lEER
Where are you located? You are in 6 and I am in 7 and I am growing lettuces and other cole crops now without a GH which is still under construction.

ole dawg.
Located in Louisville Ky.
I'm looking down the road from Dec. on

You need at least 2 fans for air circulation and a heater. A humidifier would also be helpful. Bubble-wrap insulation (buy locally from packaging house) will save you a bundle on heat. Auto vent openers are almost a must. And then tables of some kind.......

This heating calculator might be helpful to get a feel for how many BTU's of heat you'd need for the temp you want to maintain. It doesn't take your insulation into account, but it's a starting point: Heating calculator

This same site also has a fan calculator to help determine the size of an exhaust fan for cooling.

I'm probably odd, but so many folks have posted here with problems about auto-vent openers that I'm not currently planning to install them. (Frankly the vent windows on my HFGH 10x12 don't operate all that smoothly anyway.) In my climate, I'm going to rely more on a 16" exhaust fan, multiple screens, and Aluminet shadecloth for cooling.

You can pull up a number of good threads on different bench types by doing a search for "benches" or "shelves" in this forum. Lots of good ideas! We made our own wooden benches, and added rubber-coated closet shelves from Lowes above the benches. The closet shelving wasn't quite strong enough to hold my heavy clay pots without some sagging, so we added wooden braces going from the closet shelves down to the wooden benches.

Just did calculations for heating and air flow. Will have to have 22,000btu heater in zone 6. Would like to hear from others that have the 10X12 HFGH as to their heater needs and how they satisfied them.

Mine was easier; my needs came out to roughly 10,000btu (zone 8 and a lower minimum temp for my succulents.) I'll be putting in two 1500w electric heaters with thermostats (figure about 5000btu per 1500w electric heater.) Gas would have been difficult and expensive to run; electric was only a few feet away, so it made more sense to us.

Hopefully others will post here with needs closer to yours.

FYI, I believe the problems with auto vent openers are with Harbor Freight's, not good ones from a greenhouse supply. They are really a time saver, I would not be without them.

Can some of you let us know what particular products i.e. heaters, covers, vents, fans, thermostats that you use.
Let us know what brands and where you got them. Also if they have worked out for you. Also products you might suggest to stay away from.

My GH is not yet up, but I have been doing some research. Lowe's had a good auto fan, 16 inch and already wire with and including an adjustable Thermostat. It is about $90 and like very much like the same fan sold at GH supply places for $150. and up. Lowe's also has a shutter/louver set up made from PVC or some other plastic. It will work with the fan and it was priced at about $25.00. The louvers are not auto. The force of the fan opens them up. I also plan to use rare-earth magnets to keep it closed when the fan is not working.
INTAKE vents: Again Lowe's has FOUNDATION VENTS that are automatic. opening I believe at 7? degrees and close FULLY at I think 38 degrees. They measure 8 x 12, exactly the same a one concrete block and they cost about $13.00 each.
I am still think on a way to make the shutter more auto, but have not come up with anything yet.

Good luck

1eyedJack and the Dawg

I have a 10x12 HFGH and I live in Northern Indiana and I can heat it with 2 1500 watt heaters but I have WAAaaaaayyyyy more insulation than what most people use.
When it gets hot you MUST have an exhaust fan and you will need to close the roof vents in order for the fan to work right. I have my roof vents locked down just open the door and when it becomes to warm the fan will come on and cool it.
Use the $160.00 that four quality vent openers would cost and buy a exhaust fan.

Unless you're rolling in extra cash stay away from Charlies Greenhouse & Garden Supplies. He's twice the price yet some people here will recommend him. I just bought two thermostats for my GHs and they were HALF his price at www.kkontrols.com. Shop around for the best prices before pulling out your cards.

Greenhouser,
noticed you are in zone 6 also. what have you done about heating needs? BTU's and gas or electric

I have two small 1500w heaters in the Rion and one 1500w in the small HFGH. They're set at the lower 1200w setting. I bought the all for less than $20 each at HD and Lowe's.

BTUs are unfamiliar to me.

1500 watt electric heater will put out 5100 BTU
If you insulate good two 1500 watt heaters should do.
Depends on how warm you want to keep it.

It is possible to use the heat calculators even if you have an insulated north wall. Just figure out how many square feet are insulated, put that figure in the top box (link below). Then enter the heat loss value which is 1/R. The R-value of your 1" insulation is probably around 6 so you would put 0.167 in the fourth box, enter your temps and hit calculate.

Then you do the same thing using the square footage of uninsulated glazing, using the heat loss value for the glazing, and click calculate. Then add the BTU for the first calculation to the BTU for the second calculation to get the total.

Basically this is the standard heat loss equation Q=deltaT*A/R broken into Q=deltaT(A1/R1+A2/R2)

SB

Here is a link that might be useful: GH heat calculator

A couple of other comments...

None of the GH heat calculators account for the floor. Why? Because heat loss through the floor is negligible.

If I where you, I would check the temps of the water in the 55 gallon containers and see if they are worth the space or trouble. The greatest value in having stored water is in its latent heat...the heat given off as it freezes. If your GH never gets near freezing, your barrels will never freeze. They will only release heat stored in the liquid state.

Now you have to consider when that heat is released. Do a little experiment (and post the results back here if you do!) Check the maximum water temp, I suspect mid to late afternoon. Then check the temp just before dawn, early morning, when it should be at its lowest. Then check it a third time in the evening when the GH air temp drops to your minimum of 60F. Using 4*55gallons, at 8.3lbs/gal, you have 1826 BTU for every 1 degree of temp change in your water. The difference, in degrees, between water temp when the air temp is 60F and the water temp at the early morning nadir, multiplied by 1826 will be the number of BTU you gain from the water each night.

If your units behave like my smaller containers, then most of the heat is given up between the mid afternoon peak and the time the heaters would kick on at 60F. The amount of heat given off from the time the heaters kick on at 60F and the nadir in early morning may be less. The point being, lots of your stored heat is lost before you need it. Got it? That is what my observations lead me to believe, let's see if you can confirm that. I will be doing this experiment this winter as well, but my barrels collect rainwater from the GH roof, so they serve dual purposes.

Seal everything up, infiltration is a major source of heat loss.

Get the HAF fans like greenhouser said. Be ready for bugs.

SB

I'm shooting for around 60F at night. I ordered two of those thermostats and can't wait till they get here. There is no way to set these little heaters to the temp you want unless you sit in your GH all night long. I thought I had them set to 60 last night, but my I/O Weather Channel says it dropped to 57F. :( The little GH with mainly cacti, succulents, begonias and ferns will be kept at 50F. None of these demand a lot of heat and the ferns, on the floor, do well with the lower humidity during winter. The north wall and roof of the HFGH have the foil type bubble wrap for insulation this winter. Even without it it stayed warm last winter - around 60 on the coldest nights.

All but the south wall of the Rion are covered in bubblewrap. There are also the tubs of water to keep over the pond tropicals. My poor Rion is packed from ceiling to floor..... I'm *GASP!* about out of space in it. :-O