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Boss
Gas Water Heater

Model # 5-40-NKRT8-2 Official Boss gas water heater

Here are the diagrams and repair parts for Official Boss 5-40-NKRT8-2 gas water heater, as well as links to manuals and error code tables, if available.

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  • In the search box below, enter all or part of the part number or the part’s name.

Not all parts are shown on the diagrams—those parts are labeled NI, for “not illustrated”.

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Error Codes

Model diagram and schematic

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ALL PARTS
Showing 10 of 27 parts  |
Water Heater Manifold Inner Door 9000281
#18

Round gas diagram

Water heater manifold inner door

Part #9000281

$17.69 | 
10% OFF Phone Price : $19.69
In Stock
Pilot 9000284
#15

Round gas diagram

Pilot

Part #9000284

Replaced by #100109070

?
Manufacturer substitution
This part replaces 9000284. Substitute parts can look different from the original.
$47.78
In Stock
Thermostat 9000249
#9

Round gas diagram

Thermostat

Part #9000249

The manufacturer no longer makes this part, and there's no substitute part

Water Heater Thermocouple 9000283
#14

Round gas diagram

Water heater thermocouple

Part #9000283

The manufacturer no longer makes this part, and there's no substitute part

Water Heater Pilot Tube Assembly (replaces Std317025, Std317255) 9000278
#13

Round gas diagram

Water heater pilot tube assembly (replaces std317025, std317255)

Part #9000278

Replaced by #100108370

?
Manufacturer substitution
This part replaces 9000278. Substitute parts can look different from the original.
$36.67
In Stock
Drain Pan 9000743
#26B

Round gas diagram

Drain pan

Part #9000743

The manufacturer no longer makes this part, and there's no substitute part

Dip Tube 9000908
#5

Round gas diagram

Dip tube

Part #9000908

Replaced by #100108608

?
Manufacturer substitution
This part replaces 9000908. Substitute parts can look different from the original.
$27.78
In Stock
Annode Rod 9000279
#21

Round gas diagram

Annode rod

Part #9000279

Replaced by #100108571

?
Manufacturer substitution
This part replaces 9000279. Substitute parts can look different from the original.
$90.00
In Stock
Heater Stand 9001422
#27A

Round gas diagram

Heater stand

Part #9001422

Replaced by #9005744005

?
Manufacturer substitution
This part replaces 9001422. Substitute parts can look different from the original.
$115.49
In Stock
Rexel Pan Base 9001609
#26A

Round gas diagram

Rexel pan base

Part #9001609

Replaced by #100108616

?
Manufacturer substitution
This part replaces 9001609. Substitute parts can look different from the original.
$64.44
In Stock

Most common symptoms to help you fix your water heaters

Choose a symptom to see related water heater repairs.

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Why isn't my water heater heating my water?

Main causes: lack of power, no gas supply, thermostat limit switch tripped, bad element, bad thermostat, gas valve failu…

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Why isn't my water heater making the water hot enough?

Main causes: thermostats need adjustment, water heater capacity too low, bad heating element, thermostat failure, excess…

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Why is there water in my water heater's drain pan?

Main causes: loose water pipe fittings, leaky drain valve, bad temperature-pressure relief valve, leaky heating element,…

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Why does my hot water smell like rotten eggs?

Main causes: water supply needs chlorine treatment, anode rod too reactive…

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Why isn't my water heater making enough hot water?

Main causes: broken heating element, thermostat failure, excessive tank sediment, tank size too small, burner valve asse…

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Why is my water heater making the water too hot?

Main causes: thermostat temperature set too high, thermostats need adjustment, faulty thermostat, shorted heating elemen…

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Why is my water heater's pressure relief valve dripping water?

Main causes: faulty pressure relief valve, water is overheating…

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Effective articles & videos to help repair your water heaters

Use the advice and tips in these articles and videos to get the most out of your water heater.

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Wiring schematic symbols explained video

Wiring schematic symbols explained video

Learn some of the most common symbols found in a wiring diagram and what they mean.…

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Using a wiring schematic to trace a current video

Using a wiring schematic to trace a current video

Find out what’s wrong with your appliance by following a circuit.…

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Easy DIY water heater repairs

Easy DIY water heater repairs

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