Worcester FKT Series Installation Instructions Manual

The Worcester FKT Series comprises high-efficiency condensing gas boilers designed for central heating and domestic hot water. This manual provides essential instructions for safe installation, commissioning, and initial setup. It is intended for qualified heating engineers only. Incorrect installation can lead to property damage, injury, or invalidate the warranty. Read all instructions before proceeding.

Safety Information & Warnings

Installation must comply with local regulations (e.g., GB in the UK: Gas Safety (Installation and Use) Regulations, BS 6798, Building Regulations).

WARNING! This appliance must be installed by a Gas Safe Registered engineer (UK) or equivalently qualified professional. Ensure gas supply is isolated before beginning work. Do not install in rooms containing a bath or shower unless a room-sealed flue is used.

Package Contents & Specifications

Unpack and verify all components are present and undamaged.

• Model Range: FKT 1, FKT 2, FKT 3 (outputs vary).
• Boiler Unit: Main heat exchanger body with integrated pump.
• Flue Kit: Concentric flue components (lengths as ordered).
• Fittings Pack: Wall mounting bracket, template, screws, sealing washers.
• Condensate Trap & Hose: Pre-assembled.
• Type: Room-sealed, fan-assisted, condensing gas boiler.
• Fuel: Natural Gas (G20) or LPG (conversion kit required).
• Efficiency: ErP rating A for heating and hot water.
• Max Working Pressure: 3 bar (central heating).
• Electrical Supply: 230V ~ 50Hz, 1A fuse.

Pre-Installation Planning

Select a suitable location adhering to clearance distances for servicing and ventilation.

1. Location: Fixed to a solid, vertical wall. Ensure sufficient space for flue terminal termination (refer to flue guidelines).
2. System Compatibility: Ensure existing system is clean and free from sludge. A magnetic system filter is mandatory.
3. Water Quality: Must comply with BS 7593. Use inhibitor after installation.
4. Condensate Drain: Plan a route to a soil stack, internal drain, or condensate pump.

CAUTION! Do not install in frost-prone areas without protection. The boiler must be level when mounted.

Mounting & Positioning

1. Use the supplied paper template. Mark the positions of the mounting bracket screw holes and the central flue hole.
2. Drill holes and secure the bracket to the wall using suitable wall plugs and screws.
3. Lift the boiler onto the bracket until it clicks securely into place.
4. Ensure a minimum clearance of 5mm around gas and water pipes. Maintain 50mm clearance below for condensate connection.

WARNING! The boiler is heavy. Use appropriate lifting techniques or a second person.

System Pipework Connections

Connect to the labelled ports on the underside of the boiler: Gas (G), Central Heating Flow (CH ➜), Central Heating Return (CH ➜), Cold Water Inlet (CW), Hot Water Outlet (HW).

1. Isolate the water supply and drain the existing system if applicable.
2. Fit isolating valves on all connections for future servicing.
3. Use PTFE tape or jointing compound on threaded connections. Do not overtighten.
4. Install a magnetic system filter on the return pipe, as close to the boiler as possible.

NOTICE: Pipework must be supported independently of the boiler. Use copper or approved plastic pipe.

Flue & Air Supply

The boiler MUST be installed with the approved concentric room-sealed flue system.

WARNING! Incorrect flue installation is extremely dangerous, risking carbon monoxide poisoning. Follow the separate flue installation guide precisely.

Gas & Electrical Connections

Gas: Connect to the boiler's 22mm male threaded connection using an approved gas hose or rigid pipe. Test for soundness after connection. The gas governor and meter must be sized appropriately for the boiler's input rate.

Electrical:

1. Connect a fused 3A spur near the boiler.
2. Run a 3-core cable (Live, Neutral, Earth) from the spur to the boiler's terminal block (L, N, E).
3. Connect external controls (room thermostat, programmer) to the low voltage terminals as per the wiring diagram inside the front cover.

CAUTION! Electrical work must comply with IET Wiring Regulations (BS 7671). Ensure correct polarity and earth continuity.

Filling & Pressurising the System

For sealed systems only (combi models).

1. Open all manual air vents on radiators.
2. Connect the filling loop (if not integrated) between the cold mains and system return.
3. Open both valves on the filling loop slowly. Listen for water entering the system.
4. Watch the pressure gauge on the boiler. Fill to 1.0 - 1.5 bar when the system is cold.
5. Close the filling loop valves and remove the loop if temporary.
6. Bleed radiators until water flows steadily, then re-check pressure. Top up if necessary.

Initial Commissioning

1. Ensure all isolation valves are open, system is pressurised, and gas supply is on.
2. Switch on the electrical supply at the spur. The boiler display will illuminate.
3. Set the front control dial to the reset/commissioning position (see control panel guide).
4. The boiler will run through a purge sequence. You must then set the maximum gas rate using a combustion analyser in the service menu to meet manufacturer's specifications.
5. Check for leaks at all connections. Verify correct operation of heating and hot water.
6. Add a suitable corrosion inhibitor to the system via a radiator or filling loop.
7. Handover: Explain basic operation to the user and leave this manual with them.

Control Panel Overview

Front panel consists of: Digital display, Power/Reset button, Mode selector dial, Temperature adjustment buttons (+/-).

Use the mode dial to select: OFF, HOT WATER ONLY, HEATING ONLY, HOT WATER & HEATING. Temperature is set with the +/- buttons.

Troubleshooting & Error Codes

Reset: For lockout faults, turn the boiler off at the spur for 30 seconds, then back on. If the fault persists, consult a qualified engineer.

Service & Support: For technical assistance, contact Worcester Bosch Technical Helpline or visit www.worcester-bosch.co.uk. Always quote the boiler's GC number and serial number.