Tankless Water Heaters – The Hard Facts that You Ought to Know About (Part 2)

Tankless Water Heaters – The Hard Facts that You Ought to Know About (Part 2)
May 9, 2013 Lorelie
Tankless Water Heaters

Tankless Water Heaters

continued from Tankless Water Heaters – The Hard Facts that You Ought to Know About part 1.

Instantaneous? No, Not Really

How long does it take to get some hot water flowing out when you open a hot water faucet?  If you have a traditional tank-type water heater, the hot water will begin to flow immediately since the water itself has already been heated up and is just waiting in the storage tank to be used up when you need it.  Even if your faucet is quite far from the storage tank, this will not affect the temperature of the water and you will still end up having hot water when you turn the hot water faucet on.

On the other hand, if you have a tankless water heater unit, it would be an entirely different story.  How long does it take before the tankless water heater beings to deliver hot water to you? It only takes about 10 to 15 seconds.  This is due to the flow sensor working, and then a fan turns on and then the burner turns up.  This is the only time that the water will be heated up.  With that said, the traditional tank-type water heaters are the true “on demand” devices here.


There are a lot of parts and sophisticated controls on tankless water heater units.  The more sophisticated they are, then the more chances that something will go wrong.  If you are living in areas with colder climates, you have to carefully drain them completely if they will not be used for some time or else they will be badly damaged by freezing.  If your area has hard water, then these water heaters are prone to lime and sediment buildup which seriously lowers their efficiency and it might even cause them to break down.  On the other hand, if you have a traditional tank-type water heater unit, the minerals, sediments and other debris in hard water will just settle at the bottom of the tank which makes it easier for users to vacuum or flush it out.

Moreover, sediments and lime that form in the bottom of a traditional tank-type water heater has been shown to have little effect on its performance.  Even if there is heavy sediment or lime buildup, the efficiency is seldom reduced (about 5%) due to the fact that most of the exchange of heat occurs in the flues, not in the bottom of the tank.  The costs for maintenance also have to be taken into consideration when it comes to tank-type versus tankless water heaters too.  Due to the fact that tankless water heaters are basically mini boilers, they need a lot more attention unlike the tank-type ones.

It is advised that you have to read the fine print due to the fact that you are likely to see that your warranty will be voided if your unit is serviced by a non-qualified technician.


With the use of a traditional tank-type water heater, it is actually possible for one to enjoy a shower and another one to do the dishes at the same time, or perform two, three or more tasks that need hot water all together.   However, if you use tankless water heaters, it will prove to be difficult or it would just be impossible.  You need to pay special attention in order to get the amount of heating done properly and the flow rate to be acceptable.  In order for you to do two or more things at the same time, you may have to acquire an even larger tankless water heater unit.  Even if you only would like to have a trickle of hot water, a tankless water heater unit probably will not even turn on for that.

In addition, there could be fluctuations in temperature which can make it difficult for an individual to have a decent hot shower.  The temperature of the water can cycle 5 degrees to cold, then just right, and then 5 degrees too hot.  Meanwhile, there’s also the dismaying “cold water sandwich effect” which typically occurs when a tankless water heater unit is turned off after it is just used.  There is actually a little amount of hot water still remaining in the piping, and if you turn it on hot even just for a few minutes after the initial task, that will begin to flow out, followed by the sandwich effect – the cold water will suddenly flow out of the tankless water heater unit before it is even heated up properly.  People try to solve this kind of dilemma by means of adding another storage tank, but of course, a lot of people tend to get tankless water heaters simply because they would like to get rid of their tanks once and for all.  If they opt to add another storage tank, then the efficiency of going tankless actually goes way down, and their energy costs go up even more.


In actuality, the place where you typically lose heat with both the tank type and tankless water heaters is from the pipes.  Whenever you use hot water, the metal plumbing heats up between the heater and the faucet, and then all the heat radiates away.  It could prove to be really expensive, but if you are able to do this, getting a tankless water heater installed at each faucet would be great, but of course, not everyone would think this is really practical.  By means of insulating all the piping, standby heat loss will significantly be reduced, whether you have a tank-type water heater or a tankless one.


Tankless water heater manufacturers typically claim that the units made in Japan normally last for about 10 to 15 years.   However, the thing is, the units that are made in Japan are not exactly the same as the ones sold in your country.  Think about this – the Japanese have different hot water demands, have a different culture and of course, different expectations when it comes to their water heaters.


When you have read all the things mentioned above, you will understand that tankless water heater units does not necessarily meet all of its water heating “goals” as claimed by a lot of water heater sellers nowadays.

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