How To Install A Tankless Water Heater

Can a Tankless Water Heater be Installed Outside?

Running out of hot water is never fun, and it’s more common than you think. Especially since we are in the 21st century, surely this shouldn’t be something we still have to think about.

Well, luckily there is a solution. If you find that this article is sounding all too familiar, have you ever considered a tankless hot water system?

Tankless hot water systems offer hot water at the drop of a hat, yet do not have to run on a continuous cycle either. The means your bills are kept to a minimum and your utility costs are lowered.

They are efficient, reliable, and won’t break the bank. Not only that, but they take up less room in your house and they will inevitably help you reduce your own energy waste and water heating costs by 10-15%.

The life span of a tankless water heater can be is nearly double the lifespan of a conventional water heater, lasting up to 20 years and more. So, what are you waiting for?

You might be thinking, yes, this sounds like a great idea, but how would I install it? Would I need a mechanic? Luckily, we’ve got you’ve covered.

With our step-by-step guide, we’ve included below, you’ll be up and running in no time.

Installation Instructions

You’ve invested, it’s arrived and now the hard part comes next. The setting up. Well, it’s not as hard as you think, we promise. 

1. Removing The Old Heating System

To install your new tankless water heating system, you need to remove the current system.

To do this, turn off the mains to your home and then disconnect the supply line running into the device.

Some residue water may be left in the pipes but don’t panic and just pop some towels and newspaper down, this is normal.

You then need to disconnect the heat source by pulling out the plug on electric-powered units or closing the supplier valve for gas-powered units.

Once everything is disconnected, you can remove the unit. Check with your local council about regulations and rules around disposing of your old heater.

2. Measuring And Cutting

Next, you need to work out where the new tankless water heater will live.

Some parts of the US have regulations around this and so it is worth checking before you go ahead and start setting up. A professional mechanic should be able to help you here.

You should then also measure the distance between the plumbing and power connections to ensure they reach. You can cut and trim the pipe as much as you need to so that it fits into the new system.

3. Drilling Holes

Next, you need to drill your holes for the venting system to be fitted. This needs to go through to the outside, so ensure you’ve positioned the system accordingly.

Without a good ventilation system, your new heater may struggle to work and can become a safety hazard, so consulting a professional before you begin is always advised. 

4. Installing The Tankless Hot Water System

Once these steps are completed, you need to fit the system. You should mount it in position and connect the cold water supply pipe before connecting all the hot water outward pipes and making sure it’s all secured.

PVC pipes in the ventilation system need to be connected and the power source should be connected too.

5. Checking The Flow And Temperature

Now you need to check the full system by switching on the power and running some cold water through the system. After a couple of minutes, you should find yourself with a continuous flow of hot water.

Have a wander around the house and check all water sources are providing hot water and that the flow and temperature are working without any leakages. 

If all seems to work, you’re good to go! When following these steps, ensure you are following proper installation safety guidelines, however.

You should make sure that you’ve got hand and eye-protective wear, that the power is switched off when installing the new system, that you’ve conducted a full review of the scope of change on the existing setup, and that before you switch anything on, get a professional to verify your work if you’ve set it all up yourself.

This is because gas connections, if not done correctly, can be dangerous. If you don’t feel confident installing the system yourself, we always would recommend you find a plumber to lend a helping hand or to do the job for you.

Maintaining The Hot Water

To avoid limescale buildup and keep your hot water running, you should clean your system regularly. To do this, switch off the mains and disconnect the power before unscrewing the lid of the unit and removing the purge port valves.

Attach the hosing lines and pour about 2.5 gallons of white wine vinegar into the system. This will clean out the unit and remove any blockages or build-ups.

You should also locate your internal filter to clean, before replacing it back in the water heater and fully flushing out the system with water before putting the whole unit back together again.

How Much Does All This Cost?

When choosing which tankless hot water system to go with, have a look around for your most affordable yet reliable options that suit your individual needs.

A single point system may be budget-friendly for example, yet it only provides an instant supply of hot water to one appliance whereas a whole system might be more expensive, but will provide hot water for the entire house.

On top of this, ensure you’ve considered the cost of the plumber if you’re not confident in installing the system yourself. If you do install it yourself, you may need to work out a budget for buying the correct tools.

Finally, if you need the home rewiring, this is a cost you may also need to consider and will need a professional to certify the work first.

Installation Considerations

Gas Line

A gas-powered tankless water heater will need around 120,000-190,000 BTU to work effectively, which could be around 5 times more likely than your existing unit and may even require your gas line size to be increased, so is something you may want to consider carefully.


From direct to concentric venting, you need to ensure how you will vent your unit and consider where it will be placed to reach the outside.

Water Hardness

If you live in an area with hard water, you need to consider how the mineral content could cause limescale damage. To combat this, you could install a scale inhibitor system to filter out any limescale, but this may come with extra costs.

In Summary

A tankless hot water system can be great if you find yourself without hot water on a regular basis, but you need to bear in mind when making that all-important decision that the installation process, although can be done yourself, may not be the easiest project you’ve encountered in your life.

You need to ensure you’ve got the professional certification, that you maintain and clean the system well and you’ve got an appropriate location for ventilation purposes.

However, if you feel confident that the system will work for you, go for it and you can always call in the professionals for help if you ever need it. The instant hot water and endless hot baths will be worth it!

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