Installing a tankless water heater under a sink is possible, but there are some important factors to consider. Tankless water heaters provide hot water on demand without the need for a storage tank. This makes them an attractive option for space-constrained areas like under a sink. However, traditional whole-house tankless heaters are quite large and require special venting, so they are not well-suited for this application. Instead, a small, point-of-use electric tankless water heater is the best option for under sink installation.
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Benefits of a Tankless Water Heater Under Sink
There are several potential benefits to installing a small tankless water heater under a sink:
– Endless hot water – Tankless heaters provide a constant supply of hot water on demand. You’ll never run out of hot water halfway through a shower or while washing dishes.
– Energy efficiency – Tankless heaters only heat water when needed, rather than maintaining a whole tank of water hot 24/7. This can reduce energy usage and costs.
– Space saving – Without a bulky storage tank, a tankless heater can fit in tight spaces like under a sink. This frees up room for more storage or other purposes.
– Reduce water waste – Getting hot water immediately means you won’t have to let the tap run waiting for hot water like with a traditional tank heater located far from the point of use.
Requirements for Installing Under Sink
While installing a small tankless water heater under sink can be a great solution, there are some important requirements to keep in mind:
Proper clearances
The under sink area must allow for the required clearances around the tankless heater for ventilation and access. This includes proper clearance to combustible materials. Consult the manufacturer’s recommendations.
Sufficient electricity
Small electric tankless heaters require a lot of power – often 20 amps or more at 240 volts. Your electrical system must be capable of providing adequate power. Upgrading an electrical panel or wiring may be needed.
Water lines
Appropriate cold and hot water lines must be available under the sink. The lines must be the correct size for the tankless heater’s connections and water flow requirements.
Condensate drain
Tankless heaters produce condensate that needs to be drained. An appropriate drain connection is required.
Venting
Venting for combustion gases is critical. Many under sink tankless heaters are designed for outdoor installation and rely on air from the outdoors for combustion. Ventilation accommodations are required.
How to Install a Tankless Water Heater Under Sink
If the under sink location meets the requirements, follow these steps for proper installation:
Turn off water supply and drain lines
Start by shutting off the cold and hot water lines under the sink and opening the faucet to drain any water from the lines. This allows for a dry installation.
Mount the unit
Securely mount the tankless water heater under the sink according to manufacturer specifications, allowing for sufficient clearances. Proper support is vital.
Connect water lines
Connect the cold water supply line to the inlet port on the tankless heater. Then connect the hot water outlet to the sink’s hot water line.
Install electrical supply
Hook up the required electrical supply to power the tankless heater. Follow local codes and manufacturer instructions.
Ventilation
Install ducting for ventilation needs, such as intake and exhaust vents. Proper ventilation is a must.
Condensate drain
Attach a drain line to the tankless heater’s condensate outlet and slope it toward an appropriate drain.
Confirm proper installation
Double check that all connections and clearances are correct before startup. Flush the unit per manufacturer directions.
Turn on and test
Turn on the water and power supply to the unit. Activate the sink faucet and test that hot water is properly flowing at the correct temperature. Confirm that the heater turns on and off as expected.
Choosing the Best Tankless Water Heater for Under Sink
The key factors to consider when selecting an under sink tankless water heater include:
Size
Choose a petite unit that can fit in the limited under sink space. Look for a compact, smaller-capacity heater designed for point-of-use installation.
Power
Select a model with an appropriate power rating and electricity requirements for your situation. Consult an electrician if needed.
Water pressure
The heater must be capable of handling the incoming cold water pressure and still deliver sufficient heated water flow for the faucet.
Temperature
Choose a unit that provides sufficiently hot water for hand washing needs, around 105°F to 120°F.
Resources
Pick a heater that works with your available resources like electricity, water lines, drainage, and ventilation.
Mounting
Look for a compact heater with built-in mounting bracket or legs to simplify under sink installation.
Top Tankless Water Heaters for Under Sink Installation
Here are some top rated tankless water heater models to consider for under sink installation:
| Brand | Model | Power | Flow Rate | Dimensions |
|---|---|---|---|---|
| Ecosmart | EOS 3 | 3000 W / 13 A | 1.5 GPM | 6.8″ x 8.7″ x 13.8″ |
| Stiebel Eltron | DHB-E Mini | 1250-1700 W | 1.5 GPM | 6.7″ x 15.7″ x 11″ |
| Bosch | Tronic 3000 T 4.5 | 4500 W / 19 A | 1.5 GPM | 6.7” x 15” x 10.5” |
| Rheem | RTE 13 | 4500 W / 19 A | 1.5 GPM | 3.7″ x 6.7″ x 11.2″ |
Conclusion
Installing a small, electric tankless water heater under a sink can be an excellent option to provide an endless supply of hot water on demand. Just be sure to select a properly sized under sink model and install it according to manufacturer guidelines, paying careful attention to electrical requirements, water lines, ventilation, and clearances. Choosing the right tankless heater and site preparations are key to maximizing the benefits and convenience of point-of-use hot water. With careful planning and execution, an under sink tankless heater can be a great solution for a kitchen, wet bar, bathroom vanity, or other sink needing instant hot water access.