How To Install a Heatworks Model 3 Tankless Water Heater

Last updated on September 13th, 2021 at 02:11 pm

We had been using a 40 gallon tanked water heater for the past three years for all of our hot water needs. When we decided we’d like to try a tankless water heater, we searched for one that would not just save space but be energy efficient and easy to install as well. We found all that in the Heatworks Model 3.

The Heatworks Model 3 uses Ohmic Array Technology which makes the unit energy efficient and maintenance free.

The following infographic summarizes how Heatworks’ Ohmic Array Technology creates hot water:

Unlike tank water heaters and other tankless models, the Heatworks Model 3 has no internal components that will corrode or malfunction. This means there’s no hassling with the twice-yearly maintenance most tankless water heaters require, and no concern about replacing burnt-out heating elements.

Installation Overview

Complete installation instructions are provided with the Heatworks Model 3 tankless water heater, and I found them easy to follow. The entire process breaks down into three basic components:

  • Mounting
  • Plumbing
  • Electrical Wiring

It should be noted that the manufacturer recommends professional installation of the Model 3 by a licensed plumber and a licensed electrician for new construction. Please be sure to follow all local and state plumbing and electrical codes when installing the Model 3 or any tankless water heater.

How To Install A Heatworks Model 3 Tankless Water Heater

As a knowledgeable DIYer with a background in both plumbing and electrical systems, I was confident I could replace our 40 gallon tanked water heater with the tankless Model 3. Here’s the process I followed while referring to the detailed instruction manual that came with the unit:


It’s important to give careful consideration to where you will mount your tankless water heater. In the case of the Heatworks Model 3, you’ll need to have sturdy support since the unit weighs around 40 pounds. You will also need to leave enough space both below and along each side of the unit for connecting the plumbing fixtures and electrical wiring.

We decided to save space in our small bathroom by installing the Heatworks Model 3 in a loft area above the room. Since this location was directly over the spot the 40 gallon tanked water heater had stood, I was able to make use of the existing configuration of hot-water plumbing. This, of course, made for a much simpler installation.

The first thing I did was make a sturdy support for the tankless water heater out of existing lumber I had laying around. I then attached the metal mounting bracket that is included with the Heatworks Model 3 unit to my wood support. This was as simple as using a few screws then sliding the unit down over tabs on the bracket to lock it in place as shown in the following illustration from the installation manual:

Here’s a photo of our Heatworks Model 3 securely mounted above our bathroom ceiling:


Once I had the Heatworks Model 3 securely mounted, it was time to connect the plumbing. As can be seen in the image below, only basic connectors are needed to attach water lines to the unit. Color-coded plastic tabs on the bottom of the unit differentiate the hot and cold water connections.

I used standard 3/4 inch flexible hot water connectors found at any hardware or big box store. I had to use 12 inch and 36 inch connectors to allow me to reach from the Model 3 to our existing water connection manifolds. To give it more length, I temporarily added the different length connectors using Teflon Tape and 3/4 inch brass close nipples until I can re-plumb at a later date.

No special tools were needed, and, once attached, I simply hand-tightened all connections with an adjustable wrench until snug, being sure to use Teflon Tape on all threaded, screw-on connectors to provide a leak-proof seal.

Copper Manifold

When we were plumbing our cabin, I installed copper manifolds with valves behind an access panel in the bathroom as pictured below.

The top manifold, with the red PEX, supplies the hot water throughout our cabin. The bottom manifold, with the blue PEX, carries the cold water.

In the event of an emergency or a needed repair, the valves allow us to turn off only the affected line without having to shut off water to the entire cabin at the main valve outside. This configuration has been a great convenience, and I highly recommend it.

The manifolds were included as part of a Shed/Cabin PEX Plumbing Kit we’ve made available in our Homestead Store HERE.

Electrical Wiring

The Model 3 can connect to a range of amperage, anywhere from 30 up to 100 amps. The higher the amperage used for the unit, the faster it generates hot water.

In our case, we were lacking in available amperage to hit the highest end of the scale. Our original 40 gallon tanked water heater operated on a 30 amp breaker, but we wanted to supply a bit more juice to our Heatworks Model 3.

I carefully considered our overall electric usage with favorable results. I was able to lower the amperage allotted to some of our other appliances and reduce the load on the panel. This allowed me to use a 50 Amp Double Pole Breaker for the installation of our Model 3 tankless water heater.

The Heatworks Model 3 was easy to wire using 8 gauge wire ( as recommended in the instructions) and removing the existing wire I had used for the tanked water heater. All the wiring for the Model 3 takes place behind a small, removable panel located on the side of the unit. The Installation Manual provides detailed wiring information that’s easy to follow as long as one has electrical wiring knowledge.

We’ve found that 50 amps provides rapid water temperature rise and more than adequately serves our hot water needs.

The Results

Once we had the Model 3 mounted, plumbed, and wired, we had hot water running to all our faucets and the shower within seconds!

We’ve used the Heatworks Model 3 for a few months now, and we couldn’t be happier. The bulky 40-gallon tanked water heater is no longer in the way, we’ve lowered our energy usage and costs, and we don’t have to worry about all the issues associated with metal heating elements.

Advantages of the Heatwork Model 3 Tankless Water Heater

The following infographic summarizes all the advantages we’re now enjoying with our tankless water heater:

Added Bonus – WIFI Adjustable

All Heatworks Model 3 tankless water heaters are wired for WIFI. Using the associated app allows you to make adjustments to your Model 3 operations from your smartphone. Tanked water heaters definitely can’t do that!

Heatworks Energy Saver Tankless Water Heater

Heatworks Model 3 with Smartphone WIFI APP

Take a Closer Look

As both an Authorized Dealer and satisfied user, I invite you to take a closer look at the Heatworks Model 3 Ohmic Array Tankless Water Heater.

If you have any questions, please feel free to email me at I’ll be happy to help.