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Stupid idea? Using attic heat?

Started by Old Greenhorn, September 09, 2020, 09:13:54 AM

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Old Greenhorn

 SO I am working up in the attic of my shop to prep for installing a chimney and you know, it gets hot up there during the day. The other day by 11am it was only around 70 outside but way too hot to work in the attic. So even though I know it can be dangerous, I got to thinking.
Many of us use house fans to suck air from the living space into the attic and keep the place cool in summer, so why not reverse the process?
 I am wondering if it would be helpful to suck the heat out of the attic in the fall and spring and perhaps even a few milder spells during the winter, and blow it down into the shop to augment the building heat. If it works, and I add some basic filtering, I could set the fan on a thermostat and just have it blow down when the temp hits 70° in the attic.
 It seems practical, but I have never heard of anyone doing this. The cost of heat in the shop is a big issue for me and if this helps keep it comfortable I am will to try it. I just ordered a remote probe thermometer to put in the attic so I can monitor the temp and humidity and get an idea of how dumb this idea might be.
 What do y'all think? We have some smart folks here, I'd like to beat this around a bit.
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

mike_belben

So theres an old man who has spent his life building houses that supposedly take no heat or very little depending on region and other factors.  I cant recall his name.. I think he called the technology something like stored geothermal or passive geothermal.  And i remember the term "capers" being used alot in his writings.  

The idea was to take the attic heat all summer and blow it by fan into tubes buried under the slab.  Obviously a new construction only sort of thing.  Capers was the term he used for all sorts of freecycled insulation to go in the dirt around the home perimeter to prevent the heat from radiating out to the cold atmosphere. Pool liners, roofing rubber and so forth.  (Not a bad idea to keep runoff from frost heaving under your slab either)  

Anyway the earth is a mass that acts as a long term heatsink. The caper made a big corral of dirt to park heat in. This stored energy supposedly would travel back under the slab and keep it warm/er without any heating system. And supposedly by the 3rd yr or so it stabilized and worked better. Idk.  


My issue was the ducts were dead ended.  You dont get much flow down a dead end pipe. Like a gascan with no vent.  If they were open ended pipes and snaked around then came back up to atmosphere i could see a flow exchanging substantial heat to the dirt.  University of colorado i think it was, did a greenhouse where two buried 55gal plastic drums acted as plenums in opposite corners.  They had a ton of 4" perforated plastic pipes buried in raised beds that started and ended at a drum, and a big industrial fan in one drum to recirculate the same air.  They said if the cfm was suffiencient to fully exchange 5x the cubic air volume of the space [iirc] that it created a substantial drop in temp and a very large one in humidity.  The moisture in the air was being fed through the raised beds which acted like a dessicant and sucked up the water.  The plants continually absorbed the moisture and removed it.  I guess the temp drop was from 90 to 80 but with the humidity removed walking inside it on a hot colorado desert day felt like air conditioning.



So anyway.  Yes you can blow your attic heat down into the house but whatever air you blow out must be replaced with some other air or you wont be doing much. Do you have vented gable ends or vented ridge?  Or are you thinking about venting ceilings of the living space into the attic to let the air circle from attic to living space to attic?
Praise The Lord

mike_belben

they make fans that go inside a piece of 8" ductwork.  And they make temp switches that look at temp differential across 2 probes.  grainger probably stocks them. 

The laziest way to do this is probably duct one of those from the shop attic to the lower level of the house somehow and set it on a switch that blows anytime the attic temp is say 10* above interior temp.  Youll probably lose 5* in the pipe before it gets there. A variable differential would be handy.  I have a pump controller from a solar water system that works exactly that way.  Just on off switching based on differential temp.
Praise The Lord

Old Greenhorn

OK, so maybe not a stupid idea. I will collect some data and see what it shows. I have no intention of getting as carried away as the fella you refer to, but anything that might help would be worth a little effort, commensurate with the ROI of time and materials. It's worth looking into. BTW, this is strictly for the shop. Now if it turns into something really worthwhile, I would look into doing something in the house after I collect a year's worth of data and run the numbers.
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

doc henderson

lots of good and fun info on passive solar.  the challenge will be making something automated that does not allow transfer of heat when you do not want it.  Our living room is concrete floor and a wall of south facing windows, and an overhang that shades them in the summer and not in the winter.  one of the solar kilns designs I reviewed had big air valves made out of rigid foam.  spring and fall is great and winter and summer needs to not compromise keeping the heat where you want it.  could also make a separate actual solar panel like for the roof or along the south wall.  basically building a small enclose well insulated attic.  I know you prob. want to keep it simple.   If it is a vented attic with an insulated ceiling, the difficulty will be the switching from daytime to night time, and maintaining your ventilation so you do not have condensation that ruins you insulation.
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

mike_belben

Well, the mudhut hippies have pretty much tried it all in the last century so that takes a lot of the pioneering out of it for you.  Today theyre splitting carbon hairs about how much evil was expelled in the production of the duct tape and gorilla glue you use to build the project over on permies.net or org or whatever it is.   

You dont necessarily have to pump the actual attic air and fiberglass and mouse poop down either.  You can use an air to air exchanger so that the lower level air is being contained and circulated inside a sealed conduit up through the warm attic and back down.  This could be as simple as a few lengths of 4" dryer duct that goes up through the ceiling, hangs from the ridge beam via wire ties to collect heat and then re-enters the shop.  Little solar circulator fan can kick it on when the sun is shining.  


Or.. Theres liquid storage. Water is 800x more times denser than air and it stores a tremendous volume of BTU comparatively.  Plenty of hut nuts have made well pumps powered by old exercise bikes with chain and sprocket driving the pump that fills the tank up in the attic every few days for gravity fed domestic water. U could pump water up for day then drain it down by ball valve to a drum in the shop by evening.  Rooftop solar hot water [parabolic trough concentrators] were all the rage in the 80s.  Subsidized by the almighty dotgov before it even had a dot mind you.


Is it worth it?  I dunno. Thats up to you.  If you spend more than you save by doing it then its officially a hobby.
Praise The Lord

Southside

One thing you need to be very careful with on system like that is creating condensation puddles in the piping which can lead to the conditions for growing the bacteria which causes Legionnaire disease. Just plan accordingly. 
Franklin buncher and skidder
JD Processor
Woodmizer LT Super 70 and LT35 sawmill, KD250 kiln, BMS 250 sharpener and setter
Riehl Edger
Woodmaster 725 and 4000 planner and moulder
Enough cows to ensure there is no spare time.
White Oak Meadows

Old Greenhorn

Well, the attic is already vented with gable vents at both ends. Not getting complicated here, just want to grab the heat out of there, if there is any. So at this point a simple 8-12" diameter riser pipe up in the attic to be away from the insulation and other 'stuff' with a simple filter and a round duct fan or 'something' to pull that air down and discharge it into the air space of the shop. Nothing more complicated than that. The ceiling fan in the shop should do the rest. It's just a little extra free heat to take some of the burden off the woodstove is all I'm thinking. But the data collection should tell the story once the temps start to drop a bit. Right now, the last thing I want is more heat in the shop. ;D
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

doc henderson

at least gable vents especially if louvered can be manipulated.  ridge with soffit vents would be tough.  if you just suck air into the living space, it may facilitate pulling outside air in and rapidly cooling the attic space.  i was thinking you might have to "un-vent"  the attic during the day to circulate shop and attic air to heat it.  great concept.  @GeneWengert-WoodDoc i know has mentioned attic spaces for drying wood.
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

Old Greenhorn

SO I quit early today, had to take the wife to the farm co-op for our weekly pickup (she is feeling poorly) and drop off a double pane window for repair ($115 bucks!), so i got home and did a little web surfing, turns out it is NOT a stupid idea and a lot of folks have worked on it. Found a page with a fella in MT that tracked his attic temps from fall thru late spring and he had an impressive number of days over 80° and even some days over 90 in January! But most of these folks get carried away and make it complicated with computers, processors, special hardware and lots of it. That ain't me. :D
 I am not looking for a miracle here, just a little extra help. If I put an 8-10" straight pipe near the center of the building with the suction end near the top sheathing, I figure any air sucked in through the vents will have time to get heated before it reaches the duct to be sucked down. A variable speed fan may help with this, and thermostatic control as Mike suggested to turn it on and off based on temp. Keeping it very simple and cheap until it is proven more time and money is worth it.
 Funny, you mention using it as a kiln. I might try that. First I need stairs up there and I have been searching CL for a setup. Just missed one, but I keep looking. With all the loft space I have up there now, it's an easy install. 3 years ago it was impossible. Right now, with the little hole I am limited getting lumber up there, but the stairs will make it easier. (would make the chimney work a dang sight easier too!)
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

doc henderson

you could set a thermostat to run the fan if the attic temp is above your target temp.  have to make sure you do not loose hot air after the stove gets going and the fan is off, up that pipe.  If you could "non vent" the attic during the time you are harvesting heat, it will help, so it reheats the partially heated shop air and not pulling in cold air from out side.  you will get it figured out, esp if you throw some remote thermometers up there and come up with a plan.  have fun!
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

Old Greenhorn

Yeah, that's pretty much the target plan for now. This is just something that popped into my brain when I let it wander off. I will play with it. When the remote temp probe shows up, I will install it and start watching and maybe moving it to find the best pick up point. Then after the stove and chimney are done and the weather starts to get less hospitable and I spend more time in the shop I will start messing with it. It's a cross between curiosity and something useful. For now, as Mike says, just a hobby, but we shall see where it goes. Knowledge is power. I have lost track of all the improvements I've made to the shop and 'operation' here over the last 10 months, but I know there have been a few. This might be another one, or maybe not.
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

doc henderson

you have got a crap load done.  some are one and done and then you move on to making stuff to support your habit!  so you are building the infrastructure for the rest of your life.
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

Old Greenhorn

DANG! you figured out my plan. Lets just keep that our little secret OK?
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

Don P

I think the full boat way would be to insulate the underside of the roof surface, bringing the attic inside the insulated envelope. Then circulate that stratified heated air either mixing it back with the downstairs air or expanding the heated area by using it in the shop. In other words I don't think there is a free lunch, that's those pesky laws of thermodynamics, but there might be more efficient ways of moving and using that warm air. 

Old Greenhorn

Don I am not following your logic. The attic floor is very well insulated now and the roof is not. The sun hits the roof and the attic becomes an oven. If I move that insulation up on the roof, the attic will no longer get the radiant solar heat and at the same time it becomes parts of the envelope I will have to heat through 'artificial means.'
 As it stands now I have what I think you are calling 'stratified heat' at the ceiling of the shop (below the attic insulation). Except that I don't, because I have a ceiling fan in there that has been running for 33 years straight. This is how I have kept the shop from freezing for all that time without any heat running. (Well, there were 2 winters where it froze for a time, but...). The sunlight enters through the windows in the front of the shop during the day, warming the slab floor and the fan keeps churning up that air all night long smoothing out the building temps.
 I wasn't looking for another major project that will likely only save me a little money or effort, just thinking I might be able to get a little extra help by pulling that heat down on those days where it is a benefit. I am just half way through my first cup of coffee, so maybe I missed it, but right now I am not seeing the benefit of what you propose. None the less, I appreciate the discussion. You are a construction whiz, so I am trying to figure out what it is that I don't understand. There have been a LOT of times I have no clue what you are talking about and then later it becomes very clear. That's why I read all your stuff and keep my mouth (and fingers) shut until the whole thing plays out. Then it makes sense. That's how I learn.
Thanks,
Tom
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

Crusarius

Sounds like an interesting experiment for sure. I cannot repeat this enough times. After the carbon monoxide scare I had a couple years ago, I highly recommend you add carbon monoxide detectors (more than 1). Remember carbon monoxide is lighter than air so it is going to be higher concentrations up high. 

I would add at least 2 up high and 2 down lower. Since you will be circulating the air, no telling where it may concentrate.

Old Greenhorn

Thanks Crusarius, it's a good safety point I have been meaning to add those in the shop but keep forgetting. I am wondering where you think the CO might be coming from in an open shop? (except of course vehicle work, which is rare and during winter months I have an exhaust hose I use for those short periods.)
 I am trying to keep this as a wood and fab shop and keep the vehicles out. But 'stuff happens' as we all know. ;D You do what you have to do.
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

Crusarius

if you continue to recycle air, and not replenish, eventually the CO levels will begin to rise. Whether you have running cars in there or not.

It may be an inconsequential rise but I feel it is still worth noting.

Another thing that raises CO levels alot more than you would think is an idling car outside. If that happens to be a place air gets into the shop it can get bad fast. I do not know what you have for square footage or air volume but still worth noting. 

Alot of factors can add to CO.

QuoteCarbon monoxide is produced when fuels such as gas, oil, coal and wood do not burn fully. Burning charcoal, running cars and the smoke from cigarettes also produce carbon monoxide gas. Gas, oil, coal and wood are sources of fuel used in many household appliances, including: boilers.

Old Greenhorn

OK, I get it now.  The attic is vented at both ends so it is not a closed loop. As I blow air down fresh air will be sucked in through the vents and heated (I hope). That is the starting plane anyway.
 As a former firefighter I have done many CO jobs and seen all kinds of strange things happen through 'poor thinking' or 'planning with disregard to physics'. It's fairly intuitive to me but your reminder is timely and good for everyone to keep in mind. 
 I am abundantly familiar with how the CO poisoning patient presents, I have had several, from mild to severe and one very acute (a fellow firefighter). Scary stuff indeed, especially if you don't recognize it quickly.
 I just added CO monitors to my shopping list, thanks.
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

Crusarius

yup. I knew you had experience. This was more for everyone else :) 

and a gentle reminder to myself to not do that again.

thecfarm

I worked for the state for a couple years working on low income houses. Seem like I remember the cold roof. The attic should be about 10° difference from the outside temperature, during the winter,  to have a cold roof so no ice is formed outside on the eves or inside either. They showed pictures of attic not vented correctly. Icicles was hanging from the rafters!!!
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

doc henderson

so the theory is that energy is neither created or destroyed.  so all you can hope for is to be efficient.  at the risk of "preaching to the choir"  I will go on to say that insulation just serves to slow down heat transfer, so we can condition a space by increasing the efficiency of retaining the heat.  in summer we have an air-conditioner (if we are lucky) that pumps the heat out and insulation to slow how fast it comes back in.  so if you insulate the roof, the attic will no longer get hot.  if the hot air from the uninsulated attic is pushed to the shop, it will simultaneously pull the outside cold air in. It may be heated some.  as we add heat, to be efficient, we would want to start with warmer air to achieve a higher overall temp.  I am afraid if it is cold outside (the point), the the air in the attic will quickly become colder than the air in the shop.  If we create a closed loop from the shop, we can add heat to the warm shop air, and make it warmer.  so the trouble is changing from daytime to night time.  and from seasons or bouts of weather change.  great discussion.  so the conundrum is both getting some free heat, and keeping it simple.  If we solve this, we all agree to give 5% to the forestry forum :)
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

doc henderson

just had another thought.  not sure of how you shop is positioned, but if you build a solar kiln on the south facing wall, when it is empty you could exchange air from it with the shop, during the day, and close it off at night.  basically a free standing solar panel.  or If you do get some cheap foam insulation, and glazing, it would be easy with a mill for lumber to build a solar panel for heat.   popcorn_smiley smiley_sun :P
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

Old Greenhorn

Ah Doc, you are starting to make my head hurt! ;D
 But I do like that idea of using the solar kiln. Problem is getting it closer to the shop than I had planned and the angle it needs to get the sun right. It would wind up at a 30° angle to the shop wall approximately. DO-able, but the kiln would then be in the back yard proper and I don't know how that will float with 'she who is to be obeyed'. Still, I will keep it in mind as those plans firm up. First lets see how the simple experiments go before we jump in with both feet.
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

doc henderson

could also put it on the roof and use insulated duct work through the roof and attic space.  just tell your better half that Doc Henderson said so!  i am sure that will work! :D :D :D

ps I take making your head hurt as somewhat of a compliment! ;) :)
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

mudfarmer

You said you don't want processors and other sorts of junk and I am right there with you but you can get differential temperature controllers for <$50 online with two temp probes that can handle ranges of below freezing to above boiling.

They are basically a relay triggered when the difference between the two probes is what you set it to. Some of them have two relays and two setpoints. You could use this to run your fan when t1-t2 > (some amount you decide on) and the second relay to run a solenoid/actuator to close off the duct like doc mentioned when attic temp is lower than shop temp to keep your heated shop air from rising back up through your pipe?

Just spitballin'

mike_belben

Hot only travels to cold.  


Insulation only slows the rate of heat travelling to cold, whether the heat is inside [winter] or outside [summer.] Insulation does not prevent a temperature rise or fall.  Only delays one.  

A cardboard house gets hot 3 minutes after the sun hits.  A regular house 3 hours, a subsurface concrete mountain bunker maybe 3 weeks.  Mass of materials also comes into play and it can be hard to tell whether it is insulation or mass creating the lag in thermal change.  Id say both.


An uninsulated, vented attic will be hot by noon.  Insulated one maybe 7pm.


I see this as a discussion about relocating unintended heat to an intended location. Not about slowing the rate of heat transfer.
Praise The Lord

Ianab

Quote from: mudfarmer on September 10, 2020, 02:12:06 PMYou said you don't want processors and other sorts of junk and I am right there with you but you can get differential temperature controllers for <$50 online with two temp probes that can handle ranges of below freezing to above boiling.


That was my thought too. What you want is a fan that runs when the attic temp is higher than the room below. During a sunny day it will be, so you want the fan to turn on once it's warm enough up there to do some good. Early morning / night you don't want that, leave the cold air upstairs. A simple differential controller would be enough to handle things, although you could get more clever if you wanted. 

You can probably shutter off the attic vents because you are going to be recirculating the air with the fan system. You could fit an interior vent that takes cool air from ground level back up into the attic when the system is running. 

Something like an extractor fan with powered louvres should be ideal as it will seal the vent when the attic space is cooler than the room, preventing warm air from leaking back into the attic.

Commercial systems like this are commonly available for homes here in NZ, but the main advantage is ventilating the house with warm dry air to reduce condensation inside. (a big problem in a humid climate) They have the benefit of helping to warm the house as well, but they don't do any good when it's most needed (cold nights).  
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

Old Greenhorn

Yes, Mike, Crusarius, Mud Farmer, Southside, Don, {edit to add} Ianab, and Doc. Starting simple, steal the wasted heat in the attic, if there is any to be got. If the return proves worthwhile I plan to go pretty much exactly as Mud Farmer suggests. In the beginning I will just crack a window to allow air to move out. I won't need much, there is already leakage around the two garage doors and human doors. If the test works, I will look into floating air from the floor level in the shop (coolest air) back up into the attic and then pumping it down from the attic at near the peak level (hottest) down into the shop. All controlled by a differential switch of 'some sort'. I would only expand on that in the event that the ROI in time and cost would prove worthwhile. I am a simple guy. Doc knows my buttons and he is baiting me into a more 'robust' project, knowing full well that I will be thinking about the seeds he planted as I go forward and may 'alter my goal' so he can see what develops. ;D I am a BIG fan of simple experiments and steps to prove the concept, THEN going in full tilt when the rewards are justified. I am not a big fan of thinking about it too much and trying to figure out EXACTLY how it will 'end'.
I won't even do any more than think about this until I have the chimney installed and the wood stove warming my coffee. Of course, I will start collecting data as soon as the gadget arrives. :)
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

doc henderson

cool!  oh sorry, I mean "warmmmm"!  no buttons were pushed intentionally in the making of this movie!   :) :) :)
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

Old Greenhorn

Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

Al_Smith

This might sound silly but I saw it .A gent I know set up a series of PVC pipe in his attic to capture the passive heat of the spring time sun to heat his in ground swimming pool .It worked .

Hilltop366

For the no electronics approach?

Wondering if one could use a mechanical line voltage cooling thermostat (in the attic space) to switch on/off circulating duct fan when the temp reaches a set levels then add a normally closed motorized dampers in the inlet and in the outlet ducts also controlled by the thermostat powering the 24v step down transformer.

For the attic vents a low voltage (24v) cooling thermostat to monitor the roof surface temp (mounted to the underside of roof deck to close normally open attic vent dampers once there is potential to heat the attic enough to provide supplemental  space heating.

So in the end it would work like this:

Sun shines on roof.

When underside of roof deck reaches preset temp the 24v mechanical thermostat turns on and closes attic vent dampers.

Attic heats up.

When the preset attic temp is reached the 110v thermostat turns on the circulating fan and powers the 110-24v step-down transformer to open the duct dampers.

Sun on roof lost. (clouds, sunset)

Roof surface temp drops below preset temp the 24v mechanical thermostat turns off and opens attic vent dampers.




doc henderson

had a buddy with with a length of garden hose back and forth on the roof, and water to fill the pool went through all that black hose during the day.  could put a circulation pump on it as well.  in college we had a big kiddie pool.  when it was cold, we put a galvanized metal container on top of the Weber grill.  use the little filter pump to pump the pool water up to the container, and siphoned the hotter water back into the pool..  was fun and made a temp difference.  say 10 degrees in 2 hours.  pool was 18 inches deep and 10 foot around.  the container bottom was about the size of the Weber grill and 12 inches tall.   thumbs-up       smiley_beertoast     smiley_sun
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

Al_Smith

My once time brother in law used a section  of perforated garden hose and let it dribble down the south facing side of garage roof of black roofing .Let it get into the eave spout and into the 4 feet deep 16 foot round pool .It used a small pump to recirculate the water and ran it through a multi screen  filter to keep the gunk out of the water .It worked pretty good . 

Old Greenhorn

Well I don't have a pool, so no worries there. I am putting this 'thing' on hold until I get the chimney and woodstove done (more of that in another thread), but I did another 5 minutes of piddling with this today while waiting for Fedex.
 My neighbor who is moving away, gave me a crawl space vent fan he had bought but never needed to install. I thought I would stick that up in the attic opening just for giggles. Turns out this fan is controlled by a humidistat. Not the best for this experiment, but it will do for now. Yes, it does move the heat down. It was cool in the shop today and mostly cloudy but the attic was pretty warm. It did move some air down. It shows promise.
 I will probably start messing with this in 2 weeks or so. For now, I am all about chimneys.
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

mike_belben

My water heater cold inlet line wound through 30 feet or so of soft copper in a big insulated lobster pot on the cooktop wood stove.  And i built a thermal siphon coil next to it too.  


We had some dang hot showers.

Friend of mine in CT has a water loop in his garage woodstove plumbed to a jeep radiator and electric fan in his upstairs apartment pretty far away.  Heats the living room. 
Praise The Lord

Gary_C

What you are trying to do is capture the energy from the sun that strikes the roof and move it to another location. It can be done but not the way you guys are approaching the idea.

First air has very little mass or weight so it has little energy holding capacity. Trying to move energy using air is difficult as it requires large ducts and lots of insulation to keep the little bit of energy air holds. Water is a far better energy transfer medium.

Second using a roof as a heat transfer material is not going to work. Yes in high ambient temperatures the roof will get hotter than ambient but that is not the time when you are needing a temperature boost. In low ambient temperatures the roof will not get warm enough to help in boosting indoor temps. The ideal roof in low ambient temps will not melt snow so it will not be of any use in indoor warming. Yes if you could collect the energy for some time it would be useful but an uninsulated roof is not going to be much above ambient outside temps and you will need air or water temps that is above indoor temps.

So how can it be done as I said earlier? Build a large enough solar collector that is insulated and where you let the sun's energy inside to heat water in black painted pipes so that you heat the water well above the temperature you need to add heat to the shop. Or use south facing windows to directly heat large thermal masses that are dark colored. Simple enough right?
Never take life seriously. Nobody gets out alive anyway.

Old Greenhorn

Quote from: Gary_C on September 12, 2020, 04:13:04 AMSimple enough right?
I say this with all due respect Gary: No, it's not simple enough. ;D You have no idea how simple my mind works. :D
 Back in the original post I said I just wanted to grab the air air from the attic and move it into the working space of the shop to Add a little heat, not heat the entire shop 24/7. I don't think it is complicated to move heated air about 50" from the Attic into the working space. When I get around to this I will just stick with the basic plan and controls that are discussed in the previous posts. It just comes to a point of ROI and putting all that effort into fancy stuff to have a fancy system is not worth it for me. BTW, my roof is not insulated, the attic floor is insulated, so the attic gets DanG hot when the sun is on it, even on cool days. There is about 1,200 sq.ft. of roof collecting that heat, so I think it is pretty easy to try and grab some of it and use it. 
 Anything more complicated than what we are planning would not be worth the effort when I can just split another half cord of wood to make up the difference.
 BTW Doc, that kiln idea sounds like it might be a winner. Some of those pine boards I threw up there are drying like crazy already in just a couple of days. I'll have to stick the meter on them to see what I have. :)
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

Old Greenhorn

Not that I am working on this now until I get the chimney and stove done, BUT I did note that the ambient temp barely broke 70 today, it was 60-65 in the shop and over 90 in the attic. This is going to work. Man, working up there is no fun. ;D
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

mudfarmer

Mike mentioned thermosiphon.. We had a stainless tank (open to atmosphere) at ceiling height heated by copper coil around stovepipe, gravity fed to bottom of coil. Heated water rises back to tank. Worked great for hot water. It would even boil in the coil and you could hear it shooting back into tank (boiler explosions are no joke and super dangerous that is why tank was open to atmosphere). Also use a copper tube preheater for our maple syrup evaporator. Lot easier to heat sap from 100*F to boiling than from 32F. That is backwards for OGH purposes, heat down not up and I am rambling.

Look up "snap disks" (discs?) online. Basically a bimetallic thermostat/switch that does a thing when it gets to a certain temp. Few dollars a piece a decade ago. Maybe epoxy to underside of roof. I want you to succeed and know you can! Don't let perfect be the enemy of good enough



Editing post, we had an apartment one time where I built a solar air heater using 2x6s, aluminum dryer duct, PC case fans, foam insulation and old free storm windows from side of road. Built a faux window A/C basically to close in the window w input and output ducts. That is where the snap disk thing came from.

Ljohnsaw

Quote from: mudfarmer on September 12, 2020, 10:51:52 PMLook up "snap disks" (discs?) online. Basically a bimetallic thermostat/switch that does a thing when it gets to a certain temp. Few dollars a piece a decade ago.
I made a solar air heater a couple of years back as an experiment.  I got a piece of twin layer Lexan from a plastic supply place.  I ordered an 8' piece but they gave me a 10' section.  I didn't realize until I went to put it into my truck bed that is was longer.  Anyhow, I got two sheets of 2" foam insulation and used aluminum foil tape to assemble.  I used some rain gutter to make a plate absorber that I painted black.  I used two inline duct fans with some 4" aluminum dryer hose.  I made a manifold on the far end to turn the air around to the other gutter.  I installed a snap switch that clicks on around 85* to fire up the fans.  I got a few different ones for a buck or two each and found one that was right for this setup.  Works pretty well.
John Sawicky

Just North-East of Sacramento...

SkyTrak 9038, Ford 545D FEL, Davis Little Monster backhoe, Case 16+4 Trencher, Home Built 42" capacity/36" cut Bandmill up to 54' long - using it all to build a timber frame cabin.

Old Greenhorn

Not that I am working on this, because I am not, but I had some time at around 4 this morning and did a little poking around. I found a solid state controller on eBay for under ten bucks that looks like it will do the job. I don't like the probe wire lengths available (3' max) but I will have to work with it. The built in relay will handle 20A, so good on that score. 
 HD has a 10" duct fan for just over 50 bucks, so that with a short piece of pipe (3'?) and some kind of grill/shutter and I will have the beginnings of an experiment. Gonna leave the shutter control off for now or maybe just go manual. This is an entry level, proof of concept test at this point so I can learn more. I will have to see how much heat I can pull and how long it holds up when I start dragging fresh air in the attic. I might need 2 of these setups, or I might need to close off the gable vents and use makeup air from the shop to re-circulate. Time will tell.
 I haven't ordered anything yet because it all looks like short lead time stuff. I have gotten by without this for a long time, I can wait a few more weeks and call it a fall project.
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

Don P

Block the fresh air, you only need to move the warm air to the shop and replace it with cooler air from the shop. The fresh air is to remove moisture. Monitor the humidity and if needed bring in fresh air to solve that, a humidistat can control the fresh air vent if needed. I doubt it will be needed, you'll probably get that exchange from shop leakage.

mike_belben

What don said.  The shop space has your cool makeup air.  You just need to shove the hot stuff down.  It will pressurize the lower level which will force itself upward to achieve equilibrium. 

The downspout tube i guess we could call it, needs to be distant enough from the upspout (probably the attic access hatch) that the dont short cycle.  If you blow the heated air right into the jetstream of the rising cool air itll just do a yoo-ee and head back up. 

 I expect youll need to cut atleast 1 ceiling hole for the final version.  And it would be well to run a round tin duct down to a tee thats laying upside down on the floor, -almost like a gutter with left and right discharge- so that the warm air can blanket the coldest wall, away from the wood stove.  If youve got say 2 overhead doors, theyre leaking in cool air at the seals. Id put that heat gutter right between the two for instance.  

The further this heated air has to travel to get back upstairs, the more of it youll get to use.
Praise The Lord

Tacotodd

OGH, have you considered scrapping the hot attic air in place of something like a geothermal setup? The reason that I ask is that I proposed a OWB for my house to one of my friends and his response was that geothermal was much more financially viable after the first year and was practically free every day after. He also said that he was part of an installation crew and the cost for the labor of this crew was negligible. I don't know how set you are on your attic heat idea, but you know, sometimes outside ideas are the bees knees!

Just a thought.  TA

Trying harder everyday.

Old Greenhorn

Well Todd, the short answer is...NO. :D I am looking for simple and cheap. Reply number 39 above pretty much covers it. I don't have the time, money, or inclination to get carried away. Just trying to make use of something already sitting there going to waste.
 The temp/humidity gauge arrived today so I stuck the probes in the attic and went back to work. I checked it a few times, but it was a cool day and hardly got up to 70 and was overcast all day. The attic temp was 83 and as the temp went up, the humidity up there went down. I will keep an eye on it for a while to decide how I will proceed.
 
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

doc henderson

surely the rest of us can dream and try to spend your time and money!!   :)  have fun.  you are putting the rest of us to shame.  my only saving grace is I still work!  
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

Old Greenhorn

OH surely y'all can conjure up anything you like, just don't give me more work to do. :D I have to stay at least a little bit focused. Going into the summer I was going to work on building some stuff to sell, that didn't really happen, and I wanted to get a bunch of lumber milled and that sort of happened, but mostly I got consumed by infrastructure improvements and things I knew had to be done. Firewood took a lot more time than I thought. So this one I am keeping simple if I do it at all. Lets see what the numbers show.
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

Don P

Quote from: Old Greenhorn on September 14, 2020, 07:44:11 PM
 Firewood took a lot more time than I thought.
Do tell ;D
Vapor drive, the direction moisture moves, is the same direction as heat flow, moisture is piggybacking on the heat flow. Right now heat, and vapor, is probably moving from the attic, to the house. As the season turns the moisture from the house will be following that heat into the attic. It'll be interesting to see if you get an uptic in humidity as you go into heating season.

mudfarmer

Quote from: Old Greenhorn on September 14, 2020, 07:44:11 PM
OH surely y'all can conjure up anything you like
Well if you do geothermal then you gotta put up a net metered solar electric setup to offset the usage. Then you might as well get a battery bank setup to cover you during outages. While you are at it you could build me a shop :-X

mike_belben

And dont forget the new truck, trailer, and mini ex youll need for the project too. Youre a new yorker with over half an acre afterall. 
Praise The Lord

Gary_C

Quote from: Old Greenhorn on September 12, 2020, 05:01:37 AM

Back in the original post I said I just wanted to grab the air air from the attic and move it into the working space of the shop to Add a little heat, not heat the entire shop 24/7. I don't think it is complicated to move heated air about 50" from the Attic into the working space. 
My attic is ventilated with eave vents and roof vents to keep the attic temps close to outdoor ambient temps. I know it gets somewhat warm in the attic on summer days and I also know it's very little above outdoor temps in the winter days. The problem is the need for warm air is not during the times you need a boost in air temps in your shop.
So I hope you do not spend too much money and effort while exploring your idea until you determine your attic temps at the time you desire additional heat. 
Never take life seriously. Nobody gets out alive anyway.

Old Greenhorn

Yup collecting data now. Today at 2pm it was 62 in the shop, 65 outside, and 95 in the attic. That's a good start.
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

aigheadish

I'm new around these parts and would love an update! I have what sounds like similar space, but I'm also digging the thoughts of a solar kiln heater...
New Holland LB75b, Husqvarna 455 Rancher, Husqvarna GTH52XLS, Hammerhead 250, Honda VTX1300 for now and probably for sale (let me know if you are interested!)

Old Greenhorn

1st post too! Well, first, welcome to the forum. 2nd, I have actually kind of dropped this idea because my data collection tells me that there are only a couple of short weeks where the numbers make sense and that just doesn't pay.  for instance, right now it is 67 in the shop (wood heat), 41 outside (mid day) and 32 in the attic (with 10" snow pack). I did put some mentions of how this was going over on the thread I post to almost daily: https://forestryforum.com/board/index.php?topic=110766.msg1779809;topicseen#msg1779809 Wherein I dribble on about the crude and boring existence that is my life. :D You will have to do a bunch of reading to catch mentions of this failed project. ;D
 Welcome aboard, hope you stick around for a while, and do fill in your profile so folks get to know a bit about you.
Tom
 
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

aigheadish

Thanks for the update, the welcome, and the link to the other post, I'll check it out!

There is a lot happening on this forum so it'll take me a while to catch up! I was suggested to come here from some of the fine folks at heavyequipmentforums.com
New Holland LB75b, Husqvarna 455 Rancher, Husqvarna GTH52XLS, Hammerhead 250, Honda VTX1300 for now and probably for sale (let me know if you are interested!)

Al_Smith

There's a lot of passive options  in essence solar heat .Capturing the heat of the sun in one form or another .
I know a guy from probably 30-35  years ago when "earth sheltered " homes were the rage. Built a very large one of nearly 3000 square feet and used water filled plastic barrels, stacked ,painted black on the sides of a huge south facing wall which was basically windows .He had heating sources but those barrels helped in winter weather . 

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