Laars MIGHTY THERM2 - User Manual

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Installation and Operation Instructions Document 1211J

H2329100J

Hydronic Boiler

Model MT2H

Volume Water Heater

Model MT2V

Sizes 500–2000 MBTU/h

WARNING

If the information in this manual is not

followed exactly, a re or explosion may

result causing property damage, personal

injury or loss of life.

Do not store or use gasoline or other

ammable 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 re department.

Installation and service must be performed by

a qualied installer, service agency, or gas supplier.

AVERTISSEMENT

Assurez-vous de bien suivres les instructions

données dans cette notice pour réduire au

minimum le risque d’incendie ou d’explosion

ou pour éviter tout dommage matériel, toute

blessure ou la mort.

Ne pas entreposer ni utiliser d’essence ni

d’autres vapeurs ou liquides inammables dans

le voisinage de cet appareil ou de tout autre

appareil.

QUE FAIRE SI VOUS SENTEZ UNE ODEUR DE GAZ:

• Ne pas tenter d’allumer d’appareils.

• Ne touchez à aucun interrupteur. Ne pas vous servir

des téléphones dansle bâtiment où vous êtes.

• Appelez immédiatement votre fournisseur de

gaz depuis un voisin. Suivez les instructions du

fournisseur.

• Si vous ne pouvez rejoindre le fournisseur de

gaz, appelez le sservice des incendies.

L’installation et l’entretien doivent être assurés par

un installateur ou un service d’entretien qualié ou

par le fournisseur de gaz.

FOR YOUR SAFETY: This product must be installed and serviced by a professional service technician,

qualied in hot water boiler installation and maintenance. Improper installation and/or operation could

create carbon monoxide gas in ue gases which could cause serious injury, property damage, or death.

Improper installation and/or operation will void the warranty. For indoor installations, as an additional

measure of safety, Laars strongly recommends installation of suitable Carbon Monoxide detectors in the

vicinity of this appliance and in any adjacent occupied spaces.

Installation and Operation Instructions for

MIGHTY THERM2

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The Laars Mighty Therm2 is a series of hydronic boilers and volume water heaters, available in sizes ranging from 500 to 2000 MBTU/h. These appliances are designed for professional installation and service by qualified technicians. They are identical in their core design, with differences primarily in manufacturing materials, labels, and ultimate use application (boiler vs. water heater).

Function Description:

The Mighty Therm2 functions as either a hydronic boiler for space heating applications or a volume water heater for potable hot water systems. It utilizes a forced draft combustion air system with blowers to pull air and vent flue gases. The appliance features a pre-mixed burner system designed for complete combustion, minimizing soot buildup. It is protected against over-pressurization by a pressure relief valve installed on the outlet header. The unit can be configured for single-stage or two-stage firing, with models 1000-2000 MBTU/h typically having two ignition controls for independent stage operation.

Important Technical Specifications:

Sizes: 500, 750, 1000, 1250, 1500, 1750, 2000 MBTU/h input.
Fuel: Natural Gas or Propane.
Firing Mode: Two-stage.
Heat Exchanger: Glass-lined cast iron with copper/bronze trim (standard for water heaters) or copper (standard for boilers). Cupro-nickel options are also available.
Inlet Gas Pressure: Must not exceed 13" W.C. (3.2kPa). Minimum inlet gas pressure is 5" W.C. (1.2kPa).
Electrical: Single 120-volt fused supply for non-pump-mounted units and pump-mounted models 500-1500. Models 1750 and 2000 require two 120-volt fused supplies. Internal pump contact rated for 20 Amps.
Boiler Minimum Inlet Water Temperature: 120°F (49°C) to avoid condensing on copper coils.
Boiler Minimum Static Pressure: 12 psi (82.7kPa).
Combustion Air Intake Pipe: Single-wall galvanized pipe, 24 gauge minimum. Maximum linear pipe length allowed is 50 feet (15.2m), with 10 allowable linear feet (3.0m) subtracted for each additional elbow.
Horizontal Vent Pipe: Stainless steel (UL Standard 1738, Type 29-4C). Maximum linear pipe length allowed is 50 feet (15.2m), with 10 allowable linear feet (3.0m) subtracted for each additional elbow. Horizontal runs must slope downwards not less than ¼ inch per foot (2 cm/m).
Altitude Adjustment: Equipped to operate up to 10,000 feet (3050m), with input reduced above 2500 feet.
CO₂/O₂ Levels: Optimal combustion for Natural Gas is 8% CO₂ or 6.8% O₂. For LP Gas, 9.2% CO₂ or 6.8% O₂.

Usage Features:

Installation Location: Can be installed on combustible flooring, in basements, closets, utility rooms, or alcoves. Not suitable for carpeting. Should be located to provide clearances for maintenance and inspection, and to protect gas ignition system components from water.
Venting: Can be vented vertically (Category I fan-assisted) or horizontally (Category III). Vertical vent systems may require a barometric damper if chimney height exceeds 25 feet or multiple units are common vented. Horizontal vent terminals must be located at least 12" above grade and 3 feet horizontally from the combustion air terminal (if on the same wall).
Combustion Air: Can draw combustion air from the room or be ducted directly from outside. Room air requires permanent openings sized based on BTU/hr input. Ducted air requires specific wall terminals or roof-supplied rain caps/elbows.
Gas Supply: Gas train allows piping from either the right or left side. A sediment trap is required upstream of gas controls. Leak testing of gas connections is mandatory before operation.
Water Connections (Boiler): Requires a closed pressure system with a minimum 12 psi static pressure. Hot water piping should be supported independently of the appliance. Includes provisions for air purger, air vent, diaphragm-type expansion tank, and hydronic flow check. Minimum inlet water temperature of 120°F (49°C) is crucial to prevent condensation.
Water Connections (Water Heater): Pump-mounted units should be located within 15 feet (4.6m) of storage tank(s). Requires a listed temperature and pressure relief valve in the storage tank system. Water flow requirements are based on water hardness to prevent scaling and tube erosion.
Freeze Protection: Not recommended for outdoor installation in freezing climates unless proper precautions are taken. Antifreeze (non-toxic, max 50% concentration with anti-foamant) can be added to hydronic systems, but requires increased water flow and headloss.
Staging Control: Can be managed by the MT2's on-board controller or an external staging control (BAS).

Maintenance Features:

Annual Inspection: Recommended by a qualified service technician, including ignition controls, ignitors, water temperature control, automatic gas valve, pressure switches, and blowers.
Burner Inspection: Check for debris and proper combustion. Clean with compressed air if necessary.
Air Filter: Washable filter with 83% arrestance. Clean with mild soap and water when dirty; replace if unwashable or damaged.
Gas Valves: Designed for 4-13 inches w.c. supply pressures. O-rings must be properly installed during re-installation.
High Limit Control: Manual reset switch with adjustable set point (up to 240°F for boilers, 200°F for water heaters/low temp boilers).
Temperature Control: Honeywell L6008.
Ignitors/Sensor: 120v hot surface type. Replace with new ignitor gasket.
Heat Exchanger Coil: Inspect for black carbon soot buildup, which can be ignited. Dampen soot deposits with a wet brush or fine water spray before servicing. Inspect copper tubes for scale buildup and clean if necessary (Laars offers a tube cleaning kit).
System Maintenance: Lubricate circulating pump, clean strainers, inspect venting system for obstructions/leakage, keep appliance area clear of combustibles, drain system if not in use during freezing, check low water cutoffs, inspect flue passages, and reseal vent/air intake joints if Category III.
Troubleshooting: Common lockouts due to inadequate gas supply, poor combustion, or ignitor failure. Delayed ignition may indicate defective burners. Short cycling can be a symptom of improper control strategy, setpoints, or load distribution. High gas consumption often indicates improper air/fuel ratio.
Replacement Parts: Only genuine Laars replacement parts should be used. Available through Laars dealers/distributors or Customer Service.