Choosing and installing the appropriately sized heater for your tiny house is pretty important. Get it wrong and you’ll a) spend long winters perpetually cold when home, or b) end up wasting power/fuel as you open windows to allow excess heat to escape. In this article, learn how to heat your tiny house while keeping weight, size, and cost in mind.
The key to proper sizing is knowing how many BTUs your space will require to comfortably condition it. British Thermal Units are defined as the amount of energy it takes to raise the temperature of one pound of water by one degree Fahrenheit. BTUs are a standardized unit of measurement in the heating and cooling industries so once you know your BTU load, you’ll pretty easily be able to compare various options.
You can calculate your BTU load by finding an online calculator, like this one or this one. You’ll need the following pieces of information on hand: insulation R-values in your walls, floor and ceiling height dimensions, and the temperature difference between a cold day and what you want your interior temperature to be.
Once the calculator has given you your BTU designation, look for a heater that can meet those requirements. If you need to choose between an under or oversized heater, choose the larger of the two and make sure it has a thermostat (built in or exterior mounted) so that you can set the temperature in your comfort range.
GRID TIED HEATER OPTIONS
If you have a reliable, grid-tied electric power source, mini-splits are pretty darn ideal. Small, wall mounted (so they don’t take up valuable floor space), and energy efficient, these sleek units can provide BOTH heating and cooling solutions from the same unit. A small exterior mounted compressor (installed typically on trailer tongue) is required for the mini-split to operate. More and more tiny housers are installing them. Be advised that as temperatures drop below -5F, these units can begin to struggle to generate heat. If you live in an extremely cold climate, make sure you choose a model properly rated for your climate zone.
Another nice option for grid-tied tiny houses are radiant floor mats (which install right below a finished floor). If you’ve ever stepped into a house with radiant floor heating, you’ll know just how magical that feels…it’s like walking into a spa! They take up no wall or valuable floor space in a tiny house, are easy to install, and pretty cost effective. Be sure to choose a model that outputs enough heat. Some of these systems are designed for small bathrooms with the assumption that there is a primary heat source elsewhere. Again, match the BTUs to your needs and you should be in great shape.
Lastly, you can always just use a plug-in heater. Some are safer than others so make sure you buy the one appropriate for your lifestyle (i.e., don’t get a unit with exposed hot coils if you have younger children or pets). Plug-in oil-filled radiant heaters are safe, economical, and depending on the size of your tiny house and its geographic location, may be all that is necessary to heat your whole home. Other options are plug-in baseboards, electric fireplaces, and wall panels.
Generating heat with electricity is incredibly demanding on an off-grid system so unless you plan on investing $20,000+ into solar (or some other alternative form of power), you’ll need to find either a 1) fuel (wood, pellets) based system, or 2) propane/gas heater. We are 100% off the power grid here at hOMe and have been so for over 3.5 years. We have no regrets at all but will say that finding an appropriate heater for our space was one of the largest challenges we faced in our entire build. Granted, at the time, hOMe was one of the largest tiny houses out there and there weren’t a ton of articles on the topic of heating small spaces out on the web.
Making the decision between going with either wood or propane heat was really tough for us and still, to this day, we sometimes wonder if we made the right one. Here’s the deal…if you go with wood as your only heat source, you’ll be married to your house in the winter. Longer days in town will mean coming back to a cold house and weekend outings will require you to drain all your water lines so you don’t risk coming back to frozen pipes. But propane is expensive (especially since we live on 5 heavily forested acres and have a lifetime of free fuel around us) and honestly not terribly efficient (about 85% for direct vent units). At the same time, we can set our propane heater to whatever temperature we want, lock the door, and go off on a tropical winter vacation without worrying about what condition our house will be in when we come back. Because wall space is so limited in our personal tiny house, we didn’t have room for both wood and propane heaters. In the end, convenience tipped the scale in favor of a propane one. When we’re here all the time we lament that we don’t have wood heat, but when we travel, or go away for the whole day, we’re grateful for the auto function that propane provides.
Sizing a wood fueled fireplace is important not only because you don’t want to waste money on an over-sized one, but because you don’t want to hog up valuable floor space with one that’s larger than necessary. One that’s too small though just won’t quite do the trick, requiring you to bundle up in layers all winter long.
Fortunately, the wood burning stove market has provided some really nice options for us tiny housers. Make sure to incorporate space for indoor wood and kindling storage. Many tiny housers build a raised platform for their wood burning stove, creating space for fuel storage below. If you plan on being mobile, it’s vital that you firmly attach your unit to your floor/subfloor. Further, keep in mind that road restriction measurements are taken at the highest and widest points and that vent stacks, gutters, etc. all count towards that overall measurement. One option is to install removable vents and take them on and off as necessary.
One of principle challenges a tiny houser will face with a wood burning stove is the clearance safety requirement for most units. Standard wood burning stoves need a fairly large safety perimeter to ensure there is no fire risk. Look for an option that has as minimal need for fire safety space around it as possible. Another potential challenge is finding an insurance broker willing to extend coverage when a wood burning stove is installed in a tiny house.
In terms of propane heaters, there are a few, but not a ton of options for tiny houses. We only recommend direct vent units (ones that directly exhaust vapor and fumes to the exterior) in tiny houses. The difference in cost and ease of installation between direct and non-vented units is significant, making the temptation to buy a non-vented option potentially high.
We fell for the non-vented heater bait ourselves, installing a unit in our son’s tree house, and it was terrible. They say they’re safe for habitable spaces but 1) they produce an acrid and unpleasant smell while in operation which made us wonder if we were being poisoned, 2) they require two windows to be left slightly ajar to allow fumes/vapor to escape meaning that a lot of fuel is being burned just to keep the room at temperature, and 3) they produce copious amounts of vapor. Even with windows ajar, significant pools of condensation were building up, and anyone that values a mold-free tiny house will know that excess moisture is a recipe for disaster.
Not sure what options to look for in a direct-vent propane heater? These are must-haves IMHO: thermostat control, non-electric ignition (in case you run out of power), and a BTU unit sized for your needs. You might also want to look for one specifically approved for mobile home use so that a warranty can be applied need be. Once you impose those parameters, you’ll likely find that there aren’t a ton of options available. Fortunately, you don’t need dozens of heaters, you just need one and there should be something that works.
In hOMe, which is 207sq ft + 110sq ft in lofts, we went with the Hampton H27 (max BTU 23,000 with 85% efficiency). We enjoy four distinct seasons in southern Oregon and our winters are often marked by 6-8 weeks of 2′-3′ of snow on the ground (we’re at nearly 4,000′ altitude). Our Hampton outputs tons of heat (even in -10F nights) but because it has a remote-controlled thermostat, it simply turns off when it goes above the programmed temperature.
The Hampton H27 requires very little safety clearance around its perimeter and was literally the only unit that would work in our little heater corner. From the left side wall to the unit it just needs 6” clearance, from back wall to unit 3”, from unit corner to wall 2”, and from unit top to ceiling 24”. No fireproof pan is required underneath the unit. The unit’s dimensions are 24.6”W x 27.1”H x 16.4”D. The weight is pretty significant (200#). The other downside is the cost ($1,600-$1,800). If you have a larger tiny house (24’ or larger), we recommend this heater. This unit can heat a space up to 400-500SF in a temperate climate. If your tiny house is smaller than 24’, it will be be overkill not only in space and heat output, but also cost.
One important point is that some propane heaters require propane tanks to be a minimum size (100 pounds/20 gallons for example). Some larger heaters won’t work with smaller 5 gallon (BBQ sized) tanks because there isn’t enough internal tank pressure to properly ignite the heater. Determine what sized propane tank you’ll install for your needs and make sure that your potential heaters will play nicely with those propane tanks. This is often not specified in the specs so will require that you call the company and speak with someone who actually knows the unit inside and out.
A smaller direct vent propane heater option (which we installed in our daughter’s 120sq ft cabin with 8′ tall ceilings) is the Home Comfort DV8. It requires no electricity to operate (Piezo ignitor) and vents all vapor and noxious exhaust gasses to the exterior. The DV8 outputs 8,000 BTUs and is designed to heat 200sq ft. It does a sufficient job of keeping her cabin warm, even on those three dog nights. The ignition system is awkward though and it sometimes takes several minutes to actually get the heater going.
The DV8 comes with an internal thermostat and automatically shuts on and off when the temperature gets beyond the designated range (adjusted with a turn dial on the heater itself). Though the sides and bottom of the unit don’t get too hot, the top most certainly does so make sure to keep clearance well above it.
The DV8 Home Comfort weighs 31 pounds and measures 12″w x 5″d x 24″h and costs about $700. Installation is fairly simple: cut hole into the exterior wall using included template, install the direct vent piping, and flash the exterior to protect the interior wall system from water. It took us about two hours to set it all up (and 24 hours to burn off the fumes from the new paint). We keep two 20# propane cylinders outside to fuel her cabin and she uses about 3 gallons per week in the winter to heat her place.
QUESTIONS TO CONSIDER
To sum things up, the principle questions you need to ask yourself when determining how to heat your tiny house
-How many BTUs does my system need to be to keep me warm and happy in the winter?
-Will I have access to grid-tied power?
-How often will I leave my home on cold winter days?
-Do I have access to free or inexpensive sources of wood or fuel?
-Can I meet minimum clearance distances for the unit in my tiny house?
-Will my tiny house have propane delivered to it or do I need to refill tanks myself? And if I need to fill them myself, do I have a trailer or some way to transport a larger 100 pound tank?
We hope this article has shed some light on the considerations that need to be factored into how to heat your tiny house. Feel free to leave comments and questions below, especially if you have direct experience with a unit that’s worked (or hasn’t) in your own tiny house. 🙂