Under Sink Water Heater Installation Guide

How To Install Under Sink Water Heater

Water heaters may be installed in many places. This is because they are highly versatile. Use the right installation technique for the heater you have in mind. How it sounds to install under sink water heater??

This is to prevent any malfunctions along the way. Our step-by-step instructions here below concern the installation of the water heater under the sink. Read through to receive the guidance.

Tools and Materials Required

  • Adjustable pliers
  • Adjustable wrench
  • Cordless drill & Drill bits
  • Double compression stop
  • Emery cloth
  • Hammer
  • The instant hot water tank system
  • Marker
  • Nail set
  • Safety glasses
  • Stainless steel drill bit

How To Install Under Sink Water Heater

Step I: Switch off the power and water systems

At first, switch off the water and the power systems. You want to ward off the risks of electrocution. Also, you do not want to predispose your kitchen and furniture to the risks of water damage.

After this, clean out the area underneath the sink. This is to further minimize any possibilities of making your room dirty in the unlikely event of an accident. You may wish to place the controls of your water heater to ‘pilot’ setting if need be.

Step II: Drain the Lines

In this step, move on to drain the water lines. To do this, turn on the faucet at that sink where you are working. Do the same to the outside faucet. Cut a hole in the sink for the sake of accommodating the water dispenser.

Step III: Mark the Sink

Generate a dimple into the sink where you intend to place the dispenser. Use the hammer and the drill set to do this.

Step IV: Drill a hole and smooth the edges

Proceed to now to drill a hole into the sink and smooth the edges thereof. Use a cordless drill and a stainless steel bit. The diameter of this hole should preferably be ¾ inches. Cut the hole using a snag booster.

To do so, eliminate the cutting wheel from the slug booster. Thereafter, proceed to place it into the hole. Re-attach the cutting below. Tighten the nut which sits atop the slug buster using bare hands. Tighten it further using a wrench until a ‘pop’ sound originates. Get rid of the slug buster as a final step.

Step V: Smooth the edges

After That, Smooth the edges of the cuts using emery cloth. It is important that you put on the safety glasses while doing this and cutting the metals. Use the relevant piece of equipment for the job. You need a hole-saw to cut into the countertop if yours is a sink cast iron.

Step VI: Insert the dispenser into the sink

At his stage, insert the dispenser into the sink. Place the seal ring into the sink’s underside foremost. Thereafter, attach the mounting ring over the threaded rod from the underside of the dispenser. Add this to the hex nut. Conclude the process by tightening to secure the joints.

Step VII: Establish the water line connections

After you are through with this, you now have to establish the water line connections. You have to foremost lose the compression nut. You will find it at the cold water to a stop underneath the sink. Remove the line thereafter.

Replace this with a double compression stop. Fix it to the waterline. Finish off by re-attaching the lines to the sink.

Step VIII: Identify a suitable location for your water tank

Time is now ripe to fix in place a water tank. To do this, you must first identify a suitable location for it. As a general rule, this tank has to be as close to the electrical outlet and plumbing as much as possible. Hold the tank firmly in place. Draw a line on the kitchen wall and mark out the top of the tank.

Step IX: Fix the tank and establish the connections

Having marked out a suitable location for your tank, you have to now fix it. Install the mounting bracket around 1 inch from the line. Use a drill bit and a 1-inch wood screw to do this. Be sure that the tank hangs firmly on the bracket.

To establish the necessary connections, push the blue tubing into the quick-connect fitting which exists on your tank. Follow this by slipping the clear vinyl tube in the middle of your fitting. Attach the larger tube to the last barbed fitting.

Step X: Fix the filter in place and add the lines

Then, Attach the filter in the water heater. Place the mounting bracket near the tank as a first step. Join the 3/8-inch tubing to the 3/8-inch Y fitting. Fix the clear vent line to the filter after this. Put in place some copper lines in between the dispenser to the Y fitting.

Step XI: Install the Double Compression Stop

Now, install the compression stop preferably at the existing water line. Tighten it using the compression nut and over the 3/8-inch tubing.

Step XII: Test the installation

Last but not least, You are almost good to go. Before you do so, test the installation. Turn on the water which is it at the back of the water heater. Open the water stops underneath the sinks. As you do so, be on the lookout for any leaks. Plug in the tank and use the heater.


Finally, Even though the procedures we have looked into above are self-explanatory, we caution against going head on if you lack the expertise. The consequences of poor workmanship are often too devastating to even contemplate.

That is why you want to bring in an expert to your rescue. Alternatively, you may carry out mock installations repeatedly until you gain the confidence and expertise necessary. All said and done, the installation of the under sink water heater is a skill you want to gaine and incorporate in your day-to-day operations. You never know when you might need it.