Homesteading Forum banner

1 - 20 of 25 Posts

·
Premium Member
Joined
·
5,905 Posts
Discussion Starter #1
So my little hoophouse we got a start on late last year, we decided to finish it off this year with a concrete floor, pex tubing in the floor and in the new center raised bed.

Last year, we got the main structure done in the fall, with raised beds around the outer edges. We grew cool weather crops like lettuce, spinach, broccoli, cabbage, etc all winter, but we had to cover them with frost blankets when the weather got in the low 20's and below......which was a lot of nights here.



Still did pretty good, but was a lot of effort to keep stuff from freezing out.



So, this summer, poured a concrete floor with pex in the floor, and where the center bed will be.....plus went back and buried a loop in the outside bed as well.





Center bed built, and full of green beans and broccoli....about the end of Sept, 2014.




Photo limit hit. Continued in post 2 below
 

·
Premium Member
Joined
·
5,905 Posts
Discussion Starter #2
Continued....

Built a frame out of 2" galvanized pipe, and 2x2 galvanized angle to hold the collectors. Bought 3 - 16 tube collectors and plumbed them in series.




Here is the completed collector with 48 vacuum tubes, plumbed into the wall of the hoophouse.



Just inside, 120gallon SS tank. Has dual exchange coils inside, I'm only using the one for the collector loop. (black insulated line with silver tape stripes is the "in" from the collector)

The heated water comes off the top of the tank, down into that red Bell&Gosset 1/12hp circulation pump, into the floor pex pipe, and back into the bottom of the tank. Right now, I've just got it controlled with a simple single pole switch. The controller that came with the hot water system does have a relay set up to control a separate pump like this, so once I get a little more down pat as to my heat production, I'll switch the pump over to that so I can set it up automatically.




The 'working station' (green pump) that comes with the system, and the differential thermostat. Measures the collector out temp (T1) and compares it with the temperature in the lower-mid part of the tank. If the collector is 8 degrees C higher, the pump runs (factory default, you can field set to what you want).




JUST got it all hooked up this morning, and the collector loop fill with antifreeze mix. Naturally, we had almost no sun today, so the tank temperature only went from 59C to 65C by the end of the day. Rest of the week is forecast to be a lot better, so we'll see how much heat I can get out of it.
 

·
Registered
Joined
·
3 Posts
Excellent! This is exactly what I'd like to do, except with a 500 - 1,000 gallon storage tank. I'll be watching for more updates - thanks!

Can you tell me about your hoop frame? I haven't seen that design before. DIY? Plans?

Chuck
 

·
Premium Member
Joined
·
5,905 Posts
Discussion Starter #4
Excellent! This is exactly what I'd like to do, except with a 500 - 1,000 gallon storage tank. I'll be watching for more updates - thanks!
I think you'll need a LOT more tubes if you go with that much storage. After a few days, which have been lousy solar days (partly to full clouds), the collector outlet has only hit about 140 degrees max, and the tank about 100. I am flipping the floor pex loop pump on every evening....figuring 100 degree water is still above ground temp, so why not.

But I'm thinking I may have to add more collectors. I'll wait for a few real sunny days to decide.


Can you tell me about your hoop frame? I haven't seen that design before. DIY? Plans?

Chuck
My plans are usually "well, that oughta work"....."and heck, if it doesn't, we'll try something else"......ahahahaaaaa

The hoop frame is simply some 1/2" x 3" strips of white oak I sawed on my mill, laminated them in pairs (screws and glue....Titebond III), put a small block every so often, then added another pair of strips. I built a work table, out of sawmill 2x6's and CDX plywood, in the yard, laid the arch out on it with a string/pencil to suit me, then built them to the line (screwing blocks down for a jig along the pencil line).










They DID have a tendency to push my short knee walls outward after I took the temporary braces off the outside, so I got some 3/16" cable at the local big box store, and looped it inside the arch up about the 9' off floor level. I put the longest turnbuckle I could find, and cranked it to about C sharp ( :D )....that plumbed the outside walls up nicely. If you look close in the pic below, you can see them. (also in last pic in post #2 above)

Also put a foil faced bubble wrap insulation (4'x25' rolls) on the northeast end, and the northwest kneewall. Wasn't gonna get a sunlight thru that anyway, and the light that does reflect off that aluminum foil REALLY brightens things up inside.

In this pic, I hadn't finished burying the PEX over on the right side bed, because I was waiting the wife to be done with those tomatoes in the back corner. They produced from early May ( a full two months before our outside ones) until late Sept, the date of this photo.

 

·
Registered
Joined
·
53 Posts
I think you'll need a LOT more tubes if you go with that much storage. After a few days, which have been lousy solar days (partly to full clouds), the collector outlet has only hit about 140 degrees max, and the tank about 100. I am flipping the floor pex loop pump on every evening....figuring 100 degree water is still above ground temp, so why not.

But I'm thinking I may have to add more collectors. I'll wait for a few real sunny days to decide.




My plans are usually "well, that oughta work"....."and heck, if it doesn't, we'll try something else"......ahahahaaaaa
A rule of thumb for glazed flat plate collectors is 1.5 to 2 gallons of storage per square foot of collector. I don't know if that applies to vacuum tubes, but you should be able to find a similar rule. The optimum ratio will also depend on the site conditions and desired water temp.
 

·
Registered
Joined
·
3 Posts
Wow.

TnAndy - great workmanship! I believe I'll follow your lead in the spring. Get any winds where your greenhouse is set up? That's an issue I'll have to deal with. That and not having any oak to work with ;-)

What I do have is lots of sun - like 280 days...and at 7,500' elevation there is not as much of that pesky atmosphere to interfere with the solar gain so I think a small collector will produce more for me.

Thanks again for the description and photos!!
 

·
Premium Member
Joined
·
2,315 Posts
What do you use for soil in your raised beds? I have used garden soil in the containers in my greenhouse and it isn't quite right, not like the garden. at all. What do you think you have tied up in your heat system, time and money? Isn't it nice to have fresh veggies that you grew yourself in December?
 

·
Premium Member
Joined
·
5,905 Posts
Discussion Starter #11
Wow.

Get any winds where your greenhouse is set up? That's an issue I'll have to deal with. That and not having any oak to work with ;-)
No wind to speak of here....we're tucked in under the eastern side of a mountain the prevaling west wind blows over the top.

Regular metal hoops are probably the way to go anyway....I just wanted to try this to see how it would work out. I'd probably buy metal framing if I did another.
 

·
Premium Member
Joined
·
5,905 Posts
Discussion Starter #12
What do you use for soil in your raised beds? I have used garden soil in the containers in my greenhouse and it isn't quite right, not like the garden. at all. What do you think you have tied up in your heat system, time and money? Isn't it nice to have fresh veggies that you grew yourself in December?
Regular soil, which here tends to be heavy in clay. To that, we mixed coarse vermiculite and peat moss, and made up a Jim Dandy mixture.

Cost in the heating system ? In the $3500 range.
 

·
Premium Member
Joined
·
5,905 Posts
Discussion Starter #13
How absolutely beautiful! You do spectacular work, and so precise. How did you learn to build greenhouses? Did you use any reference books?

Thanks for those pictures.
I kinda make things up as I go. Most construction is simply common sense, and you just sorta build it in your head first, then go do it.
 

·
Registered
Joined
·
675 Posts
So you going to grow matter's all winter ?

Looks really good, maybe a road trip in our future.

It's amazing how much better growing under cover makes. Ours out produced the field big time.

Good job my friend !


ETA- went back and looked over the pics, why 2 expansion tanks ? 1 for the collector & 1 for the tank ?
 

·
Premium Member
Joined
·
5,905 Posts
Discussion Starter #15
So you going to grow matter's all winter ?

Looks really good, maybe a road trip in our future.

It's amazing how much better growing under cover makes. Ours out produced the field big time.

Good job my friend !


ETA- went back and looked over the pics, why 2 expansion tanks ? 1 for the collector & 1 for the tank ?
Thanks ! Take that road trip ! Wife is retired now, you get to meet her this time around.

On the tanks: Separate systems. The collector loop is only a couple gallons, and doesn't really need a 2 gallon expansion tank, but it was the smallest one Lowes carried. The collector loop is a 50/50 mix of water and antifreeze.

The larger tank (5 gal) is for the tank, which is 120gal + the amount in the floor loops (maybe another 4-5 gallons). Probably little over sized as well, but it was only few bucks more.

Now for some pics of the biggest broccoli we have EVER grown ! (I think it's a combination of no bugs, good loose soil, fish fertilizer and good temps)(like you said, under cover is beating out in the garden all to pieces......I seriously considering another hoop house, a LOT bigger this time)
 

Attachments

·
Registered
Joined
·
431 Posts
Very very nice. had a similar idea on a much smaller scale.
 

·
Premium Member
Joined
·
5,905 Posts
Discussion Starter #19
Not as well as I'd hoped.

For one thing, I think I put too much storage tank. I used a 120gal, and even though the collector loop hits 150 degrees, the tank never seems to get above 105-110.

I aimed the collectors due east, because it gets morning sun just as soon as the sun rises above a mountain to the east side of our valley. Unfortunately, with the low winter angle, the sun isn't hitting my collectors past about noonish, because we have a tall ridge with tall trees on our place to that side. I should have scouted the collector location better....but then I would have had to move it quite a ways back too, along with the associated pipe run.

Lastly, I think 48 tubes simply is NOT enough collector surface. I'd have to double it (or more) give the location/orientation. Lesson learned.

SO, my fix is gonna be this:
1. Not gonna add more collector.

2. I'm going to eliminate the tank from the system, and let the collector loop go directly into the floor PEX tubing. It's rated for 190 degrees, and so far, I haven't seen over 150 come out of the collector. The ground/floor temp is in the 50 degree range, so I think, based on a SWAG, that I'd simply be better off to take whatever heat I get out of the collector, and dump it in the floor directly, then let it radiate off as it will.

3. For extra cold nights, like the 10 degrees we had from the Polar Vortex last week, instead of using auxiliary propane, or frost blankets, I'm going to install a wood stove....to be fired up only on the nights it looks like the temps will dip in the low 20's or lower.

4. She MAY just have to let her tomatoes go, and go back to just cool weather crops.

It's all a grand experiment.....ahahahaaaaa
 

·
Registered
Joined
·
363 Posts
I'm mostly posting to follow this thread because your ingenuity and persistence inspire me... :)

I did wonder if I was understanding the picture of the PEX going in rightly. Did you just put it in the bare dirt under the concrete? No insulation under? And then build up a 2-3 foot bed over that to plant in? It seems like you're expecting a lot from the hot water in the tubes to get it to make much difference at the roots of the plants. Does the tubing go up into the planter bed?
 
1 - 20 of 25 Posts
Top