Author Topic: Tankless hot water heater or tank?  (Read 3438 times)


  • 5 O'Clock Shadow
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Tankless hot water heater or tank?
« on: September 19, 2014, 09:53:49 AM »
So we are making a two bedroom apartment in the basement of our 3 bedroom home.  We've been debating back and forth between an on demand tankless water heater or a 50-60 Gallon water tank.  Either would be natural gas powered. 

Tankless - never run out of hot water
              - more energy efficient

Tank - Cheaper
        - less abuse of hot water (it will run out)

What are people's thoughts?  Does anyone here have a tankless system in their rental?  Do people seem to abuse it and use more hot water than normal, thus not making it more energy efficient?


  • Guest
Re: Tankless hot water heater or tank?
« Reply #1 on: September 19, 2014, 12:04:35 PM »
I don't have one in any of my rentals.  But I have considered them.  Main reason I haven't done so is the upfront cost. 

In my opinion the water abuse is a non issue.  If they are going to abuse how much hot water they use they will do so with a water tank as much as they will with an on demand.  Turning up the heat of the tank will keep the hot water flowing longer then just draining the tank.  Your biggest difference is going to be your up front cost in purchasing the on demand.  Good luck.


  • Walrus Stache
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Re: Tankless hot water heater or tank?
« Reply #2 on: September 19, 2014, 12:55:10 PM »

It may depend on your heat source.

I have a tankless and I am on propane.  When we decided to build it was easily 10+ years on payback (maybe more... I forget).   Propane is damned expensive.

And a tankless with electric is probably non-optimal.  They often take 240 amps (not volts, mind you -- AMPS!) to run a tankless.  This often means upgrading the panel to a 400 amp panel.

And you're spot on with the "abuse"... you sometimes do sort of zone out and forget.  There's no "cue" that says "I feel it getting slightly cooler; time to end this." 


  • Bristles
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Re: Tankless hot water heater or tank?
« Reply #3 on: September 19, 2014, 07:49:03 PM »
We opted for two 40gallon tanks vs thankless as it was much less expensive but still provides endless hot water. We definatley take longer showers when we have both tanks on. We tend to turn one tank off and drain it to keep our water consumption down.

Not worth the cost in a rental for tankless.


  • Walrus Stache
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Re: Tankless hot water heater or tank?
« Reply #4 on: September 20, 2014, 08:45:04 AM »
When I renovated my Accessory Dwelling Unit (in which I now live, while I rent out my main house), I installed a tankless water heater (natural gas).  I love it.  The only hot water I use is for showers and doing dishes (by hand). 

Just a side note:  Right now, my city is beginning a process of inspecting and permitting these ADUs.  According to them, one huge no-no would be a gas-fire hot water heater in a bathroom.  That's where mine is.  When I called the city planning people and inquired about it, they said because mine is tankless, it is not a problem.


  • Stubble
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Re: Tankless hot water heater or tank?
« Reply #5 on: September 25, 2014, 11:13:02 AM »
It all depends on the details...

Where I live (Alberta, Canada), we have natural gas.  However, when our hot water tank blew out about a month ago, we chose to replace it with another tank as the payback period for the tankless was longer than the anticipated life of the unit itself. Until the cost of these units comes down 20-30%, it just doesn't make sense. 

Also, check into the installation requirements for the tankless heaters.  They usually require venting to the outside and we only had a 3' side yard adjacent to our nearest neighbour but needed a minimum of 4' to meet bylaw requirements.  As a gas fired appliance, permits will be required to be legit (there's another long thread on this topic elsewhere!).


  • 5 O'Clock Shadow
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Re: Tankless hot water heater or tank?
« Reply #6 on: September 26, 2014, 11:24:46 AM »
I was a renter living with a tankless once and the owners figured out a way to turn the water pressure way down before they moved far away, I assume to avoid the over-consumption you're worried about, somehow in a way that was impossible to turn back up.  We tried everything.  Since there wasn't enough pressure going through the tankless heater, we did not have hot water at all in the winter.  We figured out if we ran 2 or 3 sinks in the house, it would provide enough pressure to have enough hot water for a shower, which obviously defeated the over-consumption problem, and all of this lead to us having maybe 15 or 20 repair guys throughout the year come try to fix it on the owner's dime of course.

So... don't do that.  :)  I've heard many horror stories about the repairs/maintenance/trouble of tankless systems.  It sounds great on paper, but be careful.


  • 5 O'Clock Shadow
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Re: Tankless hot water heater or tank?
« Reply #7 on: September 27, 2014, 01:38:00 AM »
Not worth the cost in a rental for tankless.