Heating A Greenhouse And/Or Cold Greenhouse

BigBen

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Hi All,
OK, so I'm still in the planning phase of my Springtime build.
It's either going to be a Greenhouse, Cold Greenhouse, or possibly both.
Size will most likely be in the range of 10' or 12' by 14' or 16', give or take a bit.

I'd like to use it to Over-Winter my trees, as well as use it to start and possibly extend veggie growing season.
That's why I think I might need 2 structures.

My questions are:

Those folks here that have either structure, how do you heat it during the cold Winter nights to maintain minimum temperature?
That is, IF you heat it at all.

Also, I've been looking at Solar Powered Geothermal/Earth Tubes/Geo-Air Tubes etc.. (similar to LDSPrepper, Morgan Brown amongst several others, yet on a smaller scale).

I believe those systems have been around for ages, does anyone here have any experience with them?
If so, would you kindly share your experiences with them , as well as pros & cons?

I see on YT that there are Horizontal Tube (LDSPrepper) AND Vertical Tube (Morgan Brown) setups.
Seems like the vertical tube setup can typically go a lot deeper into the Earth without too much hassle (using a long auger), as opposed to having a larger surface area utilizing longer runs of tubes, but then having to bring in a backhoe to dig a huge hole to bury the loops under the structure (which I'm not too keen on ).


I want to do it right the first time, and build it to last.
In a perfect world, it'd be some sort of combination structure, but not sure it's possible.

I'm certain that I'll have even more questionies. LOL...

Thank You For The Help, and Happy Thanksgiving!
BigBen

PS: Thanks again to JudyB for all of her help so far, I will be employing several of your ideas.
 
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Bonsai Nut

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Most of the battle is quality of construction and location.

If your greenhouse is attached to a heated building (like a conservatory or sun room) and is built on a foundation and facing the south, you may find you don't need to heat it at all - and that it might get too warm for your needs.

If it is free-standing, sitting on dirt, and doesn't get direct sun... and doesn't have a solid base or insulated panels... you will be dumping money into it trying to keep it warm.

Do you have more specific plans for where it will be located and how robust your construction is going to be?
 

BigBen

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Thanks BN.

Here’s a few thoughts so far...

Leaning towards a free-standing structure, running East to West so it’ll be facing South with plenty of Sun.

Thinking about a solid wood roof with short walls with 5MM solexx as the glazing. I could always use shades too if needed.

4x4 or 6x6 frame on the ground or blocks, with 2” or 4” rigid insulation around the perimeter sunk in the ground 2’-4’ to prevent ground heat loss.

Then running piping into the ground, connected to a blower box & Solar powered fan.

The floor will probably be pea gravel or pavers.

Also planning automatics venting.
 

BigBen

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Forgot to mention that I’m currently also looking at solar powered radiant heat options for the structure(s).

Any thoughts/suggestion?

Thanks Again!
 
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JoeR

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Most of the battle is quality of construction and location.

If your greenhouse is attached to a heated building (like a conservatory or sun room) and is built on a foundation and facing the south, you may find you don't need to heat it at all - and that it might get too warm for your needs.

If it is free-standing, sitting on dirt, and doesn't get direct sun... and doesn't have a solid base or insulated panels... you will be dumping money into it trying to keep it warm.

Do you have more specific plans for where it will be located and how robust your construction is going to be?
Yup. I’m on the dumping-money into it side. Also would like some ideas to save money. I’ve insulated the sides with this foam stuff I can’t remember the name of and it’s made a tremendous difference, but everything helps
 

hemmy

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Paradox

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If you do build a greenhouse type thing make sure you have a way to vent it or it could get too hot on warmer winter days.


I use a cold frame on the north side of my house and I don't worry about heating it.

This will be my 3rd year using it.
Worked awesome the first 2.
 

BigBen

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Thanks for the link, Hemmy. I've sourced it several times.

Thanks Paradox.
Automatic vents and fan(s) are in the plans too.
If you wouldn't mind, would you please post a photo of your setup? I'd greatly appreciate it.

I'd also appreciate seeing any other folk's green-houses and/or cold-houses too.
I want to plan and build just once.

We have the space, so I'm starting to lean towards 2 structures though, with a cold structure being smaller, but we'll see what options are out there.

Man, I love this place!!!

Thanks Again!


If you do build a greenhouse type thing make sure you have a way to vent it or it could get too hot on warmer winter days.
I use a cold frame on the north side of my house and I don't worry about heating it.

This will be my 3rd year using it.
Worked awesome the first 2.
 

BrianBay9

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You can save quite a bit by developing some heat sinks in your plan. I used 55 gal barrels of water as support for shelving all around the perimeter. They heat during they day and release the heat at night. They may not substitute for a heater, but they will reduce the energy costs.
 

JudyB

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pea gravel or pavers.
Pavers are a much better heat sink than pea gravel. Easier to keep clean as well, and they will keep humidity up too. They suck up water when you water your trees, instead of it just filtering down thru the pea gravel. More level of a surface to walk around and work on...
 

BigBen

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I agree, the pavers is the way to go, or a poured concrete floor (which I’m trying to avoid).

As we “speak”, I’m working on designing a thermostatically controlled solar powered DC radiant heat system. Utilizing PV panels, a DC pump, battery bank, a small DC powered water heater, and some sort of plug-in heater as a backup.
So far, I believe this’ll work.
Gonna speak with a couple engineers this week.


I also looked thermosyphon systems, but freezing pipes could be an issue here on Long Island, unless Glycol is used, which could cause other issues.
In warmer climates, they supposedly work great though.

In order to prevent freezing of my radiant system, I’d insulate the frame to 3’-4’ below grade, to help retain heat.
Then again, Glycol is always another option.
 

JoeR

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Pavers are a much better heat sink than pea gravel. Easier to keep clean as well, and they will keep humidity up too. They suck up water when you water your trees, instead of it just filtering down thru the pea gravel. More level of a surface to walk around and work on...
Yeah I have pea gravel in my greenhouse, not the best option but certainly the cheapest. It doesn’t absorb heat at all, but it looks decent and the GH tidy.
 

River's Edge

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You may wish to consider a Cafaro Brand greenhouse heater. I use one on the frost setting only. The concept is that it only comes on to prevent freezing. has a circulation fan setting that can be continuous. My greenhouse is small 10 by 14. It has worked well to provide winter protection for my more sensitive species, recently grafted, recently collected etc.
I reccomend an additional fan for circulation throughout. My climate can be very humid and the air movement is important.
 

BigBen

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Thank you for the suggestion, I’ll check it out too.

I’m also considering running a radiant heat zone off of my boiler, for the structure.
 

JoeR

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As per someone on here’s suggestion, I’ve insulated my greenhouse with this and it has helped tremendously. It’s ugly (my dad did it for my while I was gonna lol) but quite functional.
 

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BigBen

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Quick update on the project(s):
I'm still working with an engineer at Solexx, as well as a couple other folks in the HVAC business with me.
Still working on designing the heating/cooling system. Quite a few viable options out there, and I want to do it only ONCE. LOL...
Exciting stuff!!!
 

rockm

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All of this kind of begs the question--what are you planning to put into in during the winter?

In Zone 7a, you have less winter issues than I do with the vast majority of temperate zone species. I don't use any kind of greenhouse (hot or cold) for 99.9 percent of my trees, from Japanese and trident maples to southern collected cedar elms and bald cypress. The only tree that gets a cold greenhouse is my collected live oak. It is stored in a 40' x 20' or so greenhouse at a bonsai nursery south of me.
 

BigBen

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Hi Rockm, I'm not really sure about your climate, but here on Long Island we can get some pretty long cold spells.
I'd like to do some veggie starts as well as extend the growing/harvesting season, might even try some tropical plants too.

I also want to overwinter my Bonsai material, hence my mentioning a second yet smaller structure.

Soooo.... I'm trying to get it to where I can accomplish all of those or at least most of them, in 1 structure.

Planning for Retirement in 2-4 years, and I'm enjoying the "chase".
 
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