TROUBLESHOOTING PROCEDURE - ELECTRONIC IGNITION SYSTEM

START

CHECK

• Turn Off Gas Supply.

 

• Check for proper volt-

 

 

 

• Ensure Valve Switch Is In ON Position.

 

age at control harness

 

•

Line voltage power

• Disconnect Control Harness.

 

(see insert A). Voltage

NO

•

Low voltage transformer

• Set Thermostat To Call For Heat.

2

should be 24V between

 

•

Limit controller

 

thermostat or pressure

 

• Thermostat

 

 

 

 

 

 

•

Wiring

 

 

switch and 24V common

 

 

 

 

 

 

 

 

and 24V hot.

 

 

 

 

 

YES

 

 

 

Insert A

• Plug control harness into

 

valve. Wait for internal check

End View of Control Harness Connector

delay.

 

 

 

24 Volt Hot

24 Volt

 

 

 

 

 

• With pilot burner cable con-

 

 

Common

 

 

 

 

1

 

 

 

 

 

 

NO

 

nected, measure voltage at

NO

 

 

 

 

• Igniter warms up and glows

 

 

• Replace valve.

 

 

 

 

 

 

valve HSI element output. 24V

 

 

 

 

 

red.

 

 

 

 

 

 

 

 

 

 

 

 

2

 

 

 

 

 

 

 

 

 

nominal. (See insert B)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

YES

 

 

24 Volt

 

 

1

YES

 

• Replace igniter/flame rod

 

 

 

 

 

 

 

 

assembly.

 

 

Switched

 

 

 

 

 

 

 

 

Check For Damaged or Missing

 

 

 

 

 

 

YES

 

 

 

 

 

 

 

 

 

 

 

Terminals in Connector

 

 

 

NO

• Check that pilot gas is flowing. Wait

NO

 

 

 

 

• Turn on gas supply.

 

to ensure pilot gas tubing is purged.

• Replace valve.

 

 

 

 

 

 

 

 

• Pilot burner lights.

 

 

Recycle call for heat if necessary.

 

 

Insert B

 

 

 

 

 

 

 

 

YES

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Igniter Terminals

 

 

 

 

• Measure voltage between 24V hot and

 

 

 

 

 

 

 

 

24V common leads to valve control.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Must measure at least 19.5 VAC with

NO

• Check transformer and

 

 

 

 

 

 

 

 

igniter powered (see insert A). To

line volt supply.

 

 

 

 

 

YES

 

 

identify proper lead, this check must

 

 

 

 

 

 

 

 

 

be done with the valve control con-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

nected and igniter powered.

 

 

 

 

 

 

 

 

 

 

 

YES

 

 

 

 

 

 

 

 

 

•

Replace Pilot Assembly.

 

 

 

 

 

 

 

 

 

•

Check that pilot flame makes good

 

 

 

 

 

 

 

 

 

 

contact with pilot burner flame rod.

 

 

 

 

 

•

Main valve opens and main

NO

• Check for good electrical connection

 

 

 

 

 

 

burner lights.

 

 

through the pilot tubing.

 

 

 

 

 

 

 

 

 

• If both of the above are good, replace

 

 

 

 

 

 

 

 

 

 

igniter/flame rod assembly.

 

 

 

 

 

 

 

YES

 

 

 

YES

 

 

 

 

 

• System Is okay.

 

• Cycle thermostat off and back on.

 

 

1

Igniter

will cycle off

and

2

When measuring voltage

 

 

 

 

 

 

back on once during the 90

at connections, use care

 

 

 

 

NO

 

 

 

 

 

 

 

 

 

second

ignition trial.

All

 

to ensure terminals are

 

•

Main burner lights.

 

• Replace valve.

 

voltage measurements must

 

not damaged.

 

 

 

 

 

 

 

be taken while the igniter is

 

 

 

 

 

 

 

 

 

powered.

 

 

 

 

 

 

 

 

 

 

13

NOTE: DIAGRAMS & ILLUSTRATIONS NOT TO SCALE.

 

 

 

13

Page 12 Page 14
Page 13
Image 13
Lennox International Inc MPB35ST-NM manual Troubleshooting Procedure Electronic Ignition System
Page 12 Page 14

MPB35ST-NM specifications

Lennox International Inc., a leader in the heating, ventilation, and air conditioning (HVAC) industry, offers the MPB35ST-NM model as part of its comprehensive range of integrated solutions. This finely engineered unit is designed to provide exceptional performance and energy efficiency while ensuring optimum home comfort.

One of the standout features of the Lennox MPB35ST-NM is its modular design, which allows for flexible installation and easy integration with existing systems. This unit is particularly beneficial for residential settings where space may be at a premium. It also supports efficient zoning, enabling tailored climate control for different areas of the home.

The MPB35ST-NM utilizes advanced multi-stage heating technology, which means it can adjust its output to match the specific demands of the environment. This significantly enhances energy efficiency and reduces operational costs. The unit operates with a high Seasonal Energy Efficiency Ratio (SEER) rating, ensuring optimal performance without excessive energy consumption.

Additionally, the MPB35ST-NM is equipped with smart technology features that allow homeowners to monitor and manage their heating system remotely. Through a user-friendly app, users can adjust settings, schedule maintenance reminders, and receive performance alerts, all of which contribute to an improved user experience.

Another key characteristic of the MPB35ST-NM is its quiet operation. The unit is designed with sound-dampening components that minimize noise during operation, ensuring that homeowners can enjoy a peaceful living environment.

Durability is another hallmark of Lennox products, and the MPB35ST-NM is no exception. Constructed with high-quality materials, this unit is built to withstand the rigors of daily use while offering long-lasting reliability. Additionally, Lennox provides robust customer support and warranty options, giving customers peace of mind in their investment.

In summary, the Lennox International Inc. MPB35ST-NM model stands out as a leader in home heating solutions. With its adaptable design, energy-efficient technology, smart features, quiet operation, and dependable durability, it meets the evolving needs of modern households, making it an excellent choice for those seeking comfort and efficiency in their heating systems.
Top Page Image Contents