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Everything About Tiny, On-Demand, Water Heaters

Questions to Ask Yourself

★ Electric or Gas?
If electric, how many volts and amps is my house?
If gas, propane or natural gas?

★ Tank or Tankless?

★ How many Gallons Per Minute do I use?

★ What is the temperature increase?

I’ll try to cover all of this, so by the end of this article, you can answer all of these questions!

But first, familiarize yourself with the…


Important Terminology

“Single Point 3.5 kW 120 Volt 0.3gpm-2.0gpm Electric Tankless Water Heater”

★ kW = kilowatt hour

★ GPM = gallons per minute

This is the amount of water – the flow rate… The higher, the better (around 2GPM is good)

★ v = volts

★ Single Point = 

★ Tankless = No tank (duh)

But this means that the water is heated “on demand” as it passes through the heater (and not stored in a tank and heated within a tank).

★ POU = point of use

If it’s a “POU,” then that means it’s small enough to put directly where you need the hot water for usually just that use. Example: under the sink in order to wash dishes.


Important Facts

Average GPM Americans use to shower = 2.1

Average water temperature for showers = 105°F


Ground Water Temperature

OK, this is actually really important and depends solely on WHERE you live – the ground water temperature is the same no matter if it’s summer or winter.

Once you know the ground water temperature, it’ll help determine how important the temperature increase is.

Ground water Map

For Example:

I am in Seattle. According to the map, ground water here is 52°F.

(Now some math): 105° – 52° = 53°, which means I need a 55° increase (because specs are in increments of 5°, usually).

So now I know what’s important for my house and location:
A flow rate at 55°F of at least 2GPM


Electric or Gas

This is probably the question I flipped back and forth on the most! I mean, I really have no gauge at all about electricity or gas usage, which one is more expensive, which one would be more efficient, etc. OK, so how does one decide?



  • Don’t need to buy propane tanks
  • Doesn’t need to be vented
  • “Safer” (no gas leak worries)


  • Usually not as cost efficient


Good For

  • Houses with more than 50 amps


Voltage (Volts)

Houses are either 240v or 120v. Most are going to be 240v and most hot water heaters are 240v. Mine tiny house is 120v, which is actually pretty difficult to find a decent hot water heater in 120v.

Amperage (Amps)

If the house is anything under 50 amps, go with gas. If it’s 50 amps or more, either electric of gas is fine… but no matter what it is, definitely check that hot water heater uses less amps than whatever your house has.





  • If your electricity cuts out,
    you can still take a hot shower
  • More “off-the-grid”


  • Needs to be mounted on the outside,
    because it MUST be vented

Good For

  • Any house


No Matter Which You Choose

Definitely get a tankless hot water heater!

A tankless hot water heater is super small, and can heat the water directly as it flows through the heater (hence, no need for a huge tank taking up precious space)!


Do I Need a Water Pump?

If you have a hose or some sort of water source with pressure, than no, you will not need a water pump. However, if you are collecting rain water and your water is just sitting there, then you’ll need a water to move the water from collection spot to water heater… so then, yes.

Tip: Buy the water pump after you buy the hot water heater.
Why? Because the pressure (GPM, “gallons per minute”) makes a difference. If your water heater can only heat 2 GPM, then you don’t want a pump that will pump more than that.


What I Use

Click pic. to see on Amazon

Eccotemp L10 Portable Outdoor Tankless Water Heater


  • Propane Gas
  • 2.6 GPM flow capacity
  • Water Pressure: 20-80 PSI
  • 20 Minute automatic safety shutoff timer
  • No water pump needed because water hose is available
  • Height 25.5″
  • Width 13.625″
  • Depth 8″
  • Weight approx. 27 lbs.


Questions? Comments?

Hot Water Heaters SQUARE Let me know if you have any questions, comments, suggestions, or overall insight… Did this article help you? Is there better info’ out there? Let me know! I’d really like to know! And feel free to share! =)




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