Nicolette Forbes

By: Nicolette Forbes on August 17th, 2022

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How to Install Isolation Valves

Tankless Water Heaters

Have you heard of the perks of having isolation valves for your tankless water heater but are unsure how they are installed? Or maybe you’ve never heard of isolation valves but want to know what they are and how they are installed in a tankless water heater? Look no further. 

Installing isolation valves for your tankless water heater is an important part of ensuring that your water heater works properly. However, while many people may be familiar with using and maintaining a tankless water heater, some may not know how to install isolation valves on the unit. That’s where we come in. We here at Monkey Wrench Plumbing, Heating & Air have been in business since 2007 and have seen firsthand why isolation valves are essential for your tankless water heater, so now we want to pass that knowledge on to you.

In this article, we will discuss: 

  • What are isolation valves 
  • How isolation valves work
  • How isolation valves are installed
  • What happens if isolation valves are installed incorrectly

By the end of this, you will have a full understanding of not only isolation valves but also how they are installed in your tankless water heater.


What Are Isolation Valves?

Isolation valves are brass or stainless steel devices that isolate a tankless water heater from the rest of your home’s plumbing system for internal maintenance purposes.

 A set of hot and cold isolation valves.

But what on earth does that mean? It means these valves make your tankless water heater go “offline” from your plumbing system for a bit while you drain and flush it. Meanwhile, you can still use your cold water. 

Isolation valves are only for internal tankless water heater maintenance and can be called many things like:

  • Service valves
  • Maintenance valves
  • A flush kit
  • Hot and cold isolation valves (or service valves) for a tankless water heater

These valves differ from shut-off valves by having a drain and cap. This drain allows you to empty your tankless water heater and run a cleaning solution through it. Shut off valves just stop and start water flow.

Wondering where your isolation valves are hiding? You can easily find your valves connected to your tankless water heater, and they are often marked with blue and red for your cold and hot water lines.


How Do Isolation Valves Work? 

Isolation valves have a mechanism called a ball valve. A ball valve mechanism has a ball with a hole inside it and an O ring to seal it. When you turn the valve handle 90 degrees to the waterline, the ball rotates and blocks water flow. An easy way to explain it is like this:

Think of the ball as a giant bead and the water as a thread. If you turn the hole away from the thread a quarter turn, you won’t be able to stick the string through.


How to Install Isolation Valves

Installing isolation valves can be a breeze if you know what you’re doing. When installing the valves, it is important to know that your water supply should be shut off first. Afterward, locate the cold and hot water inlet ports on the unit. But what does that even look like? *Hint: Each port will have a threaded fitting.*

Then a pipe wrench is used to loosen the nuts that secure the flexible hoses to the inlet ports. Once the hoses are removed, the isolation valves are screwed onto the inlet ports. Teflon tape or pipe dope is then used on the threads to create a watertight seal. Once the valves are in place, it is now safe to turn on the water supply again.

A technician with the isolation valves.

You can test to see if your isolation valves are installed correctly by running water through the faucets. If there are any leaks, there is a chance that your isolation valves are installed incorrectly. While you can install isolation valves yourself, if you are not particularly handy, we recommend that you contact a certified technician to install your valves. They will be able to help you choose the right type of valves for your tankless water heater and install the valves for you.


What if Isolation Valves Are Installed Incorrectly?

If your isolation valves are installed incorrectly, you won’t be able to flush your tankless water heater. And that’s an important part of tankless water heater maintenance and is a key task to getting the most out of your tankless water heater. Check out this article here as we dive deeper into the importance of flushing your tankless water heater.

Your isolation valves can be incorrectly installed if they’re:

  • Installed in a way that you can’t access them
  • Installed upside-down

If you feel as though you may need help installing your isolation valves, we recommend that you call a certified technician for assistance.


Closing Out Installing Isolation Valves

Isolation valves are important for your tankless water heater for many reasons, which is why having them installed is key. The valves help with tankless maintenance, which will ultimately prolong the life of your water heater, giving you years and years of endless hot water.

Still have more questions about tankless water heater maintenance like flushing or if there are other types of tankless maintenance? Check out the articles below as we discuss whether or not it’s a good idea to flush an unmaintained tankless and the types of tankless maintenance available. Knowing how to maintain your tankless water heater is key to making it last its full life.

Can I Flush an Unmaintained Tankless Water Heater?

What Type of Maintenance Does a Tankless Water Heater Require?

We here at Monkey Wrench Plumbing, Heating & Air want to make sure that you are set up for success. If you live in the Los Angeles area and have any other questions regarding isolation valves or tankless water heaters, call us at 310-853-8690 and one of our call center representatives would be happy to help you.