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13

Maxitrol M511 and M611 

Low Fire Bypass Screw 

 

Mod Valve Voltage Summary 

Volts DC 

Firing Mode 

0 to 5 VDC 

Low Fire 

5 to 15 VDC 

Modulation 

15 to 20 VDC 

High Fire 

 

Maxitrol MR212 Low 

Fire Bypass Screw 

 

Average Manifold Pressure vs. Firing Rate/Ft. of Burner

-1.00

0.00

1.00

2.00

3.00

4.00

5.00

6.00

0

100000

200000

300000

400000

500000

600000

Firing Rate (BT U/Hr/Ft. of Burner)

M

a

n

if

o

ld

 P

re

s

s

u

re

 (

in

w

.c

.)

Natural Gas

Propane Gas

Main Burner Adjustment

 

1.  Once  the  pilot  has  been  properly  established,  the 

manifold  gas  pressure  or  temperature  rise  should  be 
adjusted  to  jobsite  conditions.    The  gas  pressure 
regulator (integral to the combination gas control on size 
1-3 heaters and located in the modulating valve on size 
4-5  heaters)  is  adjusted  at  the  factory  for  average  gas 
conditions.    It  is  important  that  the  gas  be  supplied  to  the  burner  in  accordance  with  the  input 
rating on the rating plate.   

2.  Create a high fire call for heat.  This should be done  with the blower on and all gas controls on.  

High  fire  can  be  achieved  by  removing  the  wire  at  terminal  #4  (remove  wires  #2  and  #4  for 
Maxitrol 44 systems) from the amplifier.   

3.  The manifold pressure should be checked 

at  the  pressure  tap  downstream  of  the 
modulating  valve.    The  graph  to  the  right 
indicates  the  proper  manifold  pressure  for 
the  desired  amount  of  BTUs  per  foot  of 
burner.  For  natural  gas  systems,  the  high 
fire manifold pressure should not exceed 
in.  w.c.    
For  propane  gas,  the  high  fire 
manifold  pressure  should  not  exceed  2.5 
in. w.c.  
Another method of checking high 
fire  is  to  measure  the  temperature  rise  of 
the  unit.    The  temperature  rise  should  be 
set  to  design  conditions  and  typically  is 
minimum 70°F.   

4.  Remove the cap from the combination gas 

valve  regulator  adjustment  (size  1-3)  or 
the  cap  from  the  MR212  valve  (size  4-5).  
Using the regulator pressure adjusting screw, adjust the high fire manifold pressure to 5 in. w.c. 
maximum  for natural  gas and 2.5 in.  w.c. maximum  for propane gas.  High fire should be  set to 
generate the  desired  temperature rise.   If the high fire screw  is at the  end of its adjustment and 
more  pressure  is  needed,  then  adjust  the  main  building  gas  pressure  regulator  spring  (located 
external  to  the  unit)  to  achieve  the  proper  manifold  pressure.    Turning  the  regulator  screw 
clockwise  will  increase  pressure  and  counter-clockwise  will  decrease  pressure.    Remember  - 
The high fire DC voltage should read 12 VDC minimum and should typically be 15 VDC on 
the Flame Safety Controller test jacks.
  

5.  Reconnect the wire on the amplifier at terminal #4 (wires #2 and #4 for Maxitrol 44).  
6.  The low fire  manifold  pressure  must now  be set.   Low fire can  be achieved 

by  removing  the  wire  at  terminal  #5  from  the  amplifier  (remove  #8  for 
Maxitrol 44).  Check the low fire flame signal to ensure that the DC voltage 
is 12 VDC minimum 
on the Flame Safety Controller test jacks. 

7.  Using the bypass screw (located on the side of the M511 and M611 valves, 

and under the cap of the MR212 valve), adjust the low fire manifold pressure 
until there is a very thin flame along the entire length of the burner.  No dark 
spots  should  be  seen  in  the  burner.    The  burner  may  be  observed  through 
the view-port located on the external wall of the heater.  Replace the cap to 
the  valve  and  restore  all  of  the  original  wiring  on  the  amplifier  and  gas 
components. 

8.  A final gas leak check shall be performed to verify the gas-tightness of the 

heater’s  components  and  piping  under  normal  operating  conditions.    This 
can  be  done  by  measuring  the  gas  pressure  at  the  ¼”  gas  plug  just 
downstream of the modulating valve.   

Summary of Contents for Modular Direct Fired Heaters

Page 1: ...VING AND INSPECTION Upon receiving unit check for any interior and exterior damage and if found report it immediately to the carrier Also check that all accessory items are accounted for and are damage free Turn the blower wheel by hand to verify free rotation and check the damper if supplied for free operation WARNING Improper installation adjustment alteration service or maintenance can cause pr...

Page 2: ......

Page 3: ...Assembly 12 Main Burner Adjustment 13 Heater Start Up Summary 14 Final Start Up Procedure 15 Pulley Adjustment 15 Pulley Alignment 15 Proper Belt Tension 15 Pulley Setscrew Torque 15 Pulley Combination Chart 16 Sequence of Operation 17 Flame Safety Control 17 Air Flow Switch 17 DC Flame Signal 17 Modulating Gas System 18 High Temperature Limit 18 Operation Summary 18 Optional Remote Panel Circuit ...

Page 4: ...capacity 5 The invoice is not paid within the terms of the sales agreement The MANUFACTURER shall not be liable for incidental and consequential losses and damages potentially attributable to malfunctioning equipment Should any part of the equipment prove to be defective in material or workmanship within the 12 month warranty period upon examination by the MANUFACTURER such part will be repaired o...

Page 5: ...rival follow the following procedure to assemble the intake to the heater 1 Apply silicone or weather proof gasket on the back side of the flanges of the intake hood or v bank intake 2 Screw the flanges of the intake hood or v bank to the unit with the supplied sheet metal screws Place caulk on the outside of the screws to prevent water leaks If the unit is a modular unit with a v bank or evaporat...

Page 6: ...ing into account through standard engineering methods the structure s designed infiltration rate by providing properly sized relief openings or by interlocking a powered exhaust system or by a combination of these methods Heaters installed with intake ductwork must be purged to replace at least four air changes of the volume of the intake duct If the failure or malfunction of this heater creates a...

Page 7: ...e heat module and the blower module 3 Support and level the end of the heat module end opposite the blower with the provided equipment legs rails 4 Attach the filter hood to the intake side of the heater module 5 Drill a hole in the discharge of the blower large enough to insert the mixing tube and discharge sensor if provided Install the mixing tube in the proper airflow direction The airflow dir...

Page 8: ...es 4 Install a ground joint union with brass seat and a manual shut off valve external to the unit casing as shown below adjacent to the unit for emergency shut off and easy servicing of controls 5 Provide a sediment trap as shown below before each unit and where low spots in the pipe line cannot be avoided 6 Blow out the gas line to remove debris before making connections Purge line to remove air...

Page 9: ... the National Electric Code This dedicated branch should be run to the junction box mentioned above and connected as shown in a following illustration labeled Fan to Building Wiring Connection 4 Make certain that the power source is compatible with the requirements of your equipment The heater nameplate identifies the proper phase and voltage of the motor 5 Units shipped with an optional remote pa...

Page 10: ...oltage that may be applied to these motors is 65VAC Running lower voltages to the motor can cause premature failure and overheating problems ECM Electronically Controlled Motor Speed Control ECM motors and control allows accurate manual adjustment of fan speed The benefit of ECM motors is exceptional efficiency performance and motor life The control used with ECM motors features a 4 digit LED nume...

Page 11: ...heater There is a terminal strip inside the remote panel that matches the terminals in the heater unit The remote panel should be wired as shown below BL YW RD BK PK RD WH OR BR GY BK RD YW PK RD BK WH BK OR BR GY PK RD BK YW RD OR BR GY WH BK 1 E PK YW BK RD WH GY BR OR RD NC BK Fire System Microswitch BK NO PR C Fan to Building Wiring Connection ...

Page 12: ...For 3 phase motors any two power leads can be interchanged to reverse motor direction 7 When the fan is started up observe the operation and check for any unusual noises Pilot Adjustment 1 Restart the fan and check the gas supply pressure at the inlet gas tap upstream of all electronic valves The inlet pressure should be 7 in 14 in w c 7 in w c 5 psi on Size 4 5 heaters If the inlet pressure is to...

Page 13: ...ove the cap from the combination gas valve regulator adjustment size 1 3 or the cap from the MR212 valve size 4 5 Using the regulator pressure adjusting screw adjust the high fire manifold pressure to 5 in w c maximum for natural gas and 2 5 in w c maximum for propane gas High fire should be set to generate the desired temperature rise If the high fire screw is at the end of its adjustment and mor...

Page 14: ...Maxitrol 44 This will drive the valve into its full open position Adjust high fire with the regulator inside the unit Turn clockwise to increase temperature rise Ensure that DC flame signal is minimum 12 VDC Replace the wires on the Maxitrol Amplifier Adjusting low fire Remove wire 5 from the Maxitrol 14 amplifier 8 for Maxitrol 44 This will drive the valve into its lowest position Adjust the low ...

Page 15: ... not set fan RPMs higher than specified in the maximum RPM chart See the troubleshooting guide for more information 3 Measure and record the voltage and amperage to the motor and compare with the motor nameplate to determine if the motor is operating under safe load condition 4 Once the rpm of the ventilator has been properly set disconnect power and recheck belt tension and pulley alignment as de...

Page 16: ... 1165 1187 1210 1232 1255 1277 1299 1322 3 to 5 HP MOTOR PULLEY Dd1 Dd2 Pd1 Pd2 BX BELTS 2VP42 2 9 3 9 3 4 Open Closed BLOWER PULLEY DATUM DIAMETER PITCH DIAMETER 6 5 1 2 5 4 1 2 4 3 1 2 3 2 1 2 2 1 1 2 1 1 2 0 2B5V278 27 8 28 1 184 189 194 200 205 210 215 220 225 230 235 240 246 2B5V250 25 25 3 205 210 216 222 227 233 239 244 250 256 261 267 273 2B5V234 23 4 23 7 218 224 230 237 243 249 255 261 2...

Page 17: ...nit Third the unit will pause to purge any gasses or combustible vapors before attempting flame ignition Then there is a Pilot Trial For Ignition PTFI and the PTFI LED comes on During PTFI the FSC opens the pilot gas valve and allows gas to flow to the pilot assembly At the same moment the spark igniter is started causing the spark to ignite the pilot gas When the flamerod sensor detects the flame...

Page 18: ... system consists of a temperature selector dial a discharge air sensor an amplifier and a modulating gas valve The two types of modulating gas systems used are the Maxitrol 14 or RTC Solutions controls and the Maxitrol 44 series The Maxitrol 14 RTC utilizes a discharge air sensor and modulates the Maxitrol gas valve to provide discharge air to match the selected temperature on the temperature sele...

Page 19: ...wered Blower Switch Nothing Happens No Power is Sent to Heater Power is Sent to Heater to Open Damper if provided and Start Blower Off Position 3 Position Panels Only Manual Blower On Light Damper is not Open or Freeze Stat has Detected Low Temperature Operation On Off Temperature Control Switch Blower Operates Heat Does not Operate Vent Position Heat Position Heat Circuit is Energized Burner On L...

Page 20: ... to provide 120V service to controls 11 Circuit Breaker Protects electrical components from high current spikes 12 Terminal Strip Central location to terminate control wiring Should be used for troubleshooting 13 Control Transformer 120V primary 24V secondary control transformer 14 Low Pressure Airflow Probe Measures profile pressure downstream of burner 15 High Pressure Airflow Probe Measures pro...

Page 21: ...witch This switch is powered when the Manual Off Auto switch is in the MANUAL position It is used to control the tempering mode of the unit The VENT position will prevent the burner from operating and the heater will deliver untempered air The HEAT position will force the burner on and the unit will heat the incoming air This switch becomes a Heat Vent Cool switch when the cooling interlock is ord...

Page 22: ...o low Determine if HP is sufficient for job Duct static pressure lower than design Reduce fan RPM Insufficient Airflow Fan rotating in the wrong direction Be sure fan is rotating in the direction shown on rotation label Poor outlet conditions There should be a straight clear duct at the outlet Intake damper not fully open Inspect damper linkage and replace damper motor if needed Duct static pressu...

Page 23: ...Check wiring to valve Defective pilot sensor Replace pilot sensor Shut off valve closed Open shut off valve Defective flame safety controller Replace flame safety controller Pilot fails as main gas valves open and main gas begins to flow Plug the first burner port next to the pilot gas tube with burner cement Not Enough Heat Main gas pressure too low Increase main gas pressure do not exceed 14 in ...

Page 24: ... Panels Only Heat Vent Switch in Vent Position Gas Pressure Switch Tripped option High Temperature Limit Thermostat Tripped Manual Off Auto Switch in Auto Position and Intake Air Thermostat not Satisfied Improper Airflow Insufficient Airflow Excessive Airflow Bad airflow switch Problem with air probes Problem with airflow tubing Broken Belt POWER Light and BLOWER ON Light and BURNER ON Light Prope...

Page 25: ...ifier is there 9 5K to 11K Ohms between the wires Replace Discharge Air Sensor Remove Terminal 4 from the Maxitrol Amplifier Does the heater go into High Fire Replace Amplifier With wires 1 2 removed from the Maxitrol Amplifier is there 9 5K to 11K Ohms between the wires Replace the Temperature Selector Is there a short or open circuit in Modulating Valve Should be 45 55 Ohms 60 80 on MR212 Replac...

Page 26: ...injury 3 All fasteners should be checked for tightness each time maintenance checks are preformed prior to restarting unit 4 Blowers require very little attention when moving clean air Occasionally oil and dust may accumulate causing imbalance If the fan is installed in a corrosive or dirty atmosphere periodically inspect and clean the wheel inlet and other moving parts to ensure smooth and safe o...

Page 27: ...d be checked for tightness each time maintenance checks are preformed prior to restarting unit Every 3 months 1 Belt tension should be checked quarterly See instructions in the previous maintenance section Over tightening will cause excessive bearing wear and noise Too little tension will cause slippage at startup and uneven wear 2 Filters need to be cleaned and or replaced quarterly and more ofte...

Page 28: ...otor Voltage Serial Number Motor Amperage Motor Volts RPM Motor Hertz Burner Differential Pressure in w c Motor Phase Pilot Flame Signal VDC Motor FLA Low Fire Flame Signal VDC Motor HP High Fire Flame Signal VDC Blower Pulley Gas Type Motor Pulley High Fire Inlet Gas Pressure in w c Belt Number Low Fire Manifold Gas Pressure in w c Gas Type High Fire Manifold Gas Pressure in w c Min Btu Hr Thermo...

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