Midco RE6700B Service Manual

Installation and Service Instructions

1007

8471 45

Printed in U.S.A.

In the United States, Installation must
conform with local codes or, in the absence of local
codes, with Installation of the National Fuel Gas
Code, ANSI Z223.1-latest edition, from the American
National Standard Institute. Further reference should
be made to the recommendation of your fuel supplier.

In Canada, Installation must conform with local
codes or, in the absence of local codes, with

Installation Codes for Gas Burning Appliances and
Equipment, CGA Standard CAN/CGA 1B-149.

Further reference should be made to the
recommendation of your fuel supplier.

WARNING: Additions, changes, conversions,
and service must be performed by an authorized
MIDCO representative, service agency, or the fuel
supplier. Use only MIDCO specified and approved
parts.

INSTALLER: Inform and demonstrate to the user
the correct operation and maintenance of the gas
utilization equipment. Inform the user of the
hazards of storing flammable liquids and vapors in
the vicinity of this gas utilization equipment and
remove such hazards. Affix this manual and
associated literature adjacent to the burner. CODE
COMPLIANCE IS THE SOLE RESPONSIBILITY OF
THE INSTALLER.
USER: Retain this manual for future reference. If
other than routine service or maintenance as
described in this manual and associated literature
is required, contact a qualified service agency. DO
NOT ATTEMPT REPAIRS. An inadvertent service
error could result in a dangerous condition.

Economite

RE6700B / RE6850 / RE6850B

Gas Burners

BURNER MODEL

BILL OF MAT'L
NUMBER

SERIAL NUMBER #

WIRING DIAGRAM

FOR SERVICE CONTACT:

Name

Address

Phone

Date of Installation

Do not store or use gasoline or other flammable
vapors and liquids in the vicinity of this or any
other appliance.

WHAT TO DO IF YOU SMELL GAS:

 Do not try to light any appliance.


Do not touch any electrical switch; do not use any

phone in your building.

 Immediately phone your gas supplier from another

building. Follow the gas supplier’s instructions. If
you cannot reach your gas supplier call the fire
department.

Installation and service must be performed by a

qualified installer, service agency or the gas supplier.

S A F E T Y I N F O R M A T I O N T E R M S : The following terms are used to identify hazards, safety precaution of special

notations and have standard meanings throughout this manual. They are printed in all capital letters using a bold type face
as shown below, and preceded by the exclamation mark symbol. When you see the safety alert symbol and one of the
safety information terms as shown below, be aware of the hazard potential.

DANGER: Identifies the most serious hazards which will result in severe personal injury or death.
WARNING: Signifies a hazard that could result in personal injury or death.
CAUTION: Identifies unsafe practices which would result in minor personal injury or product and property damage.

WARNING: If the information in these instructions

is not followed exactly, a fire or explosion may result,
causing property damage, personal injury or death.

Midco International Inc.

4140 West Victoria St. - Chicago, Illinois 60646
tel [phone] fax [phone]

web www.midcointernational.com e-mail [e-mail]

Quality Designed for Proven Performance

Part 1 Installation

Specifications

1

CAUTION: The ECONOMITE Models RE6700B, RE6850 and RE6850B burners are
not intended for outdoor installation and must be protected from excessive moisture.
Provide adequate clearance for service and proper operation.

If the former automatic oil burner gave trouble-free operation, it is probable that the heating
plant area has sufficient infiltration of air for combustion and dilution of flue gases.

Nevertheless, the area must be checked.

 Open basement or utility areas of normal construction, without storm windows or tight
doors, will generally allow sufficient air infiltration. However, if the heating plant is located in
a tight or separate room, ventilation to an open area as described above will be required.
Install two permanently open grills, each sized on the basis of one square inch free area per
1,000 BTU (but not less than 100 square inches) of the total input rating of all gas utilization
equipment in the combined space. One grille should be located within 12 inches of the
ceiling, the other within 12 inches of the floor.
 If the heating plant is located in an area of unusually tight construction, or if an exhaust
fan, kitchen ventilation system, clothes dryer and/or fireplace is installed in the building,
provisions must be made for an outside air supply near the heating appliance area. Install
permanently open grills sized at not less than one square inch free area per 4,000 BTU of
burner input. When ventilating through horizontal ducts, grills should be sized at not less
than one square inch free area per 2,000 BTU of burner input. In any case, the minimum
dimension of rectangular air ducts shall not be less than 3 inches.
 In Canada, for detailed ventilation requirements, refer to standard CAN 1-B149.1 or .2
and/or local codes.

____________________________________________

Part 1

Installation

2

I Ventilation

The ECONOMITE Models RE6700B, RE6850 and RE6850B burners with intermittent
spark ignited pilot are adaptable to most gas utilization equipment, including gravity and
forced circulation furnaces, boilers and hot water heaters. They are particularly
recommended for firing horizontal or downdraft equipment since no draft is required to
maintain a pilot. Power burner design makes them perfectly suited for oil burner
replacement, including rooftop and industrial applications.
AIR DELIVERY (Approximate Air Delivery at Zero Draft)

RE 6700B RE 6850 RE 6850B
146SCFM

2

180SCFM 2180SCFM

2

FIRING RATE (NATURAL OR PROPANE )

3

RE 6700B RE 6850 RE 6850B

MAX MBH

4

700 825 825

MIN MBH

4

275 275 275

GAS SUPPLY PRESSURE REQUIRED

NATURAL ......................................................................................... 6.0" to 14.0" W.C.

PROPANE ........................................................................................ 5.0" to 14.0" W.C.

TUBE DIAMETER.................................................................................6"

TUBE LENGTH.....................................................................................9"

RECOMMENDED COMBUSTION CHAMBER SIZE (AT MAX. BTU/HR)

RE6700 RE 6850 RE 6850B
WIDTH 15" 15" 15"
LENGTH 25" 30" 30"

ELECTRICAL SUPPLY..................120 VAC....... 60 Hertz

5

............... 3.5 AMPS

7

IGNITION CONTROL MODULE VOLTAGE ....... 24 VAC, RE6700B / RE6850B

FLAME SAFETY....Electronic Flame Safety with Spark Ignited Pilot and 100% Shut-Off

6

........ 120 VAC, RE6850

TABLE 1: Burner Specifications

1. Standard burners are shipped as NATURAL gas models. Contact your Midco dealer for
PROPANE gas burners.

2. SCFM = Standard Cubic Feet / Minute.

3. All Ratings Based on 1000 BTU/Cu. Ft. NATURAL, 2500 BTU/Cu. Ft. PROPANE at sea level.
Derate burner for altitude over 2,000 feet by 4% for each 1,000 feet above sea level.

4. 1 MBH = 1,000 BTU/hr.

5. For 50 Hertz applications the RE6700, RE6700B, RE6850 and RE6850B will be derated by 20%.
Contact the factory for details. NOTE: Burners rated for 50Hertz are not UL Listed.

6. See Section XII of Operational Sequence.

7. Inrush AMP draw us higher - if needed, consult the factory.

 Clean the gas utilization equipment combustion chamber, heat exchanger interior, and flue
connections. Remove all adhering tars, scale, dirt and soot. Inspect for actual or potential
leaks.
 Cement all joints, including those in the heating appliance base and around the door
frames, to prevent leakage into, or out of the combustion chamber.
 The access or firing door should open easily to relieve pressure. If positive latches exist,
they should be modified to permit easy opening; a spring loaded door holder is
recommended.
 On all boilers, make certain the pressure relief safety valve is in good operating condition.

____________________________________________

A combustion chamber liner is normally required to protect non-heat transfer surfaces and to
provide a radiant bed for rapid heat transfer to the primary surfaces of the heat exchanger.
In most cases the existing chamber liner can be used, if in good condition.
 In the case of wet base boilers, where the entire firing chamber is comprised of heat
exchange surfaces and no chamber liner was provided for oil firing, a liner is usually not
required for the ECONOMITE. However, a liner or target wall may be necessary if the firing
chamber is unusually short, in order to avoid excess flame contact on the heat exchanger
walls or flueways.

 If a built up chamber liner is required, use 2,300°F minimum insulating material.
 The burner tube, must be sealed air tight into the combustion chamber opening with

refractory material or with supplied ceramic fiber rope.

CAUTION: In no case should the burner tube be allowed to extend into the

chamber proper.

WARNING: BURNER MUST BE MOUNTED IN ORIENTATION SHOWN IN
FIGURES 1 AND 2. ANY OTHER MOUNTINGS MAY CAUSE A DANGEROUS
CONDITION, AND WILL VOID BURNER WARRANTY AND AGENCY APPROVALS. NON­STANDARD ARRANGEMENTS MAY BE AVAILABLE FOR SOME MODELS. CONSULT
FACTORY FOR DETAILS IF REQUIRED.

 Before permanently setting the burner in place, check that the main burner and pilot ports
are free of foreign materials, and also that the spark electrode assembly has not been
damaged or displaced. See Figure 6.

____________________________________________

WARNING: The chimney shall be inspected for unsafe conditions such as
deteriorated masonry and excessive soot or other blockage or potential blockage.
Installation must conform with local codes or in the absence of local codes with NFPA,
ANSI Z223.1 latest edition.

WARNING: The vent connector shall not be connected to a chimney already
venting solid fuel burning equipment, an incinerator or an open fireplace.

 The Vent Connector shall be made of non-combustible, corrosion resistant material
capable of withstanding the vent gas temperature produced by the gas utilization equipment
and of sufficient thickness to withstand physical damage.
 The Vent Connector shall be as short as possible. The entire length shall be readily
accessible for inspection, cleaning, and replacement.
 The length of horizontal uninsulated Vent Connector between the chimney and a single
gas utilization equipment shall not exceed 75% of the the height of the chimney above the
connector, or 100% if the Vent Connector is insulated.

3

Part 1

Installation

Continued

Part 1 Installation

II Preparation of

the Gas Utilization

Equipment

III Combustion

Chamber

IV Chimney, Vent

Connector and

Draft Control

Figure 1: Dry Base Boiler with Combustion

Chamber Liner (Warm Air Furnace

Construction is Similar)

Figure 2: Wet Base Boiler with Unlined

Combustion Chamber

 The Vent Connector shall be installed so as to avoid turns or other construction features
which create excessive resistance to flow of vent gas. It shall be installed without any dips or
sags and shall slope upward at least 1/4" per foot.
 A manually operated damper shall not be placed in the Vent Connector or chimney of
any gas utilization equipment.
 The Vent Connector shall be firmly attached to draft hood outlets and flue collars. Joints
between sections of connector piping shall be fastened by sheet-metal screws or other
approved means. The Vent Connector shall be supported for the design and weight of the
material employed to maintain clearance and prevent physical damage and separation of
joints.
 A draft hood or a barometric draft regulator shall be installed in the same room or
enclosure as the equipment in such a manner as to prevent any difference in the pressure
between the hood or regulator and the combustion air supply (see Figures 3 and 4). In no
case shall the relief opening of the draft hood or barometric draft regulator be located at a
point lower than the top of the highest flue passage in the equipment.

Part 1

Installation

Continued

4

Part 1 Installation

Figure 3: Recommended Locations for Draft Hoods

IV Chimney, Vent

Connector and

Draft Control

Continued

Figure 4: Location for Barometric Draft Regulators

Note: Figures 3 and 4 :
Copyright by American

Gas Association.

Used by permission of

the copyright holder.

Note:
Figures 3 and 4 :
Copyright by
American Gas
Association.
Used by
permission of the
copyright holder.

 Gas utilization equipment requiring controlled draft may be equipped with a listed double
acting barometric draft regulator, if approved by local codes (see Figure 4).
 A device which will automatically shut off gas to the burner in the event of sustained
backdraft is required. It shall be of the listed manual reset type and installed and adjusted by
a qualified service technician in accordance with the manufacturer’s instructions.
 Refer to gas utilization equipment manufacturer for recommended vent connection
requirements.

____________________________________________

CAUTION:Refer to wiring diagram located on the inside of the burner housing
cover or above wiring diagram. Before proceeding verify burner model number for
correct wiring diagram.

Installation wiring and grounding to the burner must conform to local codes, or, in their
absence in the United States to National Electric Code, ANSI/NFPA No. 70 latest edition;
in Canada, to Canadian Electrical Code Part 1, CSA Standard C22.1
 Use copper wire not less than 14 gage for line voltage wiring. Hook up to a dedicated line
with an on-off disconnect switch and a minimum 10 Amp breaker.
 The frame of the burner should be well grounded. Normally the piping and/or electric
conduit will provide sufficient grounding. However, a ground lug is located in control box for
positive grounding where insulated pipe couplings are used or where any doubt exists
regarding grounding sufficiency.
 Confirm that the polarity is correct—hot wire to strip terminal L1, neutral L2—and that the
neutral line is not subject to induced low voltage (check L2 to earth ground) from other
equipment, as that can cause the Ignition Control Module to malfunction.
 Each installation must include suitable limit control(s). Existing oil burner combination
operating and limit controls are normally NOT SUITABLE for gas burner use.
 Connect motors used on forced air furnace fans or boiler pumps to a combination limit
control and switch.
 Set the thermostat heat anticipator for the total current draw handled by the thermostat.
The current draw of the ECONOMITE 24V operating circuit is 0.9 amps.

CAUTION: Label all wires prior to disconnection when servicing controls.
Wiring errors can cause improper and dangerous operation. Verify proper operation
after servicing.

5

Part 1

Installation

Continued

Part 1 Installation

V Electrical

Wiring Diagram for RE6700B and RE6850B - 24V

6

____________________________________________

CAUTION: The available gas pressure should be within the limits shown in
SPECIFICATIONS section. Excessive pressure may damage electric valves, regulators
and manual valves. If the supply pressure exceeds the 14.0"W.C. maximum, a suitable
high pressure regulator must be installed between the Main Manual Shut-Off Valve and
burner shut-off valve as shown in Figure 5.

Part 1

Installation

Continued

Part 1 Installation

VI Piping

Capacities shown are for a
total pressure drop of

0.3"W.C. For 0.5"W.C.
pressure drop, multiply
capacity shown by 1.3 .
Propane capacities shown
are for a total pressure drop
of 0.5” W.C. For higher
permissible pressure drops,
consult your gas supplier.

Table 2: Schedule 40 NPT

Pipe-Capacity Chart

10
200
590
400

1075

900

40

275
200
500
450

1040

650

75

190
150
360
325
750
475

20
150
400
275
730
600

900

Pipe
Size

3/4
3/4

1

1
1 1/4
1 1/4
1 1/2
1 1/2

Natural

Propane

Natural

Propane

Natural

Propane

Natural

Propane

100

160

300
275
630
400
975

Approximate Capacity -MBH

Pipe Length

Type

of Gas

V Electrical

Continued

Wiring Diagram for RE6850 - 120V

7

 The burner gas supply piping should branch off from the main line as close to the gas
meter as possible. Do not connect to the bottom of a horizontal section. Use new black pipe
and malleable fittings free of cutting and threading burrs or defects.
 Provide a sediment trap, union and 1/8" pressure tap in piping close to burner as shown in
Figure 5.

 Use pipe joint compound approved for use with Liquid Petroleum Gases.
 Piping must also comply with your local codes.
 To obtain the maximum firing rate of the burner, the gas supply piping must be sized to

provide a minimum of 6.0"W.C. pressure to the inlet of the upstream automatic safety shut­off valve when the burner and all other gas utilization equipment are on. The pilot regulator
can be mounted in any position, the main regulator, if equipped, should be mounted upright
and in a horizontal run of pipe.

CAUTION: Because it is difficult to accurately control pressure during supply
pipe leak testing, it is recommended that all low pressure (14.0"W.C. max.)
components, both main and pilot, be disconnected during testing. Exposing low
pressure regulators and valves, including manual valves, to pressures over 1/2 PSIG
(14.0"W.C.) will cause damage and void all warranties.

DANGER: Explosion hazard.

Do not use oxygen for pressure testing.

An explosion could occur during initial start up.

 If the burner piping must be rearranged because of space limitation, be sure to carry out
the general arrangement shown in Figure 5. Refer to valve and regulator manufacturers
specifications for acceptable mounting orientation.
 Run full size pipe or tubing from regulator vent openings to outside of building. Provide no
traps in the vent lines and terminate away from all doors and windows; also make provisions
for keeping rain and foreign objects from entering the vent piping.
 When high supply gas pressure is encountered, as in the case in many industrial plants,
the gas line size can be reduced to allow for a greater pressure drop; however, the size must
be sufficient to deliver burner rating pressure.

Part 1 Installation

Figure 5: Piping Diagram for RE6700B - 24V

RE6700B

Valve Train Assembly

24VAC

VI Piping

Continued

Part 1

Installation

Continued

8

Part 1

Installation

Continued

Part 1 Installation

Figure 5 (Cont.): Piping Diagram for RE6850 - 120 V and RE6850 B - 24V

RE6850B

UL, Valve Train Assembly

24VAC

RE6850

UL, Valve Train Assembly

120VAC

Piping

Continued

CAUTION: High gas pressure supply lines require the proper pressure
reducing regulators. Install a high pressure regulator of the Tight Shut-Off type
upstream of the low pressure regulator. Sized for main gas input, and suitable for
the minimum flow regulating capacity of the pilot.

 The high pressure regulator must be adjustable to 14" W.C. outlet pressure.
 When the gas supply line is about to be put into service it must be tested to insure that it

is gas tight. Use air or inert gas under pressure and test with soap and water to locate leaks.
 Before gas is turned onto the system, a check must be made to see that there are no open
fittings and to make sure the burner main and pilot manual valves are closed.
 After checking for leaks, purge the gas line up to the burner inlet. Purging the air from the
gas supply line at this step will expedite the first light-off.

NOTE: If there is more than 1.0" W.C. differential in the inlet pressure to the burner

compared to when all other gas utilization equipment are off, refer to Section VI.

____________________________________________

Burners are approved for use with NATURAL gas or PROPANE gas and should be used only
with the gas specified on the rating plate.
 The gas input should be set at the heating rate determined by the building heat loss and/or
heating plant survey, but not exceeding the rated maximum input of the gas utilization
equipment or Economite burner.
 For orifice selections and gas pressure settings refer to Table 3

____________________________________________

WARNING: Ignition is automatic. Make spark observations into combustion
chamber only with Main and Pilot Manual Shut-Off Valves closed. Confirm that gas
utilization equipment does not contain any accumulated gases. Purge as described in
step 3 below.

CAUTION: Cover plates, guards, and enclosures must be maintained in place
at all times except during maintenance and service.

1. Check the burner piping and valves for gas leaks by applying a weak liquid soap

solution to unions and joints with the gas supply on. Leakage will be indicated by the
appearance of soap bubbles. Locate and correct all gas leaks before proceeding.

WARNING: DO NOT USE OPEN FLAME.

2. Purging the air from the gas supply line at this step will expedite first light-off.

IMPORTANT: Purge outside the building. Do not purge into the gas utilization
equipment.

3. To purge the gas utilization equipment and chimney of any accumulated gases, turn

main Manual Gas Cock OFF, close Pilot Manual Shut-Off Valve, turn burner power on,
and set operating control to ON or thermostat to call for heat. Let the blower run long
enough to accomplish four combustion chamber volume air changes, but not less than
five minutes.

CAUTION:Make sure that the capacity range of the burner, manifold pressure,
and the combustion air shutter setting are suitable for capacity rating of the gas
utilization equipment. Refer to Section VIII and Table 3.

4. RESET the 24 volt ignition Control Module by setting the operating control to OFF or the

thermostat below room temperature for at least 30 seconds. RESET the 120 volt
RM7895 control by pushing its reset button. See Section XII.

5. Confirm that Main and Pilot Manual Shut-Off Valves are open. Turn main Manual Gas

Cock ON.

6. Turn operating control to ON or set thermostat above room temperature. After the pre-

purge is complete, the pilot should ignite. Whenever the burner pilot fails to light during
the ignition trial, or if the flame is lost during the burner run and is not reestablished
within 15 seconds after the pre-purge, the ignition system will shut off the Automatic
Safety Shut-off Valves and LOCK OUT. RESET the 24 volt ignition Control Module by
setting the operating control to OFF or the thermostat below room temperature for at
least 30 seconds. RESET the 120 volt RM7895 control by pushing its reset button. If
burner still fails to light, turn it off and repeat from step 4 above. Then if necessary, refer
to the TROUBLE CHART to isolate the problem.

WARNING: Repeated unsuccessful attempts to light will result in accumulated
gases in gas utilization equipment and chimney. To prevent these gases from
reaching an explosive level, periodically purge the gas utilization equipment and
chimney as described in step 3 above.

7. To make a preliminary setting of the burner input, determine the manifold gas pressure

required from Table 3 and adjust the Main Gas Pressure Regulator accordingly. See

Section XI.

Part 1 Installation

9

Part 1

Installation

Continued

VII Main Gas

Input Selection

VIII Initial Start-

up /Adjustment

VI Piping

Continued

8. To determine the firing rate for NATURAL gas, accurately time test dial for the number
of seconds for one revolution and use the following formula. All other gas utilization
equipment must be off.

3600 x test dial size x BTU value

= BTU/Hr.

No. of seconds for one rev. test dial

Then divide by 1,000 for MBH value.

Example: 3600 x 1 x 1000

= 360,000 BTU/HR = 360 MBH

10

10

Part 1

Installation

Continued

Part 1 Installation

RE6700B

2.4

2.1

2.2

2.4

2.3

2.5

2.2

2.5

2.4

2.0

0.563

0.563

0.484

0.422

0.404

0.358

0.332

0.297

0.277

0.277

2.5

2.3

2.7

2.3

2.8

2.3

2.1

3.0

2.2

2.2

No Orifice

No Orifice

0.563"

0.563"

0.484"

0.484"

0.422"

0.358"

0.358"

0.332"

700

650

600

550 *

500

450

400

350

300

275

Table 3: Capacity and Preliminary Gas Settings

1.

Adjust the main regulator to vary the manifold gas pressure and burner input within the range shown.
Do not exceed pressure as listed in Table 3, under any circumstances. Use combustion readings (CO
or O2) to determine exact inputs.

2.

If you need an orifice that is not included with the burner, drill out the provided 0.358 orifice
(stamped J ) to the required hole size as per chart above

3.

Natural gas to LP gas conversion kits are available, consult factory.

*

Orifice size and approximate manifold gas pressure setting as shipped. Air shutter is set on mark 4.

DATA FOR TABLES IS APPROXIMATE AND BASED ON “0" OVERFIRE PRESSURE AT SEA LEVEL

2.5

2.3

2.7

2.4

2.1

2.2

2.4

2.3

2.5

2.2

2.5

2.4

2.0

No Orifice

No Orifice

0.563"

0.563"

0.563"

0.484"

0.422"

0.404"

0.358"

0.332"

0.297"

0.277"

0.277"

3.7

3.5

2.9

2.5

2.3

2.7

2.3

2.8

2.3

2.1

3.0

2.2

2.2

No Orifice

No Orifice

No Orifice

No Orifice

No Orifice

0.563"

0.563"

0.484"

0.484"

0.422"

0.358"

0.358"

0.332"

Input

MBTU/HR

1

Orifice

Size

(Inches)

Natural Gas

Natural Gas / Propane Gas Orifice Size and Pressure Settings

Manifold

Pressure

("W.C)

Orifice

Size

(Inches)

825

800

750

700

650

600

550 *

500

450

400

350

300

275

Propane Gas

Manifold

Pressure

("W.C)

-

-

-

-

-

H

H

O

O

F

J

J

K

-

-

H

H

H

O

F

P

J

K

L

N

N

Letter

Stamp

Letter

Stamp

-

-

H

H

O

O

F

J

J

K

H

H

O

F

P

J

K

L

N

N

Note: Manifold Pressure settings are based on zero back pressure

RE6850 & RE6850B

VIII Initial Start-

up /Adjustment

Continued

11

9. Check the operation of the burner; start and stop it several times with the thermostat
or operating control.

10. With the burner running, check the operation of all limit and associated controls.

11. Perform the following final adjustments for combustion and flue gas temperature. Take the
flue gas samples and temperature immediately upstream of the draft control.
A. The flue gas temperature should be above 325°F but not exceeding 550°F.

Excessive flue gas temperatures will result in low efficiencies. Low flue gas
temperature may cause excessive condensation. Reset gas input, if necessary, to
adjust stack temperature.

B. Make the final setting of the combustion air shutter by checking the flue gases

with an ORSAT or similar combustion testing instrument. The carbon monoxide
content should conform to local codes, or in their absence, to the level specified
in the United States or Canadian Standard referenced on the front cover of this
manual; and the carbon dioxide content should be approximately 9.5% for
NATURAL or 12% for propane , or within the limits prescribed by local codes.

12. Check the draft control to make sure there is no spillage of flue products into the room.

13. FILL OUT THE INSTALLATION ADJUSTMENT DATA TAG and affix to the burner or
gas utilization equipment.

NOTE: For subsequent normal starting and shut off procedure, refer to CONSUMER
INSTRUCTIONS, located in part 3 of this manual,or to the instruction plate mounted

on the burner.

____________________________________________

PART 2 SERVICE

Part 1

Installation

Continued

Figure 6 : General Assembly for RE6000 Series

Part 2 Service

Part 2

Service

VIII Initial Start-

up /Adjustment

Continued

Part 2 Service

DANGER: Do not
tamper with the unit or
controls. If trouble occurs
contact the installing
contractor, service agency,
or fuel supplier. See front
cover.

DANGER: Be sure
that the main and pilot
manual Shut-Off Valves are
closed and the burner
power supply is turned off
before removing any parts for service.

CAUTION: Cover plates, guards, and enclosures must be maintained in place
at all times except during maintenance and service.

The pilot is of the premix, blast type. The full force of blower air is brought into the mixing tube
where the proper amount of gas is added through the pilot orifice. This mixture is discharged
through the pilot. The mixture provides the flame that contacts the flame sensing rod and also
ignites the main gas.

____________________________________________

CAUTION: Do not indiscriminately increase pilot orifice size. Pilot troubles are
rarely cured in this manner and new troubles may be created.

 Under normal conditions, with a slight negative pressure in the combustion chamber, pilot
operating pressures should be set as indicated in Table 4.
 Some conditions which may require a change from the normal setting include: extremely
long tubing connections between the regulator and pilot solenoid, high negative or positive
combustion chamber pressure, actual air shutter setting and altitude extremes.
 Do not subject the pilot to an inlet pressure over 14.0"W.C. See Section VI PIPING for
high pressure gas.
 To adjust outlet pressure, remove the seal cap for access to the adjusting screw. Turning
the screw clockwise will increase outlet pressure, counter clockwise will decrease outlet
pressure.
 The spark rod for a natural gas burner is welded to a round 1/2” perforated

retention plate.

(The spark rod for a propane gas burner is welded to a round 1/2” solid

retention plate.) The
1/2” retention plate is centered in the 3/8” Tee pilot and is positioned so the high tension
voltage will arc to the inside of the 3/8” Tee pilot.(See Figure 6).
 The flame sensing rod must be positioned as shown in Figure 6 so that the controller will
detect a proper flame.
 Both the spark and flame rods are current carrying conductors and, along with their
connecting wires, must be kept free of contact with conductive metal parts of the burner. Rod
insulators and wire insulators should be clean, dry and free of cracks.
 Both the spark and flame rods are made from heat resistant alloys and can be expected
to have a long service life. They should be routinely inspected, however, for corrosion or loss
of metal.
 The pilot air tubing must be kept free of kinks or inside obstructions and must be positioned
per Figure 6, otherwise air flow could be reduced and adversely affect the pilot flame.

____________________________________________

CAUTION: BEFORE SERVICING, mark with a scribe line or measure opening
of air controlling shutter, so that it can be reset to its original position following
servicing.

Figure 7: Motor / Blower Assembly

Part 2

Service

Continued

12

X Motor Blower

Interlock

IX Pilot

6000
6000
6000

3.0"
to

4.5" W.C.

Model

RE 6700
RE 6850
RE 6850B

0.055"

0.055"

0.055"

Table 4: Pilot Specifications

Gas

Orifice

Diameter

#54

Wire Drill

Approx.
Capacity
BTU/Hr.

Pilot Gas Pressure

2.5"
to

3.5" W.C.

Natural

Propane

Part 2 Service

 Cleaning of the blower wheel is usually the only service required. Need for cleaning is
indicated if the character of the flame indicates a deficiency of air. Motor cooling air vents (if
present) should also be cleaned at this time.
 The motor and wheel are removed as an assembly. Disconnect the motor wires from the
motor terminal strip. Disconnect the motor conduit from the motor and remove the mounting
bolts.
 The burner is equipped with a diaphragm type air pressure switch so as to prevent the
burner from firing if the blower wheel is not running at its operating speed. When the motor
is off there is no air pressure present to activate the pressure switch and in turn there is no
power flow to the Ignition Control System.
 To make a specific test of the air pressure interlock switch circuit:

1. Turn burner power OFF.

2. Turn Manual Gas Cock OFF.

3. Disconnect the motor wire from the terminal strip to keep the motor off.

4. Turn burner power ON and set the operating control to ON or thermostat to call for
heat. Verify there is 120VAC line voltage by using a multimeter. Check for 24V
between the Ignition Control Module 24V and 24V GND terminals.
A. No voltage: Interlock circuit OK.
B. Voltage present: check that the switch is wired properly or check switch

operation. Replace if switch tests bad.

____________________________________________

 Should replacement or service be required, valve manufacturer's instructions must be
followed as outlined in their information sheet.

 Outlet pressure settings must be checked while the gas is flowing.
 To adjust outlet pressure, remove the seal cap for access to the adjusting screw. Turning

the screw clockwise will increase outlet pressure, counter clockwise will decrease outlet
pressure.

____________________________________________

 Prepurge S8670J
When power is applied to L1 and L2 through a safety and operating control, the

combustion air blower starts, once the air proving switch closes and proves blower
operation, energizes the S8670J, and initiates a 30 second delay to allow system prepurge.
After a 30 second prepurge, the 15 second trial for pilot ignition sequence begins.
 Trial for Pilot Ignition

On a “call for heat” and after 30 second prepurge, the module energizes the spark source
and the pilot valve relay simultaneously. The pilot valve opens, allowing gas to flow to the
pilot burner during the 15 second ignition trial time. The spark lights the pilot flame when
pilot gas is present. A flame rectification circuit confirms the presence of the pilot flame,
shuts off the spark source, and energizes the main valve relay.
 Main Burner Operation

When the main valve opens, gas flows to the main burner where it is lit by the pilot flame.
There is a 2 second flame stabilization period as the main valve opens. The system is now
in the run mode with the presence of the pilot flame continuously monitored by the flame
rectification circuit. If the pilot flame goes out, or pilot flame signal drops below 1.1micro
amps, the control senses loss of pilot flame and shuts off both the pilot valve relay and the
main valve relay.
 The control has two LEDs; one for flame sensing and one for system status:

. Flame LED (Yellow)
. Indicates flame presence and strength.
. Status LED (Green)
. Indicates system operation status and error conditions.
 FAILED TRIAL FOR PILOT IGNITION S8670J

If pilot flame is not lit and sensed before the end of the15 second trial for ignition time, the
control shuts off the pilot valve (100% shutoff) and goes to lockout. Or if proof of flame is
lost during burner run cycle the system will retry once, if pilot flame is not proven within the
15 second trial for ignition time, the control shuts off the pilot valve relay and lockout. The
control remains in lockout until power is cycled by the system thermostat or removing and
restoring system power.
 For operation characteristics, maintenance, service procedures, and LED codes refer to
manufacturer’s literature provided.

WARNING: Explosion hazard. Do not use any electronic device if it gets

wet. It can malfunction and cause serious injury or death. Replace any device that
has been wet.

____________________________________________

XI Valve Train

XII Sequence of

Operation

Part 2

Service

Continued

13

X Motor Blower

Interlock

Continued

Part 2 Service

 For operation characteristics, maintenance, and service procedures, refer to
manufacturer's literature provided with burner.

____________________________________________

 The standard RE6850 burner is equipped with a Honeywell RM7895 microprocessor
based burner control, employing a flame rectification system of flame detection. Burner
construction for special codes and/or insurance requirements such as Factory Mutual
or Industrial Risk Insurers (IRI) may require alternate controls. A safe start and run control
sequence is provided with instantaneous response to presence or loss of flame signal.
Flame failure response time is 3-seconds; Pilot Flame Establishing Period (PFEP) is field
selectable from 4 or 10-seconds. The RM7895 features a pre-purge time (30-seconds for
ON-OFF, 90-seconds for 2-Step or Modulating burners), and a plug-in amplifier. An airflow
circuit is also field selectable to allow either lockout or recycle upon loss of airflow. Five
LED’s (light emitting diodes) are provided to display sequence information. Refer to the
Honeywell RM7895 literature for detailed operating information, configuration requirements,
testing, and service.
INITIATE SEQUENCE ("POWER" LED is lit)
 The RM7895 enters the INITIATE sequence when it is powered. The INITIATE
sequence lasts for ten seconds unless the voltage or frequency tolerances are not met
(refer to Honeywell RM7895 literature for criteria). When tolerances are met, the INITIATE
sequence will restart. If the conditions not corrected and the hold condition exists for four
minutes, the RM7895 will lock-out. Causes for hold conditions in the INITIATE sequence
are in the Honeywell RM7895 literature.
STANDBY ("POWER" LED is lit).
 The RM7895 is idle in this state of sequencing. When the burner switch, limits, operating
limit controls, and all microprocessor monitored circuits are in the correct state for the
RM7895 to continue, sequencing will advance to PREPURGE.
PREPURGE ("POWER" LED is lit).
 The RM7895 in this application features a prepurge time of 30-seconds for ON-OFF,
90-seconds for 2-Step or Modulating burners.
 Once the STANDBY sequence has a "CALL FOR HEAT" input, normal start-up
prepurge will be initiated.

A. The blower motor is powered to start the prepurge sequence.
B. The airflow interlock switch must close in ten seconds of prepurge or within the

specified purge card timing. Otherwise a recycle to the beginning of prepurge
or lockout will occur, depending on how the airflow switch selectable jumper is
configured. Refer to Honeywell RM7895 literature for configuration requirements.

IGNITION TRIAL

1. PILOT FLAME ESTABLISHING PERIOD (PFEP)
A. The pilot valve and spark generator are energized.
B. Flame must be proven by the end of the 4 or 10-second PFEP to allow the sequence

to continue. If flame is not proven by the end of PFEP, a safety shutdown occurs.

2. MAIN FLAME ESTABLISHING PERIOD (MFEP)

 After the ignition trials, and with the presence of flame, the main valve is energized.
("MAIN" LED will be lit.) If a flame-out occurs, the RM7895 will lockout or recycle within
3-seconds, depending on "jumper" configuration. Refer to Honeywell literature for proper
configuration.
 The RM7895 is now in RUN mode and will remain in run mode until the controller input
opens, indicating that the call for heat has been satisfied or a limit has opened. Once this
occurs the RM7895 will sequence back to the STANDBY mode.
Notes: 1. During STANDBY and during RM7895 sequencing the "POWER" LED will

blink every four seconds. This is normal.

2. The "ALARM" LED will be lit in the event of any flame failure.

3. To maintain proper operation of this device it MUST be electrically grounded.
Refer to Honeywell RM7895 literature for criteria.

____________________________________________

 Special equipment, either factory or contractor installed, may cause variation in the
procedures and descriptions given in this manual.
 Consult the OEM's manual to identify the differences in the information.

____________________________________________

The major difference for the CUL version of the RE6700B / RE6850 / RE6850B is the French
/ English specification plate and the firing valve for the pilot line.

____________________________________________

14

XVI Canadian

Specifications

XIII S8670J Ignition

Control Module

XIV Primary

Safety Control

RM7895

XV Special

Equipment

(OEM Versions)

Part 3 Maintenance

PART 3 MAINTENANCE

CONSUMER INSTRUCTIONS

 Keep the area around the burner clear and free of combustible material, gasoline or other
flammable liquids or vapors. Do not obstruct burner air openings or ventilation grills for
combustion air.
 The motor features permanently lubricated ball bearings and requires no maintenance.

WARNING: If any flame is observed when the burner is on standby, or if the
ignition spark or valve operator is heard to come on before the motor reaches
operating speed, immediately turn off the manual gas control and burner power. A
dangerous condition has developed and must be corrected. CONTACT A QUALIFIED
SERVICE TECHNICIAN FOR CLEANING, READJUSTMENT OR REPAIR.

 Check that the pilot ignition spark does not come on before the motor reaches operating
speed. If it does, the air switch is defective and must be replaced. (See Section X, Motor /
Blower Interlock).

____________________________________________

LIGHTING INSTRUCTIONS

1. SET OPERATING CONTROL TO OFF OR THERMOSTAT BELOW ROOM

TEMPERATURE.

2. TURN MANUAL GAS COCK ON.

3. TURN BURNER POWER ON.

4. SET OPERATING CONTROL TO ON OR THERMOSTAT TO CALL FOR

HEAT.

5. IF THE PILOT FLAME IS NOT PROVEN WITHIN 15 SECONDS, AFTER THE

PRE-PURGE, THE CONTROLLER WILL SHUT OFF THE AUTOMATIC
SAFETY SHUT-OFF VALVES AND LOCK OUT. IF THE PROOF OF FLAME IS
LOST DURING BURNER RUN AND THE PILOT IS NOT RE-ESTABLISHED
WITHIN 15 SECONDS AFTER THE PRE-PURGE, THE CONTROLLER WILL
SHUT OFF THE AUTOMATIC SAFETY SHUT-OFF VALVES AND LOCKOUT.
RESET THE 24 VOLT IGNITION CONTROL MODULE BY SETTING THE
OPERATING CONTROL TO OFF OR THE THERMOSTAT BELOW ROOM
TEMPERATURE FOR AT LEAST 30 SECONDS. RESET THE 120 VOLT
RM7895 CONTROL BY PUSHING ITS RESET BUTTON.

6. REPEAT STEP 4 FOR RESTART.

TO SHUT OFF

1. TURN MANUAL GAS COCK OFF.

2. TURN BURNER POWER OFF.

SHOULD OVERHEATING OF THE APPLIANCE OCCUR

1. Shut off the manual gas control valve to the appliance.

2. Do not shut off the electrical supply power to the blower.

____________________________________________

15

Part 3

Maintenance

Lighting Instructions

Consumer Instructions

Midco International Inc. 4140 West Victoria Street * Chicago, Illinois 60646

tel [phone] fax [phone] web www.midcointernational.com email [e-mail]

TROUBLE CHART

Make sure the thermostat and operating controls are calling for heat.

CAUTION: If a test indicates an electrical component may be defective,

before replacing it, make sure that its associated wiring is not at fault.

ELECTRICAL AND FLAME CHECKS MUST BE MADE IN THE ORDER LISTED BELOW.

I. MOTOR WILL NOT RUN

A. Confirm 120V between strip terminals L1 and L2 and verify the circuit polarity and

electrical ground between strip terminal L1 and burner Ground.

B. Check for 120V between strip terminals L1 and L2.

1. No voltage, open circuit in operating controls.

2. Voltage present, motor is defective.

II. MOTOR RUNS CONTINUOUSLY, PILOT WILL NOT LIGHT

A. Confirm that ALL Main Manual Shut-Off Valves are in the ON position.
B. After the pre-purge, if the pilot flame is not proven within the pilot flame

re-establishing period, or if the proof of flame is lost during the burner run and the
pilot is not re-established after the pre-purge, the Ignition Control Module will lock

out. RESET the 24 volt ignition Control Module by setting the operating control to
OFF or the thermostat below room temperature for at least 30 seconds. RESET the

120 volt RM7895 control by pushing its reset button. See Section XII.
C. Clogged pilot orifice.
D. Pilot regulator mis-adjusted or defective.
E. Defective spark electrode, Ignition Control Module or Transformer for 120V.
F. Defective high tension wire.
G. Wrong pilot orifice.
H. Defective pilot valve.
I. Pilot air tube clogged.
J. Incorrect spark gap.
K. Pilot regulator vent clogged.
L. Defective blower air switch.
M. Step down transformer is defective, (if applicable).
N. Insufficient pilot flame sensing signal.

III PILOT LIGHTS, NO MAIN FLAME

A. Poor pilot flame adjustment.
B. Clogged pilot air tube.
C. Defective flame sensing rod or wire.
D. Flame sensing rod mis-located.
E. Pilot regulator vent clogged.
F. Defective Ignition Control Module, if applicable.
G. Defective main gas valve.
H. Low gas pressure.
I. Grossly mis-adjusted main gas and air mixture.
J. Insufficient pilot flame sensing signal.

1007

8471 45

Printed in USB

I Motor Will

Not Run or Motor
Runs in Repeated

Cycles

II Motor Runs

Continuously, But

No Flame

III Pilot Lights,

No Main Flame

Trouble Chart

Part 3 Maintenance

Part 3 Maintenance

Continued