Why You Need A Professional To Install A Tankless Water Heater?


Installation of a tankless water heater is a complicated procedure, and proper installation is essential for its performance and efficiency.

Further, many parameters shall be considered during installation, and if you are an amateur installing by yourself, you might face many problems.

In this article, we will help you understand why installing the tankless heater by yourself is not a good idea, and why you need a professional to do that.

Why Involve Professional to Install Tankless Water heater?

In this section, we will guide you towards the reasons to involve professional help while installing a tankless water heater.

Complex instruction manuals

Most of the instruction manuals that come up with the heater have a technical and complex vocabulary, which is challenging to understand as they are targeted towards professionals.

The reason behind this is most companies expect that the customers hire a professional for the installation.

Even with thorough research, there are high chances that you will misinterpret or forget some points, and your insufficient product knowledge might result in the breakdown of your new appliance.

Deciding the best place for installation

Choosing the best location to install your tankless water heater is very important as it defines the flow rate and overall efficiency of the heater.

Specific models cannot be installed outside, and some point-of-use water heaters cannot be installed in a basement or attic.

Installing in the place of your old heater might look simple, but indeed it might need extra plumbing, electric wiring, and venting.

If you don’t consider all these parameters, your appliance might breakdown incurring losses. A professional knows all these parameters and can choose the best place based on your tankless model and the state of the house.

Regulations and permits for the installation

Installing an electric or gas-based tankless heater means dealing with the home’s electrical configuration, water, and gas supplies.

As all of these are under central, state, or local jurisdiction, you need to follow some codes and permits set by them. Venting system installation also needs to develop a protocol.

If you are an amateur, you are less likely to know such rules and regulations and may be fined by the authorities if you install improperly.

A professional is well informed about such codes and permits that need to be obtained before installing the tankless heater and saves you lots of headaches in the future.

Assessing gas supply requirements

You need to get a dedicated gas line supply for water, which is different from your regular kitchen supply.

Further, you may need to upgrade your gas lines if you are replacing your tank style with tankless water heaters.  A tank-style heater usually uses a ½″ gas supply line while ¾″ gas lines.

Also, if you want to change your fuel source from propane to natural gas or vice versa, they need additional changes to be done.

Assessing such size and fuel requirements is very important for proper functioning and is usually out of commoner’s knowledge. A professional is capable of determining such requirements and correctly installing them.

Understanding venting system requirements

Venting is essential for a tankless unit as if improperly vented; It will result in the buildup of harmful carbon monoxide in the house.

Venting through a chimney results in the entrapment of harmful gases inside the house. Venting through existing ducts is not desirable either as it is hard to access them for joints inspection.

Some tankless models need vertical venting, another horizontal venting; some need plastic pipes and other stainless piping. Each has its own set of venting requirements, which sometimes involves complete reconstruction.

A professional will have a better understanding of such sizing and reconstruction requirements.

Sizing of the water inlet

The size of your water inlet defines the flow rate and temperature rise you will require. Tankless water heaters need a minimum flow of water, usually about 0.5 gallons in a minute, but it varies on the models. 

Consult a professional will ensure the size of water inlet meets your minimum flow requirements.

Knowledge about required alterations

There are some switches and control modules in the tankless heater system which can be altered by the user, and some are fixed and can never be touched by the user.

If you modify them without knowing, it might result in the breakdown of the device or worse, might harm you.

There were many cases previously where users tried to alter the rating that is not meant to be changed or removed by anyone.  A professional would quickly know which are intended to be touched and which are not.

Safety concerns

Working with a tankless water heater, either electric, gas, or propane, one is like playing with fire. Even minor gas leakage or misconnected electric wires could be a recipe for disaster.

You need a complete knowledge of how to shut off the gas supply and disconnect the existing system without leaking gas.

Installing a new tankless water heater involves making new water lines and discharge lines for pressure relief valves that require soldering.

Further, you need to know how to dispose of your old heater if you have one properly. A professional is experienced in working with such systems, and it’s safer to handover the installation to them.

The total cost of installation

If you are an amateur following the manuals, there is a high chance you might not possess all the tools required for plumbing, venting, and wiring. Buying or renting them will cost you a lot.

If you forget to get all of them in one to go, multiple trips to the hardware store are unavoidable.

Further, after installation, it is recommended to have an inspection, and if you made some mistake, you have to redo it again. All of these will add a lot to the total cost of installation.

If you hire a professional, you are ensured that there will be no mistakes and no need to buy extra working equipment.  

Company warranty

Finally, companies usually offer warranty services on repairs or replacements of the damaged parts for the new tankless water heaters.

Most of the time, warranty is valid only when a professional install because companies know that there is a high chance of making mistakes when you do the installation.

If you don’t hire a professional and make mistakes during installation, you might end up not getting any warranty.  To avoid the hassle better, go for professional help.

Besides, a professional might offer you some free advice on how to maintain the heater for overall efficiency.


1. Can any plumber perform the installation?

Since tankless water heaters are becoming more popular these days, many plumbers have previous experience or knowledge regarding it. It’s always best to call beforehand and make sure if the person can do it.

2. Where should I never install the tankless water heaters?

You shall not install them in the vicinity of electric joints, air conditioners, combustible substances as this may cause a fire if leakage occurs from the heater.

3. What are the best places to install tankless water heaters?

Some of the best locations to install tankless water heaters are the basement, attic, garage, outdoors, previous heater area, near the point-of-use, and the electric panel.

4. Is it okay to install a tankless water heater in the bathroom?

There are point-of-use install tankless water heaters that you can install in the bathrooms. Point-of-use heater with 1.2 gallons per minute flow rate can be used for a single bathroom sink, and higher ratings can operate two shower heads at the same time.

5. Can you install a tankless water heater near the furnace with a single gas line?

No, because in most of the cases, a single gas line is not enough for both the furnace and the heater to work, and you might end up with no hot water.

6. Can you install a tankless heater in a manufactured/mobile home?

Yes, if you are installing inside, get the appropriate or conversion models with direct venting. If you live in warmer climates, you can simply use a conventional tankless heater by installing it outside.

7. Do electric tankless water heaters need venting?

No, only gas-based tankless water heaters need a venting system.

8. Can the existing venting be used?

It is recommended to use the suitable venting according to the product requirements rather than adjusting the existing air pipes because every model has different needs. Some have a power venting system and are run through a sidewall; others have a direct venting system.

9. If I am using multiple tankless water heaters, can I use a standard venting?

Yes, you can. The intake and exhaust vents can be combined into two standard pipes, and a common venting system can be created.

10. Do tankless water heaters freeze if installed outside?

Most of the time, if the winter is extreme tankless heater will be left defenseless to the cold temperatures and may freeze.
Some gas tankless water heaters might work well, even in cold climates, as long as the unit has been sized correctly and enclosed correctly, but there is always the risk of freezing.


Although it seems economical to install the tankless heater by you, we have put together a few reasons why it is not a good idea.

Hopefully, now you understand the importance of seeking professional help for such complex installations and have your tankless system installed without any worries.

Installing a tankless water heater is a complicated procedure. It demands knowledge about instruction manuals, rules, and regulations, warranties, safety concerns, choosing the best location for installation, assessing gas supply, water inlet sizing, and venting requirements and required alterations, which are better understood by a professional.

About Donald Parker

Donald has more than 15 years of experience working with power tools. But his main area of expertise is working saws, especially chainsaws. He's always had an affinity for the cutting edges and all that they can do.