Installing a point-of-use tankless water heater is one of the highest-return DIY plumbing projects you can tackle in a Canadian home. You eliminate cold-water wait time, cut standby energy loss, and free up under-sink space — all in an afternoon. This guide covers everything from the tools you need to final testing, so you can do it right the first time.
Tools and Materials You Will Need
Before you start, gather everything on the bench. Nothing slows a plumbing job down faster than mid-install hardware runs.
- Adjustable wrench (or basin wrench for tight under-sink spaces)
- Pipe cutter or hacksaw — for trimming supply lines to length
- PTFE (Teflon) tape — 3 wraps on every threaded male fitting
- Flexible braided supply lines — 3/8" compression fittings for most under-sink connections
- Wire strippers and screwdriver — for electrical connections (220V units)
- Voltage tester / multimeter — confirm power is OFF before touching any wire
- Drill and wall anchors — for wall-mount units
- Bucket and towel — to catch residual water when disconnecting supply lines
The TapHeat 3.5kW Mini (120V) ships with mounting hardware included. Higher-wattage units like the 5.5kW bathroom heater and 6kW touch-screen model require a dedicated 220V/240V circuit — confirm your panel has capacity before purchasing.
Step 1: Turn Off the Water Supply
Locate the shut-off valve under the sink (or at the main if there is no dedicated valve). Turn it clockwise until it stops. Open the existing tap to bleed remaining pressure. Hold a bucket under the supply line before disconnecting — there will be residual water.
Safety rule: Never work on a pressurized line. Even a momentary burst at a loose fitting will soak your cabinet and create a water damage claim.
Step 2: Turn Off the Electrical Circuit
Go to your electrical panel and switch off the circuit breaker for the outlet or circuit you are using. For 120V units: find the outlet circuit. For 220V units: find the double-pole breaker for the dedicated circuit.
Use your voltage tester at the outlet or wire ends to confirm zero voltage before touching anything electrical. This step is non-negotiable.
Step 3: Remove the Existing Fixture or Water Heater
If replacing an old tank heater, disconnect the cold-water inlet line and the hot-water outlet line. Drain residual water from the tank. Remove mounting brackets and set aside for disposal.
If installing fresh: simply disconnect the cold-water supply line from the fixture. The heater will sit in-line between the supply valve and the tap.
Step 4: Mount the Unit
Under-sink models: Identify the mounting bracket holes on the back of the unit. Hold it against the cabinet interior wall, mark the drill points, and anchor with the supplied screws. Most TapHeat under-sink units mount in 10 minutes — the cabinet backing is typically particle board, so use the included plastic anchors for a solid hold.
Wall-mount models: Use a stud finder to locate wall studs if possible. If mounting to drywall only, use toggle bolts rated for the unit weight (typically 4–6 kg). Level is important — the unit houses a flow sensor that works best plumb.
Step 5: Connect the Cold-Water Inlet
Most point-of-use heaters have a 1/2" NPT or 3/8" compression inlet. Wrap male threads with 3 layers of PTFE tape, clockwise. Hand-tighten first, then snug with a wrench — do not overtighten ceramic fittings. The inlet is typically labelled with a blue dot or "IN" marking.
Connect the flexible braided supply line from the shut-off valve to the heater inlet. The same PTFE and snug-not-cranked rule applies at both ends.
Step 6: Connect the Hot-Water Outlet
Run the outlet line from the heater to the faucet supply port (hot side). Same fittings, same PTFE process. On under-sink models, the outlet is typically the upper port, labelled "OUT" or with a red dot.
Keep outlet lines as short as practical — every inch of pipe between the heater and the tap is heat you are paying to maintain.
Step 7: Make the Electrical Connection
120V plug-in units (e.g., TapHeat 3.5kW Mini): Simply plug into the outlet in the cabinet. Done.
220V hardwired units: This step requires comfort with residential electrical work. If you are not comfortable, hire a licensed electrician for this step only — the plumbing you can still do yourself, and the electrical hookup is a 30-minute job for a pro. For DIYers:
- Confirm breaker is off and verify zero voltage at the wire ends.
- Strip 15mm of insulation from each wire.
- Connect black wire to one terminal, white wire to the other. Green or bare copper connects to the ground terminal.
- Torque terminals to the specification on the unit label — loose terminals cause arcing and fire.
- Close the junction box cover before restoring power.
Step 8: Restore Water, Check for Leaks
Open the shut-off valve slowly. With the heater unpowered, run the tap at the fixture and watch every connection point for 60 seconds. A drip at a fitting means turn off the water and snug the connection a quarter-turn. Do not power the unit until you have zero drips.
Step 9: Power On and Set Temperature
Restore the circuit breaker. The unit will initialize — most TapHeat models display the set temperature on the LED panel. The factory default is typically 45°C, which is adequate for handwashing. For kitchen use, 50–55°C is preferred. For a dedicated bathroom shower unit, do not exceed 50°C to prevent scalding.
Run the tap at full cold for 10 seconds to purge any air from the lines, then test hot water. It should arrive within 3–5 seconds at the fixture.
Common Mistakes to Avoid
- Undersizing the unit. Match the GPM rating to the fixture. A 1.5 GPM unit cannot supply adequate flow for a full shower — use it for sinks only.
- Skipping PTFE tape. Thread sealant on every male NPT fitting is mandatory, not optional. Dry-threaded fittings will weep within months.
- Powering on a dry unit. Never energize a tankless heater without water flowing through it. The heating element will overheat and fail. Most units have a dry-fire protection sensor, but do not rely on it.
- Wrong voltage. A 220V unit plugged into a 120V outlet will not heat effectively and may trip the breaker repeatedly.
Ready to Start?
Browse the full TapHeat tankless water heater collection — all models ship with installation hardware and a printed quick-start guide. Free shipping across Canada on every order.