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

[solarhotairpanels]

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

[Exeric]

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.

[solarhotairpanels]

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.

[Exeric]

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.

[solarhotairpanels]

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.

[iamgeo]

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.

[solarhotairpanels]

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!

[iamgeo]

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.

[solarhotairpanels]

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.

[iamgeo]

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.