Fire pit heat channelling - Small Cabin Forum

- Forums - Register/Sign Up - Reply - Search - Statistics -

Small Cabin Forum / Off-Grid Living / Fire pit heat channelling

Author

Message

# Posted: 20 Mar 2019 03:17pm
Reply

A challenge for you inventive, problem solving folks:

I always wanted to come up with a means to passively move heat from a fire pit to where we were sitting.

Yes could do reflectors, walls, propane heaters, longjohns, stay indoors, etc.

My idea was always about putting some pipes in the ground. Starting from a raised position in the fire pit itself to get heated up and then going underground to the perimeter.

Considerations?
- Getting air to move through pipes
- water, rust, pests etc getting into pipes
- using plumbing glycol instead of air
- trip hazards
- melting pipe
- carrying smoke to seating area

On thought I've had is that we often have a prevailing wind from the NW. This carries the smoke and the heat to the SE. So everyone sits at the edges of the smoke and the smoke naturally moves about and people constantly shift their chairs about in trying to get that optimum but always smoke compromised position.

So.. Maybe a raised funnel (maybe a horizontal rectangular shape as part of a canopy) could capture the prevailing wind to force air through the pipes that would go into the fire and then come out upwind of the fire pit and the smoke.

Ideas?

rockies
Member

# Posted: 21 Mar 2019 07:31pm - Edited by: rockies
Reply

The Romans used to build a fire on the lower level of a building and then pipe the hot air underneath a raised floor (Pic 1 - usually used for bath houses).

This is a modern method (pic 2), but in order to make it work the fire should be at a level that is lower than you are so that the heat can rise into a "chimney" and then be piped under some seating benches.

da2417d5a6190332673a.jpg

1970sinteriordesig.jpg

ICC
Member

# Posted: 21 Mar 2019 08:11pm
Reply

I thought the problem that was posed was how to enjoy an open fire and not get smoked out but be warm. The Roman warm floor works for an interior space but hides the fire. You may as well not bother with a fire pit if you can't see the fire and can't make S'Mores.

ICC
Member

# Posted: 21 Mar 2019 08:16pm
Reply

The best idea I have seen was at a friend of a friend's place. A chiminea ina screened in gazebo. The screening kept the bugs at bay and the chiminea chimney was extended through the roof. Sorry no pictures.

Google "chiminea" if you don't know what they are. The one I saw was cast aluminum with a screened open front and used black pipe to a wood stove type roof thimble and insulated pipe. I've seen clay ones in stores as well as sheet metal ones.

montecristo
Member

# Posted: 22 Mar 2019 09:09am
Reply

Maybe something like this?

images.jpg

ICC
Member

# Posted: 22 Mar 2019 10:16am
Reply

Put a pipe long enough to get a good draft going

Jebediah
Member

# Posted: 22 Mar 2019 01:05pm - Edited by: Jebediah
Reply

I seen a pic where the whole seating area was dug into the ground at a depth of what looked like 4' and the fire pit was another 2' deeper....I wonder if that would keep the wind at bay....Not sure about the water drainage!

Cowracer
Member

# Posted: 22 Mar 2019 01:24pm
Reply

Quoting: rockies

The Romans used to build a fire on the lower level of a building and then pipe the hot air underneath a raised floor

The correct term for that feature is a Hypocaust. I help win a trivia contest by knowing that.

Tim

KinAlberta
Member

# Posted: 24 Mar 2019 10:31pm - Edited by: KinAlberta
Reply

Also known as a hot tub when it fills with water.

Still think a wind scoop might work.

KinAlberta
Member

# Posted: 22 Oct 2023 08:25pm - Edited by: KinAlberta
Reply

So would just a bunch of rebar laid out on the ground like spokes on a wheel and then covered with sand and gravel allow much heat to move 6â€™-8â€™ outwards from the fire?

Iâ€™m back with some research.
Looks like the sand and gravel around the pit would have to be a great insulator to allow the heat to travel very far. So tubular metal would likely work better.

Heat Transfer in a bar of steel - Mechanical engineering general discussion - Eng-Tips

https://www.eng-tips.com/viewthread.cfm?qid=297220

NorthRick
Member

# Posted: 25 Oct 2023 06:30pm
Reply

I don't think rebar would move anywhere near enough heat for you to notice. I think your best bet is something heat reflective.