Well I am relieved that Derek and I were able to get the last end completed last week. It feels good to know that the greenhouse is pretty much enclosed. The man door that you can see in the image above is still open, and the garage door opening on the other end is without a door. My plan is to build the door for the man door out of the strut and hang it on hinges within the next week. The garage door I will probably wire a sheet of film in place for the winter. This will allow me to do the job right, and not rush through it just to be able to heat the greenhouse this winter.
Speaking of heating the greenhouse, I just signed a contract for Suburban Propane to be our propane supplier for the next year. This was an obvious choice considering that they have an office just four miles away on US-25. They will be delivering a 400 gallon storage tank on December 3, 2020. This causes more work!! I have purchased black iron pipe to run my gas lines for the two new heaters we will be using to start our market plants this Winter. Yes just like the water lines, I will be running my own gas lines. This, just like the water will be a first for me. The concept is actually straight forward, tape the threaded ends and connect them. It’s the same for any of the fittings. I have 1/2″ EMT clamps to mount the pipe inside of the house and along the outside where Suburban will be making their connection.
I have done quite a bit of research on heaters. Natural gas, propane, electric, wood burners, pellet shoves, and alternative methods such as compost heating. Natural gas is not available here so I didn’t do much with this type, electric is expensive, and we don’t currently have a pole set. I like the alternative methods, but I have no experience with this method and I need something that is proven and reliable out the gate. Wood and pellet burning looked to be the best for a couple of reasons. A pellet stove with a larger capacity hopper can burn for long periods of time without needing to be tended. A wood burning stove is a cheap means of heating, especially with all of the wood available on the farm. I have actually purchased a steel 55 gallon drum to build a drum stove. I would build a double drum stove which I have actually found the kit to build it. The issue I have with wood or pellet burning is running the stove pipe for venting. I really needed to finish up the ends, so for now I have put this idea on the back burner. Next Spring I can revisit this and build a gable so that I can pass the pipe through the film without melting anything. Propane heat proved to be the best method under the conditions and situations we have currently. So I have ordered the propane radiant heater pictured above. I did all of the research about radiant and convection heaters. So based on my research our primary heater will be a 22K BTU radiant heater. Now keep in mind we are not planning on heating the entire greenhouse. There is no need for this. I have done the calculations and the 22K BTU heater should be fine for the space we are planning on using for starting our early market baskets. We will be using a 320 sqft. area for basket production this Winter. The plants for the baskets require a 50F minimum temperature, so I assumed a 55F minimum in the calculations. We will need 20,429 BTU to maintain 55F if the temp outside stays above 15F.
That’s where this convection heater comes in. This heater is capable of heating the entire greenhouse. So you might ask, “Why not just use one heater?” Good question. The radiant heater above had a fuel burn rate of 0.274 gallons/hr, This convection heater burns 2.3- 3.7 lbs./hr with propane being 4.2#’s per gallon at 60F. So that’s 2-3 times more fuel than the radiant heater. The name of the game is provide heat at the best price. The radiant heater has a thermostat so it will run on a regular basis when heat is needed. If we have a winter event that requires more than the radiant heater can supply, then the convection heater can supplement the needed heat on a temporary basis. The best of both worlds. My long term plan is to implement thermal mass inside the greenhouse and insulate the floor to reduce heat loss through the ground. We will also use a double drum wood burning stove. The theory is to retain the heat by insulating the ground, to heat the air by burning wood which in turn heats the thermal mass. So what is this thermal mass you ask?
My thermal mass shall be several 275 gallon IBC tanks full of water. Water is a perfect substance to store heat, and water temperature fluctuates very slowly. What you wind up with is a buffering of the inside temperature. The water absorbs the heat all day long during growing season and gives it off at night which keeps temps quite stable. In the winter it absorbs the temps at night which is when you will be heating and buffers during the day. So year around the temperatures are rather stable. erratic temperature swings are really tough on plants that are actively growing, such as our hanging baskets for Mothers day which are trying to make it in February and March. So there is still a lot going on at the farm. We also have plants that need to be potted up for Spring sales. This will be another project over the Winter as we prepare for Spring 2021 sales.