By Tim Greer
Tankless water heaters have not always been at the forefront of contractors’ or plumbers’ minds when renovating a home or constructing a building. It’s a technology that entered the North American market only a few decades ago. And along with many new and innovative technologies introduced into a market, there have been myths spread about tankless water heaters that are not completely accurate. These tankless myths have caused uncertainty for many PROs on a tried-and-true product. One such myth I wanted to dive into is: venting for tankless is too expensive.
Historical Significance
Historically, venting was a large expense both from a material and labor standpoint, ranging in cost from $200 to as much as $1000. However, over the last 50 years, the cost of venting a tankless unit has decreased dramatically (now vent systems can be under $100). This change was brought on by continuous research in new technologies and innovation, making the venting portion of the installation process much more affordable.
Some tankless units were previously only compatible with 3-inch PVC in comparison to the much more cost-effective 2-inch PVC. Many companies, such as Rinnai, heard the concerns from PROs on high costs inhibiting customers from installing tankless units. Rinnai then launched their Sensei Models, which are compatible with 2-inch (schedule 40, solid core) PVC, creating a much more affordable solution.
Cost-Effective Solution
When researching PVC costs at Home Depot, a standard 3-inch by 2-foot PVC pipe is priced at $21.14 and a 2-inch by 2-foot PVC pipe is priced at $9.86. That is a 47% savings when switching to 2-inch PVC. It’s even more of a cost savings when installing a tankless unit that requires up to 65 feet of venting. The savings adds up quickly. It’s important to note, installing PVC can be more labor-intensive than a concentric system that requires no priming, gluing, and curing times, but the price offset is still there, especially when looking at the flexible installation methods for tankless units.
Flexible Installation
There are multiple vent methods for installing tankless water heaters, including roof penetration, wall penetration and external (outdoor) models that require no venting at all. Each method has its costs associated, but the flexibility provides options that would otherwise not be available with your traditional tank water heater, where a roof penetration (sometimes up to two penetrations at times) is required for venting. On top of the expensive install, standard atmospheric tank venting is not required to be tightly sealed completely preventing exhaust leakage. This is by design due to the extreme, hot air temperatures traveling through the tank’s venting. Additionally, tankless water heaters commonly have more integrated safety technologies as compared to atmospherically vented tanks—including combustion fan proving and vent temperature monitoring to ensure the end user has peace of mind.
As tankless venting is made with efficiency in mind, there are more flexible options to terminate hot air, including horizontally, which is not an option for the standard tank water heater. And installing horizontally into a wall rather than through a roof will save on venting labor and materials and installation time, providing a cost-effective solution for your customers. In addition, there are tankless units available that do not require any venting, including external units. These units are specifically designed for outdoor use, which eliminates all need for any venting. These tankless units are commonly installed in warmer, southern climates, so having the roof and wall penetration option is essential for other areas of the country.
By comparing material prices and installation options, I can securely say the common misconception that venting is too expensive has been debunked.
Tim Greer is a technical training developer and instructor with Rinnai America. With over 20 years in the mechanical and electronics industries, he began his journey with Rinnai over 16 years ago. He has held various roles in technical support, commercial service, product management, & training development.