S05 - Laars Boiler Might Therm PW 325 Install Operation and Maintenance Manual.pdf

Installation, Operation and Maintenance Instructions Document 2051F

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F

Installation, Operation and 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.

Improper installation and/or operation will void the warranty.

WARNING

If the information in this manual is not followed exactly, a fire or explosion may result causing property damage, personal injury or loss of life.

Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other appliance.

WHAT TO DO IF YOU SMELL GAS

• Do not try to light any appliance.

• Do not touch any electrical switch; do not use any phone in your building.

• Immediately call your gas supplier from a nearby phone. Follow the gas supplier's instructions.

• If you cannot reach your gas supplier, call the fire department.

Installation and service must be performed by a qualified installer, service agency, or gas supplier.

LAARS Heating SystemsPage 2

TABLE OF CONTENTS

SECTION 1.

General Information

1.1 Introduction

1.2 Warranty

1.3 Technical Assistance

SECTION 2.

Installation Instructions

2.1 General Information

2.2 Field Assembly

2.3 Site Location

2.3.1 Installation Information

2.3.2 Outdoor Installation (U.S. only)

2.3.3 Flooring - Typical Installation

2.4 Combustion and Ventilation Air Supply

2.4.1 Outdoor Air Supply

2.4.2 Indoor Air Supply

2.4.3 Exhaust Fans or Vents

2.5 Venting of Combustion Products

2.5.1 General Information

2.5.2 Replacement of Existing Heater

2.6 Water Flow

2.6.1 Reversible Water Connections

2.6.2 Water Chemistry

2.6.3 Freeze Protection

2.6.4 Water Hardness

2.6.5 Pump Requirements

2.6.6 Pressure Buildup in Water System

2.6.7 Pressure Relief Valve

2.6.8 Water Pressure

2.6.9 Pump Installation

2.6.10 Storage Tank Installation

2.6.11 Thermal Circulation of Hot Water in

Cold Water Supply Lines

2.7 Gas Supply and Piping

2.7.1 General Instructions

2.7.2 Special Precautions for Propane Gas

2.8 Electrical Wiring

2.9 Combined Space Heating/Potable

Water Heating Systems

2.9.1 Combined Space Heating

SECTION 3.

Operating Instructions

3.1 Normal Operating Sequence

3.2 Start-Up Procedure

3.3 Setting the Temperature Controls

3.3.1 Remote Water Heater Temperature

Control:

3.3.2 Internal Water Heater Temperature

Control:

3.4 Adjustment for Minimum Input Rate

(models with modulating gas valve)

3.5 Hi-Limit Switch Checkout

3.6 Shut-Down Procedure

SECTION 4.

Maintenance

4.1 General Instructions

4.2 Replacement of Gas Controls

4.3 Heat Exchanger

4.3.1 Inspecting the Heat Exchanger

4.3.2 Cleaning the Heat Exchanger

SECTION 5.

Troubleshooting

5.1 Gas Pressure Tests

5.1.1 Checking the Main Line Gas Pressure

5.1.2 Checking the Manifold

Regulated Gas Pressure

5.2 Electrical Troubleshooting

5.2.1 Heater Does Not Come On

5.2.2 Testing the Transformer

5.2.3 Testing the Electrical Power Supply

5.2.4 Testing the Manual Reset

Hi-Limit Switch

5.2.5 Testing the Flow Switch

5.2.6 Testing the Fusible Link

(Flame roll-out switch)

5.2.7 Testing the Fuse

5.2.8 Testing the Ignition Control

(for spark ignition)

5.2.9 Testing the Ignition Control

(for standing pilot)

5.2.10 Testing the High Voltage Ignition Lead

5.2.11 Testing the Safety Shutoff

(for standing pilot)

5.2.12 Testing the Safety Shutoff

(for automatic pilot)

5.2.13 Testing the Igniter Electrode

5.2.14 Testing the Pilot Thermocouple

(for standing pilot)

5.2.15 Testing for Pilot burner

(for spark ignition)

5.2.16 Testing for Burner Ignition

(for standing pilot)

5.2.17 Heater Will Not Shut Off

5.2.18 On-Off Main Burner Cycling

5.2.19 Testing the Terminal Strip/External

Controls

SECTION 6.

Parts List

6.1 General Information

6.2 Parts List

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SECTION 1.

General Information

1.1 Introduction

This manual provides installation, operating, and maintenance instructions for Models VW and PW Volume Water Heaters, Sizes 175 through 400. Review all application and installation procedures completely before proceeding with the installation. Experience has shown that most operating problems are caused by improper installation.

The VW-PW heaters are offered in a basic configuration (see Figure 1). On PW heaters the pump is factory installed. On VW heaters the pump is field installed.

1.2 Warranty

The VW-PW heaters are sold with a limited factory warranty.

Make all warranty claims to an authorized Laars representative or directly to the factory. Claims must include the heater serial number and model (this information can be found on the rating plate), installation date, and name of the installer. Shipping costs are not included in the warranty coverage.

Some accessory items are shipped in separate packages. Inspect everything for damage immediately upon delivery, and advise the transporter of any shortages or damage. Any such claims should be filed with the transporter. The transporter will not accept a claim from the shipper, Laars.

The warranty does not cover damage caused by improper installation, operation, or field modification.

1.3 Technical Assistance

Consult Laars or your local wholesaler with any questions or problems involving the specification, installation and operation of Laars equipment. An experienced technical support staff is ready to assist in assuring the proper performance and application of Laars products.

Gas Connection Size Water C C V

Connect. U.S. Only (Indoor) Vent Nat. Propane Size A B (Outdoor) Dia.

Size in. mm in. mm in. mm in. cm in. cm in. cm in. cm in. mm

175 3/4 19 1/2 13 11/2 38 18 46 261/2 67 141/16 36 23/2 60 6 152

250 3/4 19 1/2 13 11/2 38 221/2 57 31 79 181/16 47 243/4 63 7 178

325 3/4 19 1/2 13 11/2 38 263/4 68 353/4 91 193/16 49 257/8 66 8 203

400 3/4 19 1/2 13 11/2 38 313/4 80 401/4 102 225/8 58 267/8 68 9 229

Note: Dimensions may vary.

Figure 1. General configuration.

Dimensions shown in inches cm.

LAARS Heating SystemsPage 4 number for the drafthood is on the heater rating plate.

Follow this procedure to make the conversion:

a. Remove the top filler plate, stamped “HOT”, by slipping a fine-blade screwdriver into the slot at the rear of the plate and gently prying it up (see Figure 2).

b. Remove the two screws attaching the adapter plate to the top assembly and lift it out (see Figure 3).

c. Remove the vent cap or drafthood from its package.

SECTION 2.

Installation Instructions

2.1 General Information

WARNING

Follow local regulations with respect to installation of carbon monoxide (CO) detectors and manufacturer's maintenance schedule of the heater.

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. In Canada, the installation must be in accordance with CAN1-B149.1 or .2 and local codes. The authority having jurisdiction may require the installation conform to the Standard for Controls and Safety Devices for Automatically Fired Heaters, ANSI/ASME CSD-1. Any changes to the heater, gas controls, gas orifices, wiring or draft diverter may void the warranty. If field conditions require a change to any of the above, consult the factory.

All gas-fired products require correct installation to assure safe operation. The requirements for heaters include the following:

1. Field assembly of drafthood or vent cap (see Section 2B).

2. Appropriate site location (clearances) and flooring.

3. Sufficient combustion and ventilation air.

4. Adequate venting of combustion products.

5. Adequate water flow.

6. Properly sized gas meter and piping.

7. Proper electrical wiring.

This manual provides the information needed to meet these requirements. Review all application and installation procedures completely before continuing the installation.

2.2 Field Assembly

The VW-PW heater is shipped from the factory with the top assembly in the low-profile configuration for outdoor installations.

The VW-PW heater is design certified for indoor installation when equipped with a special drafthood, which must be installed without modification. The part

Figure 2. Top filler plate. Figure 3. Adapter plate.

Figure 4. Flue transition Figure 5. Vent cap with ring. adapter plate

(outdoor).

Figure 6. Drafthood with Figure 7. Drafthood switch adapter plate receptacle.

(indoor).

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d. Disengage the flue transition ring from the stack extension and place it on top of the collector assembly as shown in Figure 4.

e. Slide the adapter plate over the bottom of the stack extension as shown in Figure 5. Fit the stack extension down over the flue transition ring. Seat the adapter plate on the top assembly and secure it with two screws (see Figure 6).

f. Indoor models, size 175 and 250 only, require an adapter cable (included with product). The cable connects the blocked vent safety switch (BVSS) on the bell of the external draft hood to the 6-position Molex plug on the side of the unit (see Figure 7). Refer to instruction sheet included with cable.

2.3 Site Location

2.3.1 Installation Information

WARNING

Improper installation or maintenance can cause nausea or asphyxiation from carbon monoxide in flue gases which could result in severe injury, property damage, or death.

Avoid placing the heater in locations where it can be damaged by water or condensate leakage. If this is not possible, provide a suitable drain pan to catch and divert any leakage. The pan must not block natural flow of air around the heater.

Locate the heater to provide adequate clearance on all sides for inspection, service and to provide adequate air circulation for proper operation.

Locate the heater so the clearances from combustible surfaces shown in Table 1 and Figure 8 are met.

Figure 8. Alcove installation.

Closet Installation (unacceptable)

A closet is any 4 sided enclosure which is less than 16* times the total volume of all the gas fired appliances within the enclosure.

Room Installation (acceptable)

A room is any enclosure which is at least 16* times greater than the total volume of all the gas fired appliances within the enclosure

Alcove Installation (acceptable)

An alcove suitable for the installation of a heater is a restricted section of a room not separated from the room by a door or partition and which meets the minimum clearances specified in this manual.

* When the ceiling height exceeds 8 feet, you are only allowed to consider 8 feet when calculating the total volume of the enclosure.

Indoors Outdoors Clearance from: inch mm inch mm

Top 37 940 Unobstructed Water conn. side 12 305 Unobstructed Opposite side 6 152 6 152 Front Alcove Unobstructed Rear 6 152 6 152 Vent* 6 152 — Flooring Combustible Combustible

Service clearance = 36 inches (914mm) at front of heater, and 18 inches (457mm) at water connection side.

*1" (25mm) if double wall vent is used.

Table 1. Minimum Boiler Clearances from Combustible Surfaces.

Locate the heater on a waterproof floor with a floor drain and a 6 inch (152 mm) minimum curb on all four sides to protect the building if heater repairs are needed.

2.3.2 Outdoor Installation (U.S. Only)

Caution Outdoor installations are not recommended in areas where the danger of snow blockage exists. VW-PW heaters can be installed in the standard low-profile, grate top configuration as received from the factory, or with an optional vent cap.

Locate the heater in an open, unroofed area. Do not locate the heater below or adjacent to any doors, windows, louvers, grills, etc., which connect in any way with an inhabited area of a building, even though the access might be through another structure such as a garage or utility room (see Figure 9 and Table 1).

There must be a minimum of 4 feet (1.22 m) horizontally and vertically between the heater and any door, window, or gravity inlet to a building (see Figure 10).

If the heater is installed close to a structure, protect it from rain water runoff with rain gutters on the roof or other measures. Do not locate the heater near sprinkler systems that could spray water on it.

LAARS Heating SystemsPage 6

Figure 11. Standard base for combustible floor.

Figure 13. Typical roof mounting with standard combustible mount base.

Figure 12. Typical roof mounting.

Figure 10. Outdoor location installation.

Figure 9. Incorrect outdoor installation.

Concrete slab must extend out a minimum of 12 in. (305mm) on all sides.

LAARS

UNIT

(Side View)

Base For Combustible Floors

Roof - Wood and Steel Construction

Mounting Platform must extend out a minimum of 12 in.

(305mm) on all sides.

LAARS

UNIT

(Side View)

Base For Combustible Floors

Raised Mounting Platform (Wood)

20 Gauge Galvanized Sheet Metal Cap

Roofing

Base Rail

Flashing

Roof

LAARS

UNIT

(Side View)

Base For Combustible Floors

Flashing 4x4 Stringer Roof

Base Rail

20 Gauge Galvanized Sheet Metal Cap

Roofing

Avoid locations where wind deflection off nearby structures might cause wind loading and downdraft conditions. Where downdraft conditions exist, locate the heater at least 3 feet (0.91 m) from the structure.

2.3.3 Flooring - Typical Installation

Do not install the heater directly on carpeting without placing a non-combustible platform between the carpeting and the heater. If the heater is installed in a carpeted alcove, the entire floor of the alcove must be covered by a non-combustible panel. The panel must be strong enough to carry the total weight of the heater and all piping, pumps, and any other equipment attached to the heater. For rooftop installation, see Figure 11 through Figure 13.

2.4 Combustion and Ventilation

Air Supply All indoor installations must have openings to outside air for combustion, ventilation and dilution of

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Method 1:

Two permanent openings, one commencing within 12" (30 cm) of the top and one commencing within 12" (30 cm) of the bottom of the enclosure shall be provided. The openings shall communicate directly, or by ducts, with the outdoors or spaces that freely communicate with the outdoors. When directly communicating with the outdoors directly, or through vertical ducts, each opening shall have a minimum free area of 1 square inch per 4000 Btu/hr (550 square mm/ kW) of total input rating of all equipment in the enclosure. When communicating to the outdoors through horizontal ducts, each opening shall have a minimum free area of not less than 1 square inch per 2000 Btu/hr (1100 square mm/kW) of total input rating of all equipment in the enclosure.

Method 2:

One permanent opening, commencing within

12" (30 cm) of the top of the enclosure shall be permitted. The opening shall directly communicate with the outdoors or shall communicate through a vertical or horizontal duct to the outdoors or spaces that directly communicate with the outdoors, and shall have a minimum free area of 1 square inch per 3000 Btu/hr (734 square mm/kW) of the total input rating of all equipment located in the enclosure. This opening must not be less than the sum of the areas of all vent connectors in the confined space.

Other methods of introducing combustion and ventilation air are acceptable, providing they conform to the requirements in ANSI Z223.1, or applicable codes.

In Canada, Table 2 does not apply. Consult local building and safety codes or, in absence of such requirements, follow CAN/CGA B149.

NOTE: Check with louver manufacturers for net free area of louvers. If screens or louvers are installed, add 50 percent for each screen/louver to the net free area Check all local codes applicable to combustion air.

2.4.1 Outdoor Air Supply

When combustion air comes directly through an outside wall, each opening must have a minimum free area of at least one square inch for each 4,000 BTU/h input of the total input rating of all appliances in the enclosed area. (In Canada, refer to CGAB149.1 and .2.)

2.4.2 Indoor Air Supply

Confined and non-confined areas have different requirements for installation. Consult the latest edition of the National Gas Code for installation requirements.

2.4.3 Exhaust Fans or Vents

Any equipment which uses air or removes air from the heater room can use up the combustion air

Required Net Free Opening Area Directly from Outside

At Top At Bottom

Model in.2 cm2 in.2 cm2

175 44 284 44 284 250 63 406 63 406 325 82 529 82 529 400 100 645 100 645

Note: For screens or louvers, add 50%.

Table 2. Air Openings to Outside.

Figure 14. Indoor installation and venting.

Notes:

1. The drafthood must sit directly on top of the heater as shown and must not be altered in any manner.

2. An Underwriters' Laboratories listed vent cap is re-quired to eliminate downdraft and allow the heater to function properly.

3. Use approved roof fitting.

flue gases from inside the building (see Figure 14 and Table 2 ). Laars does not recommend indoor installations that do not provide combustion air from outside the building.

In the United States, the most common requirements specify that the space shall communicate with the outdoors in accordance with method 1 or 2, which follow. Where ducts are used, they shall be of the same cross-sectional area as the free area of the openings to which they connect.

LAARS Heating SystemsPage 8 supply or reverse the natural draft action of the venting system. This could cause flue products to build up in the heater room. More air must be supplied to make up for the decrease.

2.5 Venting of Combustion Products

2.5.1 General Information

When installed indoors, the drafthood must be connected to a venting system. The venting system must be installed by a qualified installer and in accordance with the latest edition of ANSI Z223.1. In Canada, the installation must be in accordance with CAN1-B149.1 or .2, and any local codes that apply.

The vent pipe must have a listed vent cap, and extend at least 2 feet (0.6 m) above any object within a 10 foot (3.0 m) radius.

NOTE: Do not use sheet metal screws at the snap lock joints of Type B double-wall gas vents.

Do not weld or bolt the vent pipe to the heater drafthood. The weight of the stack must not rest on the heater. The drafthood and heater top must be easily removable for normal heater service and inspection.

WARNING

Avoid ending heater vents near air conditioning or air supply fans. The fans can pick up exhaust flue products from the heater and return them inside the building, creating a possible health hazard.

Avoid horizontal runs of the vent pipe and 90 degree elbows, reductions, and restrictions. Horizontal runs should have at least a 1/4 inch (6.3 mm) rise per foot in the direction of flow. Support a vent connector for the design and weight of the material used to maintain clearances and physical damage and separate of joints.

Always use double-wall or insulated vent pipe (Type B or equivalent).

WARNING

In cold weather, uninsulated outside vents can chill the rising flue products, blocking the natural draft action of the venting system. This can create a health hazard by spilling flue products into the heater room.

Avoid oversize vent piping or extremely long runs of the pipe which may cause too much cooling and condensation of flue gasses.

When the installation of a power vent or draft fan in the venting system is necessary, qualified personnel should design the installation following good engineering practices and all applicable codes. A suitable draft switch must be wired into the heater control circuit at the terminal designated Field Interlock to keep the heater from firing unless there is a positive draft.

2.5.2 Replacement of Existing Heater

When a heater is removed from a common venting system, the venting system may be too large for proper venting of the other appliances connected to it.

If replacing an existing heater with a VW or PW heater and the existing heater was connected to a common venting system, the common venting system must comply with ANSI Z223.1/National Fire Protection Association (NFPA) 54. When resizing any portion of the common venting system, the common venting system should be resized to approach the minimum size as determined using the tables in ANSI Z223.1/NFPA 54, Appendix G. In Canada, the common venting system should be resized so the installation will be in accordance with CAN/CGA B149.1 or .2.

2.6 Water Flow

2.6.1 Reversible Water Connections

NOTE: This procedure is not recommended for the PW pump-mounted models.

Laars ships the VW heater with the water connections on the right side. The VW heater can be installed with the water connections on either side. It could be necessary, or helpful, to switch the connections to the left side to improve access for installation service. Have a professional service technician perform this modification before installing the heater using the following procedures:

1. Remove the front cover.

2. If there is a vent cap or drafthood installed, they must be removed before removing the grate top assembly. On indoor installations (sizes 175- 250), the drafthood switch must be disconnected at the left side of the heater.

3. If the unit is in the low-profile outdoor configuration, remove the hex-head screws (see Figure 15) and lift the grate top assembly straight up.

4. Remove the screws that fastens the flue collector holddown clamps and remove the clamps (see Figure 16).

5. Remove the flue collector assembly by lifting it out of the chassis.

6. Remove the screws that fastens the gap closures and put them aside.

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Figure 15. Heat exchanger reversal.

Figure 16. Flue collector Holddown Clamps.

LAARS Heating SystemsPage 10

9. Remove the four screws that fastens the metal channels covering the capillary tube on the right side of the jacket, and lay the channels aside.

10. In the control compartment, find the manual reset high-limit switch box (see Figure 15) and loosen the screw on the top to remove the cover.

11. Loosen the screw that fastens the white wire and remove it from the terminal. Pull it out through the top of the case and separate the other white wire from the red wire coming from the fuse holder. Gently pull the two white wires out of the control compartment and coil them on top of the heat exchanger.

12. A temperature control sensing bulb is located in the front of the header on the inlet side and a manual reset hi-limit sensing bulb is located on the back side of the header on the outlet side (see Figure 17). Remove these sensing bulbs from the header. The following steps for removal apply to all sensing bulbs:

a. If there is more than one capillary tube coming out of the header, label the capillary tubes.

b. Loosen the screw on the capillary tube retaining clip, then gently pry the clip apart until it comes free from the temperature control (see Figure 18).

c. Pull the sensing bulbs out of the temperature control.

d. Gently pull the capillary tubes into the control compartment.

e. Pull the temperature sensing bulb out of the header, and temporarily route it to the front of the heater.

13. Use a pair of diagonal cutters to cut the plastic tie around the wire bundle in the control compartment.

14. On the terminal strip, disconnect the two brown wires from No. 5 and No. 6 terminals.

15. Remove the flow switch conduit retaining clip and the elbow leading into the jacket.

16. Reach inside the control compartment and release the retaining nut in the upper right corner.

The nut should only be finger-tight.

17. When the conduit is pulled away from the jacket, pull the two brown wires out of the control compartment. Coil the conduit and wires on top of the heat exchanger.

18. Use a chassis punch to put two 7/8 inch (22 mm) holes in the front left side of the jacket (see Figure 19).

19. Remove the front and rear tile covers (see Figure 15).

Figure 19. Hole location, left side.

Figure 17. Sensory bulb locations.

Figure 18. Retaining clip removal.

7. Remove the three grommets.

8. Remove the drain valves and plug. There is one hex plug on the left side, near the rear of the jacket. The drain valves are located on the left side and right side of the heater (see Figure 9).

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40. On indoor installations (sizes 175-250), insert the draft hood switch plug into the receptacle on the left side of the heater.

2.6.2 Water Chemistry

20. Lift out the heat exchanger assembly, turn it 180 degrees, and reseat the unit in the heater with the water connections on the left side.

21. Reinstall the front and rear tile covers.

22. Push the capillary tube(s) out through the lower hole in the left side of the jacket.

23. Install the sensing bulb(s) into the appropriate temperature control (keep in mind that the positions of the inlet and outlet have been reversed. The inlet is now behind the outlet).

24. Fasten the capillary tube(s) by squeezing the retaining clip together, then tighten the screw.

25. Feed the two brown wires through the top hole on the left side until the conduit elbow is against the jacket.

26. Fasten the conduit by sliding the retaining nut over the two brown wires (inside the control compartment) then screwing it down finger-tight on the conduit elbow.

27. Straighten the capillary tubing and fasten it to the side of the heater under the channel. Use the self-tapping screws to fasten the channel to the jacket.

28. Feed the two white wires into the control compartment. Attach one wire to the terminal in the manual reset hi-limit switch. If one is not installed, attach it to terminal No. 1. Connect the other wire to the red wire attached to the fuse holder.

29. Attach the two brown wires to terminals No. 5 and 6 on the terminal strip. Keep all wiring away from surfaces that will get hot during heater operation.

30. Replace the gap closures and tighten the screws securely.

31. Replace the three grommets and the cap.

32. Reinstall the drain plug and drain valves.

33. Slip the flue collector assembly back down inside the enclosure.

34. Carefully slip a hand inside to make sure there are no gaps between the heat exchanger and the flue collector.

35. Check to make sure the wiring is not pinched against sharp edges, or resting on the collector assembly.

36. Replace the two flue collector holddown clamps.

37. Replace the top assembly and fasten it with the hex-head screws.

38. Replace the front cover.

39. Reinstall the vent cap or drafthood if one was removed.

Hardness Grains per Parts Category Gallon per Million

Soft 1 through 7.5 17 through 128 Normal 7.6 through 17 129 through 291 Hard Over 17 Over 291

Table 3. Water Hardness.

Laars equipment is designed to be used in a variety of water conditions. With the proper pump, the water velocity in the heat exchanger tubes is kept high enough to prevent scaling from hard water, yet low enough to avoid erosion by soft water.

NOTE: It is possible to have hard and soft water in the same city. Check with the local water companies.

If an installer sees damage to any water handling equipment at the installation site, it should be repaired as soon as possible to help reduce maintenance costs.

If there is erosion, resize the pump to reduce water velocity before the tube ruptures. If scaling is bad, set up a heat exchanger tube-cleaning maintenance schedule to prevent heat exchanger tube cracking and wear. Not fixing the condition will mean serious damage to the heater and the water system.

NOTES:

• In areas where the water supply is soft or corrosive, the heater must have cupronickel tubes in the heat exchanger.

• Laars does not warrant heat exchangers damaged by scaling, corrosion, or erosion.

2.6.3 Freeze Protection

Although VW-PW heaters are design certified by the International Approval Services (IAS) (formerly American Gas Association [AGA] and Canadian Gas Association [CGA]) for outdoor installations, such installations are not recommended in areas subject to freezing temperatures unless proper precautions are taken. Consult the local factory representative or Laars for additional information.

2.6.4 Water Hardness

Consider the water hardness when selecting a pump for the heater (see Table 3). Hard water needs a pump which can provide high flow to prevent scaling, while soft water needs low flow to prevent erosion.

LAARS Heating SystemsPage 12

Heat Flow Pressure* Water Temp Exch. Water Rate Drop Rise

Model Passes Category gpm L/s ft. m °F °C

175 2 Soft 22 1.4 5.8 1.8 13 7 Normal 34 2.1 11.2 3.4 8 4 Hard 46 2.9 19.1 5.8 6 3

4 Soft 11 0.7 4.9 1.5 25 14 Normal 17 1.1 9.3 2.8 16 9 Hard 23 1.5 15.9 4.8 12 7

250 2 Soft 22 1.4 5.8 1.8 18 10 Normal 34 2.1 11.2 3.4 12 7 Hard 46 2.9 19.1 5.8 9 5

4 Soft 11 0.7 4.9 1.5 35 19 Normal 17 1.1 9.3 2.8 33 18 Hard 23 1.5 15.9 4.8 17 9

325 2 Soft 34 2.1 12.5 3.8 18 10 Normal 34 2.1 12.5 3.8 18 10 Hard 46 2.9 21.7 6.6 11 6

4 Soft 17 0.7 10.4 3.2 36 20 Normal 17 0.7 10.4 3.2 30 17 Hard 23 1.5 18.1 5.5 22 12

400 2 Soft 34 2.1 13.3 4.1 19 11 Normal 34 2.1 13.3 4.1 19 11 Hard 46 2.9 23.4 7.1 14 8

4 Soft 17 0.7 11.1 3.4 37 21 Normal 17 0.7 11.1 3.4 37 21 Hard 23 1.5 19.5 5.9 27 15

*Pressure drop includes head loss of heat exchanger and through 30 feet (9.1 m) of pipe and normal fittings when heater is installed with storage tank. Pipe and fittings are assumed to be 1-1/2 inch (38 mm).

Main Circulating Loop (With Own Pump) Water Maintained Less Than 110°F (43°C)

Adjustment Procedure

1. Turn on heater and open gate valves A and B.

2. After 15 minutes, read T1.

3. If T1 is less than 110°F (43°C), slowly close valve B until T1 climbs to 110°F (43°C).

4. If T1 is greater than 110°F (43°C), slowly close valve A until T1 drops to 110°F (43°C).

5. Check after 5 minutes operation and make final adjustments.

Figure 20. Cold water application.

Table 4. Pump Performance Requirements.

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Figure 22. Hot water supply with horizontal tank.

Note:

Heavy line indicates heater-to-tank circulation loop.

Figure 21. Hot water supply with vertical tank.

LAARS Heating SystemsPage 14 valve is directed to an open drain and protected from freezing.

2. Install a properly sized thermal expansion tank on the cold water supply line.

2.6.7 Pressure Relief Valve

The pressure relief valve must be installed in the tapped opening provided in the boiler header with its outlet piped to a drain or floor sink. Special attention must be given to relief valve settings in installations where the boiler is located on the ground floor of a tall building, or where the operating temperature of the boiler is above 210°F. In both instances, the static pressure of the system is elevated, and could cause the relief valve to leak. Where no special setting of the relief valve is ordered, the factory will furnish a 125 psi setting.

WARNING

Hot water can scald! Hot water can produce third degree burns in 6 seconds at 140°F (60°C) and in 30 seconds at 130°F (54°C).

2.6.8 Water Pressure

Keep the water pressure in the system above

30 psi (207 kPa). If the system pressure drops below 30 psi (207 kPa), it could damage the heater through lack of circulation. If for any reason, the water is turned off temporarily, to service the equipment for example, airlock could be a problem when the heater is turned back on. To eliminate the airlock, open the pressure relief valve (see Figure 23) and allow the air to bleed out until water starts to flow. As soon as full circulation is restored, the trapped air will be released through the hot water faucets.

2.6.9 Pump Installation (Model VW)

1. Install a properly sized pump to provide water circulation between the heater and the storage tank.

2. Size the pump to avoid an excessive temperature rise (see Table 4), and to provide the correct flow for prevailing water hardness conditions.

3. Install the pump in a cool location. The life of the pump can be shortened by exposure to excessive heat. If the pump is equipped with a thermal protection device, excessive heat may trip the thermal switch. This could cause the pump to shut down intermittently, resulting in rapid scaling of the heat exchanger.

4. If designed for floor mounting, install pump securely on concrete block or pad at least 6 inches (152 mm) above floor level. This will prevent flooding of the motor when the floor is washed.

5. Do not suspend floor mounted pumps from piping.

6. Plumb piping to avoid putting strain on the pump casing.

2.6.5 Pump Requirements

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 pump which is for heater-to-tank circulation only.

VW and PW heaters are not designed for applica-tions where the temperature of the water flowing through the heater remains below the dew point, 110°F (43°C).

If low inlet water temperatures are expected, bypass plumbing as shown in Figure 20 should be used to temper the incoming water.

The factory provided pump on the PW heaters, and the pumps recommended for field installation on VW heaters, are sized to provide proper circulation through the heater, and through the heater-to-tank circulation loop (see Figures 20 through 22).

If the heater-to-tank circulation loop does not contain more than 6 elbows or 30 feet (9.1 m) of pipe, the minimum pipe fitting should be 1-1/2 inches (38 mm). If the loop does contain more than 6 elbows or 30 feet (9.1 m) of pipe, the minimum size should be 2 inches (51 mm).

2.6.6 Pressure Buildup in Water System

The water utility supply meter may contain a check valve, back flow preventer, or water pressure reducing valve that will create a closed water supply system. Contact the water supplier or local plumbing inspector on how to control this situation.

Figure 23. Pressure relief valve.

During the heating cycle of the heater, the water expands creating a pressure buildup in the water system. The pressure relief valve may discharge hot water under these conditions, causing a loss/waste of energy and a buildup of lime on the relief valve seat.

NOTE: Do not plug the relief valve.

There are two methods to prevent the relief valve from discharging hot water in a closed water system:

1. Install a pressure relief valve on the cold water supply line. Make sure that the discharge of this

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7. Check the oil level in the pump before starting the heater. Oil the pump every three months. Oil pumps located in excessively hot or dusty locations once a month. Self-lubricating pumps do not require oiling.

8. Fill the bearing assembly to the lower level of the overflow vent.

9. Add 5 or 6 drops of oil to the front and rear of the motor. Use 20W non-detergent oil.

2.6.10 Storage Tank Installation

1. Be sure the floor is structurally capable of supporting the tank when it is filled with water, and is waterproof.

2. Place the tank so that manholes, inspection covers, nameplates and drain valves are accessible.

3. Be sure the tank is suitable for the water in the system. Some water is corrosive and requires a protected tank. Most tanks are available with glass, plastic, or galvanized linings.

4. If the tank is glass-lined, it should be equipped with a suitable magnesium anode. It is a good practice to replace the anode when it is approximately 50 percent used. The factory warranty on a glass-lined tank may be void if a satisfactory anode is not in place at the time of a failure or if it is consumed by cathodic action.

5. The tank must be lined if a water softener is installed in the system.

6. Make sure the tank connections in the heater-tank circulating loop are the proper size (see Section 2F-5). If tappings are smaller than the recommended pipe size, a larger pump may be required. Consult the factory if in doubt.

7. Install a pipe in the tank drain fitting that goes to a floor sink, and install a drain valve. If a floor sink is not available, install a hose bib.

8. Hot water tanks in an existing installation are likely to have silt deposits on the bottom.

Therefore, it is important to extend the pump suction pipe in the tank to a position near the top.

Pipe the return from the heater to the bottom of the tank.

Incorrect installation can cause rapid failure of water tanks due to electrolysis. Tanks must be installed with dialectric connections to electrically isolate the tank from stray current.

Note that use of brass or bronze connectors does not replace the need for dialectric connections.

2.6.11 Thermal Circulation of Hot Water

in Cold Water Supply Lines

Under certain circumstances, thermal circulation will occur in the cold water pipe supplying the water to the heating system. This happens in a multi-story building when the cold water pipe rises from its

Figure 24. T-Fitting and sediment trap.

connection to the system. To correct the problem, a check valve in the cold water line supplying the heater will prevent thermal circulation, and a small expansion tank will permit heated water to expand without popping off the relief valve.

Distance from Gas Meter or Last Stage Regulator

0-100 feet 100-200 feet 200-300 feet 0-30 m 30-60 m 60-90 m

Boiler Nat. Nat. Nat.

Size in. mm in. mm in. mm

175 1 25 1¼ 32 1¼ 32 250 1¼ 32 1¼ 32 1½ 38 325 1¼ 32 1½ 38 1½ 38 400 1¼ 32 1½ 38 2 51

Notes:

1. These numbers are for natural gas (0.65 Sp. Gr.) and are based on ½ inch (13mm) water column pressure drop. Check supply pressure with a manometer, and local code requirements for variations. For liquefied petroleum gas, reduce pipe diameter one size, but maintain a ½ inch (13mm) minimum diameter.

2. Check supply pressure and local code requirements before preceding with work.

3. Pipe fittings must be considered when determining gas pipe sizing.

4. For propane gas: Reduce pipe diameter one size, but maintain a ¾ inch (19mm) minimum diameter.

Table 5. Natural Gas and Propane, Pipe Size Requirements.

Supply Pressure Natural Gas Propane Gas

Water Column in. mm in. mm

Minimum 6.5 165 11 279 See Rating Plate

Maximum 9 229 14 356

Table 6. Gas Supply Pressure Requirements.

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10. The correct burner manifold gas pressure is stamped on the rating plate. The regulator on the gas valve is preset at the factory, and does not normally need adjustment.

11. Before operating the heater, test the complete gas supply system and all connections for leaks using a soap solution.

Caution Since some leak test solutions (including soap and water) may cause corrosion or stress cracking, rinse the piping with water after testing.

2.7.2 Special Precautions

for Propane Gas

Liquefied petroleum (LP) gas is heavier than air.

Therefore, do not install heaters using LP gas in a pit or locations where gas might collect. Locate heaters a safe distance from LP gas storage and filling equipment. Consult local codes and fire protection authorities about specific installation restrictions.

2.8 Electrical Wiring

WARNING

Electrically ground the heater in accordance with the latest edition of the National Electrical Code, ANSI/ NFPA 70. In Canada, use C22.1. Do not rely on the gas or water piping to ground the metal parts of the heater. Often, plastic pipe or dielectric unions isolate the heater electrically. Service and maintenance personnel who work on or around the heater may be standing on wet floors and could be electrocuted by an underground heater.

1. Check heater wiring and pump for correct voltage, frequency, and phase. Check to make

2.7 Gas Supply and Piping

2.7.1 General Instructions

Review the following instructions before continuing the installation.

WARNING

The conversion of heaters from natural gas to propane gas, or propane to natural, must be done by a professional service technician. Laars provides kits and detailed instructions for converting the heater.

Changing burner and/or pilot orifices is prohibited.

The installer must add and sign a gas conversion tag when the conversion is made.

1. Gas piping installation must be in accordance with the latest edition of ANSI Z223.1. In Canada, the installation must be in accordance with CAN1-B149.1 or .2 and all local codes that apply.

2. Check the rating plate to make sure the heater is fitted for the type of gas being used. Laars heaters are normally equipped to operate below a 2000 foot (609 m) altitude. Heaters equipped to operate at higher altitudes have appropriate stickers or tags attached.

3. If a gas pressure regulator is required, the installation must be in accordance with the latest edition of ANSI Z223. In Canada, the installation must be in accordance with CAN1-B149.1 or .2 and all local codes that apply.

4. The figures in Table 5 should be used to size the gas piping from the gas meter to the heater.

5. Install a sediment trap (drip leg) ahead of the gas controls (see Figure 24 ). Fit the trap with a threaded cap which can be removed for cleaning.

6. Install a manual gas shutoff valve for service and safety. Check the local codes.

7. Disconnect the heater and its individual shutoff valve from the supply gas system during pressure test of the system at pressures higher than 1/2 psi (3.4 kPa).

8. Gas supply pressures to the heater are listed in Table 6.

NOTE: The heater and all other gas appliances sharing the heater gas supply line must be firing at maximum capacity to properly measure the inlet supply pressure. Low gas pressure could indicate an under-sized gas meter and/or obstructed gas supply line.

9. Do not exceed the maximum inlet gas pressures specified. Excessive pressure will result in damage to the heater's gas controls. The minimum pressures specified is for gas input adjustment.

Figure 25. Installation of tempering valve.

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WARNINGS

Vent pipes, drafthoods, and heater tops get hot!

These surfaces can cause serious burns. Do not touch these surfaces while the heater is in operation. Adding a vent cap reduces the temperature on the top.

For your safety, when starting the heater, keep your head and face well away from the lower firebox opening to prevent any risk of personal injury.

LP GAS: To avoid possible injury, fire and explosion, read and follow these precautions and all instructions on this heater before lighting. This heater uses LP gas which is heavier than air and will remain at ground level if there is a leak. Before lighting, sniff at ground level.

If you smell gas, follow these rules:

1. DO NOT light matches. DO NOT turn electric lights or switches on or off in area. DO NOT use an electric fan to remove the gas from area.

2. Shut off gas at LP tank.

3. Telephone gas company and fire department for instructions. Give your name, address and phone number.

If your LP tank runs out of fuel, turn off gas at the heater. After the tank is refilled, the heater must be relit in accordance with the instructions found on the inside of the heater. DO NOT attempt repairs on the gas control or heater. Tampering is dangerous and voids all warranties.

3.2 Start-Up Procedure

Lighting instructions can be found on the inside of the heater. To start up the heater:

1. Make sure the system pump is running and there is water flow.

2. Remove the control access panel.

3. Set the temperature control (see Figure 28) to its lowest setting.

4. Turn electric power to the appliance to off.

5. Turn manual gas valve off.

6. Wait 5 minutes to clear out any gas, then smell for gas, including near the floor. Be sure to smell next to the floor because some types of gas are heavier than air and will settle on the floor.

Caution This heater is equipped with an ignition device which automatically lights the burner. Do not try to light the burner by hand.

sure heater is wired for 120 volts alternating current (VAC). If 240 VAC, contact local factory representative or Laars.

2. Wire the heater and pump exactly as shown in the wiring diagram supplied with the heater. See Figure 26 and 27 for a typical example of a wiring diagram.

3. Electrically interlock the pump and heater so the heater cannot come on unless the pump is running.

4. Connect all field-installed devices (draft switches, relays, timers, outdoor temperature reset devices, etc.) (see Figures 26 and 27) to the heater wiring at points labeled Field Interlock.

2.9 Combined Space Heating/Potable

Water Heating Systems

2.9.1 Combined Space Heating

NOTE: These systems are not allowed in the

Commonwealth of Massachusetts.

Piping and components connected to this water heater for the space heating application shall be suitable for use with potable water.

Toxic chemicals, such as used for boiler treatment, shall not be introduced into the potable water used for space heating. Do not use solder containing lead in the potable water lines.

This water heater when used to supply potable water shall not be connected to any heating system or components(s) previously used with a non-potable water heating appliance.

When the system requires water for heating at temperatures higher than required for other uses, an anti-scald mixing or tempering valve (see figure

25) shall be installed to temper the water for those uses in order to reduce scald hazard potential.

Some jurisdictions may require a backflow preventer in the cold water line. In such cases, the temperature and pressure relief valve may discharge water due to expansion. A diaphragm type expansion tank will normally eliminate this condition. Follow the manufacturer's instructions for installation of the expansion tank.

SECTION 3.

Operating Instructions

3.1 Normal Operating Sequence

NOTE: Safe lighting and other performance criteria were met with the gas manifold and control assembly installed on the heater during tests specified in ANSI Z21.13.

LAARS Heating SystemsPage 18

Figure 26. Typical example of wiring schematic, System 1.

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Figure 27. Typical example of wiring schematic, System 12.

LAARS Heating SystemsPage 20 hot water in the application.

After a setting has been chosen for the tank temperature control, set the heater temperature control 10°F (6°C) higher. The heater’s temperature control senses the inlet water temperature to the heater. The heater’s manual reset high limit (and automatic reset high limit, if applicable) senses heater outlet temperature.

If the unit is equipped with an automatic reset high limit, set the automatic reset high limit 20°F (11°C) above the outlet temperature to avoid nuisance lockouts. Set the manual reset high limit 5°F (3°C) above the automatic reset high limit.

For units that only have a manual reset high limit (no automatic reset high limit), set the manual reset high limit 20°F (11°C) above the outlet temperature to avoid nuisance lockouts.

Example, Imperial units: If the tank temperature is set to 140°F, set the heater’s temperature control to 150°F (140°F + 10°F). Further, if the temperature rise through the heater is 25°F, the outlet temperature will be 175°F (150°F + 25°F). Therefore, set the automatic reset high limit to 195°F (170°F + 20°F), and the manual reset high limit to 200°F (195°F + 5°F).

Example, Metric units: If the tank temperature is set to 60°C, set the heater’s temperature control to 66°C (60°C + 6°C). Further, if the temperature rise through the heater is 15°C, the outlet temperature will be 81°C (66°C + 15°C). Therefore, set the automatic reset high limit to 92°C (81°C + 11°C), and the manual reset high limit to 95°C (92°C + 3°C).

3.3.2. Internal Water Heater Temperature

Control:

When an external control is not used, the circulator between the heater and the storage tank must run continuously, so that the heater’s temperature control can detect and control the water temperature in the storage tank. The water heater’s temperature control is adjusted to its lowest temperature position (130°F, 54°C) when shipped from the factory. This is the preferred starting point for setting the temperature control.

If the unit is equipped with an automatic reset high limit, set the automatic reset high limit 20°F (11°C) above the outlet temperature to avoid nuisance lockouts. Set the manual reset high limit 5°F (3°C) above the automatic reset high limit.

For units that only have a manual reset high limit (no automatic reset high limit), set the manual reset high limit 20°F (11°C) above the outlet temperature to avoid nuisance lockouts.

Example, Imperial units: If the heater’s temperature control is set to 130°F, and the temperature rise through the heater is 25°F, the outlet temperature will be 155°F (130°F + 25°F). Set the automatic reset high limit to 175°F (155°F + 20°F) and set the manual reset high limit to 180°F (175°F + 5°F).

Figure 28. Temperature controls.

7. Turn manual gas valve on.

8. Reset all safety devices (some units have manual resets on hi-limit switch, low water cutoff, etc.).

9. Set temperature control to desired setting.

10. Replace control access panel.

11. Turn electric power to the heater on.

12. If the heater will not operate:

a. Turn gas to heater off following the instructions found on the inside of the heater and call a qualified service technician or gas supplier.

b. Turn main electrical switch off.

c. Close all manual gas valves.

3.3 Setting the Temperature Controls

The hi-limit switch is factory set, and should not be adjusted above the factory setting.

WARNING

Adjusting the temperature control past the recommended setting can result in a scalding injury.

Hot water can produce third degree burns in 6 seconds at 140°F (60°C) and in 30 seconds at 130°F (54°C).

3.3.1. Remote Water Heater Temperature

Control:

The water heater can be used with a field-supplied tank aquastat, sequencing control, or other temperature control device, which will call the unit for heat when the temperature goes below the controller’s setpoint. For the most efficient setting, set the tank temperature at the lowest possible setting for adequate

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Electronic Pilot Standing Pilot

Figure 29. Flame patterns.

Example, Metric units: If the heater’s temperature control is set to 55°C, and the temperature rise through the heater is 14°C, the outlet temperature will be 69°C (55°C + 14°C). Set the automatic reset high limit to 80°C (69°C + 11°C) and set the manual reset high limit to 83°C (80°C + 3°C).

3.4 Adjustment for Minimum Input Rate

(models with modulating gas valve) Adjust the red knob on the modulating gas valve to the dial number for the desired water temperature (see Table 7).