Maxwell_Jeeves

Where did you find out about this concept? As a mechanical engineer interested in HVAC, I have never heard of this.

Very cool, thanks for sharing. From an engineering standpoint this makes a lot of sense. Combustion can be very inefficient. Heat recovery has been used in industry for a very long time in the form of cogeneration, so not sure why people would doubt this would work. Instead of using waste heat to heat other processes, waste heat is going to a thermal mass or storage system for later use.

The fact that steam is leaving in the exhaust would suggest that there is still fugitive heat leaving the system, but creating a condensing system would probably not be cost effective when considering material costs and occupant needs being met. It would also require removing condensate. Would you agree?

I want to do more research on this, but should I decide that I want to get involved, how would I do so? And what kind of help are you needing? How are you looking to improve?

Consider this tire kicking, so if you have higher priorities, don't feel the need to respond to this.

Disclaimer: I am not an expert in HVAC, just have interest in it and study it when I can because it helps me in my job. Im essentially a plant engineer, so I deal with multiple systems.

I think this solution could be great for remote areas in cold climates that may not have access to cheap natural gas, or electricity. And even if they do have electricity, that is a very expensive way to heat a home.

Regulation of heat output would be difficult. It would essentially be a function of the convective heat transfer coefficient. Like you said, opening windows adjusting convection increasing airflow in the dwelling. I would need to run a heat and mass balance to see how that pens out.

ASHRAE recommends 15 cfm of outside air per person to maintain a building with adequate IAQ, so without a forced air system, the home would need to be fairly leaky to maintain this.

This prompted me to watch a few videos on this, and I saw one where they talked about using this to cool a home in the summer using natural convection and the stack effect. I couldnt see this working in humid environments with hot nights, but could definitely be an option in dryer climates that get cool at night. Pretty cool!