Laars FTHW FT-Series Wall-Mounted Condensing Boiler User Manual

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Laars FTHW FT-Series Wall-Mounted Condensing Boiler Manual

The laars FTHW FT-Series Wall-Mounted Condensing Boiler is a wall-hung, modulating gas boiler designed for residential hydronic heating systems. Its sealed-combustion design, high-efficiency condensing operation, and fully modulating burner help match heat output to changing demand rather than operating only at full fire.

The FTHW series is available in 100,000, 140,000, and 199,000 BTU/h input models. Natural gas is the factory configuration, while field conversion to propane is supported when performed according to the installation instructions by a qualified professional. The boiler is intended for indoor installation and can serve homes, additions, replacement heating systems, and multi-zone hydronic applications.

Key benefits include compact wall-mounted installation, direct sealed combustion, flexible venting, and controls intended to support stable water temperatures. The condensing heat exchanger can recover additional heat from flue gas when the system operates with sufficiently low return-water temperatures. This makes the unit particularly suitable for modern baseboard, radiant-floor, panel-radiator, and other hydronic systems designed for efficient low-temperature operation.

This guide explains the main specifications, setup process, operating precautions, troubleshooting approach, and practical advantages and limitations of the boiler. Installation, gas conversion, combustion adjustment, electrical work, and service must be completed by a qualified heating professional.

Laars FTHW FT-Series Specifications and Features

Product type: Wall-mounted, modulating gas, condensing, heating-only boiler.
Available input ratings: 100,000, 140,000, and 199,000 BTU/h models.
Fuel: Natural gas from the factory; field conversion to propane is available when completed using the approved conversion procedure.
Installation: Indoor, wall-hung installation with sealed combustion.
Combustion arrangement: Direct-vent configuration using separate combustion-air and flue connections.
Venting: Approved 2-inch or 3-inch vent systems are used according to model, vent material, equivalent length, and installation conditions. Consult the exact manual before selecting components.
Operating environment: The published operating ambient range is approximately -10 to 60°C.
Burner control: Fully modulating operation adjusts firing rate to heating demand.
Heat exchanger: Condensing design intended to recover latent heat when return-water temperature allows condensation.
Controls: Built-in boiler controls monitor operating conditions and provide status or fault information through the appliance interface.
Applications: Residential hot-water heating systems, including multiple heating zones when correctly designed and hydraulically balanced.

Exact water connections, minimum flow requirements, clearances, electrical ratings, vent limits, and efficiency values vary by model and installation configuration. Always use the rating plate and the current Laars installation and operating manual for final design decisions.

How to Set Up the Laars FTHW Boiler

Confirm the installation location. Choose an indoor wall that can support the boiler and allows the clearances required for service, combustion air, venting, piping, and drainage.
Verify fuel and model information. Confirm whether the appliance is configured for natural gas or has been properly converted for propane. Never operate the boiler with an unverified fuel setup.
Install the mounting hardware. Secure the boiler using the approved mounting method. Do not rely on drywall or unsuitable anchors alone.
Connect the hydronic circuit. Install supply and return piping, isolation valves, pressure relief protection, expansion equipment, air elimination, and system fill components according to the system design.
Install the vent and air pipes. Use only approved materials and routing. Keep terminations away from openings, combustion hazards, and locations where condensate or exhaust could cause damage.
Connect power and controls. A qualified electrician or heating technician should connect the boiler to the correct electrical supply and wire thermostats, zone controls, pumps, and any approved outdoor-reset or system-control devices.
Fill and purge the system. Remove air, check operating pressure, inspect every connection for leaks, and confirm that condensate drainage is open.
Commission the appliance. The technician must verify gas pressure, ignition, combustion, temperature operation, safety controls, and applicable high-altitude settings before handover.

Do not attempt to pair the boiler with unrelated wireless accessories unless the accessory and connection method are specifically approved for the installation. If ignition fails, turn off the appliance and contact a qualified service technician rather than repeatedly resetting it.

FTHW Boiler Troubleshooting Guide

No heat: Check the thermostat setting, electrical supply, service switches, system pressure, and whether another control is preventing a call for heat. A technician should inspect pumps, sensors, and wiring if the call is present but the burner does not start.
Ignition or flame failure: Confirm that the gas service valve is open and that other gas appliances operate normally. Do not adjust the gas valve or ignition components without combustion-testing equipment and the required qualifications.
Low system pressure: Look for visible leaks and confirm that the fill and expansion components are functioning. Repeated pressure loss requires professional diagnosis.
Overheating or rapid cycling: Restricted flow, closed valves, air in the system, incorrect pump operation, or an undersized heating circuit may be responsible. Turn off the boiler if pressure or temperature rises abnormally.
Condensate drainage problem: Inspect the drain for blockage, freezing, poor slope, or improper termination. Never remove safety devices or bypass a condensate switch.
Vent or air fault: Check for blocked terminations, damaged piping, snow, ice, debris, or an installation outside the approved length and material limits.
Displayed fault code: Record the exact code and appliance status, then consult the model-specific installation manual. Fault codes and corrective procedures can differ by control revision.

Before servicing, shut off gas and electrical power when instructed, allow hot components to cool, and follow lockout procedures. Keep maintenance records and arrange periodic inspection by a qualified service agency. For technical help, contact the installing contractor or Laars customer support through the official Laars website and provide the model, serial number, displayed fault code, fuel type, and installation location. Warranty coverage depends on the applicable product terms and proper installation, commissioning, and maintenance.

Pros and Cons of the Laars FTHW FT-Series Boiler

Advantages

Efficient condensing operation: Low return-water temperatures can allow the heat exchanger to recover additional heat from combustion exhaust.
Modulating output: The burner can reduce firing rate as demand falls, which may improve temperature stability and reduce unnecessary cycling compared with basic on/off boilers.
Space-saving format: Wall-mounted installation is useful in mechanical rooms, utility areas, and replacement projects where floor space is limited.
Sealed combustion: Direct venting separates combustion from indoor room air when installed correctly.
Multiple sizes: The 100,000, 140,000, and 199,000 BTU/h range supports different residential heat-load requirements.
Fuel flexibility: The product line supports natural gas and approved propane conversion procedures.

Limitations

Professional installation required: Gas, venting, combustion, condensate, and hydronic controls demand specialized knowledge and testing.
System design affects efficiency: A high-temperature system or excessive return-water temperature can reduce condensing benefits.
More components than a conventional boiler: Venting, condensate drainage, sensors, pumps, and controls require appropriate inspection and maintenance.
Not a domestic hot-water combi model: The FTHW is a heating-only boiler, so domestic hot water requires a compatible indirect tank or separate water-heating system.

The FTHW is best suited to homeowners and contractors seeking a compact, modulating heating-only boiler for a properly designed hydronic system. A different product may be more appropriate when integrated domestic hot water, simpler atmospheric venting, or a floor-standing installation is required.

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Faqs

How should the laars FTHW FT-Series Wall-Mounted Condensing Boiler be installed and configured for the first time?

Initial installation should be completed by a qualified heating professional because the boiler requires correct wall mounting, gas and water connections, venting, condensate drainage, electrical wiring, and combustion checks. The installer must confirm the fuel type, system pressure, safety controls, and circulation arrangement before firing the unit. After filling or draining the system, the complete setup procedure should be followed rather than simply turning the boiler on. Keep the installation and operating manual available for commissioning and future service.

What wall, venting, and utility requirements should be checked before installing a laars FTHW FT-Series Wall-Mounted Condensing Boiler?

Choose a wall and mounting surface capable of supporting the boiler and associated piping. The wall bracket and lower anchors must be secured correctly, with the boiler fully seated on the mounting hooks. A qualified installer should verify approved vent and intake materials, termination clearances, condensate disposal, gas piping, electrical supply, and water connections for the exact model. Do not substitute components or route venting by guesswork, since incorrect combustion-air or exhaust installation can create unsafe operating conditions.

Can the laars FTHW FT-Series Wall-Mounted Condensing Boiler be converted from natural gas to propane?

The FTHW model is factory-configured for natural gas and may be field-convertible to propane, but conversion must follow the exact manufacturer procedure for the installed model. A qualified gas technician should install the approved conversion components, verify gas pressure, adjust combustion, update identification information, and test the boiler under operating load. Never change fuel type by adjusting valves or controls alone. Confirm the boiler rating plate and installation manual before ordering parts or beginning any conversion.

What should I do if the laars FTHW FT-Series Wall-Mounted Condensing Boiler shows an ignition fault?

Read the displayed fault and note when it occurs before resetting the boiler. Check only safe, user-accessible items, such as whether the gas service valve is open, the electrical disconnect is on, and the system has not been intentionally shut down. If the fault returns after a single reset, stop operating the unit and contact a qualified service technician. Do not open the combustion chamber, bypass safety switches, or repeatedly reset an ignition failure, especially if gas odor is present.

How can I use the control display on the laars FTHW FT-Series Wall-Mounted Condensing Boiler?

Use the control dial and buttons to view operating information, change permitted temperature set points, and review status parameters. The display can also show operating mode and fault information, while installer-level settings may include outdoor reset and external set-point control. Avoid changing installer parameters unless the service technician has provided specific instructions, because incorrect values can reduce comfort, increase cycling, or affect safety. Record existing settings before any authorized adjustment so they can be restored if needed.

Why does the laars FTHW FT-Series Wall-Mounted Condensing Boiler cycle frequently or fail to maintain the desired temperature?

Frequent cycling can result from an incorrect temperature setting, inadequate water flow, air in the heating system, restricted filters, poor circulation, improper outdoor-reset settings, or a mismatch between boiler output and system demand. Check the display for active faults and confirm that thermostats and zone controls are requesting heat. Do not alter gas or combustion settings to solve cycling. A qualified technician should verify pump operation, system pressure, flow, sensor readings, and control configuration.

What maintenance does the laars FTHW FT-Series Wall-Mounted Condensing Boiler require?

Arrange professional inspection and startup maintenance at least annually, or more often when required by local conditions and the service manual. Maintenance typically includes checking combustion, gas pressure, venting, condensate drainage, electrical connections, safety devices, system pressure, and heat-exchanger condition. The system may also require flushing when contamination or scale is present. Keep the area around the boiler clear, never block air openings, and report unusual noise, leaking water, corrosion, or repeated faults promptly.

How should I protect the laars FTHW FT-Series Wall-Mounted Condensing Boiler during a power outage or freezing weather?

The boiler and connected heating system need protection from freezing, particularly during extended power outages or when the building is unoccupied. Follow the manual’s freeze-protection instructions and ask a qualified technician whether system water should contain an approved heating-system antifreeze. Do not rely on the boiler’s controls when electrical power is unavailable. If the system must be drained, the complete setup and refill procedure should be performed before restarting, including purging air and checking pressure.

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