DIY Guide on steps of Installing Gas Tankless Water Heater

Installing a gas tankless water heater

To get the full range of benefits, it’s super important to select the right water heater for your household’s specific needs. The range of options on the market is vast and it’s all too easy to get an inadequate unit for your needs or to overpay for the one you won’t fully make use of. For us, we would advise that you purchase a tankless gas water heater. Below, we would be giving you a rough sketch of how much money you’d spend installing one, so it’s easier to make your choice.

An Estimated cost of Installing Gas Tankless Water Heater.

The installation estimates: $865 for a 50-gallon storage-tank heater and $1,470 to $2,500 for a gas-fueled, tankless water heater. To see how a tankless investment might pay off, take the median, or $2,000, as the average installed cost, plus a few hundred more to disconnect and remove the existing conventional tank.

Installing a gas tankless water heater tends to be the most complicated due to the fact that the units must be vented. Depending on the location of the unit and the model selected you may vent be able to vent horizontally or vertically or rather get a gas fireplace.

Take a look at these when Installing Gas Tankless Water Heater:

1. Do I have the correct gas connection coming into my house and do I have enough gas power to run the tankless water heater I purchase?

If you contact your local gas company or installation professional, they can determine whether you have enough gas coming into your house to power a tankless water heater. You should print out one of the installation guides above as a reference for yourself and person installing the unit.

2. Do I have proper ventilation?

All gas tankless water heaters must vent the excess warm air they create. They can either vent vertically up through a chimney or roof pitch or horizontally through a sidewall. Some units can only vent horizontally, some vertically, and some units can vent either way. You will want to know what options you have for venting before you make a decision on which gas tankless water heater may be right for you.

Components You Need to Consider when Installing Gas Tankless Water Heater

There are several components you will need to consider when installing a gas or liquid propane tankless water heater:

1. Vent Adapter and Stainless Steel exhaust hose

A vent adapter is required to attach the tankless water heater to the exhaust hose. You will need to select either a 3-inch adapter or 4-inch adapter depending on the model you select. All venting of gas or liquid propane tankless water heaters REQUIRES UL approved Stainless Steel vent pipes due to the heat produced in the venting process. Standard PVC piping is not recommended.

2. Vertical vs. Horizontal Installation

Gas or liquid propane tankless water heaters can be installed either vertically or horizontally. Some models can only be installed one way or the other so please read the product information listed on our site regarding the product to get a better understanding of how it can be installed.

Horizontal Installation:

There are two types of horizontal installation. With a downward slope installation, you will need a vent adapter, 90-degree elbow, and an appropriate length of stainless steel vent hose to run the exhaust out of your sidewall. You can then end the exhaust by using a wall thimble connecting the interior part of the vent with the exterior wall. You would then end the connection with a 90-degree elbow. With an upward slope vertical installation, you will simply need to add a vertical condensate trap to your parts list.

Vertical Gas Installation:

Vertical installation of gas tankless water heaters can have more variables that the horizontal installation. However, the components necessary for the installation will remain the same. You will need a vent adapter, at least one 90-degree elbow, and condensate trap (condensate trap is only required for Rheem gas units. Bosch units have a built-in condensate trap).

You will need to buy enough stainless steel venting pipe to reach the exterior of your home. You will need a firestop for each ceiling the unit is vented through. Finally, you will need roof flashing, a storm collar, and either a 90-degree elbow or rain cap to terminate the installation.

Combustion Air:

Tankless water heaters require combustion air. It’s important to understand how combustion air will be delivered to your water heater and how much combustion air is needed. When placed in an unconfined area, combustion air can simply be the air within your home. Some of the tankless units we sell are meant to function in this type of environment where they do not pull fresh air from outside the room they are installed in.

As a general rule of thumb, any gas tankless water heater that uses internal combustion air must have at least 10,000 cu, ft. of space around the unit. Confined areas (such as a closet) may require air ducts or additional air inlets. Models that require external combustion air require a second hose to be installed that pulls fresh air from outside of your home into the room you are installing the tankless water heater in. Check the installation manual for more information about combustion air requirements.

Factors we think you should consider when hiring a contractor for installation

1. Request cost estimates in writing

2. Ask for references

3. Check the company with your local Better Business Bureau

4. See if the company will obtain a local permit if necessary and understands local building codes, etc.

We always recommend you discuss the electrical requirements with an electrician or professional installer before purchasing an electric unit. Outdoor gas tankless water heaters do not require venting, however, they do require a minimum amount of space around the unit.

We always recommend consulting a professional installer or gas company in conjunction with the installation manual for each model before installing a gas tankless water heater.

But if you’re planning on installing a gas tankless water heater on your own (DIY), we’ve curated 6 easy steps for you to follow and you’d have yourself a heater set up in your home in no time. Please bear in mind to be extremely careful while installing a gas tankless water heater.

Some of these steps might be strenuous, especially for individuals that aren’t experienced. Again, we would advise that you get a professional installer, even if it’d add much more to your overall costing.

Also Read Practical Steps to Installing an Electric Tankless Water Heater

Here’s a Breakdown of the Basic Process of Installing a Gas Tankless Water Heater.  

1. Remove the old water heater.

Start by turning off the water supply to your home and disconnecting the old unit from the water supply line. As there may be some water left in the supply line, this is where having a bucket on-deck can help. Next, you’ve got to disconnect the unit from its heat source.

2. Shut off the gas supply valve before moving forward.

Once you’ve completely freed your traditional water heater from all power and supply lines, get rid of it in accordance with local laws.

3. Install a new gas line.

Install a gas line connector to your existing line, and run a CSST supply line through the other end. Make sure the gas line is still shut off, and connect the CSST line to your tankless heater.

4. Tighten all nuts and gas line connections, and turn on the gas.

At this stage, you may want to use a gas sniffer to check for gas leaks or loose fittings. If there are no such leaks, you can turn on the gas and pilot light as per the manufacturer’s instructions and test your unit. It may take time to initially heat up water on first use.

5.  Install new water lines, Mount the water heater, Connect the water heater, Install the vent.

6. Turn on the water heater.


Materials Needed for Installing a gas tankless water heater.

Moving on to the materials you’ll need for the job. When it comes to Installing a gas tankless water, most of the tools and fixtures you need will come packaged with the unit:

1. Your new tankless heater, plus the hardware and instructions that come packaged with it.

2. A screwdriver

3. CSST supply line

4. Gas line connector

5. New water lines (as needed)

6. Hanger brackets for the water lines

7. Heat-resistant sealant

8. A bucket

Pros of Installing a gas tankless water heater

1. So instead of maintaining a full tank of water being heated at all times, tankless water heaters are more energy efficient.

2. Certain companies manufacture water heaters that feature a secondary heat exchanger that uses 9 or so percentage than conventional tankless water heaters.

3. They only heat water when it’s needed. (On demand only)

4. Tankless systems come in two varieties, the point of use is small, and their heats sinks. Their size means they can fit inside a cupboard, and their closeness to the outlets means the water won’t cool down. The second variety is the whole house heaters.

5. They come in various types; gas, electrical, propane, or natural gas. The gas and propane powered models will give out more power than the electric models.

6. It increases your home value with the use of premium and energy smart technology.

7. Some heaters feature copper for maximum heat efficiency and use up to 40% less energy than a traditional tank.

8. They take up less space than traditional tanks, and they never run out of hot water.

9. The tankless water heaters last longer than tank heaters.

10. No potential flooding if ruptured.

Cons of Installing a gas tankless water heater

1. They can cost up to three times as much as a traditional tank heater, so that’s something to consider.

2. The hot water output is split among the fixtures of your house that demands its use – the shower, the bath, the hot water taps, water radiators etc.

3. If you’re using a gas-powered heater, you might need a larger gas line to supply the unit with the fuel to power the heat exchanger.

4. Venting (gas & propane) requires expensive stainless steel tubings to work properly.

5. An additional circuit might be needed for the electrical models.

6. Greenhouse gases with regular gas-powered heaters.

7. Lag time might occur with whole house heaters.

Frequently Asked Question when Installing a Gas Tankless Water

So we compiled some frequently asked questions we’d like you to read through in order to get a better knowledge of what you should know about gas tankless water heaters. There are as follows;

How long does it take to install a tankless water heater?

Typically, a licensed plumber should have your new tank installed and working within 2-3 hours barring unforeseen complications

Which is more efficient gas or electric water heater?

Depending on your local utility costs, gas water heaters are typically cheaper to operate than electric. They also cost more upfront than an electric. However, based on energy savings, gas heaters generally make up the difference in price in about one year.

What size gas line is needed for the tankless water heater?

You can see that, in a typical gas system, a tankless water heater with a capacity of 199,900 BTU will require a 1-inch pipe size for a 20 ft branch length (based on the 0.3 in w.c. pressure drop in Table 2). The same appliance would require just a ½” pipe size based on Table 4 the 3.0 in w.c. Gas-fired tankless water heaters produce higher flow rates than electric ones.


Recent Posts