Low-temperature levels, in simpler terms cold, has long been an enemy of mankind, causing a considerable amount of discomfort as well as other infections that thrives and spreads quickly in the season. As a result, many devices have been made to fit the class “best portable gas heater,” in order to provide more warmth, and in this class also falls the best unflued gas heaters today.

The best gas heaters are designed with a high capacity and are able to increase atmospheric temperatures in a considerate period of time effectively, and amongst the champions, are the flueless (or vented) gas heaters as well as the gas heaters (unflued). These type produces a tremendous amount of heat comped to regular electric heaters, and are very suitable for large spaces.

There are, however, a few dangers associated with using this device (Unflued Gas heater), all of which would be discussed in this article. Trust us when we say that reading till the end would leave you much more enlightened than you are now.

Also Read: How to fix carbonmonoxide leak in a furnace

What is an unflued gas heater?

Gas heater class generally generates heat by creating combustion through the use of gas. Narrowing it down a little, when gases burn, there is always some sort of residue pollution produced, and the manner in which the device deals with is directly responsible for whether it is a flued or unflued device.

Unflued gas heaters are the ones that don’t have an exclusive venting arrangement; therefore, it releases the residues directly into the environment.

These gas heaters have no flue or chimney to carry its combustion residues outside and are mostly portable or mountable, with a source of either just only gas or gas along with electricity. An excellent example of this is a patio heater, and they are not recommended to be used indoors.

Also Read: 5 Reasons Why you feel sick after Sauna

What are the types of unflued gas heaters?

Unflues gas heaters generally work the same way, leaving a distinction only in its power requirements. Depending on manufacturers, some heaters are designed to run the old analog way, burning gas directly with the aid of a pilot flame, and releasing heat produced directly into the atmosphere.

Others also make use of gas, but also requires an additional source of electrical power, which is used for control of automatic functions like timer and auto mode of it has one. As a result, there are majorly two kinds of unflued gas heaters, which are the gas-powered or electricity and gas-powered.

Are unflued gas heaters safe for you?

How safe an unflued gas heater is, is directly tied to where it is being used. We recommend that these heaters should not be used in enclosed or not vented paces.

This is due to the tendency of its gas residues released into the air, and building up, which could cause harm. Some of these residues include carbon monoxide and nitrogen oxide, which, when inhaled into the body, would cause harm.

The heater is much suitable and harmless in open and well-vented areas, and we recommend it be used in such areas only.

Also Read: Which Appliances Gives off CO

Features to consider in choosing the best-unflued gas heaters

  • Heat output capacity:

The heat capacity of heaters is usually measured in BTU, and the higher the BTU rating, the more heat it is able to produce per minute, and the larger the size of the room it is able to serve. It is, therefore, vital to look out for products with the best BTU rating, which is just enough to get the job done; in this way, you wouldn’t overspend on what you don’t need, or end up with some cheap piece of junk.

  • Auto shutoff/ timer:

these features are beneficial for heaters, and we recommend you purchase a product that has at least one of the two qualities. A heater (unflued, especially), without an auto-shutoff feature, is at risk of overrunning, making the temperature too high and eventually not conducive for people in the home.

Devices with the timer feature are also suitable, as they allow the user to choose specific running durations, this way you can simply anticipate the bow long it would take the device to heat up the environs properly, and as a result, set it to not work beyond that point.

  • Installation cost:

Due to being gas-powered, these heaters require unique installations as opposed to the ones that make use of just electricity. Professional input includes mounting, connecting to a gas source, as well as installation of other necessary fittings to get the product to work.

It is crucial that all these are put into consideration before the device is purchased in order not to end up punching far above your weight.

  • Maximum elevation height:

Depending on the manufacturer’s design, there is only so much some heaters can take as regarding elevation in height, after which it ceases to function. This feature should be taken into consideration, especially for those who live in high altitude areas so that you don’t end up with a device that cannot work as far as it is mounted in your home.

  • Quiet operation:

This is always useful to have for household devices generally, ranging from humidifiers to air purifiers, ceiling fans, and all of the rest. The quieter a device is, the more convenient it would be to have around, as well as blend into the home without much fuss to inhabitants.

  • Warranty:

let’s face the reality, getting a good and useful gas heater would surely cost money and a lot of it.

This is basically seen as a gamble by many, until it pays off by the device performing its intended function, however, to ensure you are in the best possible position not to lose should in case something happens, we recommend you purchase a product with decent warranty duration attachment.

Most times, heaters with warrantees are really durable since manufacturers know that the expensive, inferior quality product would always be shipped right back to their doorstep.

Top 4 best unflued gas heaters

1) Rinnai EX22CWP Wall Mounted Direct Ventilation Furnace Propane 

Special features: cabinet design, variable temperature unit measurement, item weight; 51 pounds, product dimensions; 30 x 10 x 31 inches, child safety lock, Verica venting, self-diagnostic control module,

Best unflued gas heaters
Check the price of this product

With a capacity that can hardly be matched, and qualities befitting of every bit its price, the Rinnai EX22CWP is pretty much a beast when it comes to generating and dispersing heat. Its capacity is sufficient to serve vast spaces; basically, the whole house purposed, as well as the comfortable, user-friendly electronic controls for smooth operation.

The device is basically a gas heater, unflued precisely. However, it also comes with a built-in humidifier tray, which can hold a decent amount of water for adding humidity to the air alongside heat. There is also a built-in air filter that stands at the outlet vent of the device, removing all sorts of particle contaminants that might be harmful to residents in the home.

It also has much flexibility in performance, being able to work as far high as 7000feet off sea level, and while in operation, its body remains cool to touch, making it very safe to be left at home around kids. It is tranquil, which we must say is a bit surprising considering its size and capacity and can be left on standby mode when not in use, which leaves it consuming next to nothing in power.

Despite its expensive price tag, this device is highly impressive, and well worth the price if you are really looking to get the right heater. It might, however, require you to hire a professional for installation, or if you are handy with stuff like this, you can do it yourself. The major downside to this device is its poorly calibrated thermostat, which leaves the device always running instead of shutting off at a particular temperature. It’s built-in timer, though, would help compensate, allowing users to set a working duration before it shuts off.


  • easy controls,
  • consumes little amount of power on standby,
  • suitable for large-sized spaces,
  • quiet operation,
  • inbuilt air filter from removing dirt,
  • can function at height,
  • timer,
  • cool to touch body surface,
  • 10-year heat exchanger warranty for residential installations


  • expensive to purchase and install,
  • poor thermostat calibration,
  • which leaves the unit running continuously.

2) Mr. Heater F260560 Big Maxx MHU80NG Natural Gas Unit Heater 

Special features: 0.5 inch gas connection, vertical or horizontal venting, 80,000 BTU output, ceiling mountable, product dimensions; 30.3 x 27.6 x 22 inches, item weight; 87.6 pounds.

Best Unflued gas heater
Check the price of this product

This is another impressive unflued heater, which is built for large-sized areas, and from experience/ tests, it actually does what they say it does. It is pretty bulky in size, which is expected owing to its capacity and volume of heat it can release and comes with ceiling mountable options.

From the manufacturer, it is recommended that this heater be installed somewhere at least 8 feet off the ground, practically making it compulsory to be mounted.

With a heat output capacity of 80,00BTU, this device is able to generate more than enough heat for your needs, though it comes with a little hike in power source, which is the use of natural gas that is then converted to propene before used as heat fuel.

This means extra cost in installation, adding to the already existing cost of installation of the heater only. Do keep this in mind before purchasing the product.

It is, however, effortless to use and control, also coming with a specially designed self-diagnostic control module that enhances overall user experience and has a built-in power exhaust, which allows for both horizontal and vertical venting.

There is no auto-shutoff feature present here, meaning the device would keep running till it’s turned off, though it comes with a 10-year warranty on heat exchanger defects, and 3 years limited warranty on other parts and burners.  


  • 3-year limited warranty on parts and burners,
  • suitable for large-sized spaces,
  • self-diagnostic control module,
  • 10-year warranty on heat exchanger defects,


  • minimum of 8ft clearance from floor to heater base,
  • conversion of natural gas to propane required,
  • lack of auto shutoff protection,
  • expensive to purchase and install

3) Rinnai FC510 Vent-Free Space Heater

Special features: 10,000 BTU heat output, item weight; 29.4 pounds, product dimensions; 3 x 10 x 20 inches, the only electricity-powered vent free

Best Unflued gas heater
Check the price of this product

Another Rinnai product on our list in the FC510 here, which in truth and fact upholds the Rinnai name by being capable of effective heating associated with the brand. It has quite smaller dimensions compared to many other heaters, making it much portable as well as being able to fit into small spaces.

It is effortless to use, coming with controls that make it more comfortable for users to interact with, though it makes use of natural gas directly as its heat generation source. However, there is also a need to be connected to an electrical power outlet for other electronic operation. As a result of this, the heater basically consumes energy on two fronts, which is responsible for a high running cost.

While operating, the body surface of the device remains cool to touch, which means it can be used in public or open places without fear of skin burn. It also works in a reticent manner, adding next to nothing on preexisting background noise and can be used at high elevations of up to 7500ft, to say the least (which we have tested practically).

In all, this device is effortless to install, as with a little bit of courage, you wouldn’t have to hire a professional compared to other heaters reviewed so far. Installations also doesn’t cost much, and mounting isn’t exactly necessary. We would say that it is well worth the cost, after all, said and done.


  • easy to control,
  • cool to touch body surface,
  • quiet operation,
  • can be used at high elevations,
  • very quiet while operating,
  • easy to install.


  • consumes both electricity and gas to generate heat,

4) Mr. Heater 30,000 BTU Vent Free Blue Flame Natural Gas Heater 

Special features: 30,000 BTU, natural gas-powered, ODS (oxygen detection safety), product dimensions; 23.8 x 1.2 x 27 inches, item weight; 26.8 pounds

Mr. Heater 30,000 BTU Vent Free Blue Flame Natural Gas Heater
Check the price of this product

If gas heaters could be classified into digital or analog type, then this device is certainly going to fall in the analog category. It features the old type of direct gas-burning, which results in heat generation, warming the air in the process, and does not radiate heat like the infrared unit.

The device works by tending to the heat initially produced by a pilot flame, and then aggravating it by gas intake, and is very quiet in doing so at that. It is wholly vented free and generates the cleanest heat amongst all the products reviewed on our list, with an almost 0% production in carbon monoxide, though it cannot be used at high elevations above 4,500feet.

This heater is designed to serve small-sized spaces of up to 700sqft and is designed not to work alone if you desire maximum effect. To maximize the capacity of this device, it should be installed with a furnace in the home, as that way, the heat can be easily carried across all areas of the home.


  • auto shut off on detecting low oxygen levels,
  • zero-carbon monoxide production making it vent-free,
  • does not require electricity to function,
  • floor or wall mounting option,
  • easy to install


  • Cannot be used at elevations higher than 4500feet,
  • suitable for small-sized rooms,
  • designed to work with a furnace for maximum impact primarily.

4 Benefits of using an unflued gas heaters

The benefits wrapped up in using unflued gas heaters includes;

  • They are mostly portable, enhancing smooth movement around wherever it would be needed.
  • They are very energy efficient.
  • They are generally more expensive to run as compared to only powered portable electric heaters.
  • They are very efficient and effective heat-generating devices.

9 Precautions of using an influed gas heater

In using unflued gas heaters, ensure you follow the precautions for safe operation;

  • Ensure the heater is not installed in confined areas, as they emit some combustion gases indoors.
  • Ensure wherever it is used is adequately ventilated in order to avoid build-ups.
  • Have your heater frequently serviced to diagnose possible faults and prevent potential hazards quickly.
  • Ensure that carbon monoxide alarms are installed all over the room. This is to pick up any buildup of the gas, and alert people in the home, and also ensure that it meets the European (EN50291) or US (UL2034) standards.
  • Clean the heater very frequently and thoroughly.
  • Keep it out of reach from children, preferably in a place they cannot get to.
  • Keep all flammable materials at least one meter away from the heater in order to avoid the buildup of heat that could cause a fire outbreak.
  • Do not leave the heater running overnight or use it in a place where you sleep, like the bedroom.
  • Ensure you replace the gas heater as at when due because old products are liable to fail quickly or lead to hazards.

Final Verdict: Top 2 Best Unflued gas heater

Of course, you guessed right; the Rinnai EX22CWP is top of the list for our recommendation on the best unflued gas heaters for you. It boasts a very impressive heat generation output, which is second to none, while also being very safe to use in the cool to touch surface and child safety lock features. There is also the benefit of being able to act as a humidifier, as well as an air purifier, making it about 3 devices in one.

Mr. Heater F260560 is the next best option from us after the EX22CWP due to its impressive 80,000 BTU output. It also comes with impressive warranty additions, though its lack of auto shutoff and compulsory mounting recommendation means that it ultimately falls short of the Rinnai product.

Important Read: