A calefont (instantaneous water heater) provides hot water on demand for your home. When your calefont fails or becomes inefficient, replacement is necessary. This comprehensive guide will walk you through the entire calefont replacement process.

Before You Start: Planning and Preparation

Assess Your Current Calefont Evaluate your existing unit for age, performance issues, leaks, or insufficient hot water. Most calefonts last 10-15 years before needing replacement.

Understand Calefont Types

• Gas calefont: Uses natural gas or propane for heating
• Electric calefont: Uses electricity for heating
• Tankless water heater: Provides instant hot water without storage

Determine Your Needs Consider your household’s hot water demand, available fuel type, space constraints, and budget. Larger households may need higher capacity units.

Choose a Replacement Unit Select a calefont with appropriate capacity (measured in liters per minute for gas, or kilowatts for electric). Consider energy efficiency ratings and features.

Check Building Codes and Permits Contact your local building department. Most calefont replacements require permits, especially for gas units. Professional installation may be required by code.

Get Professional Help For gas calefont installation, hire a licensed plumber or gas technician. Gas work requires proper certification and safety precautions.

Tools and Materials You’ll Need

Tools:

• Adjustable wrench
• Pipe wrench
• Screwdriver set
• Drill/driver
• Tape measure
• Level
• Caulking gun
• Teflon tape
• Flashlight
• Safety glasses and gloves
• Bucket (for water drainage)

Materials:

• New calefont unit
• Flexible gas line or copper tubing (if needed)
• Water supply lines (copper or flexible)
• Teflon tape
• Pipe dope or thread sealant
• Mounting brackets
• Screws or anchors
• Caulk (if needed)
• Drain pan (optional but recommended)

Step-by-Step Calefont Replacement Process

Step 1: Turn Off Utilities

Gas Supply:

• Locate the gas shut-off valve
• Turn the valve clockwise to close
• Verify gas is off by attempting to light a burner

Water Supply:

• Locate the main water shut-off valve
• Turn the valve clockwise to close
• Open a faucet to release pressure

Electricity (Electric Units):

• Turn off the circuit breaker for the water heater
• Verify power is off with a voltage tester

Step 2: Drain the Old Calefont

• Attach a hose to the drain valve (if present)
• Direct water to a drain or bucket
• Open the drain valve and allow water to flow out
• Close the drain valve once empty
• Some units may not have drain valves—be prepared for water spillage

Step 3: Disconnect Water Lines

• Use a wrench to disconnect the cold water inlet line
• Use a wrench to disconnect the hot water outlet line
• Have a bucket ready to catch residual water
• Cap the water lines to prevent debris entry
• Keep track of connection types and sizes

Step 4: Disconnect Gas Line (Gas Units Only)

• Use a wrench to disconnect the gas line
• Cap the gas line to prevent gas leaks
• Have a professional handle this step if unsure
• Never force connections—use proper wrenches

Step 5: Disconnect Electrical (Electric Units Only)

• Verify power is off with a voltage tester
• Disconnect the electrical wires
• Take photos of wire connections for reference
• Cap or insulate wire ends
• Have a licensed electrician handle this if unsure

Step 6: Remove the Old Unit

• Locate mounting brackets or fasteners
• Remove screws or bolts securing the unit
• Carefully lower the unit from the wall
• Have a helper support the unit during removal
• Dispose of the old unit properly (recycling center or scrap metal)

Step 7: Prepare the Installation Area

• Clean the wall where the unit was mounted
• Inspect the wall for damage or moisture
• Repair any damage before installing new unit
• Ensure the wall is level and suitable for mounting
• Install a drain pan if desired (recommended for safety)

Step 8: Install Mounting Brackets

• Position mounting brackets on the wall
• Ensure brackets are level and secure
• Use appropriate fasteners for your wall type (anchors for drywall, bolts for masonry)
• Brackets should support the weight of the filled unit
• Test bracket security before hanging the unit

Step 9: Mount the New Calefont

• Carefully position the new unit on the brackets
• Ensure the unit is level
• Secure the unit with fasteners if required
• Verify the unit is stable and secure
• Do not overtighten fasteners

Step 10: Connect Water Lines

Cold Water Inlet:

• Wrap the inlet connection with Teflon tape (3-4 wraps)
• Apply pipe dope or thread sealant
• Connect the cold water line using a wrench
• Tighten firmly but don’t overtighten
• Check for leaks once water is turned on

Hot Water Outlet:

• Wrap the outlet connection with Teflon tape
• Apply pipe dope or thread sealant
• Connect the hot water line using a wrench
• Tighten firmly but don’t overtighten
• Check for leaks once water is turned on

Step 11: Connect Gas Line (Gas Units Only)

Important: Have a licensed gas technician perform this step

• Wrap the gas connection with Teflon tape
• Apply pipe dope rated for gas
• Connect the gas line using a wrench
• Tighten firmly but don’t overtighten
• Test for gas leaks using soapy water (bubbles indicate leaks)
• Never use a flame to test for leaks
• Have the system inspected by a professional

Step 12: Connect Electrical (Electric Units Only)

Important: Have a licensed electrician perform this step

• Verify power is still off
• Connect wires according to manufacturer’s instructions
• Use wire nuts or appropriate connectors
• Ensure all connections are secure
• Turn on the circuit breaker
• Test the unit for proper operation

Step 13: Turn On Water Supply

• Slowly open the main water shut-off valve
• Open a hot water faucet to bleed air from the lines
• Allow water to flow until steady (no sputtering)
• Close the faucet
• Check all connections for leaks
• Tighten any leaking connections slightly

Step 14: Turn On Gas Supply (Gas Units Only)

• Slowly open the gas shut-off valve
• Allow gas to flow for a moment
• Follow manufacturer’s instructions for ignition
• Light the pilot light (if applicable)
• Verify the burner ignites properly
• Check for gas leaks using soapy water

Step 15: Test the Unit

• Turn on a hot water faucet
• Allow water to flow for 1-2 minutes
• Verify hot water reaches the faucet
• Check water temperature (should be adjustable)
• Test multiple faucets to ensure proper operation
• Monitor the unit for leaks or unusual sounds

Step 16: Adjust Settings

• Set the water temperature to desired level (typically 120°F/49°C)
• Consult the manual for adjustment procedures
• Test temperature at various faucets
• Make adjustments as needed

Step 17: Final Inspection

• Check all connections for leaks
• Verify the unit is secure and level
• Ensure proper ventilation (gas units)
• Check that all safety features are functioning
• Review the manual for maintenance requirements

Gas Calefont Installation: Special Considerations

Ventilation:

• Gas units require proper ventilation to the outside
• Ensure the flue pipe is properly connected
• Verify no blockages in the vent
• Check that the vent terminates outside safely

Safety:

• Install a carbon monoxide detector nearby
• Ensure proper clearance around the unit
• Keep flammable materials away from the unit
• Have the system inspected by a professional

Electric Calefont Installation: Special Considerations

Electrical Requirements:

• Verify adequate circuit capacity
• May require a dedicated circuit
• Ensure proper grounding
• Have a licensed electrician verify installation

Water Pressure:

• Electric units may require minimum water pressure
• Check manufacturer’s specifications
• Install a pressure regulator if needed

Pro Tips for Successful Calefont Replacement

✓ Hire professionals for gas work. Gas installation requires certification and expertise. Don’t attempt this yourself.

✓ Use Teflon tape and pipe dope. These create watertight seals and prevent leaks.

✓ Don’t overtighten connections. This can damage threads and cause leaks. Tighten firmly, then stop.

✓ Bleed air from water lines. Air in the lines causes sputtering and reduces performance.

✓ Test for leaks immediately. Address any leaks before closing up the installation.

✓ Follow manufacturer’s instructions. Each unit has specific requirements and procedures.

✓ Keep the manual. You’ll need it for maintenance, troubleshooting, and warranty information.

✓ Install a drain pan. This catches leaks and prevents water damage to walls and floors.

✓ Schedule regular maintenance. Descaling and inspection extend unit life and maintain efficiency.

Common Calefont Replacement Mistakes to Avoid

✗ Attempting gas work without proper certification ✗ Not using Teflon tape on connections ✗ Overtightening connections ✗ Failing to bleed air from water lines ✗ Not testing for leaks ✗ Improper ventilation (gas units) ✗ Ignoring building codes and permits ✗ Using incorrect pipe sizes ✗ Not following manufacturer’s instructions ✗ Skipping safety inspections

When to Call a Professional

• Gas calefont installation (required by code)
• Electrical work (if not experienced)
• Structural modifications
• Ventilation or flue work
• If you’re unsure about any step
• For warranty and safety compliance

Timeline Expectations

Professional Installation: 2-4 hours DIY Installation (Electric): 3-6 hours Gas Installation: Must be done by professional (2-4 hours)

Cost Considerations

Unit Costs:

• Gas calefont: $300-$800
• Electric calefont: $200-$600
• High-efficiency units: $800-$1,500+

Installation Costs:

• Professional installation: $200-$500
• Permits and inspections: $50-$200

Total Project Cost: $500-$2,000+

Maintenance Tips

• Descale the unit annually (in hard water areas)
• Check connections regularly for leaks
• Verify proper ventilation (gas units)
• Test temperature and pressure relief valve
• Keep the area around the unit clear
• Have the system inspected annually

Conclusion

Replacing a calefont is an important home maintenance task that ensures reliable hot water supply. While professional installation is recommended for gas units, understanding the process helps you communicate with contractors and ensure proper installation. With proper planning, quality materials, and professional help when needed, you can successfully replace your calefont and enjoy years of reliable hot water.

Have you replaced your calefont? Share your experience, unit choice, or tips in the comments below!

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Disclaimer: This guide is for informational purposes. Always hire licensed professionals for gas and electrical work. Follow local building codes and manufacturer’s instructions. Improper installation can be dangerous and void warranties.