Laarsen Associates VW, PW 3B. Initial Start-Up, Single Installation Piping Diagram, Model IW

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Mighty Therm Volume Water Heater

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proven to be lit. Whenever the pilot flame is interrupted, the main gas valve closes within

0.8 seconds.

b.Electronically Supervised Standing Pilot System (System #16):

When pilot flame fails, the ignition control module responds in less than 0.8 seconds and provides 100% safety shutdown.

2.Operating Controls:

a.Electrically Operating Controls:

Single, two-stage, four-stage or modulating aquastats are provided in models VW, PW and IW heaters to control the desired service water temperature. The temperature sensing bulb is located in the heater inlet.

b.Modu-snap Valves:

These valves are furnished in addition to the main electric gas valve when heater is ordered with mechanical modulation. Each valve has a remote capillary bulb immersed in a well at the outlet header to maintain a constant outlet temperature. Consult Table 5 for desired temperature setting.

3.High Limit Controls:

The manual reset high limit switches are provided as standard equipment on all heaters. Automatic reset switches are optionally

Dial No.

1

2

3

4

5

6

7

8

9+

 

 

 

 

 

 

 

 

 

 

Temp °F

120

128

135

143

150

158

165

173

180+

 

 

 

 

 

 

 

 

 

 

Table 5. Modu-Snap Temperature Settings.

provided. The temperature sensing bulb of the switch is always located in the heater outlet. Burners will automatically shut down whenever overheating of water occurs.

4.Flow Switch:

Standard on all models: Models VW and PW, the switch is mounted in the outlet “tee” connection. Model IW, the switch is mounted directly in the header outlet. The flow switch shuts down all burners in case of low water condition or pump failure.

5.Low Water Cut Off:

The low water cut off automatically shuts off heater whenever water level drops below probe. Located at heater inlet (model IW and PW) and at return header (model VW).

3B. Initial Start-Up

Before placing the heater in operation, be certain that the heater is filled with water and all air is purged from the system. Once the heater is connected to the

Figure 18. Single Installation Piping Diagram, Model IW.

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Contents Mighty Therm Table of Contents 1B. Heater Identification General Information1A. Introduction 2A. Heater Placement Installation2B. Installation of Indoor Heaters 1C. Flow RequirementsInstallation on Concrete Blocks or Tile 2B-1. Combustion Air Supply 2D. Gas Supply and Piping 2C. Installation of Outdoor Heaters2F. Water Piping of System 2E. Electrical WiringPressure Relief Valve Location 2G. Water Expansion2H. Pump Performance and Installation Hot Water Supply System Model VW & PW With Vertical Tank HorizontalSplit System Piping Diagram, Model IW Dual Installation Piping Diagram, Model IW With Vertical Tank With Horizontal TankMighty Therm Volume Water Heater 2K. Two-Temperature System 2J. Tank InstallationOperation 2I. Water Pressure3B. Initial Start-Up Hi-Limit Checkout 3C. To Start Up System3D. To Turn Off Heater Maintenance3E. To Shut Down System Indoor ModelsHeater will not Fire Troubleshooting and Analysis Service ProblemsIII. Water Dripping Firebox Numbers Parts Identification Laars Heating Systems Tile Assemblies Ignition Control, Electronic Safety Gas Valve, On-Off Two Stage Nat Plug, 3/4, Sq. Hd Outdoor Parts See Parts Illustration On Outdoor Parts Descriptions and Order NumbersMighty Therm Volume Water Heater Energy Management Monitor EM2 Pump Rotating Sections and Repair PartsOptional Parts Descriptions and Order Numbers