Going Tankless

The Toronto Star had a completely one-sided article today on the pitfalls of switching to a tankless water heater.

For those who may not be aware, yes, you can have a water heater that does not involve heating up a tank and keeping it hot forever just in case you might want some.  Here’s a typical installation if you’ve never seen one.



The first time I ever heard of tankless hot water was from my mother after her trip to Europe in 1978.  These heaters were commonplace in Holland then and still are.  In fact, tank based systems for residential use are hard to find there. (Likely since they make less sense than the tankless version.)

Mollie and I switched to tankless two years ago after buying our “recession house.”  Yes, it was a bit of a learning curve, but the savings are there if you are willing to adjust your thinking a bit.

But back to the Star…

A tankless water heater needs extra maintenance, he found. It has to be serviced once a year with a vinegar solution to keep it clean and functioning properly.

“Estimated cost is $100 a year – more than the gas savings.”

This is an apples and oranges comparison.  Yes, you have to be aware to keep the unit clean by doing the annual flush AND/OR by having a water softener for all water going into it.  But if the owner was not ALSO flushing his tank every year and willing to live with the constantly degrading efficiency, why the double standard?

He had to remove his water-saving shower heads, since there wasn’t a strong enough flow to keep the water heater on.

Admittedly there are issues with pressure and this takes a bit of work/thought.  There can be a problem with these shower heads, but I think it’s more likely that there are other contributing factors.

The tankless heaters have an inherent pressure drop just from the design of the heat exchanger that tanks don’t have, so if you make the mistake of installing them without any other changes in your piping system you might notice a pressure problem.  I had this problem and had to go back and replace a few gate valves with ball valves to avoid the problem.  You also have to look at your cold water system to make sure you have somewhat equal pressure drops in hot and cold sides, or else adjusting your temperatures can be problematic.

It should also be noted here that this problem would be avoided with a tankless unit installed in new construction since the system could be designed to accomodate.  It’s only an issue for retrofits and it just takes a bit of careful thought.

“I now waste more water waiting for the hot water to arrive. It takes 10 to 15 seconds every time you turn on the tap for the hot water to get up to temperature – and up to a minute with the tap on full for the hot water to arrive on the second floor.”

Really?  And the hot water residing in your tank was magically transported to the second floor?  Instantaneously?  No waiting?  Gimme a break.

But seriously, in new construction the heater could be placed closer to the faucets and avoid some of this delay.

“Many households take longer showers. From 10 minutes, they go to 12 minutes, knowing they won’t run out of water. So, what happens to the savings? Zero.”

Yeah.  I don’t know what to say to that.  Apples … meet oranges.  Comparing 10 minute showers with a tank to 12 minute showers with tankless and being disappointed with the result is rather a giant mental leap.  So, if the price of gas were higher this article would say that people are switching to 15 minute showers and saving nothing?  BS!  THEY ARE HAVING 15 MINUTE SHOWERS, which I think we could all agree is the basis of the problem.  Forget the tankless water heater, why don’t you start by keeping your showers to under 5 minutes!

Realistically I think that most people who go so far as to install one of these things is already in the mindset to save water as well as energy, so this comment is moot.

You may be disappointed with what you get when you need a trickle of water – say, to clean a razor blade while shaving. The cold water has to flow through the tankless unit and kick on a heating mechanism. This can take a while.

“Tankless systems won’t give you the same hot water in a low-flow scenario as what you get from a storage tank,” Krill says.

No kidding.  So try putting some hot water in the sink and leave the tap off while you shave.  Was that so hard?  Again, these tankless hot water heaters require a bit of thought about your habits.

A hot water tank uses about 40,000 BTUs of energy (British thermal units) but a tankless unit uses five times that, or 200,000 BTUs. “It fires up the burners and pounds the cold water to raise the temperature to 120 degrees Fahrenheit,” he says.

Well, mine is 130,000 BTUs.  They come in different sizes just like tanks do.  So what?  This represents an instantaneous energy flow.  To get to total energy used you have to consider how often the burner is firing compared to the smaller burner on a tank that fires far more often.

And there’s a second problem here.  120 degree F?  Are you kidding me?  Why would you possibly need your water that hot?  If you have it set that high you will have to mix in cold water for your shower and lose all that energy that you just paid for in heating the water for nothing.

A friend bought a model that has a remote panel so he can dial in the temp water he wants and then only needs to turn on the hot water for showers.  Each family member has their prefered shower temp.  Sadly, the one I bought does not have this but my next house will.

The municipal water temperature is about 70F in summer, but can drop as low as 40F in winter.  The tankless unit has to work harder to heat water from 40F to 120F. This means your endless supply can run out in the cooler months.

I see.  And the tank does not have to work harder because it is on that different, magical municipal system?  I’m sorry, but if you run out in the winter you merely did not choose the correct size of heater for the conditions in your house.  End of story.

So, scale back your expectations in winter. Instead of two showers and doing dishes at the same time, do the dishes later.

Ah, now we get to the heart of the problem.  [Dripping sarcasm deleted.] As I said before, these heaters do take a bit of getting used to and some adjustment of habits.  Yes, larger units are available which would allow for two showers and doing dishes at the same time, but they will not have nearly the savings of a smaller heater which requires that showers not be simultaneous.  Two people in the same shower works well, but this could also results in substantially more than 12 minutes. 

Next week we’ll look closely at the cost of buying/renting a tankless water heater system.

I can’t wait.