Gravity Furnice

Does anyone have some good information on gravity furnices? How they operate, how to inspect, what to look for, etc?

Any help would be apprecited.

In case someone isn’t aware of this type of heating system.

** GravityFurnace.jpg
Gravity Air Heat**
A gravity air system is similar to a forced air system. Both systems use air to transfer heat from the furnace to the living areas. A gravity air system does not have a blower. Instead, the natural convection created by warm air rising circulates air throughout the system. Gravity air system maintenance is similar to the forced air system maintenance discussed above. Gravity air systems, of course, do not have blowers to maintain. In addition, there are no filters to obstruct the slower moving air. Like forced air systems, gravity air systems require annual maintenance by a professional heating contractor.

Years ago I had one of thee in a house I owned. They have very large supply and return vents that must be left unobstructed to allow enought air to move my convection. There can be asbestos issues due their age.


Michael - thanks for the information. My wife is an agent, and one of the house she is listing, has one of these in it. I’ve never seen one, until this weekend and was amazed at how large the duct work is. YES - there is asbestos tape all over it.

Your welcome. The one you describe is probably very inefficient as well. Replacement may be in order but dealing with the asbestos may seriously affect that decision.


Is another name for these types of furnaces “OCTOPUS”? I have never seen one up close just in books.

What is a furnace? We never see them in the deep south.

Yes, That term is commoon here.

octopus furnace.jpg

octopus furnace.jpg


Go ahead rub it in!!


What is a swamp cooler? We never see them in the far North.:stuck_out_tongue:

It’s 35 deg. F and mixed precip(snow and rain) today.


This is the second time I have seen this phrase “swamp cooler” Are you referring to an evaporator?



See the following link: