Installing an under-sink water heater is a straightforward project that can provide instant hot water right where you need it. This on-demand system delivers hot water quickly without needing a tank or large storage unit under the sink.
An under-sink water heater can save space, energy, and money while giving you instant access to hot water for washing dishes, hands, or food. This article will show you how to install one in just 5 easy steps.
Benefits of Under-Sink Water Heaters
Here are some of the biggest benefits that under-sink water heaters offer:
- Endless Hot Water – Get instant hot water whenever you need it without running out or waiting for a tank to recover. These units heat water on demand.
- Energy Efficient – Only heat water when needed rather than keeping an entire tank hot 24/7. This saves a significant amount on energy bills.
- Space Saving – Compact size installs neatly under your sink to free up room compared to larger tank water heaters.
- Lower Upfront Cost – More affordable price point than whole house tankless systems.
- Simple Installation– Hooks up to your sink, water supply, and electricity easily with common tools.
Now let’s go through the installation process step-by-step:
Step 1: Gather Tools and Materials
Installing an under-sink water heater is generally a two-person job.
You will need to gather the following tools:
- Adjustable wrenches
- Pipe wrenches
- Teflon tape
- Emergency shut-off valve
- Sink hookup hardware
- Electric drill and bits
Safety gear:
- Work gloves
- Safety goggles
Materials/Parts:
- Under-sink water heater unit
- Water supply lines/hoses
- Shut off valve
- Pipe joint compound/paste
- Quick connect fittings
- Electrical wire nuts
- Strain reliefs
- Wood screws or self-tapping screws
Ensure you have all the necessary tools, safety gear, and materials before beginning.
Step 2: Turn Off Water Supply and Electricity
Before installing the under-sink water heater:
- Locate the main water shut-off valve for your house and turn off the water supply
- Find the electrical circuit breaker that powers the kitchen sink and switch it OFF
Turning off water and power is crucial to safely work on the water heater.
Step 3: Mount and Connect Water Heater
Follow this process to mount the under-sink water heater and connect it to the water supply lines:
- Choose installation location – Select an area under your sink with enough space for the compact water heater, ideally close to existing water lines. Be sure a three-prong electrical outlet is accessible nearby.
- Mark and drill mounting holes – Use a pencil to mark the bracket holes on your determined mounting spot. Take measurements. Drill holes into wall/cabinet using properly sized drill bit.
- Secure mounting bracket – Line up holes on bracket with newly drilled holes in cabinet/wall. Insert wood screws through the holes to firmly mount the bracket.
- Hang water heater – Pick up water heater and hang it on the installed bracket by lining up openings. Make sure it sits evenly.
- Connect hot/cold water lines – Use flexible water supply lines to connect to dedicated hot water line on one side of heater and cold water line on the other:
a. Hot water line connects from water heater output to sink hot water hookup
b. Cold water line runs from the off valve to water heater inlet - Install shut off valve – Place a shut off valve on the cold water supply line at an easily accessible point. This enables turning off water to the heater for maintenance.
Use pipe joint compound on all connections and firmly tighten with a wrench.
Double-check that the hot water line goes to the hot water hook-up on the sink faucet!
Step 4: Wire and Connect Electricity
With the water heater mounted and plumbed, wire it to electricity:
- Run cable from electric outlet to water heater
- Secure cable firmly using a strain relief
- Use wire nuts to connect:
- Ground wire to green grounding screw
- Hot wire to black input wire
- Neutral wire to white input wire
- Make snug electrical connections
- Allow the unit to hang freely so no pinching occurs
- Return power to outlet circuit breaker
Be sure that you follow all local building codes for approved electrical wiring methods. Consult an electrician if needed.
Step 5: Test and Confirm Operation
Before using your new under-sink water heater:
- Turn water supply back on slowly
- Check carefully for leaks on water connections and fix any drip or leak
- Turn on hot water tap
- Allow unit to run until hot water flows from the tap
- Feel water to confirm it has reached an appropriately hot temperature
- Adjust temperature dial on the unit if needed
- Inspect that all connections remain leak free
- Your under-sink water heater should now supply on demand hot water when the tap is opened!
Enjoy instant endless hot water from your sink now that the under-sink heater is properly installed.
Troubleshooting Under-Sink Water Heaters
Here are solutions to common problems with under-sink water heater installations:
No hot water:
- Verify unit has power and breaker/outlet is turned on
- Check if overheating protection activated and needs reset
- Try adjusting temperature setting higher
Not enough hot water flow:
- Make sure shut off valves are fully open
- Check for kinks or bends in supply lines
- Verify water pressure meets unit minimum requirement
Leaking water:
- Tighten connections gently
- Reapply pipe compound to threads
- Replace worn gaskets or seals
- Check for cracks in supply lines
Not heating water:
- Confirm power is still connected properly
- Test heating mechanism and replace if faulty
- Inspect wiring for damage or corrosion
- Check if flow rate is too high for unit
If problems persist, contact manufacturer support for additional troubleshooting or service assistance.
Professional plumbing or electrical help may be needed in some situations.
Conclusion
Installing an under-sink water heater is an easy, convenient upgrade that can be completed in 5 main steps:
- Gather necessary tools and materials
- Shut off water and power
- Mount unit and connect to sink
- Wire and connect electricity
- Test operation
Following proper safety procedures throughout allows even novice DIYers to enjoy an efficient mini tankless water heater directly at the sink.
Just think—no more running out of hot water halfway through doing dishes or waiting impatiently for cold water to heat up! Under-sink water heaters deliver an instant stream of hot water whenever you need it.
Hopefully, this guide gave you the confidence and knowledge to install one of these handy hot water appliances under your sink. Enjoy the space-saving, energy-efficient convenience today!