Solar syphon- 'free' shop heat

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Project by NedB posted 10-26-2012 11:33 PM 3701 views 12 times favorited 28 comments Add to Favorites Watch

simple shop built solar syphon heater mounted in/through the window of my workshop. Loosely based on plans from the Maine Solar Energy Assoctiation:

Being in a northern climate, I built the ‘vertical’ variant, and used simple plastic sheeting for the see through section, and landscape cloth for the black section.

I finished just as the sun went down today, will report back with how effective it is.

-- Ned - 2B1ASK1

28 comments so far

View a1Jim's profile


117268 posts in 3748 days

#1 posted 10-26-2012 11:41 PM

Interesting idea..

-- wood crafting & woodworking classes

View Joe Lyddon's profile

Joe Lyddon

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#2 posted 10-26-2012 11:57 PM

I hope it works…

I would sure like to study this a little more…

Never heard of a Heat Siphon before…

Thanks for working on it!

-- Have Fun! Joe Lyddon - Alta Loma, CA USA - Home: ... My Small Gallery:"

View Woodstock's profile


254 posts in 3459 days

#3 posted 10-27-2012 12:12 AM

I saw a lot of these outside the south facing side of mobile homes that had a passive diagonal version of this while living in Blacksburg, VA @ Virginia Tech in the early 80’s. Most folks I talked to seem to like them to supplement their kerosine stoves that most of us had. Wasn’t a lot of added warmth but on a starving student’s budget every little bit helped.

A noted difference on the siphon was diagonal and fully inclosed and fully insulated on the outside. The top of the unit’s hot and cold openings through the outside wall typically were just above the inner floor level and with the bulk of the siphon mass below floor level. Colder dense air that had settled at the bottom of the room entered into the lower back chamber of the siphon and did a U shaped turn at the bottom into the front section that had double pain glass and 3 walls insulated and painted flat black. The sun warmed and expanded this air which rose on its own and back up the top section of the siphon and back into the room, which in turn sucked more colder air in behind it from the same room inside.

Clear as mud?


-- I'm not old. Just "well seasoned".

View NedB's profile


659 posts in 3736 days

#4 posted 10-27-2012 12:22 AM

I’m also going to be putting a 4×8’ panel on the south end of the shop, and will be putting a ‘drop’ ceiling in using rigid insulation.
Cost was under $20, for that price I’ll take ‘any little bit’ of heat I can get.

-- Ned - 2B1ASK1

View JJohnston's profile


1622 posts in 3462 days

#5 posted 10-27-2012 12:28 AM

Here in the desert southwest, houses are occasionally built with the entire south wall like this (with more permanent materials). They call it a trombe wall. They’ve kind of fallen out of favor with all except the “boutique” builders (I don’t know why, they work so well), so they’re mainly found on either pueblo-style McMansions, or older, genuine adobes.

-- "A man may conduct himself well in both adversity and good fortune, but if you want to test his character, give him power." - Abraham Lincoln

View lew's profile


12378 posts in 3926 days

#6 posted 10-27-2012 12:36 AM

Great post for a neat and functional idea!
Made one of these years ago . Only difference was that I used florescent lamp tubes , with the ends cut off. Painted them black. Placed it at about a 45 degree angle. Heated our bed room with it!

-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.

View Beginningwoodworker's profile


13345 posts in 3844 days

#7 posted 10-27-2012 05:06 AM

Neat idea!

View NedB's profile


659 posts in 3736 days

#8 posted 10-27-2012 08:37 AM

I was an avid solar fan back in high school, this differs from a Trombe wall, in that the Trombe is designed to heat up a wall which then radiates heat into the structure, the syphon is a ‘direct’ heat source vs indirect. I’ve been doing a bit more reading, and may expand my planned solar panel on the south side to include most of that wall (minus the door initially, though there’s no reason not to include a collector on the back of that as well)

-- Ned - 2B1ASK1

View HalDougherty's profile


1820 posts in 3408 days

#9 posted 10-27-2012 10:26 AM

Great project. A solar kiln over my heat pump might help lower my heating costs this winter…

-- Hal, Tennessee

View NedB's profile


659 posts in 3736 days

#10 posted 10-27-2012 06:03 PM

Today is mostly overcast, but even with that, the syphon was bringing in heat to the shop. Give me some decent sun on it and it will bring the shop temps up considerably!

-- Ned - 2B1ASK1

View Grandpa's profile


3261 posts in 2846 days

#11 posted 10-27-2012 06:22 PM

You might build a heat exchanger in front of your air filter system and get double duty from this too. Just a thought.

View Joe Lyddon's profile

Joe Lyddon

10293 posts in 4223 days

#12 posted 10-27-2012 06:25 PM


Now, can you come up with a COOLING syphon?! ... for the warmer / hotter months??


-- Have Fun! Joe Lyddon - Alta Loma, CA USA - Home: ... My Small Gallery:"

View Woodwrecker's profile


4196 posts in 3746 days

#13 posted 10-27-2012 07:40 PM

Pretty cool, or should I say “hot” idea Ned !
Let us know if it does the trick.

View NedB's profile


659 posts in 3736 days

#14 posted 10-27-2012 08:05 PM

View TopamaxSurvivor's profile


18379 posts in 3847 days

#15 posted 10-27-2012 08:08 PM

Great work. I have thought about this a lot, but we have too many overcast days.

Joe, Solar cooling is by a thermal chimney to draw air up and out. The intake is run underground to get the air temp down in the 40s.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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