Xylem McDonnell & Miller 51 Series User manual

INSTRUCTION MANUAL
MM-315H
210424
• Before using this product read and understand instructions.
• Save these instructions for future reference.
• Allworkmustbeperformedbyqualiedpersonneltrainedintheproperapplication, 
 installation,andmaintenanceofplumbing,steam,andelectricaland/orsystemsin  
accordance with all applicable codes and ordinances.
• Topreventseriousburns,theboilermustbecooledto80°F(27°C)andthepressuremustbe
 0psi(0bar)beforeservicing.
• Topreventelectricalshock,turnofftheelectricalpowerbeforemakingelectrical  
connections.
• This low water cut-off must be installed in series with all other limit and operating controls
 installedontheboiler.Afterinstallation,checkforproperoperationofallofthelimitand 
 operatingcontrols,beforeleavingthesite.
• Werecommendthatsecondary(redundant)LowWaterCut-Offcontrolsbeinstalledonall 
 steamboilerswithheatinputgreaterthan400,000BTU/houroroperatingabove15psi 
of steam pressure. At least two controls should be connected in series with the burner control
circuit to provide safety redundancy protection should the boiler experience a low water
 condition.Moreover,ateachannualoutage,thelowwatercut-offsshouldbe  
 dismantled,inspected,cleaned,andcheckedforpropercalibrationandperformance.
• Boiler manufacturer schematics should always be followed. In the event that the boiler
 manufacturer’sschematicdoesnotexist,orisnotavailablefromtheboilermanufacturer,refer
to the schematics provided in this document.
• Topreventare,donotusethislowwatercut-offtoswitchcurrentsover10.2A,1/2HPat 
 120VACor5.1A,1/2HPat240VAC,unlessastarterorrelayisusedinconjunctionwithit.
• ThisproductcanexposeyoutochemicalsincludingLeadandHexavalentChromiun,whichare
 knowntotheStateofCaliforniatocausecancerandbirthdefectsorotherreproductiveharm.
 Formoreinformationgoto:www.P65Warnings.ca.gov.

2
Determine which situation applies:
a. For models 51-2, 51-S-2 or 53-2 on steam boilers:
Always set the control to shut off the burner while
there is water visible in the gauge glass. This applies
when the gauge glass is directly mounted in the boiler
or on a water column.
b. For models 51, 51-S or 53 on steam boilers:
Set the line on the casting 31/8" below the boiler
manufacturer’s normal water level.
c. For all models on steam process boilers when no
condensate is returned to the boiler: Set the line
on the casting 11/8" below the boiler manufacturer’s
normal water level.
Models 51 / 51-2, Models 51-S / 51-S-2 and Models 53 / 53-2 –
For Steam Boilers with 1” (25mm) Equalizing Lines
INSTALLATION –
TOOLS NEEDED:
One (1) flathead screwdriver and two (2) pipe wrenches.
STEP 1 - Determine the Location of the Feeder and/or Low Water Cut-Off
Operating Levels of 51/51-2,
51-S/51-S-2 or 53/53-2
Drip tight valve off – 11/8"
Casting line – 0”
Burner on – 1/8" (± 1/4")
Burner off – 7/8" (± 1/4")
Series 51 and 53 Operating Level
Valve Off -11/8"
Casting Line - 0"
Burner On - 1/8" (±1/4")
Burner Off - 7/8" (±1/4")
Casting
Line
Failure to follow this warning could cause property damage, personal injury or death.
California Proposition 65 warning! This product contains chemicals known to the
•state of California to cause cancer and birth defects or other reproductive harm.
Previous controls should never be installed on a new system. Always install new
•controls on a new boiler or system.
CAUTION:
A more frequent replacement interval may be necessary based on the condition of
the unit at time of inspection. McDonnell & Miller's warranty is one (1) year from date
of installation or two (2) years from the date of manufacture.
•

a. Using the criteria in Step 1,
determine the location of the
51/51-2, 51-S/51-S-2 or 53/53-2.
This applies when the gauge
glass is directly mounted in the
boiler or on a water column.
b. Use Figure 1 or Figure 2 as a
general guide.
c. Connect steam equalizing lines
to any available opening other
than steam flow line.
(Take off line).
d. Test the Model 51/51-2, 51-S/51-S-2 and 53/53-2 Before Turning it Over to the Owner
Open the blow-down valve while burner is operating. As the water level drops the feeder will begin to
add water. As the water continues to drop the burner will shut off (on the 51-2, 51-S-2 and 53-2 only).
STEP 2 - Installation of the Models 51/51-2, 51-S/51-S-2 and 53/53-2
3
Lower
Gauge
Glass Connect to Return
Header on Boiler
Side of all Valves
1" Crosses
Gauge Glass
Level
Mark
1" Steam Equalizing Line
(Short as Possible)
1" Minimum Blow-down
Valve for Feeder
Float Chamber
1" Water
Equalizing Line
(Short as Possible)
Cold City Supply
Normal Water Line
Swing Check Valve
By-Pass
Feeder Casting Mark
(See Installation Location)
1" Crosses
Level
Mark
Water
Column
1" Steam Equalizing Line (Short as Possible)
1" Minimum Blow-down Valve
for Feeder Float Chamber
Normal Water Line
Feeder Casting Mark
(See Installation Location)
Connect to Return
Header on Boiler
Side of all Valves
Swing Check Valve
Cold City Supply
By-Pass
1" Water Equalizing Line (Short as Possible)
1" Minimum Blow-down Valve
Figure 1
Gauge Glass Mounted in the Boiler
Figure 2
Gauge Glass Mounted on a Water Column

4
Strainer
Basket
Assembly
Swing Check Valve
By-pass
Hand By-Pass Valve
Connect to return
header on boiler
side of all valves
City Water
Supply
Supply To
Feeder
CAUTION
Before turning
on city water
pressure be
sure to open
this valve
a. Follow the drawing to the right for piping the
valve to boiler and city water supply. When
piping the valve remember to leave room for
servicing the valve.
Models 51 / 51-2, Models 51-S / 51-S-2 and Models 53 / 53-2
For Steam or Hot Water Boilers
INSTRUCTIONS FOR PIPING THE WATER FEEDER VALVE
TOOLS NEEDED:
Two (2) pipe wrenches.
STEP 1 - Piping the Valve on Models 51/51-2
Swing Check Valve
By-pass
Hand By-Pass
Valve
Connect to return
header on boiler
side of all valves
CAUTION
Before turning
on city water
pressure be
sure to open
this valve
City Water
Supply
Supply
Valve
Strainer
Basket
Assembly
a. Follow the drawing to the right for piping the
valve to the boiler and city water supply.
When piping the valve remember to leave
room for servicing the valve.
STEP 2 - Piping the Valve on Models 51-S/51-S-2, 53/53-2

5
Models 51-2, 51-S-2 and 53-2
ELECTRICAL WIRING
TOOLS NEEDED:
One (1) flathead screwdriver.
Conduit opening facing
toward float chamber
Conduit opening facing
away from float chamber
Manual reset button
on No. 2m Switch
a. The No. 2 switch can be positioned with the
conduit opening facing toward or away from
the float chamber. These are the only positions
in which the switch will function properly.
See drawing at right.
b. On initial fill-up, push the 2M manual reset
button after the proper water level is reached
to energize the burner. If a low water condition
occurs and the water level has been restored,
push the reset button to energize the burner.
c. Follow the wiring diagrams below to wire the
No. 2 Switch. Terminals C and NC are the low
water cut-off switch. Terminals C and NO are
alarm switch. If the electrical load exceeds the
rating of the switch, use an auxiliary relay or
motor starter.
USED AS A MAIN LINE SWITCH
AND/OR LOW WATER ALARM
USED AS A PILOT SWITCH TO COIL
OF RELAY OR MOTOR STARTER
N. O.
N.C.
C.
N. O.
N.C.
C.
Neutral
120 V.A.C.
Supply Hot Low
Water
Alarm
Burner
Circuit
Line
Load
SCHEMATIC OF SWITCH OPERATION
Water Level Normal
Burner On
Alarm Off
Low
Water
Alarm
Terminals
Low Water
Cut-Off
Terminals
C.
N.O.
N.C.
Water Level Low
Burner Off
Alarm On
C.
N.O.
N.C.
N. O.
N.C.
C.
• To prevent electrical shock, turn off the electrical power before making electrical connections.
• This low water cut-off must be installed in series with all other limit and operating controls installed on the
boiler. After installation, check for proper operation of all of the limit and operating controls, before leaving
the site.
Failure to follow this warning could cause electrical shock, an explosion and/or a fire, which could result in
property damage, personal injury or death.
!
WARNING

Xylem Inc.
8200 N. Austin Avenue
Morton Grove, Illinois 60053
Phone: [phone]
Fax: [phone]
www.xylem.com/mcdonnellmiller
McDonnell & Miller is a trademark of Xylem Inc. or one of its subsidiaries.
© 2019Xylem Inc. MM-315HMarch 2019Part No. 210424
COMMERCIAL WARRANTY
Warranty. For goods sold to commercial buyers, Seller warrants the goods sold to Buyer hereunder (with the exception of membranes, seals, gaskets, elastomer
materials, coatings and other “wear parts” or consumables all of which are not warranted except as otherwise provided in the quotation or sales form) will be (i) be built in
accordance with the specications referred to in the quotation or sales form, if such specications are expressly made a part of this Agreement, and (ii) free from defects
in material and workmanship for a period of one (1) year from the date of installation or two (2) years from the date of manufacture, whichever shall occur rst, unless a
longer period is specied in the product documentation (the “Warranty”).
Except as otherwise required by law, Seller shall, at its option and at no cost to Buyer, either repair or replace any product which fails to conform with the Warranty
provided Buyer gives written notice to Seller of any defects in material or workmanship within ten (10) days of the date when any defects or non-conformance are rst
manifest. Under either repair or replacement option, Seller shall not be obligated to remove or pay for the removal of the defective product or install or pay for the
installation of the replaced or repaired product and Buyer shall be responsible for all other costs, including, but not limited to, service costs, shipping fees and expenses.
Seller shall have sole discretion as to the method or means of repair or replacement. Buyer’s failure to comply with Seller’s repair or replacement directions shall
terminate Seller’s obligations under this Warranty and render the Warranty void. Any parts repaired or replaced under the Warranty are warranted only for the balance
of the warranty period on the parts that were repaired or replaced. Seller shall have no warranty obligations to Buyer with respect to any product or parts of a product
that have been: (a) repaired by third parties other than Seller or without Seller’s written approval; (b) subject to misuse, misapplication, neglect, alteration, accident, or
physical damage; (c) used in a manner contrary to Seller’s instructions for installation, operation and maintenance; (d) damaged from ordinary wear and tear, corrosion, or
chemical attack; (e) damaged due to abnormal conditions, vibration, failure to properly prime, or operation without ow; (f) damaged due to a defective power supply or
improper electrical protection; or (g) damaged resulting from the use of accessory equipment not sold or approved by Seller. In any case of products not manufactured
by Seller, there is no warranty from Seller; however, Seller will extend to Buyer any warranty received from Seller’s supplier of such products.
THE FOREGOING WARRANTY IS EXCLUSIVE AND IN LIEU OF ANY AND ALL OTHER EXPRESS OR IMPLIED WARRANTIES, GUARANTEES, CONDITIONS OR
TERMS OF WHATEVER NATURE RELATING TO THE GOODS PROVIDED HEREUNDER, INCLUDING WITHOUT LIMITATION ANY IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, WHICH ARE HEREBY EXPRESSLY DISCLAIMED AND EXCLUDED. EXCEPT AS OTHERWISE
REQUIRED BY LAW, BUYER’S EXCLUSIVE REMEDY AND SELLER’S AGGREGATE LIABILITY FOR BREACH OF ANY OF THE FOREGOING WARRANTIES ARE LIMITED
TO REPAIRING OR REPLACING THE PRODUCT AND SHALL IN ALL CASES BE LIMITED TO THE AMOUNT PAID BY THE BUYER FOR THE DEFECTIVE PRODUCT.
IN NO EVENT SHALL SELLER BE LIABLE FOR ANY OTHER FORM OF DAMAGES, WHETHER DIRECT, INDIRECT, LIQUIDATED, INCIDENTAL, CONSEQUENTIAL,
PUNITIVE, EXEMPLARY OR SPECIAL DAMAGES, INCLUDING BUT NOT LIMITED TO LOSS OF PROFIT, LOSS OF ANTICIPATED SAVINGS OR REVENUE, LOSS OF
INCOME, LOSS OF BUSINESS, LOSS OF PRODUCTION, LOSS OF OPPORTUNITY OR LOSS OF REPUTATION.
LIMITED CONSUMER WARRANTY
Warranty. For goods sold for personal, family or household purposes, Seller warrants the goods purchased hereunder (with the exception of membranes, seals, gaskets,
elastomer materials, coatings and other “wear parts” or consumables all of which are not warranted except as otherwise provided in the quotation or sales form) will be
free from defects in material and workmanship for a period of one (1) year from the date of installation or two (2) years from the product date code, whichever shall occur
rst, unless a longer period is provided by law or is specied in the product documentation (the “Warranty”).
Except as otherwise required by law, Seller shall, at its option and at no cost to Buyer, either repair or replace any product which fails to conform with the Warranty
provided Buyer gives written notice to Seller of any defects in material or workmanship within ten (10) days of the date when any defects or non-conformance are rst
manifest. Under either repair or replacement option, Seller shall not be obligated to remove or pay for the removal of the defective product or install or pay for the
installation of the replaced or repaired product and Buyer shall be responsible for all other costs, including, but not limited to, service costs, shipping fees and expenses.
Seller shall have sole discretion as to the method or means of repair or replacement. Buyer’s failure to comply with Seller’s repair or replacement directions shall
terminate Seller’s obligations under this Warranty and render this Warranty void. Any parts repaired or replaced under the Warranty are warranted only for the balance
of the warranty period on the parts that were repaired or replaced. The Warranty is conditioned on Buyer giving written notice to Seller of any defects in material or
workmanship of warranted goods within ten (10) days of the date when any defects are rst manifest.
Seller shall have no warranty obligations to Buyer with respect to any product or parts of a product that have been: (a) repaired by third parties other than Seller or without
Seller’s written approval; (b) subject to misuse, misapplication, neglect, alteration, accident, or physical damage; (c) used in a manner contrary to Seller’s instructions for
installation, operation and maintenance; (d) damaged from ordinary wear and tear, corrosion, or chemical attack; (e) damaged due to abnormal conditions, vibration,
failure to properly prime, or operation without ow; (f) damaged due to a defective power supply or improper electrical protection; or (g) damaged resulting from the use
of accessory equipment not sold or approved by Seller. In any case of products not manufactured by Seller, there is no warranty from Seller; however, Seller will extend to
Buyer any warranty received from Seller’s supplier of such products.
THE FOREGOING WARRANTY IS PROVIDED IN PLACE OF ALL OTHER EXPRESS WARRANTIES. ALL IMPLIED WARRANTIES, INCLUDING BUT NOT LIMITED
TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE LIMITED TO ONE (1) YEAR FROM THE DATE OF
INSTALLATION OR TWO (2) YEARS FROM THE PRODUCT DATE CODE, WHICHEVER SHALL OCCUR FIRST. EXCEPT AS OTHERWISE REQUIRED BY LAW,
BUYER’S EXCLUSIVE REMEDY AND SELLER’S AGGREGATE LIABILITY FOR BREACH OF ANY OF THE FOREGOING WARRANTIES ARE LIMITED TO REPAIRING OR
REPLACING THE PRODUCT AND SHALL IN ALL CASES BE LIMITED TO THE AMOUNT PAID BY THE BUYER FOR THE DEFECTIVE PRODUCT. IN NO EVENT SHALL
SELLER BE LIABLE FOR ANY OTHER FORM OF DAMAGES, WHETHER DIRECT, INDIRECT, LIQUIDATED, INCIDENTAL, CONSEQUENTIAL, PUNITIVE, EXEMPLARY
OR SPECIAL DAMAGES, INCLUDING BUT NOT LIMITED TO LOSS OF PROFIT, LOSS OF ANTICIPATED SAVINGS OR REVENUE, LOSS OF INCOME, LOSS OF
BUSINESS, LOSS OF PRODUCTION, LOSS OF OPPORTUNITY OR LOSS OF REPUTATION.
Some states do not allow limitations on how long an implied warranty lasts, so the above limitation may not apply to you. Some states do not allow the exclusion or
limitation of incidental or consequential damages, so the above exclusions may not apply to you. This warranty gives you specic legal rights, and you may also have
other rights which may vary from state to state.
To make a warranty claim, check rst with the dealer from whom you purchased the product or call [phone] for the name and location of the nearest dealer
providing warranty service.