LAARS NeoTherm NTV (Sizes 399-850 MBTU/h) - Service Manual - Manual (Page 7)

Service Manual - NeoTherm 500
Table of Contents
Section A - Troubleshooting - Start Here
Sect. Title ................................................................................Page
A1
Troubleshooting - Start Here ............................................... 1
A2 Unit Will Not Fire - Blower is Not Running ........................... 2
A3 Blower Runs Continuously, No Display ............................... 4
A4 Control Unit is in “Standby” Mode ........................................ 5
A5 Changing Control Settings, Change Not Complete -
Unit with Original (White) User Interface ............................. 7
A6 Unit is Running, But Building is Still Cold ............................ 8
A7 Control Unit Says “Run”, But Boiler is Not Firing ................. 9
A8 Open Safety Chain - Fault #63 ........................................... 9
A9 Unit Runs in High or Low Fire Only -
Unit with Current User Interface ........................................ 10
A10 Unit is Noisy ....................................................................... 10
Section B - Troubleshooting Procedures
Sect. Title
Page
B1 Quick Check of Components in the
Safety Chain ...................................................................... 11
B2 Troubleshooting the 24V AC Power Supply ...................... 15
B3 Checking the Safety Interlocks .......................................... 16
B4 Checking the Low Water Cutoff Switch ............................. 18
B5 Controller for Low Water Cutoff ......................................... 19
B6 Removing and Replacing the
Low Water Cutoff Switch ................................................... 20
B7 High Water Temperature Limit Switch ............................... 22
B8 Checking the Flow Switch ................................................. 22
B9 Testing the Flow Switch ..................................................... 23
B10 Removing and Replacing the Flow Switch ........................ 24
B11 Removing and Replacing the Gas Valve ........................... 26
B12 Checking the High Gas Pressure Switch ........................... 29
B13 Checking the Low Gas Pressure Switch ........................... 30
B14 Testing the Low Gas Pressure Switch ............................... 31
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