Self Cleaning Commercial Gas Water Heaters
with Flue Damper and Electronic Ignition
M O D E L S C O V E R E D
SBD71 120 Through SBD85 500
Also includes Parts List
Part Number STC-072
Printed in the U.S.A. - 0106
COMMERCIAL
The Expert’s Choice®
SBD TANK TYPE HEATERS
SERVICE HANDBOOK
SBD
HANDBOOK
TABLE OF CONTENTS
PAGE PAGE
Troubleshooting (continued)
Introduction 1-2 Troubleshooting the Efflkal 28-30
Wire Harness Test 31
Installation 3 IID Module 32
Clearances 4 Pilot Spark 33
Air Requirements 5-8 Pilot Valve 34-35
Contaminated Air 9 Main Burner Test 36
Flammable 9 Flame Rectification 37
Gas Pressure 10 IID Module 38
Gas Valve 11 Main Gas Valve 39-40
Venting 12-15
Sequence of Operation
Mechanical 16 Service Charts and General
Electrical 17-18 Questions and Answers 41-42
Troubleshooting Parts List 43-50
Transformer 19
High Limit 20-21 Component Part Information 51
Damper (on Standby) 22
PC Board 22-23 Service Check List 52-53
Thermostat 24
Effikal Damper 25 Comments 54
Effikal Harness Test 26 Normal Operation 26-27
SBD SERVICE HANDBOOK INTRODUCTION
This service handbook is designed to aid in servicing and troubleshooting State SBD water heaters in the
field. No duplication or reproduction of this book may be made without the express written authorization of
the State Water Heater Company.
The following text and illustrations will provide you with a step by step procedure to verify proper installation,
operation, and troubleshooting procedures. Additional quick reference data is included to assist you in
servicing this product.
The information contained in this handbook is designed to answer common questions encountered in the
operation of the SBD product line and is not meant to be all inclusive. If you are experiencing a problem not
covered in this handbook, please contact the Technical Information Department at 1-800-365-0577 or your
Local State Water Heater Sales Representative for further assistance. This handbook is intended for use by
licensed plumbing professionals and reference should be made to the installation manual accompanying the
product. This handbook contains supplemental information to the SBD installation and operation manual.
This portion of the handbook will review some often overlooked installation considerations,
taking note of necessary installation requirements for the SBD 71120 through SBD 85500
model heaters. The installation manual covers most of these items in detail.
A 24 inch clearance for all serviceable parts is recommended. Clearances may vary
between SBD models – See instruction manual or the label on the heater, for clearances
applicable to your specific model.
"Copyright by the American Gas Association. Used by permission of the copyright holder".
This illustrates the exterior roof clearances for SBD units with natural draft venting. The
vent shall extend at least 3 feet above the highest point where it passes through a roof of
a building, and at least 2 feet higher than any portion of a building within a horizontal
distance of 10 feet (for vents of 12" in diameter or less). (NFPA 54 ANSI Z 223.1 SEC
7.5.2a). (Sec 7.6.2a may allow reduction to 8 feet with a “ Listed vent cap”).
Stoichiometric or theoretical complete combustion requires 10 cubic feet of air per 1000
BTUH input of the gas input. The National Fuel Gas Code also recommends an
additional 2.5 cu.ft. of "excess" air. This 12.5 cu.ft minimum supply air per 1000 BTUH
input applies to natural and propane gas models.
The National Fuel Gas Code also specifies minimum make-up air opening sizes for
various building installations. (Ref: NFPA 54, ANSI Z223.1, sec 5.3)
A fresh supply of make-up air for combustion can be supplied to the heater through makeup air ducts which directly communicate with the out of doors. Two openings are required
- one within 12 inches of the top of the enclosure and one within twelve inches of the
bottom of the enclosure. Each opening shall have a free area of not less than 1 square
inch per 4000 BTUH of the total input of all appliances within the enclosure.
The lower opening is primarily providing combustion air. The upper opening is providing
vent dilution air and acts as a relief opening for flue gases should the vent become
obstructed or a downdraft condition occur. Additionally, when the heater is installed in a
confined space and communicating with the outdoor air, one permanent opening,
commencing within 12 in. (30 cm) of the top of the enclosure, shall be permitted where
the equipment has clearances of at least 1 in. (2.5 cm) from the sides and back and 6 in.
(16 cm) from the front of the appliance. The opening shall directly communicate with the
outdoors and shall communicate through a vertical or horizontal duct to the outdoors or
spaces (crawl or attic) that freely communicate with the outdoors, and shall have a
minimum free area of:
a. 1 sq. in. per 3000 BTU per hr (7 cm
located in the enclosure, and
b. Not less than the sum of the areas of all vent connectors in the confined space.
Often it is more practical to install vertical make-up air ducts to the out doors. Again, two
openings are required - one within 12 inches of the top of the enclosure and one within
twelve inches of the bottom of the enclosure. Each opening shall have a free area of not
less than 1 square inch per 4000 BTUH of the total input of all appliances within the
enclosure.
MAKE-UP AIR
HORIZONTAL DUCTS
When the heater is installed in an interior room with no roof access for vertical ducts,
horizontal make-up air ducts should be installed. When using horizontal ducts, two
openings are required - one within 12 inches of the top of the enclosure and one within
twelve inches of the bottom of the enclosure. Each opening shall have a free area of not
less than 1 square inch per 2000 BTUH of the total input of all appliances within the
enclosure.
Insufficient make-up air is a major cause of combustion problems. One common example
is in a restaurant installation where exhaust vent equipment was not considered in sizing
make-up air requirements. This may result in air being backdrafted by the restaurant
exhaust equipment through the heater causing flue gas spillage, flame roll out, improper
combustion, inconsistent pilot operation, and/or erratic heater shut down.
Along with adequate make-up air, the quality of the air is important. Contaminants in
combustion air can lead to premature heater failure. Vapors from bleaches, soaps,
waxes, salts, etc. are drawn into the combustion chamber with the make-up air and, once
fired, mix with water vapor in the gases to form extremely corrosive hydrochloric or
hydrofluoric acid and other corrosive byproducts.
AIR FOR COMBUSTION
Flammable Items
Flammable items, pressurized containers or any other potentially hazardous articles must
never be placed on or adjacent to the heater. Open containers of flammable material
should not be stored or used in the same room with the heater.
The supply gas pressure is normally measured at the dirt leg or at the gas pressure
tapping on the gas supply shutoff valve. This reading must be measured with 'flowing'
gas.
The manifold gas pressure is measured at the manifold pressure tap of the gas valve
when the gas is flowing.
The gas valves used on all SBD water heaters are
24 volt AC combination step opening gas valves.
They incorporate the pilot valve, main valve, and gas
pressure regulators into one body. The inlet view of
the valve features a filter screen and the top knob.
The top knob is a manual on/off gas control for both
the pilot and main gas valves. When the top knob is
placed on the black mark, gas is supplied only to the
pilot valve.
On the top view, we see the pilot solenoid and
pilot and main gas regulators. The top view also
displays the “TH and “TR” terminals. The pilot
gas regulator is found under its cover screw. It is
factory preset at 3.5” W.C. but can be adjusted from
2.5 to 5 inches water column. The main gas
regulator is found under its cover screw. It is
factory preset to 3.5 inches W.C. and adjusts gas
pressure output from 2.5 to 5 inches water
column. The two electrical terminals are marked
TH and TR. The TH terminal is the common
between the pilot valve solenoid coil and the main
valve solenoid coil. The other wire emerging from
the pilot solenoid connects to the pilot valve
electrical output on the IID (terminal PV). The TR
terminal connects directly to the main valve
electrical output from the IID module
(terminal MV).
On the outlet view of the gas valve, we see the
pilot gas connection port, manifold gas connection
port, a limited bleed vent port, the manifold gas and
pressure tap.
All SBD water heaters are classified by ANSI as category I (non-condensing, negative
pressure venting) appliances. They are approved for type B vent.
For larger applications, SBD water heaters can be common vented together either in a
tapered manifold or constant size manifold. (Follow National Fuel Gas Code
requirements for sizing and installation.)
Combined Vents
When vents are combined, the area of the combined vent should be equal to area of the
largest single vent, plus 50% of area of all others joining.
EXAMPLE: To combine two 6” vents with an
8” vent, the area of a combined vent should be
one half area of two 6 inch vents (14 + 14)
plus area of 8 inch vent (50) or 78 sq. inches.
Referring to chart, 78 sq. inches require 10”
diameter vent.
SBD water heaters can be used with power vent
kits for sidewall venting. State offers power vent
kits for use on installations with a maximum of
100 equivalent feet of vent piping. The power
vent kits also use type B vent materials. When
power venting, specific exterior clearances must
be maintained, as outlined in the National Fuel
Gas Code. (NFPA 54, ANSI A223.1, sec 7.8)
To understand SBD tank type water heaters, an examination of their sequence of
operation is necessary.
When the thermostat calls for heat, the relay in the draft hood assembly activates the
flue damper motor. The damper opens and power flows to the IID (Intermittent
Ignition Device). This activates the IID module to open the pilot valve and begin
sparking at the pilot burner assembly. Once the pilot flame is established and
confirmed back to the IID, the sparking is stopped and the main gas valve is opened,
allowing gas flow to the main burner. When the thermostat satisfies, main and pilot
gas is shut off. Damper is returned to closed position.