Install Instructions

ManualsBrandsMcdonnell & Miller ManualsHeating Supplies750-HW-MT-120, GuardDog Electronic Reset High Water Cutoff (120V)

Model 750-HW-MT-120

Probe Type High Water

Manual Reset Control Unit

Applications:

Conductance type control for steam boilers

when a manual reset high water alarm or

cut-off is required.

5-1/2"

Model 750-HW-MT-120

Probe Type High Water

Control Unit

Model 750-HW-MT-120

Control Unit

• Before using product, read and understand instructions.

• Save these instructions for future reference.

• All work must be performed by qualified personnel trained in the proper application, installation,

and maintenance of plumbing and electrical equipment and/or systems in accordance with all

applicable codes and ordinances.

• 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 serious burns, allow the control and surrounding equipment to cool to 80˚F (27˚C)

and allow pressure to release to 0 psi (0 bar) before servicing.

• To prevent an electrical fire or equipment damage, electrical wiring insulation must have a

rating of 167˚F (75˚C) if the liquid's temperature exceeds 180˚F (82˚C).

• This control can be installed in series with all other limit and operating controls installed

on the boiler. After installation, check for proper operation of all the limit and operating

controls, before leaving the site.

• When using mixed voltages, do not jumper from terminal 1 to terminal 3.

• To prevent electrocution, when the electrical power is connected to the control, do not touch

the terminals, or electrical wires.

• To prevent electrical shock, turn off the electrical power before making electrical connections.

Failure to follow this warning could cause property damage, personal injury or death.

WARNING

CAUTION

WARNING

McDonnell & Miller

Installation & Maintenance

Instructions

MM-273A

Summary of content (8 pages)

PAGE 1
McDonnell & Miller Installation & Maintenance Instructions MM-273A Model 750-HW-MT-120 Probe Type High Water Manual Reset Control Unit Model 750-HW-MT-120 Probe Type High Water 5-1/2" Control Unit Applications: Conductance type control for steam boilers when a manual reset high water alarm or cut-off is required. Model 750-HW-MT-120 Control Unit ! WARNING • Before using product, read and understand instructions. ION CAUT ING WARN • Save these instructions for future reference.
PAGE 2
SPECIFICATIONS The Model 750-HW-MT-120 control provides continuous protection against a high water condition in steam boilers. It can be used to interrupt the burner circuit to turn off the burner, interrupt the feedwater pump circuit to turn off the pump, or both. The control can also be used to provide an alarm (light, horn or both) when a high water condition occurs. The manual reset function will require that the unit be reset after water has dropped below the level of the probe.
PAGE 3
STEP 1 - Where to Install the Remote Sensors Determine where to install the remote sensor based on the following requirements: Option A a. The Remote Sensor can be installed directly in a 1" or larger tapping in the top of the boiler. or b. The probe of the RS-1-BR-1 Remote Sensor will need to be cut to appropriate length based upon the level where high water cutoff/alarm is desired. c.
PAGE 4
STEP 2 - Installing the Remote Sensor For the Model RS-1-BR-1 sensors, only: a. Cut the probe (purchased separately) to desired length. Screw, clockwise, the threaded stainless steel probe extension (A) into the remote sensor (B). Carefully tighten the locking nut to approximately 1 ft•lb (1.7 N•m). Do not cut the clear plastic protective tube. B A For All Remote Sensors b. Apply a small amount of pipe dope to the first threads (L) of the remote sensor.
PAGE 5
STEP 3 - Installing the Control Box a. Using the flatblade screwdriver or nut driver (C), loosen the two (2) screws (D) and remove cover (E). C D (x2) Model 750-HW-MT -120 Probe Type High Water Control Unit E IMPORTANT: To protect control from damage caused by liquid or debris, mount as shown with buttons on top. b. Using the four (4) 3/16" (4.8mm) mounting holes (F), attach the control (G) to the boiler jacket, entry plate, or other suitable location. G F (x4) NOTE: Mounting hardware is not included.
PAGE 6
• Install electrical conduit between Probe Housing and Control Box. RS1-BR-1 SENSOR NOTE Wire must be 18 AWG stranded with glass braided silicone jacket (UL 3071) suitable for high temperature (200˚C) service. NOTE Refer to and follow local codes and standards when selecting conduit and electrical fittings. Wires from Probe Housing and Control Box must be in their own conduit. If they are run in conduit with other wires, there may be interference that can affect the performance of the control. b.
PAGE 7
c. Secure the sensor housing cover (Q). R 1. For model RS-1-BR-1, using the flatblade screwdriver (R), tighten the four (4) screws into the housing (Q) to approximately 3 ft•lb (4 N•m). 2. For model RS-1-LP, using the flatblade screwdriver or nut driver (R), tighten the two (2) screws into the housing (Q) to approximately 2 ft•lb (2.6 N•m). R Q Q OR Model RS-1-BR-1 d.
PAGE 8
McDonnell & Miller Troubleshooting If control fails to operate as required, perform the following diagnostic checks: 1. Check to be sure that the water level in the boiler is below the level of the probe. 2. Re-check all wiring to ensure proper connections as specified in boiler manufacturer’s wiring diagrams or these instructions. 3. Check to ensure that Teflon® tape has not been used on the threaded connection of the remote sensor to the boiler. 4.