Bradford White M-2-50T6DS User manual

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Manual 238-47104-00A
SERVICE
MANUAL
Troubleshooting Guide
and Instructions for Service
(To be performed ONLY by
qualified service providers)
Models Covered
by This Manual:
Residential Energy Saver:
M1& M2(HE) UprightModels.
M1& M2 Lowboy Models.
M1& M2 UtilityModels.
M1& M2 Wall HungModels.
Light DutyEnergy Saver:
LD Upright Models.
LD Utility Models.
LD Lowboy.
LD WallHung.
Dairy Barn Deluxe Energy Saver:
DB Models.
RESIDENTIAL ELECTRIC AND LIGHT DUTY
COMMERCIAL ELECTRIC WATER HEATERS
Photo is of
M-2-50T6DS

Table of Contents Page Service Procedure
Introduction ………………………………………………………………………. 2
Tools……………………………………………………………………………… 2
General Information ……………………………………………………………… 3 - - -
Sequence of Operation …………………………………………………………… 6 - - -
Single Element Operation ……………………………………................... 6 - - -
Double Element, Non-Simultaneous, Single Phase………………………. 7 - - -
Double Element, Simultaneous, Single Phase, 4 wire Service …............... 8 - - -
Double Element, Non-Simultaneous, 3 Phase ………................................ 9 - - -
Double Element, Simultaneous, 3 Phase ………………………………… 10 - - -
Double Element, Non-Simultaneous, Single Phase, Off Peak …………... 11 - - -
Troubleshooting …………………………………………………………………. 12 - - -
Line Voltage and High Limit ECO Testing……………………………………… 14 RE-I
Heating Element Testing ……………................................................................... 15 RE-II
Residential Thermostat Testing ……..................................................................... 16 RE-III
Single Element ……………………………............................................... 16
Double Element, 4 wire, Simultaneous, Single Phase …………………... 16
Double Element, Non-Simultaneous, Single Phase ………....................... 17
Double Element, Non-Simultaneous, 3 Phase …………………………... 19
Double Element, Simultaneous, 3 Phase ………………………………... 21
Double Element, Non-Simultaneous, Single Phase, Off Peak ………….. 23
Light Duty Commercial Thermostat Testing …..................................................... 25 RE IV
Double Element, Non-Simultaneous, Single Phase ……………………... 25
Double Element, Simultaneous, Single Phase …………………………... 27
Double Element, Non-Simultaneous, 3 Phase …………………………... 29
Double Element, Simultaneous, 3 Phase ………………………………... 31
Thermostat Removal and Replacement …………………………………………. 33 RE-V
Heating Element Removal and Replacement ……………………………………. 34 RE-VI
Dip Tube and Anode Inspection and Replacement ……………………………… 35 RE-VII
Generic Parts List ………………………………………………………………... 36 - - -
Page 2
This service manual is designed to aid service and maintenance professionals on the function, proper diagnosis and repair of
Bradford White residential electric and light duty commercial electric water heaters.
The text and illustrations in this manual provide step by step instructions to facilitate proper operation and troubleshooting
procedures. Contact the Bradford White Technical Support Group immediately if diagnosis can not be made using the
methods described in this service manual.
Introduction
Residential and Light Duty
Commercial Electric Water Heaters
Tools
- Multi Meter. - Phillips Head Screw Driver.
- 1-½ Deep Well Socket (element removal). - Thermometer.
- ¼" Nut Driver. - Drain Hose.
- Various Hand Tools: Pipe Wrench, Channel Locks, Pliers (common & needle nose), Wire cutters, Wire Strippers,
Flash Light.
2

GENERAL INFORMATION
120 VOLT
Ungrounded
Grounded
(Neutral) Grounding
BLACK
WHITE
GREEN
120 0
120
240 VOLT
Ungrounded Ungrounded Grounding
BLACK RED GREEN
240 120
120
120
ABCNeutral
RED BLACK RED
120
120 208
208 208
208 3Ph
277
ABCNeutral
RED BLACK RED
277
277 480
480 480
480 3Ph/277 1 Ph
120
ABCNeutral
RED BLACK RED
120
120 240
240 240
240 3Ph
Common Service Wire Configurations
Amps = Watts (for single phase units) Example 4500W/240V = 18.75A
Volts
Amps = Watts (for balanced 3 phase units) Example 4500W/240V x 1.732 = 10.82A
Volts x 1.732
Watts = Amps x Volts Example 18.75A x 240V = 4500W
Ohms = Volts Example (240V) / 4500W = 12.8 Ohms
Watts
22
Commonly Used Formulas
Page 3
3

GENERAL INFORMATION
Wattage Limitations at Various Voltages
Residential Electric Upright M1 & M2 Series (Non-Simultaneous operation)
Maximum
Wattage
Element
Upper/Lower
Voltage
3,000 0
21000,3/000,3
6,000 6,000/6,000 208, 240
6,000 277, 480
Residential Electric Upright M1 & M2 Series (Simultaneous Operation)
Maximum
Wattage
Element
Upper/Lower
Voltage
3,000 021005,1/005,1
10,000 802000,5/000,5
11,000 042005,5/005,5
12,000 6,000/6,000 277, 480
6,000/6,000
Residential High Efficiency Upright M2HE Series (Simultaneous Operation)
Light Duty Commercial Electric LD Series (Simultaneous Operation)
Residential Electric Lowboy M1 & M2 Series (Non-Simultaneous Operation)
Maximum
Wattage
Single
Element
Voltage
3,000 021000,3
6,000 042,802000,6
6,000 772000,6
6,000 084000,6
Residential Electric Utility Series (Single Element Operation)
Light Duty Utility Series (Single Element Operation)
Dairy Barn Deluxe DB Series (Non-Simultaneous Operation)
Dairy Barn Deluxe DB Series (Simultaneous Operation)
Residential High Efficiency Upright M2HE Series (Non-Simultaneous operation)
Residential Electric Lowboy M1 & M2 Series (Simultaneous Operation)
Page 4
Light Duty Commercial Electric LD Series (Non-Simultaneous Operation)
4

GENERAL INFORMATION
Surface Mount
Combination Thermostat/
ECO (high limit)
89T Series
Manual
ECO (high limit)
Reset button
Temperature
control Dial
Temperature
control Dial
Surface Mount
Thermostat
59T Series
Surface Mount
Combination Thermostat/
ECO (high limit)
89T Series
Surface Mounted Thermostats
Surface mounted thermostats are mounted into a bracket which holds the thermostat against the side of the tank.
Surface mounted thermostats respond to tank surface temperatures to sense a call for heat, set point temperature
settings and high limit (ECO) activation. It is import that the entire back surface of the thermostat is in full contact or flush
with the tank. Improperly mounted thermostat will lead to improper heater operation.
1-½ Hex
Screw-in Flange
Terminal Block
Screw
Terminal Block
Zinc Plated Copper or
Incoloy Sheath
Element Rating Ink Stamped
on side of Terminal Block.
Direct Immersion “Screw-in” Type Heating Element
Page 5
5

SEQUENCE OF OPERATION
Residential and light duty commercial electric water heaters are designed to operate using several different operating
modes. The common modes and sequence of operation are as follows:
1.Single Element Operation.
2.Double Element Non-Simultaneous Operation (single phase).
3.Double Element Non-Simultaneous Operation (3 phase).
4. Double Element Simultaneous Operation (single phase).
5. Double Element Simultaneous Operation (3 phase).
Sequence of Operation- Single Element Operation.
Line voltage is applied across terminals
L1 &L3 of the thermostat. ECO is
closed, so there is voltage at terminal L4
and to one side of the element.
1
2
When the thermostat is satisfied, it opens at
terminal T2 interrupting current flow through the
element. System is now in stand-by mode, waiting
for the next call for heat.
3
1
ECO
Closed
2
Thermostat closed
at terminal T2
3
Thermostat opens
at terminal T2
Tank is cold therefore thermostat
is closed at terminal T2 (calling for heat).
This completes the circuit and allows
current to flow through the element.
Page 6
6

Non-Simultaneous and Simultaneous Operation
Double element electric water heaters are designed to operate in a Non-Simultaneous or Simultaneous mode.
Non-Simultaneous Mode: Allows only one heating element to operate at a time. For example, when the tank is cold,
the upper element is energized first, heating the top of the tank. Only when the upper thermostat is satisfied, the upper
element is de-energized and power is directed to the lower thermostat, energizing the lower element and heating the
bottom portion of the tank until the lower thermostat is satisfied. As hot water is drawn off the tank, it is replaced with
cold water delivered through the dip tube to the bottom of the tank. The bottom of the tank cools, the lower thermostat
will call for heat energizing the lower element. If enough hot water is drawn from the tank, the top portion of the tank
cools and the upper thermostat will call for heat, de-energizing the lower element and allowing only the top element to
energize until the upper thermostat is satisfied.
Simultaneous mode: allows both heating elements to operate at the same time. That is, if either thermostat (upper or
lower) is calling for heat, the corresponding heating element is energized independent of the other.
SEQUENCE OF OPERATION
Sequence of Operation- Double Element, Non-Simultaneous Operation, Single Phase.
Line voltage is applied across terminals
L1 & L3 of the upper thermostat. ECO is
closed, so there is voltage at terminal L4
and to one side of the upper and lower
elements.
Tank is cold therefore both thermostats
are closed at terminal T2 & 2 (calling for heat). The
circuit is complete through the upper thermostat
only, allowing current to flow through upper
element.
1
2
1 2
ECO
Closed Thermostat closed
at terminal T2
When upper thermostat is satisfied, it opens at
terminal T2 interrupting current flow through upper
element, and closes at terminal T4 allowing voltage
to pass to terminal 1 of lower thermostat. This
completes the circuit through the lower thermostat
and allows current flow through lower element.
3
3
Thermostat closed
at terminal T4
4
Thermostat open
between terminals
1and 2
Upper
T’stat
Upper
Element
Upper
T’stat
Upper
Element
Lower
T’stat
Lower
Element
Lower
T’stat
Lower
Element
When the lower thermostat is satisfied, it opens at
terminal 2 interrupting current flow through lower
element. The system is now in stand-by mode
waiting for the next call for heat
4
The lower thermostat/element
combination will generally
cycle on and off more often
then the upper. In some cases,
such as a cold tank or in high
demand periods, the upper
thermostat will call for heat
(opening at terminal
T4 and closing at
terminal T2) prior to the lower
thermostat being satisfied. This
will interrupt current flow
through the lower thermostat
and element and allow current
to flow through the upper
element only. When the upper
thermostat is satisfied, it
resumes operation as
described in sequence #3
above.
5
5
Thermostat closed
between terminals
1and 2
Upper
T’stat
Upper
Element
Low er
T’stat
Lower
Element
Upper
T’stat
Upper
Element
Lower
T’stat
Lower
Element
Upper
T’stat
Upper
Element
Low er
T’stat
Low er
Element
Thermostat closed
atterminal 2
Thermostat closed
at terminal T2
Page 7
7

SEQUENCE OF OPERATION
Sequence of Operation- Double Element, Simultaneous Operation, Single Phase, 4 wire service installation.
A4wire, double element heater wired for simultaneous operation is essentially two single element systems operating
independently. The heaters are wired internally with two independent circuits, one circuit for each thermostat/element
combination. When installed using a two wire service, the blue and red (or white) wires will be connected together,
likewise black and yellow wires will be connected together.
Line voltage from circuit one is applied
across terminals L1 & L3 of the lower
thermostat. Likewise, line voltage from
circuit two is applied across terminals L1 &
L3 of the upper thermostat. ECO in both
upper and lower thermostat is closed, so
there is voltage at terminal L4 of each
thermostat and to one side of the upper and
lower elements.
Tank is cold therefore both thermostats
are closed at terminal T2 (calling for heat).
This completes the circuit through the
thermostats and allows current to flow
through the elements.
1
2
Circuit one
Circuit two
1
ECO
Closed
ECO
Closed
Circuit one
Circuit two
2
Thermostat closed
atterminal T2
Thermostat closed
at terminal T2
When either thermostat is satisfied, it will
open at terminal T2, interrupting current
flow through the corresponding element. As
both thermostats satisfy, the system will be
in stand-by mode waiting for the next call
for heat. Thermostats will operate
independent of the other.
3Circuit one
Circuit two
3
Thermostat open
at terminal T2
Thermostat open
at terminal T2
Page 8
8

SEQUENCE OF OPERATION
Sequence of Operation- Double Element, Non-Simultaneous Operation, 3 Phase.
Line voltage is applied across terminals L1
&L3 of upper thermostat. Likewise, Line
voltage is applied to terminal L3 of lower
thermostat. ECO in both upper & lower
thermostat is closed, so there is voltage at
terminal L4 of both thermostats and to one
side of both upper & lower elements.
Tank is cold therefore both thermostats
are closed at terminal T2 (calling for heat).
The circuit is complete through the upper
thermostat only allowing current to flow
through the upper element.
1
2
When the upper thermostat is satisfied, it
opens at terminal T2 interrupting current
flow through upper element, and closes at
terminal T4 allowing voltage to pass to
terminal L1 of lower thermostat. This
completes the circuit through the lower
thermostat allowing current flow through
lower element.
When the lower thermostat is satisfied, it
opens at terminal T2 interrupting the
current flow through the lower element. The
system is now in stand-by mode waiting for
the next call for heat.
3
4
The lower thermostat/element combination
will generally cycle on and off more often
then the upper. In some cases, such as a
cold tank or in high demand periods, the
upper thermostat will call for heat (opening
at terminal T4 and closing at terminal T2)
prior to the lower thermostat being satisfied.
This will interrupt current flow through the
lower thermostat and element and allow
current to flow through the upper element
only. When the upper thermostat is
satisfied, it resumes operation as described
in sequence #3 above.
5
ECO
Closed
1 2
Thermostat closed
at terminal T2
Thermostat closed
at terminal T2
3
Thermostat closed
at terminal T4
Thermostat closed
at terminal T2
4
Thermostat closed
at terminal T4
Thermostat open
at terminal T2
5
Thermostat closed
at terminal T2
Thermostat closed
at terminal T2
ECO
Closed
Page 9
9

SEQUENCE OF OPERATION
Line voltage is applied across terminals L1
&L3 of upper thermostat. Line voltage also
extends to terminal L1 of lower thermostat.
Also, line voltage is applied to terminal L3
of lower thermostat. ECO in both upper &
lower thermostat is closed, so there is
voltage at terminal L4 of both thermostats
and to one side of both upper & lower
elements.
Tank is cold therefore both thermostats
are closed at terminal T2 (calling for heat).
This completes the circuit through the
thermostats and allows current to flow
through the elements.
1
2
Sequence of Operation- Double Element, Simultaneous Operation, 3 Phase.
When either thermostat is satisfied, it will
open at terminal T2, interrupting current
flow through the corresponding element. As
both thermostats satisfy, the system will be
in stand-by mode waiting for the next call
for heat. Thermostats will operate
independent of the other.
3
Thermostat closed
at terminal T2
ECO
Closed
ECO
Closed Thermostat closed
at terminal T2
12
3
Thermostat open
at terminal T2
Thermostat open
at terminal T2
Page 10
10