If you are planning to install a tankless water heater in your modern homes then it is the most effective decision. If you want to know about how to install a tankless water heater then you are at the right place. This guide will explain the full process and steps in a professional and easy to understand way. As having knowledge about something is very important for safety, efficiency and performance,
The most positive feature of tankless water heaters is that they deliver water only on demand and don’t require a storage tank. This not only saves space but also reduces the consumption of energy. So when you are thinking about DIY installation or contacting professionals like our team at MileHi HVAC understanding about the whole process is essential before starting tankless water heater installation.
What is a tankless water heater?
Tankless water heaters are also known as on demand systems as they only give hot water when needed. Like old traditional systems they don’t store water in tanks which makes them more efficient and reliable. Nowadays most homeowners prefer tankless hot water heater installation due to their durability and consistent performance.
Tankless water heater advantages
So when you are at the planning or deciding stage about how to install a tankless water heater it is important to first know about its benefits.
- Gives endless supply of hot water
- Operates efficiently
- Saves a lot of utility bills
- Have a compact and space saving design
- Longer lifespan as compared to traditional heaters
- There is no risk of tank leakage
- Have a environment friendly performance
So these plus points make your tankless water heater installation a smart and long term investment.
Step-by-Step Guide: How to Install Tankless Water Heater
Choose the right location
The first step in installation is choosing the right location for your system. The location should be near the main water supply and a well ventilated area. Especially in case of gas units proper airflow and venting is essential. Therefore choosing a right location makes your tankless water heater install more efficiently, according to safety and other standards.
Turn off the main supply
Before starting, make sure to turn off the main supply of water,gas or electricity. As safety is a very important concern in tankless hot water heater installation. Ignoring this crucial step can lead to serious damages like leaks or electrical issues.
Remove the old system
If you have already installed a system in your home then first remove that and drain the old tank, disconnect all the connections. Carefully do this step for preparation of tankless water heater installation. This process ensures clean and clear setup of your system.
Mount the tankless unit
The most crucial step is mounting the tankless unit with the wall. You must ensure that the wall easily carries the weight of the unit and there is also some space for maintenance. Proper and professional mounting is essential for both tankless gas water heater installation and electric systems.
Install the water lines
For its functioning connect the system with all the components like:
- Connect the cold water inlet and hot water outlet
- Use copper and stainless steel piping
- For maintenance install the shut off valves
- Add a sediment filter if necessary
Connection of gas and electrical supply
For gas units:
- Connect the system with gas line
- Through detector check for leaks
- Ensure proper levels of pressure
For electric units:
- Connect the system with electrical wiring according to guide
- Use the correct size of breaker
- Verify the voltage requirements
This stage of connection is very important in installation of tankless gas water heater installation and electric setups.
Test the system
For ensuring proper installation check the system before operating it. Follow these steps
- Turn on the water supply
- Restore the system of gas or electricity
- Inspect all the connection for leaks
- Run hot water to monitor the performance
Testing is a good step as it confirms to you that your tankless water heater installation is correct and the system is functioning properly.
Read More: What Size Tankless Water Heater Do I Need?
Mistakes to Avoid for a Safe and Successful Installatio
For keeping safety and efficient performance of the system , be careful of the following things.
- Selecting the wrong size of system
- Loose venting connections
- Improper ventilation system
- Not following manufacturers guidelines
- Incorrect gas and electrical connections
So avoiding these mistakes will result in successful tankless hot water heater installation and saves you from repairs and heavy costs.
What Supplies Do You Need to Install a Tankless Water Heater?
Nobody talks about this enough — the installation itself isn’t usually what trips people up. It’s standing in the middle of the job realizing you grabbed the wrong fitting or forgot a tool entirely. Get everything together before you touch a single pipe.
The Unit Itself
Match the heater to your fuel source first — gas, propane, and electric units are not swappable after purchase. Then check the GPM rating carefully. Buy for your peak demand, not your average. A unit that struggles when two showers run at once is a unit you’ll regret buying.
Plumbing Supplies
Isolation valves on both the hot and cold sides are essential — they let you service the heater later without shutting water off to the whole house. Add a pressure relief valve on the hot outlet, this isn’t optional.
For pipe material, PEX-B is flexible, freeze-resistant, and easier for most DIYers. Copper holds up better in high-heat situations but costs more and needs soldering. Easiest rule — match what your existing plumbing already uses. Finish the list with correctly sized fittings, Teflon tape, and pipe thread sealant on every threaded connection.
Gas-Specific Tools
A gas-rated flexible connector sized to your unit’s BTU load is non-negotiable. So is a manometer — it measures actual gas pressure and confirms your existing line can handle the demand. Most people skip this and regret it when the unit short-cycles or throws error codes on day one. Also grab pipe thread sealant rated specifically for gas lines, and have soapy water or leak detector spray ready to test every joint before firing anything up.
Venting Supplies
Condensing models can use PVC or CPVC venting — affordable and easy to run. They also need a condensate trap, since these units produce acidic drainage that will damage internal components if it has nowhere to go. Non-condensing models require Category III stainless steel vent pipe — the exhaust runs hot enough to melt PVC, so there’s no substitute here. Either way, grab a termination cap for the exterior wall.
Electrical Supplies
Electric units need a dedicated 240V circuit with the exact breaker size listed on the spec sheet. Match the wire gauge too — undersizing it is a fire risk. Always use a voltage tester before touching anything in the panel.
General Tools
Pipe wrench, adjustable wrench, power drill with the right bits for your wall type, a level, and a garden hose with a bucket for draining the old tank. Nothing exotic — just have it ready before you start.
One thing worth catching early — switching from a tank heater to tankless sometimes means upsizing your supply lines. Tank heaters usually run on ¾ inch pipe, but some tankless units need a full 1 inch line. Check the spec sheet before buying fittings.
Cost of tankless water heater installation
The total cost of tankless water heater installation depends upon several factors like size,unit type, labour and complexity. However electrical systems are not much costly as compared to gas systems because of additional venting and gas line work.
The average cost of both systems is:
- Electric installation: $1,000–$3,000
- Gas installation: $2,000–$5,000
Although a properly installed tankless gas water heater installation is costly, it also gives benefits and comfort in the long run.
Key Differences Between Electric and Gas Tankless Water Heater Installation
One question homeowners ask constantly — is gas or electric easier to install? Honest answer: electric wins on simplicity every time. Gas gets you better long-term energy savings, but it comes with more steps, more checkpoints, and more surprises along the way.
Here’s how they actually compare side by side:
| Electric | Gas | |
| Install Time | Few hours, pretty straightforward | Longer process, more steps involved |
| Venting | None needed | Required — sometimes means cutting through walls |
| Hidden Costs | Rarely any surprises | Older gas lines often need upgrading first |
| Inspection | Simpler, fewer people involved | More checkpoints, stricter sign-off required |
| Main Requirement | Dedicated 240V circuit | Proper gas line sizing plus venting |
| Best For | Smaller homes, cleaner straightforward install | Larger households with an existing gas setup |
The biggest thing that catches people off guard with gas — your existing gas line was sized for a traditional tank heater, not a tankless unit. The BTU demand is completely different, and older lines usually can’t keep up without an upgrade. That upgrade costs money and adds time before installation even begins. Electric simply doesn’t have that problem.
That said, if your home already runs on gas and your household burns through hot water daily, gas makes sense in the long run. Lower monthly energy bills add up over time and offset the higher install cost.
But if your priority is getting it done quickly, cleanly, and without unexpected bills showing up mid-job — electric is the easier path. Pick based on your situation, not what sounds more impressive.
Before You Begin | Things to Consider
Most installation headaches don’t happen during the job — they happen because nobody checked these things beforehand. Run through this list before you buy anything.
Size the Unit for Your Actual Demand
This is the mistake people regret most. Don’t buy based on price alone — add up the flow rate of every fixture you might run simultaneously. A shower runs 1.5 to 2.5 GPM, a kitchen faucet around 1.5 GPM, a dishwasher about 1 GPM. Two showers plus a dishwasher puts you at 5 to 6 GPM minimum. Also consider your groundwater temperature — colder climates need a higher rated unit because the incoming water starts colder.
Check Your Gas Line Capacity
Tankless gas units demand 150,000 to 200,000 BTUs. Your existing line was probably sized for a traditional tank heater at 30,000 to 40,000 BTUs — a massive gap. Have a technician test actual gas pressure with a manometer before installation day. An undersized line causes short cycling, error codes, and a frustrating callback.
Check Your Electrical Panel
Whole-house electric tankless units can pull 150 to 200 amps at peak. If your home runs on 100-amp service, that’s a problem before installation even starts. Talk to an electrician first if your panel is already close to capacity.
Test Your Water Pressure
Too low and the flow sensor won’t activate. Too high and you risk leaks and heat exchanger damage. Most units need between 25 and 80 PSI. Grab an inexpensive pressure gauge from any hardware store and test at an outdoor spigot. Anything above 80 PSI means installing a pressure reducing valve first.
Know What Venting Your Home Can Handle
Condensing units vent through PVC — easy to run almost anywhere. Non-condensing units need stainless steel venting, which is harder to route. If your install spot is far from an exterior wall, a condensing model saves a lot of headache. Also check whether your existing vent is reusable — old B-vent flues don’t work with tankless units.
Pull the Permit
Don’t skip this. Most areas require a permit for water heater replacement, especially gas work. Beyond the safety inspection, an unpermitted installation will surface during a home sale and cost you far more to sort out than the permit ever would have.
Maintenance tips for optimal performance
For proving your investment worthwhile follow these professional tips for ensuring best performance.
- Annual flushing of tank
- Clean the air filters regularly
- Inspect for leaks
- Check the venting systems
- Schedule the professional servicing with experts like MileHi HVAC
So regular maintenance makes your tankless water heater run efficiently for a long time.
MileHi HVAC professional guidance
When it comes to tankless water heater installation choosing professionals like MileHi HVAC gives better services with safety. We will guide you in the whole process from selecting to complete tankless hot water heater install. Our expert and certified team offers reliable and efficient services for both tankless hot water heater installation or tankless gas water heater installation. Our team minimizes risks, prevents costly mistakes and ensures optimal performance for giving homeowners peace of mind and comfort the whole year.
Final Thoughts
Knowing about how to install a tankless water heater helps you in making informed decisions.This installation or upgrades requires some precision and safety awareness. Whether you choose DIY or professional tankless water heater installation near Dever from Milehi HVAC proper installation is very crucial for maximizing efficiency and optimal performance. As a well executed tankless water heater install delivers hot water,low energy costs and a friendly environment.
FAQS
Is installing a tankless water heater challenging?
In particular, for gas systems, it can be complicated. Professional knowledge is needed for many tankless water heater installation operations.
What is the duration of installation?
Tankless water heater installation typically takes four to eight hours.
Am I able to do it myself?
Electric water heaters can be installed do-it-yourself, while tankless gas water heaters should be installed by experts.
Do tankless systems require upkeep?
Indeed, maintaining durability and efficiency requires routine maintenance.
Is it worthwhile to purchase a tankless water heater?
Of course. Installation of tankless water heaters is a wise long-term investment due to its effectiveness, robustness and performance.
