gas used.  
1
.5 INCH V4/8944C/L REGULATION AREA  
100  
2. Consider both valves as one unit. Determine the  
maximum pressure drop across the one unit.  
3
.
Find the pressure drop across the first valve by assuming  
it to be 45 percent of the total pressure drop.  
Find the valve size from Figs. 2–9.  
4.  
.
5
The second valve will be the same size as the first valve.  
10  
ANY PO  
INSTALLATION  
PO < 8 IN.  
1
WARNING  
Explosion hazard.  
Can cause serious injury, death or equipment  
damage.  
Installation and service by trained professionals only.  
Exceeding the pressure rating or use of unspecified  
fuel can lead to improper operation of the valve and can  
create an explosion hazard. Property damage, severe  
bodily injury or death can result.  
0
.1  
1
00  
1000  
10000  
M23382  
FLOW LP GAS (CFH)  
Fig. 8. Capacity vs. pressure drop of LP Gas  
curves for 1-1/2 in. valve.  
When installed in the Commonwealth of  
Massachusetts, the installation and servicing of this  
product must be done by a licensed gas fitter or  
plumber.  
Consult specifications before installing valve.  
65-0214—08  
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V4943/V8943B,C,N; V4944/V8944B,C,L,N REGULATING DIAPHRAGM GAS VALVES  
4
.
Install the valve in a horizontal pipe line in an upright  
position with the gas flow in the direction indicated by the  
arrow on the casing. The valve must be upright  
(electrical connection tower in the up position) on a  
horizontal axis with respect to the inlet connection  
(see Fig. 10). Certain models may be mounted in the  
limited horizontal position (any position from upright to  
90 degrees to upright on an horizontal axis with respect  
to the inlet connection. See Specifications section.)  
When Installing this Product...  
1.  
Read these instructions carefully. Failure to follow them  
could damage the product or cause a hazardous  
condition.  
Check the ratings given in the instructions and on the  
product to make sure the product is suitable for your  
application.  
2.  
3
.
.
Installer must be a trained experienced flame safeguard  
control technician.  
After installation is completed, check out product opera-  
tion as provided in these instructions.  
5. Apply a parallel jaw wrench only to the flat next to the  
pipe being inserted. A wrench applied to the valve body  
itself or to the end farthest from the pipe being inserted  
can distort the casting and cause a malfunction.  
4
6.  
The gas flow must be in the same direction as the arrow  
on the bottom of the valve body.  
WARNING  
Explosion hazard and electrical shock hazard.  
Can cause serious injury or death.  
1
2
. Turn off gas supply before starting installation.  
. Disconnect power supply before beginning  
installation to prevent electrical shock and equipment  
damage.  
WARNING  
Explosion and Fire Hazard.  
Can cause serious injury or death.  
If flow is not in direction of arrow, valve may not  
shut off; which can cause excess gas and harm to  
equipment or personnel.  
3. Do not remove seal over valve inlet or outlet until  
ready to connect piping.  
7
.
Make electrical connections as illustrated in the wiring  
diagrams (see Figs. 11–14).  
Prepare Piping and Install Valve (Fig.  
0).  
1
1
8. Turn on the main gas and, with a soap solution, check  
the valve installation for leaks.  
.
Use new, properly reamed pipe free from chips.  
Do not thread pipe too far. Valve distortion or malfunction  
can result from excess pipe in valve.  
9.  
The V4943/V8943, V4944/V8944 combination valve  
pressure regulating sections are provided with integral  
vent limiters.  
2
3
.
.
Apply good quality pipe dope resistant to the action of LP  
gas; put a moderate amount only on the pipe threads. If  
pipe dope lodges on the valve seat, it will prevent proper  
closure.  
7
65-0214—08  
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V4943/V8943B,C,N; V4944/V8944B,C,L,N REGULATING DIAPHRAGM GAS VALVES  
EXCESS DOPE CAN PUSH DISK  
TWO CLEAN  
OFF THE  
THREADS,  
VALVE  
MODERATE  
AMOUNT  
AVOID  
USING  
VALVE AS  
HANDLE  
SEAT  
OF DOPE  
LOOSE  
CHIPS  
CORRECT  
NORMAL  
FULL THREAD  
INCORRECT  
TOO LONG;  
DISTORTS  
VALVE SEAT  
CORRECT  
NORMAL  
FULL  
REAM PIPE,  
BLOW OUT CHIPS (THAT  
CAN LODGE ON SEAT)  
INCORRECT  
TOO LONG,  
DISTORTS  
THREAD  
VALVE SEAT  
INCORRECT  
WRENCH  
HERE STRAINS  
VALVE BODY  
CORRECT  
VISE GRIPS  
END NEXT  
TO PIPE  
CORRECT  
WRENCH  
CORRECTLY  
APPLIED NEXT  
TO PIPE BEING  
INSERTED  
BEING  
INSERTED  
M6877  
Fig. 10. Preparing the piping and installing the valve.  
4
.
.
Check the power supply circuit. The voltage and  
frequency must match those of the valve.  
See Fig. 11 through 14 for typical field wiring  
connections. Follow the burner manufacturer wiring  
diagram, if provided.  
Wiring  
5
WARNING  
Electrical Shock Hazard.  
6. Make wiring connections at the electrical wires provided  
Can cause serious injury, death or equipment  
damage.  
at the top of the valve.  
Disconnect the power supply before making  
connections to prevent electrical shock and equipment  
damage.  
CAUTION  
Equipment Damage Hazard.  
Miswiring can cause equipment damage.  
1
.
.
All wiring must comply with applicable electrical codes,  
ordinances and regulations. Use NEC Class 1 (line  
voltage) wiring.  
For normal installations, use moisture-resistant No. 14  
wire suitable for at least 167°F (75°C) when using a  
flame safeguard primary control, or for at least 194°F  
90°C) when using a flame safeguard programming  
control.  
For high temperature installations, use  
moisture-resistant No. 14 wire selected for a temperature  
rating above the maximum operating temperature.  
1
. Label all wires prior to disconnection when servicing  
valves. Wiring errors can cause damage to the  
equipment through improper and dangerous  
operation.  
2
2
3
. Verify proper operation after servicing.  
. After the installation is complete, cycle the valve  
several times with the manual fuel shutoff cock  
closed. Make sure the valve and actuator function  
properly.  
(
3.  
4
. If the installation is gas tight and functioning properly,  
proceed to the Checkout section.  
65-0214—08  
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V4943/V8943B,C,N; V4944/V8944B,C,L,N REGULATING DIAPHRAGM GAS VALVES  
TWO-STAGE  
CONTROLLER  
V4943B,C,N  
SINGLE-STAGE  
VALVE  
LINE VOLTAGE  
THERMOSTAT  
OR CONTROLLER  
FLAME  
SAFEGUARD  
CONTROL  
PV  
PV  
MV  
LIMIT(S)  
BLACK  
ORANGE  
L2  
L1  
JUNCTION  
BOX  
L1  
HOT  
L2  
1
1
PV MV  
ORANGE  
(HOT)  
PV  
MV  
FLAME  
TRANSFORMER  
SAFEGUARD  
CONTROL  
V8944B,C, L, N  
TWO-STAGE VALVE  
LIMIT(S)  
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS  
AND OVERLOAD PROTECTION AS REQUIRED.  
1
2
POWER SUPPLY. PROVIDE DISCONNECT MEANS  
AND OVERLOAD PROTECTION AS REQUIRED.  
M6887  
V8944B1050, V8944B1068, V8944B1076,V8944B1084  
V8944C1041, V8944C1058, AND V8944C1066 HAVE A  
MOLEX® CONNECTOR WITH 72 IN. (1829 MM) LEAD  
WIRES: ORANGE (MV), PINK (PV), GRAY (COM).  
Fig. 11. Typical wiring diagram for V4943B,N.  
M6889A  
V8943B,C,N  
SINGLE-STAGE  
VALVE  
24-VOLT  
THERMOSTAT  
Fig. 14. Typical wiring diagram for V8944B,C,L,N with three  
leadwire electrical termination.  
LIMIT(S)  
PV  
PV  
MV  
OPERATION  
BLACK  
ORANGE  
L1  
(
HOT)  
1
General  
L2  
TRANSFORMER  
FLAME SAFEGUARD  
CONTROL  
The V4943/V8943B,C, N and V4944/V8944B,C,L, N Valves are  
solenoid-operated diaphragm gas valves with one or two  
stages of regulation. They can operate as a shut-off valve and  
a pressure regulating valve. The V4943/V8943B,C,N have a  
single stage of regulation (high fire) and the V4944/  
V8944B,C,L,N have two stages of regulation (high fire and low  
fire). The models with L and N suffixes are rapid opening  
devices while the B- and C-suffixed models are slow opening  
devices.  
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS  
AND OVERLOAD PROTECTION AS REQUIRED.  
M6888B  
Fig. 12. Typical wiring diagram for V8943B,C,N.  
FLAME  
SAFEGUARD  
CONTROL  
SECOND  
STAGE  
CONTROLLER  
LIMIT(S)  
CONTROLLER  
In a redundant valve (two valves in series) system, it is  
recommended that the V4943/V8943B,C, N and  
V4944/V8944B,C,L, N Valves be positioned downstream from  
the redundant valve for proper operation of the pressure  
regulator(s). The V4943/V8943N and V4944/V8944L,N models  
have a 0.022 in. bleed orifice in the bleed line (the valves bleed  
internally to the outlet side) and are rapid opening valves  
L1  
(
HOT)  
1
L2  
(
maximum opening time is six seconds). The V4943/V8943B,C  
and V4944/V8944B,C models have bleed orifices varying in  
diameter from 0.014 to 0.018 in. to control the opening time.  
V4944B,C,L,N  
TWO-STAGE VALVE  
The range of outlet pressure is adjusted by turning a screw  
which changes the compression in the regulator spring. The  
valves are suitable for natural gas (B and N models) or LP  
PV PV MV  
MV  
(
C and L models) applications. Do not adjust or operate valve  
outside of the specified ranges (see Table 3).  
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS  
AND OVERLOAD PROTECTION AS REQUIRED.  
Leadwires and a cover for electrical conduit connections are  
provided with each valve.  
M6886B  
Fig. 13. Typical wiring diagram for V4944B,C,L,N with three  
leadwire electrical termination.  
The valves are available in 1 in., 1-1/4 in., 1-1/2 in. and 2 in.  
sizes. The 1 in. and 1-1/4 in. valves share a common body  
casting and the 1-1/2 in. and 2 in. valves share a larger body  
casting. The valves are intended to replace the  
V4843/V8843B,C,N and V4844/V8844B,C,N lines of valves.  
The valves are used as combination controls, providing both  
pressure regulation and shutoff functions for burners. Typical  
burner applications include boilers, process equipment, ovens,  
incinerators, water heaters, rooftop units, and commercial/  
industrial atmospheric/power burners. The burner firing rates  
range from 400 kbtu/hour to 5,000 kbtu/hour.  
9
65-0214—08  
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V4943/V8943B,C,N; V4944/V8944B,C,L,N REGULATING DIAPHRAGM GAS VALVES  
Operation of the V4943B,C,N/  
V8943B,N  
The V4943/V8943B,C,N Valves are combination gas controls  
that include a single stage of pressure regulation in addition to  
the shut-off function. They have a single solenoid and a single  
regulating diaphragm.  
Operation of the V4944/V8944B,C,L,N  
Valves  
These models use two pressure regulators (low fire and high  
fire) and two solenoids to provide two distinct stages of  
pressure regulation. The first stage pressure regulator solenoid  
activates the same quick-close orifice valve and servo valve as  
in the V4943/V8943 models, but the bleed gas now flows  
through a first stage (low fire) regulator valve to the outlet. This  
maintains the outlet at a pressure controlled by the low fire  
regulator. The second stage regulator (high fire) is set to a  
higher outlet pressure. When the second stage solenoid is  
energized, gas is shunted past the low fire regulator through a  
timing orifice. The increased flow of supply gas (due to the  
second servo valve opening) further reduces the pressure  
above the main diaphragm, causing it to open more. The  
corresponding increase in outlet pressure forces the low fire  
regulator closed, and the valve regulates off the high fire  
regulator.  
When the controller is not calling for heat, the valve solenoid  
coil is not energized. Static gas inlet pressure and a spring act  
together to close the valve. In this condition, a three-way servo  
valve directs inlet pressure directly above the main diaphragm,  
creating static pressure on both sides of the main diaphragm.  
On a call for heat, the controller contacts close and the valve  
solenoid coil is energized, opening the servo valve and  
allowing the gas that is above the main diaphragm to bleed  
downstream, and diverting inlet (supply) gas through a supply  
orifice. This reduces the pressure above the diaphragm, and  
the gas that is bled off flows through a regulating valve to the  
outlet of the gas valve. The pressure differential across the  
main diaphragm is greater than the spring force, so the valve  
opens. The valve opening rate is controlled by a timing orifice  
through which the bleed gas passes.  
The V4944/V8944L and N models use a timing orifice that  
gives an opening time to low fire of less than six seconds. The  
slower opening V4944/V8944B and C use timing orifices that  
give an opening time of three to 25 seconds.  
Once the valve is open, outlet pressure is sensed through the  
bleed passage. The outlet pressure acts on the regulating  
Both regulators can be adjusted separately and the springs are  
sized so that the highest achievable pressure of the low  
pressure regulator range is less than the lowest achievable  
pressure of the high fire pressure regulator. The high fire  
setpoint cannot be achieved without the first stage solenoid  
being energized.  
(
servo) diaphragm and tends to open or close the integral  
regulating valve until a force balance is established between  
the outlet pressure acting on the servo diaphragm and the  
regulator spring that acts on the atmospheric side of the servo  
diaphragm.  
Valve closing operation is identical to that described for V4943/  
V8943B,C,N valves.  
The system is balanced when the flow of supply gas through  
the supply orifice is equal to the outflow of gas through the  
regulating valve. The regulated output pressure required to  
achieve equilibrium is varied by increasing or decreasing the  
spring force acting on the atmospheric side of the regulating  
diaphragm. Pressure adjustment is done through the use of a  
threaded nylon screw acting on the regulating spring.  
Regulator springs with different spring rates provide the  
various ranges of pressure regulation needed for natural and  
LP gases.  
CHECKOUT AND  
TROUBLESHOOTING  
WARNING  
Explosion or Fire Hazard.  
After the controller is satisfied, the procedure is reversed. The  
controller contacts open and the solenoid coil is de-energized.  
The plunger is released, moving to the down position. The  
servo valve closes, diverting supply gas away from the orifice  
and allowing the gas inlet pressure to act directly above the  
main diaphragm. The resulting increase in upper chamber  
pressure, along with the main spring, forces the main  
Can cause serious injury or death.  
Do not let fuel accumulate in the combustion chamber.  
If fuel is allowed to enter the chamber for longer than a  
few seconds without igniting, an explosive mixture  
could result.  
diaphragm against the valve seat, stopping the gas flow.  
CAUTION  
Equipment Damage Hazard.  
Failure to complete tests can cause equipment  
damage.  
In the event of a power failure during automatic operation of the  
valve, the V4943/V8943B,C,L,N Valve servo valve closes,  
diverting supply gas away from the orifice and allowing the gas  
inlet pressure to act directly on the main diaphragm. The  
change in upper chamber pressure, along with the main  
spring, forces the main diaphragm against the valve seat,  
stopping the gas flow. Normal operation will resume upon the  
restoration of power.  
1
. Do not put the system into service until you have  
satisfactorily completed all applicable tests  
described in the Checkout section of the instructions  
for the flame safeguard control, and any other tests  
required by the burner manufacturer.  
2. Close all manual fuel shutoff valves as soon as  
trouble occurs.  
65-0214—08  
10  
href="
V4943/V8943B,C,N; V4944/V8944B,C,L,N REGULATING DIAPHRAGM GAS VALVES  
8
.
Immerse a 1/4 in. tube vertically 1/2 in. (13 mm) into a jar  
of water.  
Checkout  
1.  
Valve outlet pressure measurements are made at a point  
approximately five pipe diameters downstream from the  
valve outlet. Consider pressure measurements made at  
the outlet pressure tap as reference measurements only,  
because turbulence and dynamic gas flow effects may  
result in erratic pressure readings.  
Shut off gas supply to valve and make sure valve is  
closed when setting up pressure measuring equipment.  
Set up pressure measuring equipment.  
9. Slowly open the test petcock (F).  
10. When the rate of bubbles coming through the water  
stabilizes, count the number of bubbles appearing during  
a ten-second period. Each bubble appearing during a  
ten-second period represents a flow rate of  
approximately 0.001 cfh.  
2
.
To meet code requirements, leakage must not exceed the  
values in Table 5.  
3.  
.
4
Make sure the valve is closed. Turn on the supply gas to  
the valve.  
Table 5. Allowable Leakage Rates.  
5.  
Set the thermostat or controller to energize the valve and  
check the final outlet pressure. See step 1. Allow enough  
time for the system pressure to stabilize.  
Pipe Size  
in.)  
Allowablea  
Leakage  
Number of Bubbles  
per 10 sec.  
(
6
.
.
For regulator setpoint and spring range, please refer to  
Table 3.  
1, 1-1/4  
-1/2, 2  
353  
453  
11 (Nat. gas), 7 (LP)  
14 (Nat. gas), 9 (LP)  
1
7
The low pressure regulator (V4944/V8944B,C,L,N) and  
high pressure regulator V4943V8943B,C,N and  
V4944/V8944B,C,L,N) adjustment screws (use a T-40  
six-lobe [TORX®] driver or 5/16-in. standard driver) are  
located under the slotted aluminum screw cap(s) of the  
adjustment screw housings (see Fig. 1). To adjust the  
pressure setting:  
a. Temporarily remove the slotted aluminum screw cap  
and gasket from the housing that contains the  
regulator adjustment setscrew.  
a
Based on air standard conditions, test pressures in  
accordance with ANSI Z21.21, Section 2.4.2 and a maximum  
of 235 cc/h per inch of seal-off-diameter. Seal-off diameter is  
not the same as pipe size.  
1
1. Close the upstream manual gas cock (A).  
2. Close the test petcock (F), remove the test apparatus,  
and replace the leak test tap plug (D).  
1
13. Open the upstream manual gas cock (A) and energize  
the safety shutoff valve (C).  
b. Turn the adjustment setscrew (use a T-40 six-lobe  
[
TORX®] driver or 5/16-in. standard driver) clockwise  
14. Test with soap bubbles to make sure there is no leak at  
the test tap (D).  
to increase the pressure setting or counterclockwise  
to decrease the pressure setting. Allow adequate time  
15. De-energize the safety shutoff valve (C).  
16. Open the downstream manual gas cock (E).  
17. Restore the system to normal operation.  
(30 to 60 seconds) for the pressure to reach  
equilibrium between pressure adjustments.  
c. After the regulators have been properly adjusted,  
replace the gasket and slotted aluminum screw cap  
on the adjustment screw housing.  
Start the system and observe its operation through at  
least one complete cycle to make sure the valve  
functions properly.  
A
B
C
D
E DOWNSTREAM  
LEAK  
TEST  
TAP  
MANUAL  
4
8.  
GAS COCK  
GAS  
SUPPLY  
BURNER  
PRV  
SSOV  
UPSTREAM  
MANUAL  
GAS COCK  
2
3
F
Valve Leak Test (See Fig. 15).  
1/4 IN. (6 MM)  
FLEXIBLE  
TUBING  
MANUAL  
This test checks the tightness closure of a gas safety shutoff  
valve. It should be performed by a qualified technician during  
the initial startup of a burner system, or whenever the valve is  
replaced (see Service Information section). It is recommended  
that this test also be included in scheduled inspection and  
maintenance procedures.  
1
TEST  
1/4 IN. (6 MM)  
PETCOCK  
ALUMINUM OR  
COPPER PILOT  
TUBING  
JAR OR GLASS  
WITH WATER  
1
.
De-energize the control system to make sure there is no  
power to the safety shutoff valve (C) shown in Fig. 15.  
Close the upstream manual gas cock (A).  
Make sure the manual test petcock (F) is closed in the  
leak test tap assembly (D).  
Remove the leak test tap plug (valve outlet pressure tap  
can be used as a test tap) and connect the test  
apparatus to the leak test tap (D).  
Close the downstream manual gas cock (E).  
Open the upstream manual gas cock (A).  
1
2
(13 MM)  
2
.
.
CUT AT  
3
45 DEGREE  
ANGLE  
1
2
3
4
CAN ALSO BE A PERMANENT PETCOCK.  
PRV = PRESSURE REGULATING VALVE.  
SSOV = SAFETY SHUTOFF VALVE.  
4.  
5.  
6.  
7.  
USE ONLY ONE OF THE DOWNSTREAM TAPS ON THE SS0V.  
M9547F  
Run the safety shutoff valve (C) to its fully open position  
(
through the safety system); then immediately  
Fig. 15. Valve leak test.  
de-energize the system to close the valve.  
11  
65-0214—08  
href="
V4943/V8943B,C,N; V4944/V8944B,C,L,N REGULATING DIAPHRAGM GAS VALVES  
a. Make sure that the gas flow is in the direction of the  
Troubleshooting  
arrow on the valve body.  
b. Make sure the valve actuator is wired in the correct  
circuit. Open the master switch to remove power  
from the valve actuator. If the valve closes now, the  
actuator may not be wired properly. Check and  
correct the wiring, if necessary.  
WARNING  
Electrical Shock Hazard.  
Can cause electrical shock or equipment damage.  
Use utmost care during troubleshooting. Line voltage  
is present right at the electrical terminations for the  
V4943B,C,N and V4944B,C,L,N valves, and present in  
all controller circuits for all V4943/V8943 and V4944/  
V8944 valves.  
c. Look for a short in the electrical circuit.  
SERVICE INFORMATION  
IMPORTANT  
Do not assume that the valve must be replaced until  
all other sources of trouble have been eliminated.  
WARNING  
Electrical Shock Hazard  
Can cause serious injury, death or equipment  
damage.  
1.  
If the valve will not open when the thermostat or  
controller calls for heat:  
1. Only qualified service technicians should attempt to  
service or repair flame safeguard controls and  
burner systems.  
2. Line voltage is present in the electrical circuits to the  
valve. Open the master switch before replacing the  
valve.  
a. Check that there is voltage at the proper electrical  
terminations. Be careful—there should be line  
voltage at the actuator of V4943 and V4944 valves.  
b. If there is no voltage at the actuator, first make sure  
line voltage power is connected to the master  
switch, the master switch is closed and overload  
protection (circuit breaker, fuse or similar device)  
has not opened the power line.  
c. For V8943A only: If line voltage power is correct,  
check transformer output. Replace the transformer if  
necessary.  
d. If there is still no voltage at the actuator, make sure  
all appropriate contacts in the thermostat or  
controller, limits and flame safeguard control are  
closed. If one or more is open, determine the  
cause(s) and correct the condition(s) before  
proceeding.  
Scheduled Inspection and  
Maintenance  
For periodic inspection and maintenance, set up a schedule  
and follow it. Include the burner valves (check for external  
leakage around all seals and joints with leak detector; also  
check for internal valve seat leakage—see Valve Leak Test  
section) and all other controls. Refer to the flame safeguard  
control instructions for more information.  
e. If there is proper voltage at the valve actuator but  
the valve still does not open, first check that the gas  
pressure at the valve is normal.  
f. If the valve still does not open, replace the valve.  
If the valve will not close when one or more of the  
appropriate contacts in the thermostat or controller,  
limit(s) or flame safeguard control is open:  
CAUTION  
Equipment Damage Hazard.  
Can cause equipment damage or improper  
operation.  
2.  
Label all wires prior to disconnecting when servicing  
valves. Wiring errors can cause improper and  
dangerous operation.  
Verify proper operation after servicing.  
Automation and Control Solutions  
Honeywell International Inc.  
1
985 Douglas Drive North  
®
U.S. Registered Trademark  
© 2011 Honeywell International Inc.  
5-0214—08 M.S. Rev. 09-11  
Printed in United States  
Golden Valley, MN 55422  
customer.honeywell.com  
6

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