Old wall and floor gas furnaces, and the old free-standing furnaces, are largely outdated and unsafe. But there are now in the market high-efficient wall gas heaters, able to overcome the disadvantages of the old gas space heaters.
Modern ductless gas space heaters are a lot more powerful than common small electric heaters; they are excellent for moderate climates - hence their popularity in countries such as Australia or New Zealand - but can also be a good option in cold climates, in airtight homes.
New wall ductless gas heaters
»» safe (they are combustion sealed);
»» popular in mild climates;
»» can replace central heating systems in super-insulated homes.
Old ductless gas space heaters Are Inefficient and Unsafe
Old gas space heaters include floor furnaces, freestanding room heaters and recessed wall furnaces, all without sealed combustion or modern heat exchangers.
These gas space heaters are energy inefficient. Their AFUE (Annual Fuel Utilization Energy) is typically between 60 and 75%. They waste up to 40% of the fuel they burn.
They are unsafe, and should be tested for CO (carbon monoxide) and draft. If you are still using any of these type of units, make sure that it doesn't pose any immediate risk and consider replacing it with a high-efficient wall gas heater.
New Wall gas Heaters are safe and very energy efficient
New wall gas heaters are ductless,with an AFUE (energy efficient coefficient) that can reach 90%.
These gas furnaces have sealed combustion.
The best models have a sealed combustion chamber, and a fan to vent the combustion gases to the outdoors, through a dedicated pipe (to draw air from the outside to feed the combustion). They are sealed direct-vent units.
They are much more powerful units than common electric portable space heaters, and they can be used as a primary source of heating in energy efficient homes, even in cold climates. They are intended for moderate and small-moderate heating requirements
Running costs and prices
Online stores like Amazon are selling wall gas heaters (Rinnai) at prices of $1,200 - $2,000.
Pay special attention to the brand, the warranties and the output. Only manufacturers with high quality products are ready to give a long warranty (say, warranties of 10 years for the heat exchanger).
Top Brands and Manufacturers & Direct-Vent sealed Gas wall heaters
Rinnai is the best-known manufacturer of wall gas heaters. Rinnai units are popular and can be bought in big retailers (Lowes, Home Depot, Amazon). Other top gas wall heater brands: Bonaire (formerly Vulcan), Braemer, Toyostove and Monitor.
See, for customer reviews/Amazon: Rinnai Direct Vent Wall Furnaces, Natural Gas
New direct-vent wall gas heaters are easy to install, as long as there is easy access to a gas line and a exterior wall.
The heater has to be installed on an exterior wall. The installation requires a terminal hole of around 3''/8 cm, connecting the unit to the outdoors.