Nicolette Forbes

By: Nicolette Forbes on May 6th, 2022

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Tankless Water Heater Rebuild vs Tankless Water Heater Replacement

Tankless Water Heaters

Keeping up with the maintenance on your tankless water heater is key to prolonging its lifespan. But what if you start running into problems with it and the calls to your local plumber are now becoming more frequent? No, the answer is not to set the tankless unit on fire. 

If you find that you’ve tried every possible option to try and fix your tankless water heater, you will now have two choices: either a tankless rebuild or a tankless replacement. 

Here at Monkey Wrench Plumbing, protecting your home is a top priority. Since 2007, we have been dedicated to providing the best service to our clients for their tankless water heaters and are experts in tankless rebuilds and replacements.

In this article, I'm going to outline what goes into a rebuild or a replacement, the process, the cost of each option, and the key differences to help you decide which option is best for you.

So without further adieu, let’s jump right in!


What is a tankless water heater rebuild?

A tankless rebuild is the process of replacing all the internal parts of the tankless water heater that have failed or corroded and replacing them with new ones. Most manufacturers are really good at sending out all the parts that need to be replaced so you won’t have to worry about scrambling to find the components yourself. But you will need a certified plumber to rebuild the unit. We do not recommend rebuilding yourself unless you have the proper training.

During a tankless rebuild, your certified technician should do the following: 

  1. Taking out everything inside of the tankless water heater (completely dismantling it).
  2. Rebuild the heat exchanger (combining the old parts with the new ones).
  3. Place the core back inside the tankless water heater.
  4. Once it’s inside, your technician will reconnect all the water lines.
  5. Reconnect all the electric lines to the computer boards and sensors.
  6. Manifold gas pressures are readjusted.

A technician working on a tankless rebuild

From there, your certified technician will start the tankless unit back up. If everything goes well, the rebuild process will take about an hour to an hour and a half.

And while it may seem like your plumber may be gutting your tankless water heater, there are parts that are still used from your current tankless unit, including the screws and sensors, that don’t get replaced. 

A rebuild could cost anywhere from $675 to $1,500 depending on the unit. However, rebuilding your tankless water heater may not solve your water heater problems. If your tankless water heater is no longer under warranty , the manufacturer usually only warranties the replacement parts for one year. So if your water heater is older or out of warranty, a tankless rebuild might not be the best option.


What is a tankless water heater replacement?

A tankless water heater replacement is the process of completely replacing your old tankless water heater with a brand new one. 

The process to replace your tankless water heater will usually go like this: 

  1. Your technician will completely remove the entire unit and fixtures, leaving only the main line and the secondary line pipes coming from the wall (some technicians will try to use as much pipe as they can from the old unit).
  2. The new tankless water heater will then be installed.
  3. Technicians will make sure your unit is leveled.
  4. Thermal expansion tanks will be pumped to the right pressure.
  5. Gas sediment traps, gas line sizes and venting will be checked properly.

A technician working on a Navien tankless water heater

If you have an older tankless water heater or if your unit is out of warranty, a tankless replacement might be the best solution. Instead of replacing all the parts to extend your water heater for a few more years (hopefully), starting over with a brand new water heater can buy you more than 20 years of hot water. Again, a rebuild is only going to temporarily fix whatever problems you are experiencing with your tankless water heater so eventually your technician may suggest you get your unit replaced to avoid spending any more money rebuilding your water heater.  

A tankless water heater replacement can cost around $4,500 to $8,200 if you’re looking to switch from an older unit to a newer one.


Key Differences Between Tankless Rebuild and Tankless Replacement

There are a few key differences between a tankless rebuild and a tankless replacement. 

  • Costs

A rebuild may be the cheaper option at first, but in the long run having to replace or fix certain parts of your tankless water heater will begin to add up in price. Rebuilding may help buy your tankless unit a little more time.

  • Labor

The process of a replacement will take longer than a rebuild as your technician will need to replace almost everything from your former unit to install a new one. With a rebuild, your technician will be using a mix of both old and new parts for just the inside of your unit.

  • Longevity 

The rebuild is only a temporary fix for whatever problems you are experiencing with your water heater. While it is possible to continue getting rebuilds over and over again, it is not recommended by our subject matter experts. With a tankless replacement, everything that is being installed will be new (or mostly new) like when you’re replacing a new part in your car.


To Rebuild or To Replace? That Is The Question

To recap, a tankless rebuild is the most cost effective option at first but the frequent calls to us or your local technician will eventually add up. A rebuild serves as a temporary fix to your tankless problems while a replacement will essentially deliver a whole new unit. Now, this isn’t to say you won’t run into any issues at all with your replacement but it does mean that you won’t be revisiting your old problems again. 

Continue your tankless education by knowing more about the top errors seen with a tankless water heater and different installation options available here at Monkey Wrench Plumbing. 

Top Issues Seen With Tankless Water Heater

Three Steps To Determine Which Tankless Is Best For You

And as always, we here at Monkey Wrench Plumbing are dedicated to giving you all the facts and answering any questions you may have so that you can make the best decision possible for you, your home or your business. If you have any further questions on tankless rebuild or tankless replacement processes and which option is best for you, click on the ‘Book’ link below or contact one of our office team members at (310)-853-8690 to further discuss the best option for you.