How-To choose a hot water heater for your Tiny House

by andrewodom on May 23, 2011 · 9 comments


This morning I awoke only to see the digital thermometer taunting me from its place on the kitchen shelf – 23° outside and 69° inside. Before I even left the warmth of my double down cocoon I could feel my toes pressing against the icy floor. This morning would begin with a shower (I say this only because not everyday begins or even includes such an act) and because of the cold, I was happily anticipating up to 5 minutes of thawing. I lathered the shampoo/bodywash/soap concoction on my head and started working it down when the water began to drop in temperature. This typically doesn’t happen. I asked myself, “Has it been 5 minutes already?” Typically both Crystal and I can take a warm shower one-after-the-other without a loss in heat. “I must have gone overboard with the hot,” I told myself. In the bungalow we have been most satisfied with our choice in hot water heater. An Ariston 4-gallon Electric Hot Water Heater fit our needs and still fits our needs well. And because we are currently tied into the grid we have not regretted our choice for an electric unit. But when considering our options for a hot water heater in our Tiny House we have thought much differently.

A trip to the Interwebs or (and I shutter to say this as gas prices continue to creep up) to the local big box home-improvement store is, well, overwhelming. There are too many brands and too many sizes to choose from. Unites use different fuel sources and display a host of energy ratings. And then you have the tankless units. Where did the tank go? It’s not that overwhelming though if you know your needs, are familiar with your options, understand your fuel possibilities, and have thought about how long you and your families showers actually are.

  • Electric – uses large coils that hang down into the tank to heat the water. The coils are similar to the ones in an electric oven. Generally, electric water heaters aren’t as efficient as those powered by other fuel sources, and electricity is more expensive than natural gas or propane. However, they’re less expensive up front and don’t require venting. If your water demand is small, then it may be a good way to go.
  • Let’s first take a quick look at the fueling options.
  • Natural Gas – This unit uses a gas burner at the bottom of the tank, with a venting chimney that runs through the center and out the top. The carbon dioxide and water vapor byproducts are vented through the chimney and then run outdoors through a chimney or side wall vent. There is a gas pilot light to produce the flame. Natural gas models cost more than electric but are much more efficient.
  • Propane – This unit works in the same way as a natural gas unit except that it uses propane as the fuel source. Propane is generally used as a fuel source when a home doesn’t have access to natural gas. The propane is supplied from a large tank on the property. This is probably the most popular option for tiny housers who intend on “parking” for an extended amount of time.
  • Oil – I have bad dreams of these units due to childhood, hitting my head on a big, ugly tank when going out long for a, um, backyard touchdown pass, and awaking to the smell of a gas station above my head. Similar to gas and propane models this unit mixes the oil with air using a power burner to create a vapor mist, which is then ignited by an electric spark. Like propane, oil heat is typically used when natural gas isn’t available and is also delivered to the location and stored in a large tank. (and usually placed in the most inconvenient place.)
  • Solar – Now we’re talking. A solar unit uses the heat from the sun to produce hot water. The heat is then harvested by an absorber panel that typically sits on the roof. Tubes inside the panel either directly heat the water flowing through them or a transfer fluid that warms a heat exchanger. This exchanger heats your home’s water in a storage tank. Solar systems can be used in conjunction with a conventional system to cut up to 80 percent of your water heating bill. I am not sure about the panel sitting on the roof or even how large the tank is as solar heating is very new to me. However, this video explains a system quite well!
  • Heat Pump – Quite simply, this unit takes heat from the air and delivers it to the water via electricity. Rated at 2 to 3  times more efficient than electric water heaters, consumer demand is low and there are few manufacturers. They cost more up front than conventional units and can only be used in areas where the temperature stays between 40 and 90 degrees year-round.

So far I think it is pretty clear to see that the decision on a hot water heater relies largely on where you “live” and what kind of unit you can support with your structure. If you have access to natural gas, it can be a very fuel efficient way to go. If you park in outlying areas where it isn’t available, then your tiny home is probably going to use oil or propane. Solar heaters are best used in areas where there’s abundant sunshine and while heat pumps can shave a great deal of money from your bill, they are uncommon. ­If you want a cost effective system that’s easy to maintain and service, then a natural gas water heater is probably the way to go.

Hurry up and get to the tankless!

Tankless hot water heaters have become quite the rage recently. They are great for tiny housers as they take up little room. For more traditional homes they currently come with a federal tax rebate and overall are more efficient than storage tank models. Tankless heaters heat water as it flows. No one will run out of hot water as I did just this morning. Tankless heaters also last up to ten years longer than a storage tank. Electric tankless units don’t produce a shred of greenhouse gas and there is no possibility of flooding due to a ruptured tank.

There are some drawbacks though as we have found out. Natural gas whole-house units can cost up to 3 times as much as conventional heaters. We have been looking at Rinnai’s V53i interior-mount tankless water heater but have been somewhat discouraged by its $870 price tag. That simply was not in our initial budget. So while you’ll have an unlimited supply of hot water, there are limits on volume because the output is split between all of your fixtures. Some houses require a larger natural gas line to supply the unit with enough fuel, adding to the price. Further expense comes from venting the gas or propane with pricey stainless steel tubing. If you go with an electric unit (which we haven’t ruled out), it may require an additional power circuit. Gas powered models produce some greenhouse gases and require annual servicing. And lastly, depending on the size of your home, the time that it takes to get the hot water from the heater to your faucet can increase water waste. This is a huge discouragement for us which has prompted us to relocate the hot water heater to inside the bathroom where it will have the least amount of space to travel.

Because I am neither a plumber nor an electrician nor even a hot water heater salesman, I have no real advice as to how to choose the right unit. There are a number of factors to consider between your needs and your desires. It is an important decision though, even for a tiny house.

What are your thoughts? Do you have a tankless? Are you still paying for oil? Do you wish now you had a different system? Please comment and let us know if we should be considering one unit over another. And as always, if you like what you read, share it on Twitter or Facebook with the social media buttons below!

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photo courtesy of howstuffworks.com

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