Tankless Water Heater Maintenance Guide

Questions to ask yourself and Simple Checks you can do now.

If you’re one of the many hundreds of thousands of families in this world that have decided to switch from a traditional, inefficient, ugly, space-taking tank-based water heater to a beautiful, modernised, more efficient both in running and in space terms, you’re likely very satisfied with your purchase.

And it’ll all run great! Usually, most homeowners don’t experience any issues with their tankless water heating system or unit throughout its entire 20+ year life span, depending on which model you have purchased. However, every manufacturer recommends maintenance and check-ups every now and then, but not all provide the clearest of instructions.

If you don’t maintain your tankless water heating system or unit as you should, you may find yourself struggling with access to hot water. Not only this, but you can risk severely damaging the actual unit itself, or the piping around it. In addition, you may find that this can actually cause thousands – if not hundreds of thousands – of dollars in property damage, if you get scolding hot water spraying your walls whilst you’re away on holiday, weakening them massively.

It is for these reasons that you should always maintain your tankless water heater system or unit. Regular maintenance, usually every six or seven months, can help you get the most out of your system without having to worry about its lifespan or put up with any of its problems.

But how exactly do you maintain a tankless water heater? This is a question that is asked often. We all know we need to, but we barely never know how. For this reason, we’ve compiled this short and sweet article explaining everything you need to know with regards to your tankless water heating system or unit maintenance.

And to begin, we share some simple checks you can do before proceeding, and some simple questions you can ask.

Three Questions . . .

Firstly, have you ever carried out maintenance on your tankless water heating unit before? If you haven’t, do you feel comfortable doing so yourself? If you do, that’s brilliant. However, if you struggle with DIY and similar tasks of this nature, you might find that it’s best to call a professional instead. Whilst you are trying to prevent damage, any marginal errors or pushes of any wrong buttons or turns of any wrong knobs can lead to a catastrophe – both physically and financially.

Secondly, do you know how often you are to service your tankless water heater? Has it been maintained and checked-up before? If not, it may be time to do so. If yes, try to remember how long ago this was, and consult the manufacturer as to how often they recommend you service, inspect and maintain your tankless water heating unit.

Thirdly and lastly, do you have the instruction manual for your tankless water heater? We cannot stress how essential this is for the proceedings that are about to follow. If you do not have the instruction manual, you could make a mistake that could cost you an entirely new tankless water heating system or unit. If you can’t find it, or remember throwing it away into a bin, you might want to consult your manufacturer or the internet. What can’t you find on the internet, with the exception of love?

Basic Water Heater Maintenance Tips

Now, let’s move onto the key steps and details of how to maintain and clean out your tankless water heater when the time has come.

STEP 1 – CONSULT YOUR MANUFACTURERS INSTRUCTIONS

This is the most useful document you will use when carrying out this process. If you can’t access it, search for it online. We strongly don’t recommend you proceed with anything until you find a copy. If you’re still struggling, you can likely call your manufacturer or retailer, and be provided with a copy.

STEP 2 – REMOVE ALL POWER FROM THE UNIT

This step is essential if you want to not lose your life during the procedure. If your tankless water heater is powered by electricity from the mains, switch off the mains using the circuit breaker next to the tank. However, if it’s powered by gas, simply twist the valve controlling the gas.

STEP 3 – EXPOSE THE WORKINGS OF THE HEATER

To achieve this, you may need to consult your manufacturers instructions, and check that you won’t be voiding any warranties. Usually, you can just use a screwdriver and turn and remove the most conspicuous screws on the unit. This should allow the cover to simply lift off, revealing all that is inside.

STEP 4 – CLOSE WATER ACCESS TO THE UNIT

Obviously, you’ll need to turn off the water supply to the heater after you disconnect the power, otherwise you’ll have a high-pressure watery mess that will likely drown all of your surrounding property, and the plumber won’t get there on time. Twist all the water valves to the “OFF” position, and – done!

STEP 5 – REMOVE ALL THE PRESSURE FROM THE TANK

Using pressure release valves and similar means, release as much pressure from the tank as you can. These can be located using diagrams and illustrations in your manufacturer’s owner’s guide or instruction manual. This step will prevent scolding hot water shooting in your face at incredibly high speeds, and – well – scolding you.

STEP 6 – WHACK ON THE HOSING LINES PROVIDED BY RETAILERS TO WATER LINES

This step is essentially the first step in purging your tankless unit. Usually, your hosing lines are provided in the box that your tankless water heater came in. Attach these to the unit.

If you are struggling to locate them, consult your manufacturer’s instructions. If you can’t find your hosing lines, call your manufacturer and request to purchase another set.

STEP 7 – PURGE PORT VALVES: ON.

Flick your purge port valves open. This will allow the purging process to proceed. This step is absolutely essential. If not done correctly, you may end up building huge pressure within the tankless water heater, causing permanent damage to the internal workings, and potentially even causing an explosion – which of course, you want to avoid.

STEP 8 – MEASURE OUT 10 LITRES OF VINEGAR

What? Vinegar? Yes! It will clean your tankless water heater like no other solution. However, we do recommend that if you do not want to use vinegar, you walk or cycle or take the car to your nearest plumbing store or tankless water heater store, and purchase special cleaning fluid. This is more expensive, but it does the same job as vinegar.

STEP 9 – FLUSH, DRAIN AND ENJOY

Now comes the time to actually flush your tankless water heater out entirely, and drain it in the same process. This will allow you to experience greater efficiency of your tankless water heater. Pour in the vinegar or specialist cleaning solution and ensure that none of it leaks on surrounding property, otherwise you may struggle with a pungent, unpleasant smell that will last for days.

Always adhere to manufacturer instructions – they know best!

STEP 10 – SHUT THOSE VALVES!

Now that you’ve finished the flushing process, it’s time to shut the purge valves and continue your day as though nothing has happened. You’ve successfully flushed out your tankless water heater, without the help of a professional!

AND NOW, CLEAN UP AND SCREW EVERYTHING BACK TOGETHER.

Now that you’ve successfully flushed your entire system, you will want to clean up and put everything back together.

To begin, start by unscrewing the hosing lines that were attached to the water inlets and outlets. You should store these safely, but ensure that there is no water left, as in the winter these can freeze over and crack if left outside or in cold conditions. Storing them safely will allow you to save money in the long run, as you won’t have to purchase new pipes every six months when it comes to maintenance.

When the pipes are removed, you may proceed to tightening all the valves back into where they were before. You can begin to reconnect the water lines, and the gas lines, although do not turn them on until all other valves are shut. When all of this is complete, and all is ready and connected, you may proceed to switch on the power and unleash the power of water through turning the valves to the open position.

If nothing is leaking, and all was done correctly, you should be ready to move on to the final steps.

Now, re-install the cover using the same screws that you have put away when unscrewing the cover, and screw them on tightly. When this is complete, all that is left to do is run the hot and cold water taps simultaneously to flush out any vinegar or cleaning material from the pipes.

When this is complete, you are ready to enjoy your hot water all over again, and have successfully serviced your tankless water heating unit or system by yourself.

Please note: If you are uncomfortable performing this, call a professional.

About the author

Steve Bates

Hi, I'm Steve and I currently reside in Chicago, Illinois. Although for most of the last 20 years I was a partner in a HVAC company down in Austin, Texas.

I understand the frustration involved with dealing with water heater repairs and replacing or upgrading to a new, more efficient model.

My aim is offer some basic advice on fixing home hot water systems. And if a repair isn't possible, then to make the process of selecting a new water heater – be it gas or electric - as simple as possible.

So that you can save money and have a safe and reliable hot water system in your home for many years to come.