Pics of 2 DIY systems being built / Hot Air Collectors and Drainback System
 

Hi everyone,

Here's a couple pdf files documenting how I constructed my latest solar hot air collectors and my solar hot water drainback system.

Hot Air Collector PDF
http://ecorenovator.org/Downloads/Ho...nstruction.pdf

Solar DrainBack Hot Water System
http://ecorenovator.org/Downloads/My...ack-System.pdf

The solar hot water system was constructed for 2 purposes.
1 - To provide my home domestic hot water by connecting my solar storage water tank directly to my tankless domestic hot water system.
2 - To provide hot water for heat distribution via a very large 14 ft Long x 1 ft High - used Runtal radiator.

If anyone has any questions pertaining to any of my construction stuff, please feel free to contact me anytime.

Pat from Rhode Island

http://ecorenovator.org/forum/attach...1&d=1383746992

Both links lead to 404 errors.

EDIT: Now it works. The hot air collector looks like it would work really well on a trailer or home with a package unit heater. It would tie right in.

Jeff5may,

both links have been fixed now.

My error.. typo I guess.

Thanks for letting me know.

I only just read through the hot air panel one. REALLY nice work. Great document to help people build their own. Thanks! I really wish more people would make these kind of panels. They're so easy and cheap to make its almost a no brainer. In addition to my solar hot water I do plan on building a few of these for my house as well.

I can't wait to read through the hot water one. :)

Thanks for the PDFs. I think it's more useful to readers of your work if the discussion happened in the open, so that everyone learned from the questions & responses, rather that just individuals.

Having said that, have you had your metal-stud hot air collectors in operation long enough to know how they stand up to the wind and weather?

-AC

Hi AC Hacker and Daox

First, Daox... thanks for your nice comments Sir,

AC Hacker
So far all 4 of my hot air collectors have with stood very harsh winters here in Rhode Island.

They not only shed the snow by themselves but kick out terrific heat in outside temps as low as 13 degrees.

1 has been in place for 3 years now.
That's the first one I built out of 2/ x 4 PT frame.. and 3/8 plywood back.

the other ones are 2 years old and have all been built with metal stud framing.

I love using the metal stud framing.
They look more professional built once done and never have to worry about treating any wood framing.

If I took pictures of these for you today they'd look the exact same way as they do in the PDF file.

The polycarbonate is holding up super.. nice and crystal clear.
All 4 of my 6 inch booster fans are working fine.. no problems with the snap disk controllers .... just no problems at all EXCEPT for backdraft issues I'm not satisfied with.

I am currently building my own new backdraft damper which will be installed on all 4 collectors. Supply and Return piping.

Heading to the store for supplies now and will post back here or start a new thread for the backdraft damper build with a bunch of pictures.

Daox,

for some reason, I'm not being notified when someone posts to this thread?
How do I 'subscribe' to a thread so I know when people post/reply?

Sometimes I get email notifications.. other times I do not?
Don't want anyone upset by my not responding to questions/comments.. know what I mean?

What's the trick I'm missing?

Thanks,

Pat B. Warwick, RI

At the top of the thread click "thread tools" and then "subscribe to this thread".

I just checked out both your systems. very cool! On your drain back system, don't you need some sort of a vacuum break to get the water to drain back into the 6 gallon tank?

The Hot Air Collector is very cool. Thanks for sharing!

Hey, thanks for the nice comments.

Appreciate it..

on the drainback system the answer is YES, air needs to be introduced into the return piping from the collector in order for the water to not get vacum locked in the piping.

Also I suggest using 3/4 copper pipe to/from the collectors on a drainback system so there's ample enough room inside the copper pipe for the water to drain easily.

What I did to allow it to drain was on top of my drainback tank just before the water dumped into the drainback tank I added a T fitting and stuck a 1/2 inch piece of copper tubing straight up into the air off the 3/4 return pipe.
I put a ball **** shut off valve on the 1/2 inch tubing kinda like an air vent.
I just leave the ball **** slightly cracked open to allow air to enter the 3/4 copper drainback pipe.

Next, just to make sure everything drained back quickly I installed a vacum release valve on the collector up on the roof.

I put it on the outbound copper pipe right where it leaves the collectors 'highest point' of the collector piping.

That allows air to enter the pipe outside at will anytime the system pump shuts off so it's impossible for the water to become vacum locked.

If you or anyone else has any other questions at all just email me or post here anytime.

I love talking about this solar stuff.

Pat from Rhode Island

Off Gassing
 

Something that very few people realize is that XPS, EPS, and Polyisocyanurate foam insulation have significant off gassing potential when used in the wrong applications. My understanding is that some of those gasses can be released at accelerated rates when in a high temperature environment. The situation is even worse when in a closed system in which the air is continually recycled from solar heater to house and back to solar heater. Some of the effects of that off gassing have been found to sensitize individuals over time and can result in chronic asthma, etc. Not good.

On the solar heating that I'm working on I'm trying to be careful not to use any of those products that will be exposed to continuous warm or hot temps. A good substitute is ductboard. It is a fiberglass product that is very stiff and has one side with a foil backing that you can paint black. You don't have to worry about fiberglass flaking off like regular fiberglass insulation. They've been using it for years in return air ducts of closed system HVAC systems with no bad results reported. Only problem: they are expensive compared to the foam boards.

Edit: I guess I should add that there are plenty of applications of using foam boards for insulation that wouldn't be problematic. But there is a reason besides fire hazards that foam board usually must be covered with drywall when in a living environment. You might even be able to get away with out getting sick using foam material that you are directly exposed to in some situations. But a situation where air is continually moving past foam board in a heated closed system does not seem like an ideal, or even a GOOD application for it.

First, Pinball - thanks for your nice comments on my systems. Appreciate it.

Exeric,

I'd be very interested in learning more of your duct board expirements.

I've never looked at Dow Tuff R foam board with reflective coverin both sides as being a hazard to our health.

Figured if they put it in residential properties all over the world it would be fine but according to what you are saying if it's exposed to extreme heat it could be a problem.

Could you elaborate on what you learned? or know?
What temps were they talking about where as the material could become hazardous?

All of the Dow Tuff R insulation boards used in my collectors are surrounded by aluminum meaning aluminum sheet goes into my frame first.. then the foarm board, then aluminum sheet 'over the foam board'

When the top piece of aluminum is heated by the sun that heat can not go out thru the back of the aluminum because the reflective coating on the foam board is face up right up against the aluminum sheet I use for the absrober plate.

So am I making things worse by not allowing heat to escape out the back?
If I did that, I'd not have any collection of heat to circulate into my house?

Aluminum releases heat as fast as it's heated so I'm hoping that the heat being generated by the aluminum absorber sheet is released and circulated into the house prior to the insulation heating up.

Dow claims the product is good to 190 degrees but that's probably before it begins to melt?
They also claim it emits no harmful chemicals into the ozone.

Great information you provided Exeric!

ya definetly got my attention!
So Im going to have to check into this situation further.

Thanks so much for jumping in and voicing your concerns about the product.

HI,
I've been looking for the article that got me scared but can't seem to locate it now. So probably best to take what I said with a grain of salt. I'm definitely nervous about using foam boards in the application your using them in but it's probably my own nervousness about it speaking and not something that has been definitely proved.

I would say you are probably safe as long as you maintain a tight air seal between the aluminum plate next to the air passage and the foam board. The main thing I worry about is summer time temperatures when the fan is off and then the inside temps reach extreme temps from stagnation. Any accelerated off gassing from those high temps will remain and then be recirculated later when you use it again. So, if I were you I'd either store them inside when out of season or make sure the back side of the foam board can get rid of any gas that accumulates.

I might be a little overly paranoid about this situation but as is often said, just because you're paranoid doesn't mean they aren't out to get you.:)

Hi Ex..

They're not completed yet but I plan on installing a T tubing pipe into the TOP pipe on my collectors, then attaching a spin type louvered vent similar to the ones used to vent attics right thru the roof.

When heat rises they spin allowing any heat to escape during the summer.
The spin type louvered vent will be easily removable and replaced with a 'cap' for winter use.

so I'll stick one of those on the top pipe and a vent on the bottom tube to allow air into the collector while it's venting.

Again.. this is only for summer use and easily sealed off with caps for winter use.

I just read the write up for the solar hot air collector. Great write up. I have been wanting to make one using metal studs like you have.
Thanks for taking the time to do the write up.

iamego,

Thank you Sir,

If I were to build new or customize anything on my hot air collectors I would pay more attention to balancing the backdraft that occurs with hot air collectors.

If you can stop/trap the cold air in the tubing/collector after you're build you are accomlishing a major issue for sure.

Good Luck on your build Sir!

Did you take any pictures of the holes you made in the house? Please explain what you did to make the holes and route the air duct.

Hi Iamgeo,

First the holes I made were 6 inch diameter, just large enough to push a 6 inch ductwork pipe thru.

I wanted the tubes to enter my basement between my basement floor joists so I went into the basement and drilled a pilot hole from the inside out (dead center between the right/left floor joist.

I then went back outside and drilled a 1 inch hole using the pilot hole as my guide.

I then stuck my recipricating saw into the 1 inch hole and cut slices from the center out to the outside 6 inch perimeter circle.

so I kept cutting a bunch of slices from the center out as I worked my way around the hole till I had a whole bunch of apple pie slices in front of me.

I then used the same saw to work my way out to the edge and cut around the perimeter of the circle.

Cutting pie slices 'first' gives your recipricating saw a break when doing the final cut.

Once I had the hole cut I just stuck a 3 ft. piece of galvanized metal duct tube thru the hole into the basement.

From that pipe I ran my insulated hose to where I wanted the floor register to be.

TIP: If you don't like fan noise it can be easily eliminated by running 'flex insulated hose' rather then pipe at least 8 feet before you come thru the floor with your supply register.

Fans blowing thru metal tubing make quite a bit of noise.. so use pipe to come into the basement but then switch over to insulated flex duct for the rest of the way to your register.

To insulate the 6 inch pipes outside I just slid 6 inch insulated flex hose right over the pipes going to the collectors.

The inner part of the flex insulation hose is reinforced plastic so I slid the plastic over the pipe real close to the collector and stuck a heavy duty plastic TIE on over the plastic to hold it in place then just slid the insulated part of the hose up over the plastic and sealed it with aluminum tape.

Sorry.. I do not have any pictures of the actual hole before inserting the piping.

Thanks for the info. My house is on piers. 8 feet off the ground at the back of the house. The front is about 3 feet. House was built on a slope. I have plenty of room to route the ducts under the house and have vents on the floor. That's my plan anyway.

Sounds like you're good to go!

Sounds like a great plan.

Hopefully, the back of your house is facing south maybe?
I hope so cuz that would make things wayyyyyyy toooooooo easyyyyyy.

heck, if your solar collectors were mounted just below the level of your main living floor you might not even need FANS.

The hot air from the collectors will rise up into your home all by itself.

I HATE GUYS LIKE YOU that have perfect house arrangements for solar missions!

just not fair for the rest of us. :-)

Thanks for some great write-ups, ideas, and humor :)
So I understand it better:
The drainback system starts up with dry collectors. Water is circulated up to them, and this can cause some steam, right? do you have a blowoff, or do the storage loops develop some pressure there?

solar hot water collector steam..
 

Hi, thank you Sir,

Yes there may be a little steam in the pipe when the colder water begins entering the collectors however the pressure in the piping is relieved by an 'air vent' and 'vacum release' valve I've installed.

The vacum relief valve is at the highest point on the collectors outside 'right where the water exits the collectors'

The air vent is installed in the 3/4 copper pipe going into the top of my drainback tank.

I T'd off that 3/4 pipe just before it enters the drainback tank and installed a 1/2 inch 6 inch pipe straight up in the air off the 3/4 pipe.

On that 1/2 inch pipe I installed a ball valve which I leave cracked open at all times.

If I had no air release pipe the pressure would kick in during 'pump on' and 'stop' the water flo dead.

so the air vent solves that problem during pressure situations and the vacum release allows all the water to quickly drain back the second the pump shuts down.

Feel free to ask me as many questions as you want cuz I love talking about this solar stuff...

I'm not an expert on solar hot water systems by no means but did do one heck of a lot of research prior to putting my drainback system together.

so far.. everything is working like a clock.. no leaks (which was amazing) and I create hot water daily.

I installed a site glass on the side of the small 6 gallon electric hot water tank that I use for my drainback tank so I can keep an eye on water volume in the tank.

I have to remove the site glass to clean the ugly brown water out of it now and then but ya hardly 'ever' have to add water.

Just one circulator pump is used to heat up 2 tanks of water.
1 for domestic hot water use. (which is tied directly into my tankless hot water heater)

the other tank of hot water is used for heat distribution which I pump over to a radiator I installed in my family room. That's an independent variable speed Taco circulator pump that I use for that.

I stuck a thermostat in my family room dedicated to the heat distribution pump. All the thermostat does is send 24v to the little controller on the side of the pump which connects the 2 wire terminals together as it's calling for heat.

TIP: Ground water temp coming into your house from the street/well is normally 55 degrees at all times. SUMMER AND WINTER

It's cold ground water that 'replaces' the water in your solar hot water storage tank when water is removed for showers, etc.

That's not good cuz the water coming IN to your tank is cooling down that water big time.

SOLUTION:
If you run your cold water (ground water from street or well) thru a preheat tank located upstairs in a conditioned air space (68 to 71 degrees) PRIOR to running it to your solar hot water (COLD IN) pipe.. your solar hot water system doesn't have to work as hard to bring the water temps up to 120 degrees.

55 to 120 = not good - solar hot water system needs more hours to heat the water up.
68 to 120 = much better.. less hours needed to heat the water up..

Preheat tank does not need to be insulated.
The room air around it keeps it at room temp so actually 'no insulation' is even better.
Tank size = anything from 10 gallons to 20 gallons is all you need cuz most showers use only 8 to 10 gallons of water for each shower.

Once the shower is over and the preheated room temp water is now in your solar tank the water in your preheat tank immediately starts to warm again via the room temp air.

All good stuff :)
I have electric everything, and a conventional water heater. I doubt I would ever go for an instant electric unit as they are pricey and draw huge loads to do what a natural gas unit does easily.
I can really insulate what I have to minimize storage losses. The solar would still do a great deal for me.
Now to show my wife pictures of your air collectors. We have a good south wall with no windows. If I can doll them up enough, she will probably go for it. I have 16 feet to work with :)
We have beloved giant trees all over, but that wall still gets a good bit of sun.

Tankless water heater
 

Hi SkyKing,

My tankless water heater does whole house heating and domestic hot water.

It's propane.
Electric is nuts in New England for what we pay for juice around here.

Yeah.. show you're wife the pics and maybe she'll give ya the heave ho.

but before that see what time the sun hits your south wall and what time it's useless later in the day. I actually monitored the hours of sun to make sure I was sticking them in the right place.

If you want them to look prettier you could go with the double wall polycarbonate. It's a smooth service / no wiggle strip insulation to goof with but 'does' cost a bit more.

Good Luck!

over here on the west coast, the juice is cheap compared to propane. If we had natural gas in the street that is the best.
I checked out the double wall polycarbonate. That is not bad at all. She is interested!
There is only the one south wall so I don't have much choice. I will watch it next time I have some sun.

She likes the poly!
That's it! You're on your way!

Angle of sun is real low in the sky and gets worse at the end of Dec. which is why we all try to mount these hot air collectors as 'vertical' as possible for the winter sun.

Many times folks attach them right to a vertical 'wall' under an eave/overhang so in the summer when the sun is straight up in the sky the collectors are 'shaded' most of the day which is what you want.

Well keep me informed as you roll ok?
We can go over stuff along the way if need be.

You bet. I may go at it with your materials, but build the whole thing in place on the wall. That way I can put the tubes through the PT plywood skirting (manufactured home) right at the start, build it up and finish it out. I have access to 4' shears and brakes, so some interior baffles are easy.
I can bring the hot in to the existing ducting under the house, and plumb the cool return into the return plenum above the electric furnace.
I'd need to fashion a damper in the main duct to keep things from just looping up through the electric furnace and right back out the return.
Probably end up with two dampers that way.
My system will be best flat on the wall as you describe. I have minimal eaves, the gutters do help. I can hang a rolled bamboo style screen in front of the system in the summer months to keep it cooler.

Hello solarhotairpanels,

I would reconsider the use of the air vent and vacuum break. There are 1000s of totally closed systems around that don't use them. A closed loop from panels to the HX allows the pump pressure created on the discharge side to be of help on the suction side of the pump. If the air vent is working, the pump will have to work harder to do the same job. If you are worrying about draining the panels, don't, as they will drain just fine with the slopes I see on your system.

Also, using an air vent and vacuum breaker means that you will have to monitor and fill the system more often which brings in more particulates and O2 which causes corrosion on the iron body pumps you have. Any potential failures in the system will come quicker and auto air vents are often the first to fail.

I cannot tell if the insulation you are using is closed cell (armaflex type) or open cell foam (used for insulating water lines in the basement and has a glue strip), but all insulation should be closed cell as the temp rating on the open cell is not high enough and it will melt to the piping in certain places near the collectors.

The tank arrangement looks good. Love the enthusiasm.

Mike

Hi Mike,

Thanks for your comments.
My air vent is a manual vent.. ball valve just cracked open.
I tested the sytem both ways.. with and without the vent and the return water actually DUMPS right back into my drainback tank with the air vent just cracked open.. as in barely open.

After I installed the vacum release valve I did not need to leave the air vent open any longer because all water 'was' draining right back just not as fast as if I left the air vent cracked open.. so I decided, being it's winter time I cracked the air vent open again just because the water literally dumps right back in quickly.

I feel much secure that nothing is going to freeze in my pipes but well appreicate your input and technical knowledge for sure.

So far so good on the insluation.
Nothing melted all summer long which I was surprised a bit.

Using the foam self stick stuff but wrapped the pipe exiting the collector with fiberglass wrap insulation prior to putting the foam over that.

The fiberglass is protecting the foam for the first 5 ft leaving the collector where the water is the hottest.

I almost forgot to do that when I was installed the foam stuff.. then remembered last minute.

so again..
so far so good..

Just wish I had about 4 more evac tube collectors during winter cuz it's hard to bring the water temps up very much with so little sun during later Nov thru end of Jan.

what are the low temps you see in your domestic tank in winter?

I love the idea of hot air collectors.. Wife hates it.. :(
 

I'm saving your hotair pdf for any Just-in-case.
One never knows when oil prices might shoot up to $15 a gallon.

I would be love to have a few collectors heating up my basement.
But, since the south side side of my house is the front, facing the street..
My dream of a warm basement is destined to remain a dream..

I don't think backyard collectors would be very effective,
since I would have run the in/out ducts about 95' to the house,
and they would have to be underground..

Sky, this the first 'start to finish' winter for my system and I don't have my 'preheat tank' hooked up yet. It's in the works but not done.

Right now my temps range from 70 to 100 degrees this time of Nov.

Once all the leaves fall off my neighbors giant oak tree I'll get some temps above 100 now and then as long as it's full sun.

I'm trying to pull a lot out of my 2 collectors too.
Feeding collector water to 2 seperate tanks isn't what a lot of people do.

If I was just doing hot water for domestic use.. using one tank I believe my temps would be a lot better.

Xringer,

Time to get creative.
Maybe build a nice big glass porch on the front of your house and use 'collectors' instead of 'lattice' to close in the bottom front section.

The glass will heat the front wall of your home and you could put the ductwork from the collectors right under the porch and pipe em into your basement.

WHALAHH! You're good to GO!

Thanks. I took a look at that south wall at mid day, and it was sad. I will start watching things, but my feel for it is, the big trees are making oxygen with my solar.

Okay Pat.. I've been thinking about one of those greenhouse things for years..
http://www.greenhousenation.com/imag...o-cw-6x8-1.jpg
http://www.smgardensheds.com/media/c...unroom6x10.jpg

I wouldn't grow anything or sit out there, but I would fill it up with some thermal mass to heat up, and vent inside the house! :)

There ya go XRinger,

Their a bit expensive but what the heck.. You've got it right!

Wow, those are some large pictures!

We get some solar gain during the day, from the windows.
But if I could increase the capture area, it would be really helpful.

http://i46.photobucket.com/albums/f1...NCL/roofed.jpg
Not that many square feel of windows..

But, my wife doesn't like the look of extra stuff on the house.
She thinks what people 'think' about her house is more important
than saving the planet.. :p (She does drive a Prius).. :rolleyes:

So, if I could sell her on anything, it would have to look very nice..
Like a nice modern looking greenhouse/sun-room thing.?.

We have opposite problems. My wife is good with the look, but I don't have good enough sun on the house. :D

I'll ditto myself XRinger..

Those things cost a few bucks for sure.
Gotta look at your l o n g r a n g e ROI

and Sky..
Only thing I can think of is build em.. stick em in place cuz they're great projects then if ya don't get enough sun you can always get out there with a hair dryer or something to get em cranking! Ha!

but seriously..
You have to check the amount of hrs you get sun on that side of the house and just go from there..

If you can get 4 to 5 hrs of sun in the winter.. that'll work.

I tell people all the time.. these are supplemental heat to help you save a few bucks on heating fuel.. They're not going to heat your whole house less you have no trees for at least 2 house lots away and tons of glass on the south and southwest side of your home.

Isn't anything better then bright sun shining thru the glass all day long.
no fans.. no collectors.. nothing but great heat from the sun.