Wall-mounted, modulating gas condensing water heater (68 pages)
Summary of Contents for Laars VW
Page 1
Maintenance Instructions for Mighty Therm Volume Water Heaters Model VW-PW Sizes 175-400 FOR YOUR SAFETY: This product must be installed and serviced by a professional service technician, qualified in hot water heater installation and maintenance. Improper installation and/or operation could create carbon monoxide gas in flue gases which could cause serious injury, property damage, or death.
The VW-PW heaters are offered in a basic 1C. Technical Assistance configuration (see Figure 1). On PW heaters the pump is factory installed. On VW heaters the pump is field Consult Laars or your local wholesaler with any installed. questions or problems involving the specification, installation and operation of Laars equipment.
Install the VW-PW heaters in accordance with the procedures in this manual (or the Laars warranty may be voided), local codes and ordinances. In the absence of such codes, install the heaters in accordance with the latest edition of the National Fuel Gas Code, ANSI Z223.1.
Mighty Therm VW - PW Volume Water Heaters Page 5 Disengage the flue transition ring from the stack extension and place it on top of the collector assembly as shown in Figure 4. Slide the adapter plate over the bottom of the stack extension as shown in Figure 5.
Page 6 LAARS HEATING SYSTEMS Concrete slab must extend out a minimum of 12 in. (305mm) on all sides. WINDOW LAARS OR GRILL UNIT (Side View) Base For Combustible Floors INDOOR ROOM Roof - Wood and Steel Construction Figure 11. Standard base for combustible floor.
Mighty Therm VW - PW Volume Water Heaters Page 7 2D-1. Outdoor Air Supply Required Net Free Opening Area When combustion air comes directly through an Directly from Outside outside wall, each opening must have a minimum free At Top...
10. In the control compartment, find the manual reset If replacing an existing heater with a VW or PW high-limit switch box (see Figure 15) and loosen heater and the existing heater was connected to a the screw on the top to remove the cover.
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Mighty Therm VW - PW Volume Water Heaters Page 9 HEAT EXCHANGER REAR TILE COVER ASSEMBLY GAP CLOSURE FLOW SWITCH CONDUIT DRAIN PLUG DRAIN VALVE REAR TILE COVER GAP CLOSURE GROMMET DRAIN VALVE HEX HEAD SCREWS METAL CHANNEL (FOR CAPILLARY TUBE)
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Page 10 LAARS HEATING SYSTEMS 13. Use a pair of diagonal cutters to cut the plastic 15. Remove the flow switch conduit retaining clip tie around the wire bundle in the control and the elbow leading into the jacket. compartment.
The VW heater does not have a factory installed pump (see Table 4 for pump performance require- ments). The PW heater does have a factory installed 2F-2.
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Page 12 LAARS HEATING SYSTEMS Heat Flow Pressure* Water Temp Exch. Water Rate Drop Rise Model Passes Category ° ° Soft Normal 11.2 Hard 19.1 Soft Normal Hard 15.9 Soft Normal 11.2 Hard 19.1 Soft Normal Hard 15.9 Soft 12.5 Normal 12.5...
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Mighty Therm VW - PW Volume Water Heaters Page 13 Optional Cold Water Supply Hot Water When Adequate Tank Opening to Building Not Available Hot Water Return from Heater Building Throttling Valve Drain Check Valve Bldg. Service Loop Valve Circ.
Figure 23. Pressure relief valve. 2F-5). If tappings are smaller than the recommended pipe size, a larger pump may be 2F-9. Pump Installation (Model VW) required. Consult the factory if in doubt. Install a pipe in the tank drain fitting that goes to Install a properly sized pump to provide water a floor sink, and install a drain valve.
Mighty Therm VW - PW Volume Water Heaters Page 15 2F-11. Thermal Circulation of Hot Water Distance from Gas Meter or Last Stage Regulator in Cold Water Supply Lines Under certain circumstances, thermal circulation 0-100 feet 100-200 feet 200-300 feet...
11. Before operating the heater, test the complete gas 2I-1. Combined Space Heating supply system and all connections for leaks using The VW and PW heaters are not to be used as a a soap solution. source of heat for a combined space heating system.
Mighty Therm VW - PW Volume Water Heaters Page 17 Turn manual gas valve off. SECTION 3. Wait 5 minutes to clear out any gas, then smell Operating Instructions for gas, including near the floor. Be sure to smell next to the floor because some types of gas are 3A.
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IGNITION SYSTEM NO. 1 - STANDING PILOT ON/OFF OR MECHANICAL MODULATION Volume Water Heaters (325-400) Version B Natural or Propane Gas PUMP INCLUDED ON PW MODELS, FIELD SUPPLIED ON VW MODELS Figure 26. Typical example of wiring schematic, System 1.
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Mighty Therm VW - PW Volume Water Heaters Page 19 IGNITION SYSTEM NO. 12 - ELECTRONIC IGNITION ON/OFF OR MECHANICAL MODULATION Volume Water Heaters (325-400) Version B Natural or Propane Gas PUMP INCLUDED ON PW MODELS, FIELD SUPPLIED ON VW MODELS...
Page 20 LAARS HEATING SYSTEMS 3E. Hi-Limit Switch Checkout Manual Reset Temp. Control After running the heater for a long enough Temperature Controller period, bring the water temperature within the range of the hi-limit switch and slowly back off the high limit setting until the heater shuts off.
Mighty Therm VW - PW Volume Water Heaters Page 21 4B. Replacement of Gas Controls Electronic Pilot Standing Pilot The gas and electric controls installed on the heaters are designed for both dependable operation and long life. Safe operation of the heater depends on their proper functioning.
Page 22 LAARS HEATING SYSTEMS Remove the two screws that fastens the anti- 15. Connect the pilot gas tube to the pilot assembly rotation bracket on the left side of the gas valve and the gas valve. (see Figure 30).
Mighty Therm VW - PW Volume Water Heaters Page 23 4C-2. Cleaning the Heat Exchanger Pressure test the heat exchanger for leaks with city water supply before re-installing (see An inspection and cleaning of the complete heat Figure 33). exchanger can only be done by removing it from the heater.
Page 24 LAARS HEATING SYSTEMS The manometer reading should be 4 inches (102mm) W.C. for natural gas and 9 inches Suggested Manometer (229mm) W.C. for propane gas. Position Turn the toggle switch to OFF. 10. Shut the system down following the instructions found on the inside of the heater.
Mighty Therm VW - PW Volume Water Heaters Page 25 Make sure the gas valve is on and there is gas pressure in the line. Check all electrical connections and wiring. Finding a loose connection or a charred wire can save a lot of time and money.
Page 26 LAARS HEATING SYSTEMS Check for leaks of the flue collector, vent pipe, gaskets, and all connections. Check the flue pipe for blockage. 5B-7. Testing the Fuse To test the fuse: Clip a lead of the voltmeter to the grounding terminal.
Mighty Therm VW - PW Volume Water Heaters Page 27 Touch the other voltmeter lead to the red 24V terminal on the ignition control. If the voltmeter reads voltage, the temperature control and the manual reset hi-limit switch are not keeping the heater from firing.
Page 28 LAARS HEATING SYSTEMS 5B-11. Testing the Safety Shutoff If the voltmeter reads 20 to 28VAC, but there is no pilot ignition, check for (for standing pilot) After lighting the heater, test the ignition system a: air in gas lines.
Mighty Therm VW - PW Volume Water Heaters Page 29 Thermocouple Thermocouple Adapter Gas Valve Pilot Millivolt Figure 42. Flame sensing current. Meter 5B-17. Heater Will Not Shut Off Figure 41. Testing the pilot thermocouple. If the heater stays on with the brown wire on the...
24. Switch, Drafthood ........E0121000 6A. General Information VENT SYSTEM 26. Vent Cap ..........R0318602-05 To order or purchase parts for the Laars VW-PW 27. Drafthood ..........R0318702-05 Volume Water Heaters, contact your nearest Laars 28. Drafthood/Vent Cap wholesaler. If they cannot supply you with what you Adapter Plate ..........
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Mighty Therm VW - PW Volume Water Heaters Page 31 Item Description Part Number Item Description Part Number 60. Tee JACKET COMPONENTS Bronze ............ P0075600 64. Jacket Assembly ........10568302-05 Cast Iron ..........P0071700 65. Door ............10448902-05 61. Bushing, Brass ........P0018500 66.
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