Thermal air collection below roof deck

It really depends on what it is going to cost you to include the new heating equipment and their maintenance compared to purchasing the kWh to run an efficient heater connected to the grid.

Some people have been able to save with a DIY type heating system but others save going the conventional way. Do the math.

A bit more detail of how you want to accomplish what you want to do please.

Do you intend to use the heated air to then heat water and then circulate the heated water to the rest of the dwelling ?
Or, duct the heated air to the conditioned space directly (or through existing ducting) ?

Either way, and not to be a naysayer by nature, schemes of this nature, while they sound like no brainers, are usually more trouble that they are worth and less than economical.

I know, been there done that (or attempted similar) and lots of other stuff for several years (including starting a homemade solar thermal collector on fire) before returning to school and getting a BSME and then working in the process industries early on chasing BTU's for a living while staying involved with alternate energy as more than a hobby but less than an job and learning that such schemes, including those similar to what you describe, while they can be a lot of fun, are most of the time neither cost effective or workable and often dangerous or at least have unintended consequences which are usually not good or at least counterproductive to the desired results.

One consideration as an example of many (if I read your post correctly): Expecting to heat water in pipes (or more correctly tubing) by exposing them to heated air is very inefficient (regardless of what you and a lot of well-intentioned but very uninformed people may think). Reason: The film heat transfer coefficients between the air and the tubing is very poor. The attic will get hot. The water won't. Lots of other examples/reasons on request.

What you describe can be a fun learning experience but without the technical background, getting something like that to work, understand how and then why it's inefficient, wasteful, usually a PITA and possibly unsafe is kind of like trying to get into an elevator that's already gone up 5 feet while wearing roller skates.

I'd respectfully suggest experimenting by starting with a small project that's easy to disassemble and move around. If your serious about doing something right and want to learn, start by crawling before you walk and walking before you run.

Take what you want of the above. Scrap the rest.

Doesn't sound that unusual to me. That's that way many homes are here with an all-in-one gas pack heating and cooling unit inside an uninsulated attic.


I can guarantee you that literally thousands of other experimenters have had the same idea and if it has not become mainstream by now then there must be logical reasons why it has not been adopted by any number of energy-minded enterprises that love to sell this kind of green system. My guess would be that is does not come with enough gains for all of the cost and trouble but I'll agree with JMP, projects like this can be interesting and rewarding in many ways including expanding your skills and brain power.