Market Forge M24G Service Manual

M24G & M36G

GAS OPERATED BOILERS

PARTS AND SERVICE MANUAL

EFFECTIVE AUGUST 29, 2014

The Company reserves the right to make substitution in the event that items specied are not available.

ERRORS: Descriptive and/or typographic errors are subject to correction.

44 Lakeside Avenue, Burlington, Vermont 05401 USA Telephone: [phone] Fax: [phone]

Superseding All Previous Parts Lists.

MARKET FORGE INDUSTRIES

www.mi.com

P/N 14-0308 (8/14)

TABLE OF CONTENTS

TROUBLESHOOTING ..................................................................3

GAS PRESSURE ADJUSTMENTS ......................................................5

WATER CONTROL BOARD TESING PROCEDURE ......................................6

WIRING DIAGRAM .....................................................................8

ILLUSTRATED PART LIST

24" BOILER BASE CABINET .......................................................... 10

PRESSURE SWITCH BOX, WITHOUT COVER..........................................11

CONTROL BOX ASSEMBLY, WITH AND WITHOUT COVER ............................. 12

PLUMBING, LEFT SIDE GAS BOILER, 24” ............................................. 13

FRONT VIEW GAS BOILER, 24”, 200K ................................................ 14

GAS TRAIN, 200K BTU BOILER SHOWN .............................................. 15

AUGUST 29, 2014 2 M24G & M36G GAS BOILERS

TROUBLE POSSIBLE CAUSE(S) REMEDY

Pilot will not ignite or does not
hold.

TROUBLESHOOTING

Gas not reaching unit. Check to make sure gas is on and gas

line is purged of air.

Main “gas cock knob” not in ON position. Depress and turn “main gas cock” to pilot

position - (refer to lighting instructions).

Air pocket or clog in gas line. Purge or blow out gas line.

Defective wiring or poor connection at pi­lots at power unit.

Defective switching across either the wa­ter level control or pressure switches.

Defective gas valve. Replace gas valve.

Water enters boiler very slowly. Clogged strainer screen on water ll so-

lenoid valve

Debris or lime accumulation on seat of

water ll valve.

Boiler overlls with water. Probes scaled. Clean.

Water supply valve fails to close. Clean valve seat or replace valve.

Defective water level control. Follow the test procedure. Replace if de-

Main Burners will not ignite or will
not remain lighted.

Boiler fails to build up any pres­sure when the water is at the
correct level and the fuel switch is
turned on.

Boiler fails to cut off after reaching
operating pressure.

No water in boiler. Check to be sure water switch is on.

Main gas cock or supply line not open. Open.

Pressure switch set too low. Reset - if continuity check shows to be

No voltage to gas valve. Check main fuse.

Gas valve defective. Replace.

Check to see that main gas is turned on. Turn on.

Check to see that gas valve is in burners
“on” position.

Current ow is broken at water level con­trol (ascertain with continuity check).

Current ow is broken at pressure control

or high limit control switches (ascertain
with continuity check).

Pressure switch set too high or defective. Adjust or replace if defective.

Check - replace or tighten.

Make continuity check – replace units
that are defective.

Clean or replace strainer screen. (P/N
08-4871).

Clean valve seat

fective.

Check to be sure main water supply is on
and the electrical supply to unit is on.

defective - replace.

Turn to burners “on”.

Check for voltage thru right side of control
board, replace if defective.

Re-adjust to proper setting -refer to in­struction for re-adjustment, replace if de­fective.

Gas valve fails to cut off gas supply when
demands of pressure switch have been
met.

Water level in gauge glass uctu­ates up and down.

AUGUST 29, 2014 3 M24G & M36G GAS BOILERS

Top shutoff valve on water gauge glass
is closed.

Replace gas valve.

Open.

TROUBLESHOOTING

TROUBLE POSSIBLE CAUSE(S) REMEDY

Boiler fails to reach full operating pres­sure of 5 lbs. or 15 lbs.

Safety valve blows off prematurely. Pressure set too high. Readjust pressure control.

Boiler builds up to pressure, shuts
down, fails to come back on.

Water does not enter boiler. Main water supply off. Turn on.

Cold water condenser does not func­tion.

Air vent leaking. Not closing. Replace.

Pressure gauge reads inaccurately. Replace.
Pressure control and high limit control

switches are out of adjustment.

Safety valve not seating properly. Purge manually or replace.
Water level too high. Adjust water level control - check wa-

Air vent not venting properly. Replace.
Insufcient ames on burners or im-

proper gas supply.

Pressure gauge reads incorrectly. Replace.
Lime or debris on seat of valve Purge or replace.
High limit switch set to low or operating

pressure control switch set too high.

Power not reaching unit. Check main fuse or circuit.
Probes Dirty. Remove & Clean
Water level control board defective. See test procedure.
Solenoid valve defective If Voltage is veried at solenoid coil, but

Main water supply off. Turn on.
Thermostat defective. Replace if defective.
Loose coil nut. Tighten coil nut.
Solenoid coil not energized. Check coil for continuity, if open re-

Follow instructions for readjusting

ter feed valve for sticking - clean or re­place.

See instructions on gas adjustments

Follow instructions for readjusting Re­place if defective.

fails to open, replace solenoid.

place.

AUGUST 29, 2014 4 M24G & M36G GAS BOILERS

GAS PRESSURE ADJUSTMENTS

If gas pressure is too low

Check your gas supply line for a restriction. If no restric­tion exists, check with your Natural gas supplier to provide
at least 5” of water column pressure in the gas supply line.
If no restriction exists and Propane gas is being used, the
tank pressure regulator should be adjusted to supply at
least 11” of water column pressure in the gas supply line.
If this adjustment cannot be made to your satisfaction, the

gas supplier should be notied.

If gas pressure is too high

Adjust the pressure regulator on the boiler gas valve to re­duce the pressure if Natural gas is being used. If Propane
gas is being used, adjust the pressure regulator supplied
by the gas supplier. If the regulator cannot be adjusted,
notify the gas supplier.

Pressure control switch adjustment

If boiler fails to maintain steam pressure in operating
range, pressure control switch may require adjustment.

1. Start boiler and allow pressure to build up to operat­ing level - 7 PSI (1kg/cm²).

2. Check boiler pressure gauge. The gas burners should
cycle ON at 5 PSI and cycle OFF at 7 PSI.

3. If boiler does not come on when pressure gauge
reads 5 PSI and does not go off when pressure gauge
reads 7 PSI, proceed as follows:

WARNING

Because power must be on to adjust pressure
switches, be sure to protect against electrical
shock.

a. Remove screw and lift front cover off control box.

b. Hand adjust operating pressure control switch

and high limit pressure control switch by turning
adjusting nut (Knurled knob) clockwise to raise
and counter clockwise to lower actuation point.
Switch should be set so that boiler comes on
when boiler pressure gauge reads 5 PSI and
goes off when gauge reads 7 PSI. Hi limit switch
should be set so that boiler will shut off if pres­sure reaches 15 PSI.

c. The actuation value (differential) is factory set

and cannot be changed.

d. The cold water condenser thermostat is preset

at factory.

e. Repeat steps, 1, 2, and 3. If 5 to 7 PSI boiler

pressure gauge reading is obtained during boiler
operation, adjustment is correct. If proper adjust­ment cannot be made contact an authorized ser­vice agent.

f. After making adjustments, replace cover on pres-

sure switch box and screw.

OPERATING SWITCH

HI LIMIT SWITCH

AUGUST 29, 2014 5 M24G & M36G GAS BOILERS