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15

201835

OWNER’S MANUAL

TROUBLESHOOTING

 WARNING: Turn off and unplug furnace and let cool before servic-

ing. Unless you need gas supply for testing, shut off equipment shutoff
valve before servicing. Only a qualified service person should service
and repair furnace.

Continued

www.desatech.com

Note:

 For additional help, visit DESA

International’s technical service web site
at 

www.desatech.com

.

Note:

 All troubleshooting items are listed in

order of operation.

OBSERVED PROBLEM

No heat

POSSIBLE CAUSE

1. Thermostat off

2. Gas supply

3. Electrical connections and power
4. Motor

5. Malfunctioning microswitch

6. Gas valve

REMEDY

1. Check to be sure thermostat is calling for heat.

Wire to thermostat could be off terminal

2. Be sure equipment gas valve is in the open posi-

tion (level or parallel to gas line)

3. Be sure all electrical connections are secure
4. Motor must be operating at top speed before

burner will come on. If blower is not operating
at top speed, check voltage supply (minimum
100 volts A.C.). If voltage supply is okay, check
for defective motor

5. Be sure the microswitch is sailing in far enough

to open the solenoid valve and to energize the
ignition control. If the switch is not sailing in,
clean any dust or dirt from the actuator pin. Other
reasons for the switch not sailing in are
A. Insufficient blower speed - Slow motor due to

faulty motor or lint and dust accumulation on
the blower wheels or restriction of return air to
the furnace

B. Faulty microswitch - Replace switch if cir-

cuit to ignition control is not completed when
switch is manually engaged. Switch should
also be replaced if blower motor running at
top speed fails to engage switch within six or
seven seconds. 

Note:

 To service switch, com-

bustion chamber must be pulled out. Follow
steps 1, 2, 3, 9 and 10 on page 8 to remove
combustion chamber

6. Within 20 seconds after motor reaches 75% of

its r.p.m. and microswitch engages, check the
following:

A. Voltage at valve - If current is present but

valve is not opening, check wire connections

B. If wire connections okay - Replace valve
C. No voltage at valve - Check circuit completion

through microswitch and limit switch as well
as wiring and wire connections. If no defects
are found, see Ignition Failures, page 16

Summary of Contents for DynaVent DNV25NB

Page 1: ...operin stallation adjustment alteration service or maintenance can cause injury or property dam age Refertothismanual for correct installation and operational proce dures Forassistanceor additional in...

Page 2: ...gas leak However the odor added to natural gas can fade Natural gasmaybepresenteventhoughnoodorexists Makecertainyoureadandunderstandallwarn ings Keep this manual for reference It is your guidetosafea...

Page 3: ...on and need not be changed for operation up to 2 000 feet elevation For operation at elevations above 2 000 feet manufactured to specified deration condi tions for Canada and the United States UNPACKI...

Page 4: ...re installing thermostat in a wall make sure there are no pipes or wiring in the hollow wallabovethefurnace Thethermostatwires will pass through this wall from the attic Mounting hardware needed to mo...

Page 5: ...000 BTU Hr Model Use a proper sized drill bit Drill holes through wall and into studs at marked locations 40 000 BTU Hr Model Use a proper sized drill bit On wall stud side of opening drill holes thro...

Page 6: ...ng Thermostat to Thermostat Mounting Plate 2 3 4 5 7 1 0 SO LID ST AT E IG NIT IO N 50 60 70 80 90 50 60 70 80 90 OF F 25 000 BTU Hr Models 3 Provide two 18 gauge insulated stranded wires for the ther...

Page 7: ...new black iron or steel pipe Copper tubing may be acceptable in cer tain areas Check local codes Use pipe large enough in diam eter to allow proper gas volume to furnace If pipe is too small undue los...

Page 8: ...lower left rear of furnace cabinet as viewed from rear see Figure 13 Remove knockout plug 9 Slide furnace back into furnace cabi net Make sure exhaust tube gaskets are in place Make sure exhaust and i...

Page 9: ...100 125 150 175 200 3 8 72 49 40 34 30 27 25 23 22 21 18 17 15 14 1 2 132 92 73 63 56 50 46 43 40 38 34 31 28 26 3 4 278 190 152 130 115 105 96 90 84 79 72 64 59 55 1 520 350 285 245 215 195 180 170...

Page 10: ...Locate NPT tap within reach for test gauge hook up NPT tap must be upstream from furnace see Figure 15 Install an equipment shutoff valve in an accessible location The equipment shutoff valve is for...

Page 11: ...net during installa tion You must correctly install furnace within cabinet If not front cover will not properly attach to cabinet Make sure gas kets for intake and exhaust tubes are in place Make sure...

Page 12: ...not try to light the burner by hand 8 Plug in furnace 9 Set thermostat to desired setting If thermostat is set above room tem perature the blower will come on 10 Allow approximately 45 seconds for ign...

Page 13: ...forces the combus tion products out of the exhaust tube s The Combustion air blower is sealed so that air does not pass between it and the circulating room air blower 3 When the blower motor reaches...

Page 14: ...mixture Wipe cabinet and front cover to remove dust Use a vacuum cleaner to remove dust from front cover louvers EXHAUST AND INTAKE VENTS Make sure the exhaust and intake vents are not blocked The in...

Page 15: ...okay check for defective motor 5 Be sure the microswitch is sailing in far enough to open the solenoid valve and to energize the ignition control If the switch is not sailing in clean any dust or dir...

Page 16: ...it WARNINGS Never connect unit or ignition circuit to 230 volts Never operate unit with glo bar touching burner or any other ground Damage to ignition control will occur Be sure sensor probe never to...

Page 17: ...bar broken 2 A Check for voltage 24 volts A C at valve 40 seconds after glo bar begins to glow If voltage present but valve not opening replace valve B If no voltage at valve check brown wire at igni...

Page 18: ...e sure probe is positioned in the burner flame and glowing cherry red Check wire and wire connections at probe and ignition control B If wire and wire connections okay check for voltage across brown a...

Page 19: ...hite Open WIRING DIAGRAMS Figure 21 Wiring Diagram 40 000 BTU Hr Model Figure 20 Wiring Diagram 25 000 BTU Hr Model Note Use only original replacement parts Thiswillprotectyourwarrantycoveragefor part...

Page 20: ...r SC 29687 0013 1 800 845 5301 803 879 3009 cuisales aol com Hughes Supply 1311 S Fern Street Arlington VA 22202 2809 703 416 8555 Tuco Industrial Products 5223 180th St SW Suite 4A 1 Lynwood WA 98037...

Page 21: ...1244 Operating Instructions Decal English 1 191246 Operating Instructions Decal French 1 531010 Warning Decal 1 191262 Nameplate 1 Parts available not shown You must order nameplate and operating inst...

Page 22: ...x 3 8 2 3 191241 Front Cover Trim 1 4 030642 Front Cover Assembly 1 5 100896 Cabinet Assembly 1 6 070511 Cabinet Insulation right and left sides 1 7 120158 Screw 8 x 3 8 2 8 160912 Thermostat include...

Page 23: ...44 Terminal Block 1 10 121224 Screw 10 x 3 4 2 11 070537 Gasket 1 12 231143 Transformer Assembly 1 13 121252 Screw 10 x 3 8 6 14 020983 Combustion Chamber Heat Shield Assembly 1 15 070606 Heat Shield...

Page 24: ...erminals 1 13 070607 Heat Shield Gasket 1 14 020982 Combustion Chamber Heat Shield Assembly 1 15 061663 Wire Clamp 2 16 121252 Screw 10 x 3 8 12 17 230560 Limit Switch 1 KEY PART NO NUMBER DESCRIPTION...

Page 25: ...3 4 5 6 7 8 9 10 11 12 KEY PART NO NUMBER DESCRIPTION QTY 1 120717 Hex Nut 10 24 2 2 121459 Screw 10 24 x 1 2 2 3 010701 Burner Assembly 1 4 180220 Main Burner Orifice 1 5 121388 Screw 10 x 1 2 4 6 07...

Page 26: ...ART NO NUMBER DESCRIPTION QTY 1 120717 Hex Nut 10 24 4 2 010621 Left Burner Assembly 1 3 010623 Right Burner Assembly 1 4 070591 Manifold Gasket 1 5 171167 Manifold Assembly 1 6 180189 Main Burner Ori...

Page 27: ...121388 Screw 10 x 1 2 4 11 070385 Crossover Tube Gasket 2 12 121227 Screw 10 24 x 1 2 2 13 070362 Universal Bushing 1 14 231231 Capacitor Boot 1 15 390296 Combustion Air and Motor Cover Assy Housing 1...

Page 28: ...205 Combustion Air Cover Assy 1 12 121388 Screw 10 x 1 2 3 13 070420 Combustion Air Crossover Gasket 1 14 390318 Combustion Air and Motor Cover Assembly 1 KEY PART NO NUMBER DESCRIPTION QTY 15 121227...

Page 29: ...___________________ _______________________________________________________________________________________________ ____________________________________________________________________________________...

Page 30: ...l be the responsibility of the owner TO THE FULL EXTENT ALLOWED BY THE LAW OF THE JURISDICTION THAT GOVERNS THE SALE OF THE PRODUCT THIS EXPRESS WARRANTY EXCLUDES ANY AND ALL OTHER EXPRESSED WARRANTIE...

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