Is One Tankless Water Heater Enough For A House: An Honest Opinion

Beginner Info, Tankless Water Heater

is one tankless water heater enough for a house
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Is one tankless water heater enough for a house, a million-dollar question isn’t it.

And, if you’ve landed on this page to feed the lust of the query, then trust me, you’re in RIGHT HANDS, indeed.

Trust me, today I and my core team has decided to end this age-old debate on whether a single tankless unit is enough for your home or NOT.

It goes without saying that if you’re a first-time buyer, then you would want to know whether a particular tankless model is enough for your entire home or NOT.


I have written a comprehensive guide on the tankless models that can suffice the hot water requirements of mid to large size homes.

Yes, you heard it, RIGHT.

A single unit will definitely serve the purpose until and unless the hot water requirement is exceptionally high.

But before we start discussing the power and credibility of a single unit, please allow me to introduce a tankless water heater to all those who are hearing this bizarre word for the very first time.

As the name suggests, a tankless hot water heater is a device that is used to suffice the hot water requirements for the faucet, dishwasher, shower, and other fixtures as well.

The demand for tankless hot water heaters have surge tremendously in the United States and other parts of the world in recent times, and the credit goes to the innovative and advanced technology that they are equipped with.

On top of it, they are energy efficient, and has a longer lifespan.

Since they are small, compact, and sleek designed, so you can install them in tiny spaces including the non-conventional ones such as a closet and an attire.

Moreover, they don’t possess any tank so standby heat loss to the atmosphere is almost negligible.

Like any other product in this world, a tankless water heater has its own share of CONS as well.

On the downside, they have a high upfront cost and you need to wait for a couple of seconds before the hot water will arrive at the faucet.

But, the pros outcast the cons with a huge margin which is clearly depicted in the rising demand for a tankless water heater.

To be honest, depending upon your household size, you can save up to 33 percent on heating costs, and models like this are a great example of such claims.

Some of the brands that have proved their mettle in the tankless domains are Rinnai, Rheem, Noritz, etc.

Many of you wouldn’t believe me but there are certain brands in the tankless water heater domain that offers a lifetime warranty.

The working style of a tankless water heater is also simple.

When you turn on the tap, water flows through the pipe that is heated by a gas burner or an electric heating element, and post that it flows to the outlet.

Depending upon the type of installation, you can divide tankless water heater into two types, that is, the indoor tankless heater and the outdoor tankless heater.

Similarly, depending upon the type of fuel that a tankless hot water heater uses, you can bifurcate it into an electric tankless heater and a gas tankless.

Further, the gas tankless can be subdivided into propane tankless and natural gas tankless.

When it comes to installation, my suggestion to you would be to hire a certified technician for this purpose as the warranty may become void for certain tankless models if you’re not getting it installed by a professional.

Sizing is definitely, one of the most important things to consider when it comes to buying a high-quality premium tankless water heater like the one that I’ve reviewed here.

In case, you’re not aware of the size of the tankless water heater that you should consider for your home, then please read this article which decodes all the nuts and bolts of a tankless water heater sizing in the easiest and most convenient manner.

Do I need one unit or multiple ones?

The number of units that you need totally depends upon the flow rate, rise in temperature, electric or gas heating source, and some additional factors such as the distance of the farthest faucet from the tankless heater.

 But, if you don’t want to get into any complex calculation which I would be explaining to you in a while then simply search for whole-house tankless water heaters on the e-commerce site and buy the one that not only syncs well with your hot water requirements but also falls well within your budget. 

Moving further, I would try to explain some of the technical terms that if you’ll know then you would be able to make an informed buying decision in a better way.

Flow rate

When it comes to buying a tankless water heater and reaping maximum benefits out of it, then you need to calculate the flow rate of all the facets that you want to run at peak hours.

By doing so, you would come to the maximum flow rate that you would be needing at peak hours and so buy a tankless heater that is able to provide such a flow rate.

For example, at peak hours you run two faucets that have a flow rate of X GPM and 3 showers that have a flow rate of Y GPM.

So, total flow rate that you would be needing is X+Y GPM.

Now, you need to look for a tankless heater that is able to provide that range of flowrate.

Temperature Rise

Another thing that can influence your decision of buying two tankless heaters over one is the rise in temperature.

Suppose you’re a resident of an extremely cold climatic condition wherein temperature falls in minus degrees in the winter.

In that case, you might be needing more than one unit for sure.

Temperature Rise = Output Temperature – Incoming Groundwater/Supply water Temperature

From the formula, it is clearly visible that during the winter season incoming groundwater temperature will fall drastically, and as a result, to get the same output temperature as in a warmer climate, the heater has to perform additional work.

Distance of the furthest faucet from the tankless heater

Sometimes if the distance of the farthest faucet is more than usual then you might be needing more than one tankless water heater.

If the distance of the farthest sink is more then the wait time will also be more than the usual so in order to decrease the wait time, you’ll have to install an under-sink tankless water heater.

These under sink tankless water heaters are meant only for one fixture.

So, if you’ve got 5 faucets that are very far from the central water heating system then you would be needing 5 different under-sink water heaters.

Household Size

For households whose daily requirement is more than 85 gallons of hot water would be needing at least two tankless systems.

On the other hand, if your household hot water requirement is less than 40 gallons per day, then one unit would be more than enough.

Single Appliance

Sometimes installing a tankless system for a single appliance can be beneficial as well.

For example, you can exclusively install a tankless unit for appliances such as dishwashers, washing machines to diversify the load on the central/main heating system.

The point-of-use systems are convenient as well.

Wrapping Up

First and foremost, I would like to thank you for being with us till the end.

Secondly, I would like to bring to your notice that I along with my team have put loads and loads of effort into coming up with this comprehensive buying guide.

And, in case, you’ve liked our efforts, then please do share this piece of information with the ones who are in need of it.

After all, sharing is caring, isn’t it.

To conclude, a single tankless unit is sufficient for most small and mid-sized households.

However, in certain scenarios such as the farthest faucet from the central heating system, you might be needing a second heater or sometimes multiple heaters as well.

Furthermore, to reduce the load on the main heating system, you can use a couple of point-of-use tankless heaters as well.

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