background image

 

13 

Trouble shooting: 

There are three factors to operate the gas burner properly: 

1.  Electricity {(main Power 120V/60 Hz /1 Ph)( secondary 24V)} 

2.  Gas flow (Incoming pressure should be 10” w.c. with proper gas line without pressure drop 

during burner operation). 

3.  Combustion air. 

Check these three items properly before proceeding in detail for other problems. 

 

Condition 

Solutions 

1.  Burner motor runs and: 

 

No flame after pre-purge & no fuel indicator (where 

applicable) 

Check 24V feed to airflow switch & after airflow 

switch to control.  Fix or replace the airflow switch.  

If there is no secondary power, then replace the 

24Vtransformer. 

No flame, fuel indicator on (where applicable), 

faulty ignition transformer or spark separately 

Check ignition transformer, electrode, cracked 

electrode or gap.  Fix or replace. 

Fenwal control defective after above tests. 

Replace 

2.  Burner locks out after 4 seconds 

 

 

First, check ionization electrode, ionization cable 

(for cracks) and boot.  Fix as needed. 

Polarity reversed 

Check power feed for broken polarity 

Bad earth grounding 

Fix the ground wire 

Gas pressure is too low 

Check the gas pressure and adjust to proper pressure 

3.  Pulsation at start 

 

 

First, check the burner head location with respect to 

the end of the flame tube.  Adjust as necessary. 

Gas pressure is too high. 

Use manometer and readjust the pressures. 

Blocked Flue 

Check draft and clear flue of foreign materials. 

4.  Pulsation during operation 

 

Burner is not correctly adjusted. 

Readjust with combustion analyzer. 

The burner is dirty. 

Clean the burner. 

Defective chimney 

Check and change if necessary with liners. 

5.  Burner locks out 

 

Ionization current is too low. 

Check current.  Minimum 0.8 micro amps. Check 

position of ionization electrode and the condition of 

the cable. 

6.  The CO content is too high 

 

Excess air is too high or too low. 

Adjust air shutter. 

The gas holes are clogged. 

Clean them. 

The fresh air intakes are too small. 

Check and readjust. 

The burner head is out of position. 

Check and readjust. 

7.  Condensation in the heat exchanger 

 

Firing Rate is too low. 

Increase the firing rate so that the stack temperature 

is 350

o

 F or HIGHER.  Insulate the chimney. 

 

 

Summary of Contents for SU-2A

Page 1: ...all the fire department A qualified installer service agency or the gas supplier must perform installation and service All installations must be made in accordance with all state and local codes which may differ from instructions in this manual The installer should inform and demonstrate to the user the correct operation and maintenance of the appliance The installer shall also inform the user of ...

Page 2: ...O2 or CO2 by the dial located on top of the burner housing which allows the air to flow more or flow less within the burner Two electrodes act as a sparker and a flame rod See Fig 1 Flame rectification by this flame rod monitors the continued presence of the burner flame With three trials for ignition consistency with Fenwal control trouble free safe operation is achieved Warning Should overheatin...

Page 3: ...oper operation of the burner AIR FOR COMBUSTION If the boiler or furnace room is unusually tight or if the house has a ventilation fan it is recommended that the combustion air be supplied to the furnace room through intakes from the outside of the building The intakes must terminate facing down in order to avoid obstruction from rain snow leaves etc Openings must have one square inch of free area...

Page 4: ...s such as tree limbs other buildings etc which may cause a down draft The chimney should be lined as required by the local Gas Company or local codes Some utilities require new chimney liners for all gas installations Use a corrosion resistant chimney liner approved for gas service of the same size as the vent pipe Fig 2 Chimney and Fresh Air Dimensions ...

Page 5: ...stalled is a conversion burner use a prefabricated chamber or build a firing chamber that can withstand 2000o F See Chart 2 on page 3 Measure the boiler or furnace mounting plate to determine the flame tube insertion required Deduct from the total length and tighten the flange on the flame tube with the deducted insertion depth The deduction will prevent the tip of the flame tube from burning off ...

Page 6: ...e blast tube into the boiler to the proper depth and tighten the two setscrews using a 4 mm allen key Seal off any free openings with either high temperature cement or high temperature silicone Picture 2 BODY FLANGE picture to the left First install the gasket and boiler flange to the boiler For heat exchangers with a diamond stud pattern one allen screw on the flange should be on the top slightly...

Page 7: ...tate codes 3 A gas union 4 A drip pipe Caution The gas valve should not be subjected to more than PSIG Therefore the burner should be isolated during high pressure gas leak tests The appliance and its individual shut off valve must be disconnected from the gas supply piping system during any pressure testing of that system at test pressures in excess of psig The appliance must be isolated from the...

Page 8: ...t 3 5 W C for Nat Gas BTU Manifold Pressure at 2 3 W C for L P BTU Approximate Head Setting Approximate Air Setting 5 32 0 156 50 000 50 000 21 0 3 16 0 188 80 000 80 000 18 2 7 32 0 219 90 000 90 000 12 6 15 64 0 234 122 000 122 000 18 14 9 32 0 281 146 000 146 000 14 11 19 64 0 297 160 000 160 000 10 10 27 64 0 422 200 000 200 000 3 15 1 2 no orifice 250 000 250 000 1 20 Assumes 0 to 0 02 Draft ...

Page 9: ... carrying lines do not power this Sometimes T T terminals are jumped with a wire nut for burners not set for post purge 3 Burner motor starts and pre purge begins 4 Burner housing pressurizes and proves air flow contacts closed Note if the contacts are closed before the motor starts blower motor runs continuously Diagnostic light flashes once every 3 seconds 5 At the end of pre purge ignition spar...

Page 10: ...e spark is energized for 4 seconds At the same time the 24 Volt transformer powers the gas valve allowing the fuel to flow 5 Within 4 seconds the flame should be established and proved The spark will shut off and the control will hold power to the gas valve until the limits open and the burner stops firing 6 If the flame is not established the blower motor continuously runs 7 To restart power shou...

Page 11: ...ms install manometers before and after the gas valve Keep the observation port of the boiler or furnace open Follow the instructions on the nameplate of the burner to turn it on Follow the sequence of operations for the control see pages 9 and 10 Use a combustion analyzer and record the readings below BURNER OPERATION Record the Readings at Steady State Draft over fire at steady state should be 0 ...

Page 12: ... compensate for backpressure in the combustion area up to 0 3 W C Caution If this is the case the flange and the combustion chamber should be completely sealed This pressure firing decreases as the firing rate increases See Graph 1 Note the burner should be adjusted while it is firing Graph 1 Chamber Pressure versus Firing Rate BTU 0 00 0 05 0 10 0 15 0 20 0 25 0 30 0 35 50 000 100 000 150 000 200...

Page 13: ...Polarity reversed Check power feed for broken polarity Bad earth grounding Fix the ground wire Gas pressure is too low Check the gas pressure and adjust to proper pressure 3 Pulsation at start First check the burner head location with respect to the end of the flame tube Adjust as necessary Gas pressure is too high Use manometer and readjust the pressures Blocked Flue Check draft and clear flue of...

Page 14: ...Blower motor D82132 20 Plastic Cover Plate 11850001 8 Shielding Plate Housing 21 Screw Long Special 11750702 9 Outside Air Boot 11859107 22 Airflow Switch Honeywell Tridelta 6041A 9A Silencer 11879302 23 Ignition Electrode 115 34708 10 Air Regulation Plate 11851001 24 Flame Rod 115 34707 11 Air Damper 11852201 25 Retention head 119 39701 12 Air Regulation Adjustment screw 11848501 26 Union 1139101...

Page 15: ...e user should do periodic visual checks of the burner and the flame 3 Laundry lint or dog and or cat hairs should not go inside the blower If they are seen they should be removed after disconnecting the power to the burner and cover parts should be installed before starting the burner 4 Keep the area around the conversion burner clear and free from combustible materials gasoline and other flammabl...

Page 16: ...16 ...

Reviews: