Going Tankless: The Hot & Cold on On-Demand Hot Water

Residential? Commercial? Are tankless water heaters beneficial for either?

The radio endorsements, the market-saturating ads – you’ve heard all the buzz about tankless water heaters lately. So what’s the real story? Are tankless water heaters a good choice for your home or business?

The Hot – Let’s Talk Residential:
Tankless water heaters are perfect for certain residential applications. Do you have a cabin in the Northwoods? If so, you probably go up there to enjoy nature – maybe you enjoy an early morning fishing trip in the summer or snowmobiling in the winter. But you’re probably not up there all year long. A tankless water heater is great for this type of residential application.

Here’s why…

No Standing Loss, Fits in Small Spaces
Because traditional water heaters hold heated water in a tank for long periods of time, they act like a thermos bottle: while you’re not using it, heat is slowly dissipating through the jacket. This is called “standing loss.” With a tankless, you don’t have any standing loss because water is continuously heated on demand – resulting in an endless supply of hot water. Not to mention, without a tank, you’re looking at a very small space footprint; a typical tankless unit is the size of a suitcase, so it hangs neatly on the wall and is directly vented through your wall or roof.

Both traditional tank-type water heaters and tankless water heaters are available in high-efficiency models; however, the tankless – with its lack of standing loss and ability to fit in small spaces – well, that means additional energy savings.

The Cold – Let’s Talk Commercial:
I know what you’re thinking – hey, if tankless water heaters are so great in residential applications, they must be really great in commercial applications!

Sorry, but unfortunately that’s typically not the case.

Here’s why…

More Faucets, Less Hot Water
Tankless water heaters don’t work as well in commercial applications for one simple reason: most commercial applications (hotels, restaurants, etc) require so much more continuous hot water. Tankless operation is measured in GPM (gallons per minute), and usually it’s just not enough to sustain commercial-use hot water demand. So when that tankless needs to heat your 50 degree groundwater up to 120 degrees, it can only do so as fast as that water can flow through the unit. So let’s say you turn on one faucet – great, you have piping hot water! But then you turn on a second, and then a third. Yes, each faucet will give you hot water, but now your pressure is reduced, so it takes longer for each faucet to produce the same amount of hot water.

More Than The Price Tag
From an installation standpoint, you could be looking at more than your budget allows. Tankless units are often not the plug-it-in-and-go solution they appear to be. To remedy the pressure problem, you’ll probably need to install a storage tank or multiple tankless units. On top of that, there’s electrical work, venting requirements, and specific repiping needs. When all is said and done, you’re likely to see much higher up-front capital cost.

The “Cold Water Sandwich”
Tankless units work on flow – so when that faucet is turned off, the unit is not operational. This means when the water in the line cools down, there is a burst of cold water before the sensor kicks in and the water is heated again. So if the chef in your restaurant is filling up a pot of water, he might think he’s getting all hot water but in reality, that “sandwich” may mean that by the time the pot is full, a fair amount of that water is actually cold.

Now think of a cold water sandwich surprise occurring when one of your hotel guests is in the shower. Yikes!

So there’s the straight talk on going tankless: yes, tankless water heaters can be beneficial in certain residential applications; however, it’s important to know that they can cause a lot of headaches, especially when it comes to commercial use.

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Featured image courtesy of Flickr user Scott Lewis licensed under CC by 2.0.