Honeywell C7027A Product Data

C7027A, C7035, C7044A, C7927A

Minipeeper® Ultraviolet Flame Detectors

C7027A

C7044A

APPLICATION

The C7027A, C7035A, C7044A and C7927A Minipeeper®
Ultraviolet Flame Detectors detect the ultraviolet radiation
emitted by combustion flames. The flame detectors are used
with Honeywell flame safeguard controls to provide flame
supervision for gas, oil, or combination gas-oil burners.

FEATURES

• C7027A, C7035A, and C7044A Flame Detectors are
used with R7249A, R7290A, R7749B and R7849A,B
Amplifiers and the appropriate Honeywell controls.

C7035A

C7927A

PRODUCT DATA

• C7044A may also be used with the following 50 Hz
Honeywell combustion controls/amplifiers:
— R4341/R7323
— R4343/R7323
— R4344/R7323

• C7027A has an integral collar threaded (internal
1/2-14 NPSM) for mounting on a one-half-inch sight
pipe.

• C7035A has an integral collar threaded (internal
1-11-1/2 NPSM) for mounting on a one-inch sight pipe.

• C7035A housing meets Underwriters Laboratories Inc.
requirements for rain tightness and complies with
NEMA enclosure standards, types 4 and 4X.

• C7044A mounts with a two screw bracket. The UV
sensor tube is enclosed in a stainless steel housing.

• C7044A has the capability of side or end viewing in
flame monitoring applications.

• Because of their compact size, the C7027A and
C7044A are particularly suitable for blast tube
mounting.

• Properly installed, the C7027A and C7035A are
pressure rated for 5 psi.

• C7035A ultraviolet radiation sensor tube is field
replaceable.

• Two C7027A, C7035A or C7044A Flame Detectors can
be wired in parallel for difficult flame sighting
installations.

• C7927A is used with only the R7851B Flame Amplifier
and the appropriate Honeywell controls.

• C7927A has an integral collar threaded (internal
1/2-14 NPSM) for mounting on a one-half inch sight
pipe.

® U.S. Registered Trademark
Copyright © 2000 Honeywell • All Rights Reserved

Contents

Application ........................................................................ 1

Features ........................................................................... 1

Specifications ................................................................... 2

Ordering Information ........................................................ 2

Installation ........................................................................ 4

Wiring (All Models—Fig. 10) ............................................. 8

Adjustments and Checkout .............................................. 9

Troubleshooting ................................................................ 12

Maintenance ..................................................................... 12

60- 2026- 10

MINIPEEPER® ULTRAVIOLET FLAME DETECTORS

SPECIFICATIONS

4 (102)

3-1/2 (89)

COLLAR WITH 1/2-14 NPSM
INTERNAL THREADS

1

C7027A1064 HAS 24 FOOT (7.32 METER) LEADWIRES.
C7027A1114 HAS 44 IN. (1.118 M) LEADWIRES WITH
22 IN. (558 MM) FLEXIBLE CONDUIT.
MODELS AVAILABLE WITH SPUD CONNECTOR (1/2-14 NPSM INTERNAL

2

THREADS) INSTEAD OF CLAMP TYPE CONNECTOR.

C7027

Fig. 1. Installation dimensions of C7027A in in. (mm).

C7027A Minipeeper® Ultraviolet Flame Detector:

Ambient Operating Temperature Ratings:

(-18°C to 102°C), or -40°F to 215°F [-40°C to +102°C),
depending on model.

Maximum Pressure Rating:
Mounting:

Collar with 1/2-14 NPSM internal threads for

mounting on a 1/2 in. sight pipe.

Wiring Connections:

NEC Class 1 leadwires, rated for 221°F (105°C).
(C7027A1064 has 24 ft [7.32 m] leadwires.) Rear of
detector has a clamp type connector for 1/2 in. flexible
metallic conduit. (Models are available with 1/2 in.
internally threaded spud connector instead of the
clamp). C7027A1114 has 44 in. (1.118 m) leadwires and
22 in. (558 mm) flexible conduit.

5 psi (34.5 kPa).

Two 6 ft [1.83 m], color-coded,

6 FOOT (1.83 METER)
LEADWIRES (2)

2

1-1/16

(27)

0°F to 215°F

1

M1943D

Dimensions:
Replacement Part:

See Fig. 1.

129685 Flange Gasket.

NOTE: The ultraviolet radiation sensing tube is not field

replaceable.

Accessory:

136733 Heat Block, laminated plastic, insulating the flame

detector from sight pipe tempera tures up to 266°F (130 °C),
1/2-14 NPSM external threads on one end and 1/2-14
NPSM internal threads on the other end (see Fig. 8).
Included with C7027A1080.

390427B Bushing, for mounting to 3/8 in. sight pipe. Included

with C7027A1080.

4-1/8 (105)

31/32

(25)

2

M1945C

COLLAR WITH
1–11-1/2 NPSM
INTERNAL
THREADS

INSERTION DEPTH

1
2
3

1

2-5/8 (67)

DIN APPROVED C7035A1064 HAS 1-11 BSP.P1 INTERNAL MOUNTING THREADS.
DIN APPROVED C7035A1064 HAS 1/2-14 BSP-F INTERNAL MOUNTING THREADS.
C7035A1056 HAS 12 FOOT (3.66 METER) LEADWIRES.

2 (51)

1-3/16

(30)

6 FOOT
[1.83 METER]
LEADWIRES (2)

C7035

1/2-14 NPSM
INTERNAL THREADS

1-1/2

(38)

3

Fig. 2. Installation dimensions of C7035A in in. (mm).

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 Home and Building Control Sales Office (check white pages of your phone directory).

2.

Home and Building Control Customer Relations
Honeywell, 1885 Douglas Drive North

Minneapolis, Minnesota 55422-4386 [phone]
In Canada—Honeywell Limited/Honeywell Limitée, 35 Dynamic Drive, Scarborough, Ontario M1V 4Z9.
International Sales and Service Offices in all principal cities of the world. Manufacturing in Australia, Canada, Finland, France,
Germany, Japan, Mexico, Netherlands, Spain, Taiwan, United Kingdom, U.S.A.

60-2026—10 2

MINIPEEPER® ULTRAVIOLET FLAME DETECTORS

C7035A Minipeeper® Ultraviolet Flame Detector:

Flame Detection:
Ambient Operating Temperature Ratings:

(-18°C to +121°C), or -40°F to 250°F (-40°C to +121°C),
depending on model.

Maximum Pressure Rating:
Mounting:

mounting on a 1 in. sight pipe. (The DIN approved
C7035A1064 has 1-11 BSP.P1 threads.)

Wiring Connections:

Class 1 leadwires rated for 302°F (150°C). One model is
available with 12 ft. (3.66 m) leadwires. Rear of detector
has 1/2-14 NPSM internal threads for connecting to a
conduit. The DIN-approved C7035A1064 has 1/2-14

BSP-F threads.
C7035A1056 has 12 ft (3.66 m) leadwires.
C7035A1080 leadwire is rated for 600°F (204°C).

End viewing.

0°F to 250°F

5 psi (34.5 kPa).

Collar with 1-11-1/2 NPSM internal threads for

Two 6 ft. [1.83 m], color-coded NEC

6 FOOT [1.83 METER]
LEADWIRES (2)

Dimensions:

See Fig. 2.

Replacement Parts:

129808 Flange Gasket.
129464M Ultraviolet Sensing Tube, 0°F to 250°F (-18°C to

+121°C).

129464N Ultraviolet Sens in g Tube, -40°F to +250°F (-40°C to

121°C).

C7027A AND C7035A:

Approvals:

Underwriters Laboratories Inc. listed: File No. MP268.
Canadian Standards Association certified: Master Report LR

95329-1.
Factory Mutual approved.
Industrial Risk Insurers acceptable.
DIN approved models: C7027A1056, C7035A1049,

C7035A1064.

Accessory:

118367A Swivel Mount; provides adjustable

positioning of the C7027A or C7035A.

MOUNTING BRACKET

3/8

(10)

7/8

(22)

3-5/8 (92)

Fig. 3. Installation dimensions of C7044A in in. (mm).

C7044A Minipeeper® Ultraviolet Flame Detector:

Flame Detection:

side or end viewing. Side viewing is 1/8 as sensitive as end
viewing.

Mounting:

secured by two 8-32 RHIS (European M-4) screws (not
included).

Wiring Connections:

Class 1 leadwires. Rear of detector has a clamp type
connector for 1/2 in. flexible metallic conduit.

Dimensions:

Housing has two openings to permit either

Bracket (included in 4074BVK Bag Assembly),

Two 6 ft. (1.83 m) color-coded NEC

See Fig. 3.

9/16
(14)

1/2

(13)

C7044

1-27/64

(36)

M1944B

C7927A Minipeeper® Ultraviolet Flame Detector:

Ambient Operating Temperature Ratings:

C7927A1016 (U.S. Version): -40°F to +200°F (-40°C to

+93°C).
C7927A1008 (European Version): -4°F to +140°F

(-20°C to +60°C).

Storage Temperature Rating:

(-28°C to +49°C).

Maximum Pressure Rating:
Mounting:

Collar with 1/2-14 NPSM internal threads for

mounting on a 1/2 in. (13mm) sight pipe.

Wiring Connections:

Two four-foot (1.2 meter) color-coded
NEC Class 1 leadwi res . Rear of detector has a cla mp -type
connector for 1/2 in. (13mm) flexible metal conduit.

Dimensions:

See Fig. 4 and 5.

Approvals:

Underwriters Laboratories Inc. (UL): Pending.
Factory Mutual (FM): Pending.
IAS: Pending.

-20°F to +120°F

5 psi 34.5 kPa).

3 60-2026—10

MINIPEEPER® ULTRAVIOLET FLAME DETECTORS

3-11/16

(94)

1 (25)

6-1/2 FT. (1.98M)

C7927A1008

3-1/4 (82)

C7927A1016

3-3/4 (95)

4 FOOT (1.2 METER)
LEADWIRES (2)

1

(25)

M17783

Fig. 4. Installation dimensions of C7927A1016 (U.S.A. version) and C7927A1008 (European version) in in. (mm).

INSTALLATION

IMPORTANT

Ultraviolet radiation sensing tubes have a life
expectancy of 40,000 ho urs of co ntinuo us use within

When Installing This Product...

1.

Read these instructio ns c aref ull y. Failure to follow them
could damage the product or 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
application.

3.

Installer must be a trained, experienced, flame
safeguard co ntrol technician.

4.

After installation is complete, check out product

operation as provided in these instructions.
Disconnect power supply before beginning installation to
prevent electrical shock and equipment damage. All wiring
must comply with applicable electrical codes, ordinances and
regulations. Use NEC Class 1 wiring.

the flame detector's specified ambient temperature
and voltage ratings. Wearout of an ultraviolet
radiation sensing tube results in failure of the UV
sensor to properly discriminate between flame
conditions.

The C7027A, C7035A and C 7044A F lame De tectors
should only be used on burners that cycle on/off
periodically or, in the absence of cycling, are
periodically checked for proper operation.

Recommended industry standards for the frequency
of sensor checks, either through cycling (employing
safe-start check methods) or periodic maintenance,
vary between once every ten seconds and once
every week, depending on the standard used and
the application needs.

M17784

60-2026—10 4

Consult the equipment manufacturer or the
governing standard for recommendations about
frequency of checks.

Controls incorporating safe-start checks, and
sensors and controls employing constant check
means are available from Honeywell. See your
Honeywell representative for specific information.

WARNING

Explosion Hazard and Electrical Shock Hazard.
Can cause serious injury, death or property
damage.

1. The C7027A, C7035A , C7044A and C7927 Flame
Detectors must be used with Honeywell flame
safeguard controls (primaries, programmers,
multiburner systems, and burner management
systems). Using with controls not manufactured by
Honeywell could result in unsafe conditions.

2. Disconnect power supply before beginning
installation to prev en t el ec tric al shock or equipment
damage, more than one disconnect may be
involved.

3. Read the installation instructions before starting the
installation.

4. All wiring must be NEC Class 1 (line voltage).

5. The flame detector must be positioned so that it
sights the flame and does not respond to the UV
radiation emitted by sparks generated by a spark
ignitor . The Q624A Solid-State Ignite r may be useful
in difficult installations.

MINIPEEPER® ULTRAVIOLET FLAME DETECTORS

Other Radiation Sources Sensed By The UV Detector

Examples of radiation sources (other than flame) that could
actuate the detection system are:

1.

Ultraviolet Sources:
a. Hot refractory above 2800°F (1371°C).
b. Spark.
c. ignition transformers.
d. welding arcs.
e. lightning.
f. Gas lasers.
g. Sun lamps.
h. Germicidal lamps.

2.

Gamma Ray and X-ray Sources:
a. Diffraction analyzers.
b. Electron microscopes.
c. Radiographic X-ray machines.
d. High voltage vacuum switches.
e. High voltage condensers.

f. Radioscotopes.
Except under unusual circumstances, none of these sources
except hot refractory an d igni tion s park wou ld be p resent in or
near the combustion chamber.

Basic Requirements For Ultraviolet Detector Installations

All flames emit ultraviolet radiation, invisible to the human eye
but detected by the UV sensi ng tube. Th ere are tw o importan t
factors in UV detector install ati on:

The detector must have a line-of-sight view of the flame.
The detector must not be exposed to other sources of

ultraviolet radiation, the most common being ignition spark.
Other sources are listed in the next section.

Because it is necessary for the detector to actually see the
flame, it is desirable to locate the detector as close to the
flame as physical arrangement and temperature restrictions
permit.

Sighting requiremen ts for different types of flame supervision
are:

1.

Pilot flame only—Sighting must be along the axi s of th e
pilot flame. The smallest pilot flame that can be sighted
must be capable of igniting the main burner (see Pilot
Turndown Test, page 9).

2.

Main flame only—Sighting must be at the most stable
part of the flame for all firing rates.

3.

Pilot and main flame—Sighting must be at the junction
of both flames.

The detector may respond to hot refractory above 2800°F
(1371°C) if the refractory surface represents a significant
percentage of the field of view of the detector. If the
temperature of the hot refractory causes the flame relay
(in the flame safeguard cont rol ) to pul l in, re-pos iti on the si ght
pipe so the detector views a cooler area of the refractory.

Ignition spark is a source of ultrav iolet radiation. When
installing the C7027A, C7035A, C7044A or C7927 Flame
Detector , m ak e sure i t does not respond to ig nit ion s park (s ee
Ultraviolet Response Test, page 9.) If the installation is such
that response to the ignition sparks cannot be avoided, the
Q624A Solid-State Ignition Transformer may eliminate the
ignition spark response. The Q624A, when properly installed,
prevents C7027A, C7035A, C7044A and C7927 ignition
spark response by alternately activating the spark generator
and the UV sensing tube.

5 60-2026—10

MINIPEEPER® ULTRAVIOLET FLAME DETECTORS

Mounting a C7027A, C7927 or C7035A

Locate the Sight Pipe

The location of the sight pipe is the most critical part of the
installation. A black iron pipe is recommended. Do not use a
stainless steel or galv an ize d pi pe because its internal surface
blackens with use as deposits from the combustion chamber
settle on it. Initial ly, its shiny internal surface reflect s ultraviolet
radiation, which could result in a satisfactory flame signal,
even though the pipe may be improperly located. As it
blackens, less ultraviolet radiation is reflected and the flame
signal may become marginal.

Under optimum sighting conditions, the C7027A , C7927 and
C7035A Flame Detectors can detect most common gas and
oil combustion flames at a distance of six feet. The critical
factors in determining the flam e-d ete ctor distance separation
are the optimized flame signal (current or voltage) and the
flame detector temperature. Other factors may be influential
and are associat ed wi th the specific insta lla tion. For minimum
flame signals, see Table 1 and for ambient operating
temperatures, refer to Specifications, page 2.

Use 1/2 in. pipe for a C7027 or C7927, and 1 in. pipe for a
C7035. Since no two situations are likely to be the same,
length and sighting angle of the pipe must be determined at
the time and place of installation. Generally, it is desirable to
have the sight pipe tilting downward to prevent soot or dirt
buildup.

Mounting The Sight Pipe (Fig. 6)

Thread one end of the pipe to fit the mounting collar on the
detector. Cut the pipe to the desired length (as short as
practicable), and at an angl e s o it fi ts fl us h with the w al l of the
combustion chamber. Tack-weld the pipe to the wall in a trial
position. Do not permanently weld the sight pipe in place until
after completing the Adjustments and Checkout beginning on
page 7.

NOTE: If you use a swivel mount (part no. 118367A) and

you are positive about the location and sighting
angle, you can permanently weld the pipe.

TEMPORARY
TACK WELD

FLARED HOLE

BLACK IRON
SIGHT PIPE

REFRACTORY

M3019A

Fig. 5. Mounting sight pipe.

BOILER
PLATE

If a C7027A or C7927A is to be used for a blast tube
installation, its location should be determined by the burner
manufacturer; contact the manufacturer before making any
modifications to the installation.

In locations wh ere water is usually sp ray ed on the body of th e
detector , use a C7 035A. Interna l threads in its base permi t the
use of waterproof flexible conduit for this type of application.

Prepare Hole In Wall Of Combustion Chamber

Cut a hole of the proper diameter for the sight pipe in the wall
of the combustion chamber at the selected location. Flare the
hole to leave room for sm all adjus tments of the s ighting an gle.
The taper of the hole should be about 1 in. for every 3 in.
(25 mm for every 76 mm) of wall thickness.

Sight Pipe Ventilation

It may be necessary to ventilate the sight pipe to cool the
flame detector or to clear the sight pipe of UV radiation
absorbing substances suc h as sm ok e, ex c ess ive m ois ture or,
in some instances, unburne d fuel .

For a negative pressure combustion chamber, drilling a few
holes in the sect ion of t he sight pipe outs ide of the co mbustion
chamber will allow air at atmosphe ric pressure to flow through
the sight pipe into the chamber. A perforated pipe nipple
between the sight p ipe and the detec tor can a lso be u sed (see
Fig. 7).

For a positive pressure combustion ch amber, connect a
supply of pressurized air from the burner blower through the
sight pipe into the chamber. The supply air pressure must be
greater than the chamber pressure.

60-2026—10 6

Swivel Mount

WARNING

M3021

C7027A (OR C7035A)

FLANGE
GASKET

BLACK IRON
SIGHT PIPE

COMBUSTION
CHAMBER
WALL

ADD PIPE TEE,
PERFORATED
NIPPLE, OR OTHER
SUITABLE DEVICE
FOR VENTILATION,
IF REQUIRED.

To facilitate proper sighting of the flame, a swivel mount (part
no. 118367A) is available. The swivel mount will require a 3/4
to 1/2 in. reducer and a 1/2 in. close nipple to mount a
C7027A, or a 1 in. pipe at least 2-1/2 in. [63.5 mm] long to
mount a C7035A. For mounting details, refer to form 60-0361
for the 118367A Swivel Mount.

Mount The Detector (Fig. 7)

Mount the detector onto the sight pipe, pipe tee, nipple, or
other fitting. Make sure the flange gaske t is in place i nside the
mounting collar on the dete ctor , and then screw the collar ont o
the sight pipe or fitting.

MINIPEEPER® ULTRAVIOLET FLAME DETECTORS

NOTE: If a win dow is ins tal led between the UV detect or a nd

the flame, it must be fabricated from quartz or fused
silica. Ordinary glass filters out ultraviolet radiation.

Using a Heat Block With a C7027 (Fig. 8)

If the temperature of the si ght pipe will be come high eno ugh to
cause the C7027A to overheat (above 215°F (102°C) up to
266°F (130°C), screw a 136733 Heat Block (orde r separ ately)
onto the sight pipe before mounting the detector.

C7027A DETECTOR

4 [102]

1
[27]

1/2-14 NPSM
INTERNAL
THREADS

HIGH TEMPERATURES (ABOVE 215° F [102° C])

DO NOT USE FOR TEMPERATURES ABOVE 266° F [130°C]

136733 HEAT BLOCK

5

1 [41]

8

9

[14]

16

1

16

1/2-14 NPSM
EXTERNAL
THREADS

Fig. 6. Mounting a C7027A or C7927A on a

combustion chamber (viewed from above).

C7035A mounting is similar.

5

[16]

8

1
[32]

1/2-14 NPSM
INTERNAL
THREADS

1/2-INCH SIGHT PIPE

1
4

M1942

Fig. 7. Mounting dimensions of 136733 Heat Block in in. (mm).

Mounting a C7044A On a Blast Tube (Fig. 9)

The C7044 is designed to be mounted on the blast tube of a
burner . The exact lo cation shou ld be determined b y the burner
manufacturer. Contact the manufacturer before making any
modifications to the installation.

Explosion Hazard.
Can cause serious injury or property damage.

The C7044 will allow air leakage through its housing.
Do not locate the C7044 in an atmosphere of fuel
vapors under positive pressure. The C7027 or C7035
should be used if internal pressure sealoff is required.

7 60-2026—10

MINIPEEPER® ULTRAVIOLET FLAME DETECTORS

8-32 RHIS
(EUROPEAN M-4)
SCREW (2)

MOUNTING
BRACKET

C7044A
DETECTOR

29/32 IN. (23.0 mm)
MOUNTING HOLE
IN BLAST TUBE

CLAMP
SCREW

WIRING (ALL MODELS—FIG. 10)

CAUTION

Equipment Damage Hazard.
Can cause improper operation.

The blue (tan with blue tracer with C7035A1080)
leadwire must be connected to the F terminal of the
flame safeguard control subbase or terminal strip and
the white (tan leadwi re without blue tracer w ith
C7035A1080) to the G terminal (see Fig. 10). Failure
to observe the circuit polarity by reversing the
leadwires (even momentarily) may cause the flame
detector to improperly supervise the combustion
flame.

1.

Disconnect power sup ply befo re beginni ng instal lation to

prevent electrical shock and equipment damage. All
wiring must comply with applicable electrical codes,
ordinances, and regulations. Use NEC Class 1 wiring.

2.

If the leadwires are not long en ough t o reach the term inal

strip or wiring subbase, make the required splices in a
junction box.

3.

If splicing is neces sary, use moisture-resistant wire

suitable for at least 167°F [75°C] if the detector is used
with a flame safeguard prim ary control, or at lea st 194°F
[90°C] if used wit h a flame safeguard programming
control.

4.

For high temperature insta llations, use Honeywell

Specification no. R1298020 or equivalent for the F
leadwire. (This wire is rated up to 400°F [204°C] for
continuous duty. It is tested for operation up to 600V
and breakdown up to 7500V.) For the other leadwires,
use moisture-resistant wire selected for a temperature
rating above the maximum operating temperature.

1-27/64 IN.
(36.1 mm)

M3020

Fig. 8. Mounting C7044A Detector on blast tube.

The C7044 is mounted in a 29/32 in. (23.0 mm) hole in the
blast tube. The mounting bracket is fastened to the blast tube
with 2 screws on 1-27/64 in. (36.1 mm) centers.

The mounting bracket is designed so that the detector can be
removed from the blast tube for cleaning and then replaced
without disturbing the sighting angle. Loosen the 2 screws
holding the bracket to the blast tube, but do not loosen the
clamp screw on the bracket. Twist both the bracket and
detector to remove them.

IMPORTANT:

Do not run the flame detector wiring in the same
conduit with high voltage ignition transformer wires.

60-2026—10 8

MINIPEEPER® ULTRAVIOLET FLAME DETECTORS

Connecting Detectors In Parallel

For a flame that is difficult to sight, using two flame detectors
connected in parallel will reduce the occurrence of nuisance
shutdowns. If only one of the parallel detectors loses the
flame signal, the other will continue to indicate the presence
of the flame and keep the burner in operation.

When the flame detectors are connected in parallel, the low
level background signals are additive. Therefore, no more
than two C7027A, C7927A, C7035A, or C7044A Flame
Detectors should be paralleled. Furthermore, the background
signal increases as temperature decreases. Because of this,
the minimum ambient operating temperature must be
increased when the C7027A, C7927A, C7035A or C7044A
Flame Detectors are paralleled.

When using detectors rated for a minimum of 0°F (-18°C),
limit the minimum ambient temperature at the detectors to
32°F (0°C). When using detectors rated for a minimum of

-40°F (-40°C), limit the minimum ambient temperature at the
detectors to -10°F (-23°C).

Connect the blue leadw ires of both det ectors to the F termi nal
of the wiring subbase or terminal strip, and the white
leadwires of both detectors to the G terminal, as shown in
Fig. 10.

Earth Ground

The detector and the flame safeguard control must be
connected to earth ground. A convenient method of
accomplishing this is to connect the detector to the flame
safeguard control with a flexible conduit, or ensure a good
ground connection at the mounting bracket.

WIRING SUBBASE

OR

TERMINAL STRIP

M3018

UV DETECTOR

UV DETECTOR

OPTIONAL
SECOND
DETECTOR

BLUE
WHITE

BLUE
WHITE

F

G

ADJUSTMENTS AND CHECKOUT

Before welding the C7027A, C7927A or C7035A sight pipe
in its final location, or before tightening the C7044A clamp
screw, c ompl ete bot h the ad ju stmen ts and check out tes ts tha t
follow and any required by the burner manufactu r er.

Uv Sensor Tube Test

NOTE: For initial burner lightoff, consult the burner

manufacturer instructions or the instru cti ons for
the flame safeguard control.

During the initial burner lightoff, make sure the flame
safeguard control starts (i.e., the load relay, usually 1K,
pulls in). If it does not start, visually check the sensing tube in
the C7027A, C7035A, or C7044A flame detector. If the tube
continues to glow when no flame is present, replace the
sensing tube (C7035A), or replace the detector (C7027A or
C7044A).

Adjust Detector Sighting Position

With the flame detector installed and burners running, adjust
the position of the flame detector for optimum flame signal.
The flame signal will be read in microamps or voltage (Vdc)
depending on the Honeywell flame safeguard combustion
control used.

Most existing Honeyw ell fl ame sa feguar d contro ls inc orpora te
a flame current jack on the flame amplifier or on the control
itself. The flame signal c an be m easured with a v olt-ohmm eter
such as the Honeywell W136A. To measure the flame current
(signal), use a cable connector (pa rt number 19614 6, included
with the W136A) in conjunction with the meter. With the
W136A (or equivalent) positioned at the zero to 25
microampere scale, make connecti on s fr om the m eter pro bes
to the two ends of the cable connector plug (red to red, black
to black). Make these connections before inserting the plug
end of the connector plug into the flame jack of the control or
control amplifier (see Fig. 11). Read the flame signal in
microamperes directly from the W 136A meter. Refer to
Table 1 for the minimum acceptable flame currents.

Fig. 9. Wiring C7027A, C7927A, C7035A, and

C7044A flame detectors in parallel.

9 60-2026—10

MINIPEEPER® ULTRAVIOLET FLAME DETECTORS

W136A VOLT­OHMMETER

RED (+)
METER
LEAD

W136A SELECTOR
SWITCH

196146 METER
CONNECTOR
PLUG

PLUG

FLAME SIGNAL
METER JACK

PLUG-IN FLAME
SIGNAL AMPLIFIER

RED CONNECTOR
BLACK CONNECTORBLACK (–) METER LEAD

M6532A

Fig. 10. Measuring microamp flame signal.

Measure the flame signal voltage as illustrated in Figs. 12
and 13. Be careful to connect the positive meter lead to the
positive (+) amplifier jack and the negative meter lead to the
negative (-) amplifier jack (BCS 7700) or the (-Com) jack for
a 7800 SERIES control. If the BCS 7700 and Series 7800
controls have the optional Keyboard Display Module, a zero
to five Vdc reading will be displayed on the module.

Move the flame detector and sight pipe (if not permanently
attached to the burner/boiler) to view the flame from various
positions. Allow a few seconds for the meter reading to
stabilize. A maximum steady microamp or voltage reading is
desirable. The flame signal must be above the minimum
acceptable level for the flame safeguard control and
associated amplifier as indicated in Table 1.

Measure the flame signal for the pilot alone, the main burner
flame alone, and both together (unless monitoring pilot only
when using an intermittent pilot or supervising the main flame
only when using direct spark ignition). Also, measure the
flame signal at low and high firing rates and while modulating
(if applicable).

The R7749B and R7849A,B Amplifiers used with the
Honeywell BCS 7700 and 7800 SERIES controls,
respectively, have a dc voltage flame signal output.

For the R7749B Amplifie r, a volt-ohmmeter with a zero to 5 or
10 Vdc scale and a mi nimum s ensitivi ty of 20, 000 volts /ohm is
suggested.

For the R7849A,B Amplifiers used with the 7800 SERIES
controls, a volt-oh mmeter wi th a z ero to 5 or 10 Vdc scale and
a minimum sensitivity of one megohm/volt is recommended,
(see Fig. 12).

POSITIVE (+)

NEGATIVE (-)
METER LEAD

METER LEAD

ONE
MEGOHM/VOLT
METER

M7382

Fig. 11. Measuring flame signal voltage

of 7800 SERIES controls.

With the flame detector in its final position, all flame signals
must be steady with a current/voltage value as indicated in
Table 1. If the minimum signal cannot be obtained or is
unstable, refer to Troubleshooting, page 10.

Pilot Turndown Test

If the detector is used to prove a pilot flame before the main
fuel valve can be opened, perform a Pilot Turndown Test.
Follow the procedures in both the Instructions for the
appropriate flame safeguard control, and in the burner
manufacturer's instructions.

RESET
BUTTON

BCS 7700 CHASSIS MODULE FOOTMOUNT

Fig. 12. Measuring the BCS 7700 flame signal voltage.

PROGRAM
MODULE

METER
PROBES

FLAME
AMPLIFER

20,000
VOLT­OHMMETER

M7860

60-2026—10 10

Table 1. Flame Signal.

Honeywell Flame

Flame

Detector

C7027A,
C7035A,
C7044A

C7927A R7851B 7800 SERIES ——1.25 5.0

Plug-in

Amplifier

R7249A BC7000 + PM720 3.5 7.5 ——
R7749B

(AMPLICHECK™)
R7249A R4075C,D,E 3.5 7.5 ——

R7290A R4795A,D 1.5 2.25 ——
None R7023C 1.5 2.25 ——
NONE R7795A,C,E,G 1.5 2.25 ——
R7849A or

R7849B
(AMPLICHECK™)

None RA890G 1.5 2.25 ——

Safeguard

Control

BCS7700A ——2.2 4.98

R4138C,D 3.5 7.5 ——
R4140G,L,M 3.5 7.5 ——

7800 SERIES ——1.25 5.0

Minimum Acceptable

Steady Current

(microamps)

Maximum Current

Expected

(microamps)

Minimum

Acceptable

Voltage (Vdc)

Maximum

Voltage

(Vdc)

Ignition Spark Response Test

Test to be sure that ignition spark is not actuating the flame
relay (usu ally 2K) in the flame safeguard cont rol.

1.

Close the pilot and main burner manual fuel shutoff
valves.

2.

Connect the appropriate meter to the flame safeguard
control amplifier. Start the burner and run through the
ignition period. Ignition spark should occur, but the
flame relay must no t pull in. The flame signa l shou ld not
be more than 0.25 microamp.

3.

If the flame relay does pull in, repo s ition the flame
detector to increase the distance between the flame
detector and the ignition spark. If the flame detector is
not in the line of sight of the ignition spark but appears
to respond to the spark, it may be responding to
reflected spark generated UV radiation. If so, relocate
the flame detector so it does not receive the reflected
UV radiation. It may be necessary to construct a barrier
to block the UV radiation generated by the spark from
the flame detector view.

4.

Continue making the adjustments until the flame signal
due to ignition spark is less than 0.25 microamp or

1.25 Vdc.

5.

The use of the Q624 or Q652 solid-state ignition
transformer may also provid e a me tho d to el im ina t e th e
C7027A, C7035A, or C7044A flame detector response
to UV radiation generated by ignition spark. The Q624
and Q652 prevents flame detector response to ignition
spark by providing alternating periods of spark
generation and UV sensor activation. If ignition spark is
detected, try reversing the leads on the Q624 or Q652.

Response to Other Ultraviolet Sources

Some sources of artificial light produce small amounts of
ultraviolet radiation. Under certain conditions, an ultraviolet
detector will respond to them as if it is sensing a flame.
Do not use an artificial light source to check the response
of an ultraviolet detector. To check for proper flame detector
operation, test for flame failure response under all operating
conditions.

Weld The Sight Pipe (o r Tighten the C7044A Clamp Screw)

When the flame signal is acceptable after all adjustments are
made, remove the fla me detect or and weld th e sight pip e in its
final position. If you are using a swivel mount, the pipe may
already be welded. Then reinstall the flame detector.

NOTE: If using a C7044A Detector with no sight pipe,

do not remove the detector; tighten the clamp
screw securely.

Final Checkout

Before putting the burner into service, check out the
installation using the procedures in the Checkout section of
the Instructions for the appropriate flame safeguard control.
After completing the che ckou t, run the burner through at leas t
one complete cycle to verify correct operation.

11 60-2026—10

Printed in U.S.A. on recycled
paper containing at least 10%
post-consumer paper fibers.

TROUBLESHOOTING

WARNING

Electrical Shock Hazard.
Can cause serious injury or death.

Be extremely careful while troubleshooting the
detector; line voltage is present on some of the
terminals when power is on.

Open the master switch to disconnect power before
removing or installing the detector.

5.

Clean the inside of the sight pi pe (if one is use d) be fore
reinstalling the detector.

6.

If the flame signal continues to be too low, replace the
plug-in amplifier (if the control has one).

7.

If you still cannot obtain a proper flame signal, replace
flame detector (C7027A, C7044A) or UV radiation
sensing tube (C7035A).

IMPORTANT:

At the completion of troubleshooting, be sure to
perform the Adjustments and Chec kout beg inning on
page 8.

Inadequate Flame Signal

If a satisfactory flame signal cannot be obtained while
adjusting the sighting position of the detector, perform the
procedures indicated in steps 1 through 7. If other difficulties
are encountered in the sy stem, r efer to T ro ubles hootin g in the
Instructions for the appropriate Honeywell flame safeguard
control.

1.

Check for proper line voltage. Make sure the master
switch is closed, connections are correct, and power
supply is the correct voltage and frequency.

2.

Check the detector wiring for defects, including:
a. incorre ct connection s.
b. wiring type or size of wire.
c. deteriorated wire.
d. open circuits.
e. short circuits.
f. leakage paths caused by moisture, soot, or dirt.

3.

With the burner running, check the temperature at the
detector. When it exceeds 215°F (102°C) for a C7027,
C7927 or C7044, or 250°F (121°C) for a C7035:
a. use a heat block (part no. 136733) if using a

C7027A Flame Detector.

b. add the additional insul ation be twee n the wall of th e

combustion chamber and the detector.

c. add a shield or screen to reflect radiated heat away

from the detector, or

d. add cooling (refer to Sight Pipe Ventilation, page 6).

4.

Remove the detecto r and clean the viewing w indow with
a soft, clean cloth.

MAINTENANCE

Periodic Maintenance

1.

Clean the viewin g wind ow a nd s igh t p ipe (i f u se d) wh en
necessary. Remove the detector and use a soft, clean
cloth to remove accumulated contaminants from the
UV radiation sensor tube glass envelope.

2.

Ultraviolet sensing tubes have a life expectancy of
40,000 hours of continuous use within the ambient
temperature and voltage ratings. Replace the sensing
tube in the C7035, or replace the C7027, C7927 or
C7044 Detector, at appropriate intervals.

3.

Keep the flame detection system adjusted for the
smoothest, most reliabl e operation as recommen ded by
the burner manufacturer.

Cleaning the C7044A Detector

When necessary, clean the C7044 Flame Detector by using
the following procedure:

1.

Loosen the two screws holding the C7044 mounting
bracket to the blast tube. To remove, twist the bracket
and detector. Do not loosen the clamp screw that holds
the mounting bracket to the detect or.

2.

Clean the viewing window with a soft, clean cloth.

3.

Insert the detector into the mounting hole, and to realign
it, twist against the mounting screws. Tighten the two
mounting screws.

Home and Building Control Home and Building Control

Honeywell Honeywell Limited-Honeywell Limitée
1985 Douglas Drive North 35 Dynamic Drive
Golden Valley, MN 55422 Scarborough, Ontario

60-2026—10 G.R. Rev. 12-00 www.honeywell.com

M1V 4Z9