Winter Greenhouse Heating Ideas

[Dan Freeman]

I think the trick would be to run glycol under the soil instead of heating the air in the greenhouse.

Or even run it through water. Water will hold more heat than soil.

 

[EbS-P]

I think the trick would be to run glycol under the soil instead of heating the air in the greenhouse.

That would be ideal with an air to water HP. I’m skeptical about the buried perf pipe if one doesn’t use crushed rock. I just don’t see enough air flow through soil.

 

[Dan Freeman]

I was looking at these 30 Gallon Black Tight Head Plastic Drums this morning. They would make great bases to run greenhouse shelves across. I could easily use 14 of them. That would be another 420 gallons of passive warm water that would gain heat during the day. They are also a nice height for older people to work at 29" tall.

I learned after my first year in my greenhouse with "built in" shelves that it is better to have shelving that is modular and/or moveable so you can rearrange it depending on what you are growing. It gives you so much more flexibility. Presently, I use cinder blocks with 2 x 4's to hold my Dura Bench tops.

30 Gallon Black Tight Head Plastic Drum, UN Rated, 2

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Dura-Bench Plastic Benchtop - 2 ft. x 5 ft.

Dura-Bench Original Plastic Nursery Bench Top is designed to replace traditional wood, metal and wire bench top, Dura-Bench offers a tougher, longer lasting growing surface while eliminating problems associated with other bench top materials. The Dura-Bench Original 5'L design is 2' wide with...

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[EbS-P]

More thinking. I think a drain back system could be utilized not sure on sizing yet. This look well thought out.

Solar Water Heating Projects and Plans

Descriptions and plans for several types of solar water heating systems, including batch systems, drainback systems, and closed loop systems.

www.builditsolar.com

 

[Dan Freeman]

I have to tell you; I find this conversation very stimulating.

I am just about to pull the trigger on purchasing a Hoklartherm Riga XL 6 Greenhouse 14' x 19' 10" x 9' 10" high. My Sunshine Greenhouse Mt. Rainier 8' x 16' is entering its 9th year of duty. I bought it without really knowing diddly about greenhouses although I researched for months. Just about all the research falls by the wayside when you have the greenhouse built and begin to use it. It is a STEEP, FAST learning curve, so buckle in or you'll lose interest very quickly when all you do is fail at it.

Perfect place to do some shameless self-promotion and insert a video of my first greenhouse which I am still using today.



I tried a lot of different methods to keep my greenhouse warm for as long as I could. Reflectix Insulation, solar, heated 55-gallon water drums, electric heating, a slate path, a greenhouse-within-a-greenhouse, and others I have probably forgotten. All helped, but even together, they could not overcome old-man-winter.

I feel that I have learned a lot. I am ready for a new greenhouse, not only because the first one is showing its age, but because I want to incorporate some things I have learned with this one.

I have learned, and if I had the money, the only 2 greenhouses I would consider for true 4 season greenhouses are those made by Ceres Greenhouse Solutions (https://ceresgs.com/) and Growing Spaces (https://growingspaces.com/), and I would not go for a little one! So, purchasing, shipping, constructing for the models I want if I could pick from one from one of these companies is up there in the $40-$50,000 range when al, is said and done.

With that said, the Riga has an exceptionally strong frame with 16mm Triple Wall Polycarbonate panels, can handle snow loads up to 75 lbs per square foot, wind loads upwards of 100 mph. The frame has a 15-year warranty (exceptional)and the Polycarbonate has a 10-year warranty (standard).

Three things I plan to do differently right off the bat are:
-Have a pond of anywhere between 425 gallons and 600 gallons for thermal mass.
-Use 14, 30-gallon drums filled with water for thermal mass (used as shelf bases)
-Put a Swedish skirt around greenhouse perimeter to keep out cold ground infiltration
-Interior floor of sand with pavers for thermal mass

A lot of this is made to hold heat. So, in the summer, I will need to make great use of the two doors, 4 roof windows, exhaust fan, circulation fans, and shade cloth to keep the temperature tolerable.

Enough rambling for now. Have to get back to work.

 

[EbS-P]

I have to tell you; I find this conversation very stimulating.

I am just about to pull the trigger on purchasing a Hoklartherm Riga XL 6 Greenhouse 14' x 19' 10" x 9' 10" high. My Sunshine Greenhouse Mt. Rainier 8' x 16' is entering its 9th year of duty. I bought it without really knowing diddly about greenhouses although I researched for months. Just about all the research falls by the wayside when you have the greenhouse built and begin to use it. It is a STEEP, FAST learning curve, so buckle in or you'll lose interest very quickly when all you do is fail at it.

Perfect place to do some shameless self-promotion and insert a video of my first greenhouse which I am still using today.



I tried a lot of different methods to keep my greenhouse warm for as long as I could. Reflectix Insulation, solar, heated 55-gallon water drums, electric heating, a slate path, a greenhouse-within-a-greenhouse, and others I have probably forgotten. All helped, but even together, they could not overcome old-man-winter.

I feel that I have learned a lot. I am ready for a new greenhouse, not only because the first one is showing its age, but because I want to incorporate some things I have learned with this one.

I have learned, and if I had the money, the only 2 greenhouses I would consider for true 4 season greenhouses are those made by Ceres Greenhouse Solutions (https://ceresgs.com/) and Growing Spaces (https://growingspaces.com/), and I would not go for a little one! So, purchasing, shipping, constructing for the models I want if I could pick from one from one of these companies is up there in the $40-$50,000 range when al, is said and done.

With that said, the Riga has an exceptionally strong frame with 16mm Triple Wall Polycarbonate panels, can handle snow loads up to 75 lbs per square foot, wind loads upwards of 100 mph. The frame has a 15-year warranty (exceptional)and the Polycarbonate has a 10-year warranty (standard).

Three things I plan to do differently right off the bat are:
-Have a pond of anywhere between 425 gallons and 600 gallons for thermal mass.
-Use 14, 30-gallon drums filled with water for thermal mass (used as shelf bases)
-Put a Swedish skirt around greenhouse perimeter to keep out cold ground infiltration
-Interior floor of sand with pavers for thermal mass

A lot of this is made to hold heat. So, in the summer, I will need to make great use of the two doors, 4 roof windows, exhaust fan, circulation fans, and shade cloth to keep the temperature tolerable.

Enough rambling for now. Have to get back to work.

So based on your experience in your location do you think you can operate the new 4 season greenhouse year round without external heat?

 

[Dan Freeman]

So based on your experience in your location do you think you can operate the new 4 season greenhouse year round without external heat?

I don't know if I can do it totally without heat. My hope is I can endure nights outside down to 20F without external heat, and only need to have a fossil fuel heat kick in if nights are below 20 or there is no sunshine for multiple days, which is not unusual here in the Pocono Mountains. It's very hard to say. But I know this new greenhouse will make my old one look like I was trying to keep my front porch warm in a blizzard. Between the quality of the greenhouse and the thermo-sink interventions I plan, I think I will have made strides in cold weather greenhouse growing. I might not be able to have tomatoes, but I will have no problem with any cold weather crop and even some medium weather crops.

Only time will tell, and this is fun. I will post the progress, although the transition from one greenhouse to the other (on the same plot of land) will not start for a few months.

 

[RomanW]

Three things I plan to do differently right off the bat are:
-Have a pond of anywhere between 425 gallons and 600 gallons for thermal mass.
-Use 14, 30-gallon drums filled with water for thermal mass (used as shelf bases)
-Put a Swedish skirt around greenhouse perimeter to keep out cold ground infiltration
-Interior floor of sand with pavers for thermal mass

I'm intrigued by your mention of sand. I never thought of it as an insulating medium... I am currently sitting on over $1M worth of fine grain sand underneath the ground on our property... I've been trying to find some use for it other than a sandbox LOL. It's honestly beach quality.

But, if I understanding your meaning correctly, I could use this in the base of my GH to combat the cold coming up from the ground especially with stone being used as heat sinks... and in conjunction with the swedish skirt that could make a signifcant difference... Especially here, where I have 12" of loam, and nothing but rocky clay under that.

Hmm....

 

[RomanW]

That being said... it probably is a big waste of time and energy if I'm planning on using the type of green house I shared earlier... From what I've seen, most of the green houses that use this system are basically a framed in and finished room, basically a tiny home.

 

[RomanW]

Another random thought, now that I'm thinking out loud...
What if someone used the solar convection idea with tubes, but pumped the water through large barrels buried in the ground. The water would be heated by the sun then heat the barrels which are already a thermal mass, but also heating the surrounding ground. Then at night it would be a source of radiant heat from the ground....?

 

[Poindexter]

Another random thought, now that I'm thinking out loud...
What if someone used the solar convection idea with tubes, but pumped the water through large barrels buried in the ground. The water would be heated by the sun then heat the barrels which are already a thermal mass, but also heating the surrounding ground. Then at night it would be a source of radiant heat from the ground....?

You can't make luau pork in Alaska. Not even in the summer, I have tried with potatos.

Now maybe, if you were to make a big hole in the ground, line it with insulating foam, and then fill that insulated hole with sand, maybe.

 

[Dan Freeman]

I'm intrigued by your mention of sand. I never thought of it as an insulating medium... I am currently sitting on over $1M worth of fine grain sand underneath the ground on our property... I've been trying to find some use for it other than a sandbox LOL. It's honestly beach quality.

But, if I understanding your meaning correctly, I could use this in the base of my GH to combat the cold coming up from the ground especially with stone being used as heat sinks... and in conjunction with the swedish skirt that could make a signifcant difference... Especially here, where I have 12" of loam, and nothing but rocky clay under that.

Hmm....

The cold coming "up" from the ground in a greenhouse (really heat being lost to the colder ground) is a function of the cold ground outside the perimeter of the greenhouse. As the outdoor temperatures drop, the cold "seeps" into the ground on the inside of your greenhouse from the outside and robs up to 15% of your greenhouse's heat. The only way to prevent this is to insulate the greenhouse floor (not recommended), insulate to greenhouse foundation down to the frost line, or create a Swedish skirt around the perimeter of the greenhouse.

Sand is not an insulator, but a decent thermal sink, however once the warmth has been sucked out of it, it does not insulate.

I plan on installing a Swedish Skirt to keep the cold ground out of my greenhouse. The ground inside the greenhouse should stay in the 50's all year, helping to heat in the winter and cool in the summer. The sand and pavers will be used to store some extra heat on sunny days.

It is not recommended to insulate the floor of a greenhouse because then you are cutting yourself off from the constant year-round soil temperature in the 50's.

 

[Dan Freeman]

That being said... it probably is a big waste of time and energy if I'm planning on using the type of green house I shared earlier... From what I've seen, most of the green houses that use this system are basically a framed in and finished room, basically a tiny home.

Yes, the best 4 season greenhouses have glazing towards the south and the rest is insulated wall to maintain heat, and if sunk into the ground, the insulation effect is even greater.

You can do a lot to help retain heat in a greenhouse, but if all 4 sides and roof are glazed with a small mm double wall polycarbonate glazing, it is going to be like pissing in the wind just about no matter what you do. That's why I said I would like to have either a Ceres GH or Growing Dome but can't afford either. With the Riga I plan to buy, I am going from 4 mm double wall poly carbonate panels to 16mm triple wall polycarbonate panels. They will greatly increase the insulating factor even if it is not as much as I would like by getting a Ceres or Growing Dome. With the pond, water drums, Swedish skirt, sand/stone floor and covering the north and east walls with something like Reflectix insulation, I should be in much better shape.

You (and I) could build a well-insulated GH from scratch, but I don't have the time or desire to do it. Plus, this 67-year-old body would probably rebel just at the thought.

 

[Dan Freeman]

Another random thought, now that I'm thinking out loud...
What if someone used the solar convection idea with tubes, but pumped the water through large barrels buried in the ground. The water would be heated by the sun then heat the barrels which are already a thermal mass, but also heating the surrounding ground. Then at night it would be a source of radiant heat from the ground....?

You could certainly do that. I would do some research about it, but it sounds viable. You saw that video I posted about the solar warm water system I used for two winters. It actually worked quite well, but took up so much room in the GH, I decided to get rid of it and just grow 3 seasons.

BTW, you would still need perimeter insulation or so much heat from the barrels will be stolen.

 

[Stove Cricket]

Very interesting…. Couple of rambles

Worked on a large vacuum sealed solar heating system at 38*N that used metal mesh screening for hail protection. Were continuously tinkering with the controls on that system. Overheating is an import controls issue (can’t shut the sun off).

Years ago (many) I worked for a retired university horticulturist. He ran two greenhouses for his retirement business. He always shut one or the other down a winter to help control white flies and bugs.

A bio-mass burner with buried loops can aid with a GH that grows directly on the soil. Hurst Boiler makes some large bio-mass wood boilers that are interesting to look at , but way out of range otherwise. ( just don’t let your your bio-mass suppliers water down their trucks before weighing in with a load)

Some projects (38*N or so) for commercial freezers require significant insulation under the pad to deal with soil freeze/thaw structural issues.

YouTuber Richard Perkins made an attached greenhouse at 59*N. I think it is heated in conjunction with his house, and visa versa when applicable.

 

[RomanW]

Now maybe, if you were to make a big hole in the ground, line it with insulating foam, and then fill that insulated hole with sand, maybe.

I think this is more what I was thinking.

Still do the swedish skirt, either horizontal, vertical, or both. And then put the barrels in the ground with the tops just poking out, maybe a group of 4 right in the middle of the GH. Back fill with a mix of aggregate, not all sand. Use pavers like @Dan Freeman said. Then have the system automated and run off of a Rasp Pi, or Arduino with flow controls from the barrels up to the solar collectors...

I wonder if playing with the aggregate would have any effect as well. Like backfilling with 40mm, then filling the gaps with sand, then topping off with pea gravel... I wonder if burying thermal mass would also help with heat retention in the ground beside those water barrels.

@Dan Freeman yeah, I saw the videos thanks! Obviously, you made it work, but space was the main issue like you said... Then there's the issue of having enough sunlight...

 

[Dan Freeman]

That certainly sounds like a viable method, but you really don't need the expense and the stoking of a bio mass burner to store heat in the soil when you have the sun that will do it for you. A fan can circulate the heat from the upper areas of the GH down into the underground tubes very efficiently where it is stored until needed. So, you are pumping heat into the ground during the day, and bringing it back up into the greenhouse at night.

 

[Stove Cricket]

RE: enough sun comment - sunrise in Utquavik in 4 days Dang

 

[Dan Freeman]

I think this is more what I was thinking.

Still do the swedish skirt, either horizontal, vertical, or both. And then put the barrels in the ground with the tops just poking out, maybe a group of 4 right in the middle of the GH. Back fill with a mix of aggregate, not all sand. Use pavers like @Dan Freeman said. Then have the system automated and run off of a Rasp Pi, or Arduino with flow controls from the barrels up to the solar collectors...

I wonder if playing with the aggregate would have any effect as well. Like backfilling with 40mm, then filling the gaps with sand, then topping off with pea gravel... I wonder if burying thermal mass would also help with heat retention in the ground beside those water barrels.

@Dan Freeman yeah, I saw the videos thanks! Obviously, you made it work, but space was the main issue like you said... Then there's the issue of having enough sunlight...

You don't need vertical AND horizontal. One method will do the job very efficiently.

I would not use rock, sand, aggregate, etc if I was going to bury barrels. I would use water. Water can hold so much more heat than rock. Water has a heat capacity that is 4-5 times higher than rock or dirt.

 

[Dan Freeman]

@Dan Freeman yeah, I saw the videos thanks! Obviously, you made it work, but space was the main issue like you said... Then there's the issue of having enough sunlight...

I had a barrel strap heater that I could switch to on cloudy days or longer cloudy periods to keep the water warm.

 

[EatenByLimestone]

Have you seen the oranges in the snow video? It looks like an inexpensive way to heat a greenhouse if you have the land.

 

[EbS-P]

So if 4 seasons is your goal why choose poly carb for four walls and roof??

 

[Dan Freeman]

So if 4 seasons is your goal why choose poly carb for four walls and roof??

Because a large, honest-to-goodness 4 season greenhouse is VERY expensive.

To get a Growing Dome or Ceres GH (about the only 2 on the market I would consider for 4 seasons) that would be the size of the Riga I plan to buy would be at least $50,000 including shipping and installation. The Riga, which is as close to a 4 season you can get without actually paying an arm and a leg will cost me $15,000 and that includes cost, shipping, foundation timbers, ventilation system and water drums. The other modification changes or additions I want to make should run another $1000 or so once completed.

Also, I am not looking to grow tropical or other plants like tomatoes in it all winter. I am looking to grow cold/cooler weather plants. A big part is also to use the greenhouse as an area for relaxation.

 

[Dan Freeman]

Have you seen the oranges in the snow video? It looks like an inexpensive way to heat a greenhouse if you have the land.

I remember watching this video a few years ago. If I remember correctly, he ran the thermal heating tubes all over his property, not just under the greenhouse. To get the length of tubing he has buried as deep as he did, you would pay a lot for the excavation and tubing, but what a great greenhouse!

 

[RomanW]

You don't need vertical AND horizontal. One method will do the job very efficiently.

I would not use rock, sand, aggregate, etc if I was going to bury barrels. I would use water. Water can hold so much more heat than rock. Water has a heat capacity that is 4-5 times higher than rock or dirt.

Yeah that was my thought. water barrels in ground surrounded by aggregate