Anybody Heat A Small Greenhouse?

There was a commercial operator on her a year or so back.

From mempory he was looking at 1m btu's.

http://www.google.com/url?sa=t&rct=j&q=bordine nursery bio mass boiler video&source=web&cd=2&sqi=2&ved=0CDcQFjAB&url=http://www.bordines.com/goinggreen/&ei=tns6T_TEBqiO0QHep_mrCw&usg=AFQjCNEw5eknYxpQkH2yDSPH1A_RBpxkug&cad=rja Copy this link,this green house is about a mile long. What to talk about storage.

Could you build and insulate the building yourself? Sometimes if you keep your eyes open you can find some fairly new, but used, windows someone is selling that are in nice shape. If insulated and decent windows, it would not take much to heat it then. Between the heat coming off of the boiler and solar heat coming through the windows. Just thinking out loud. I kept looking for a few years and collected wood 2x4, 2x6, sheeting material, etc. Then I built a 12'x28' detached garage for cold storage. Built it myself, just had to have one person help me a few times in raising the walls and putting the trusses up. Double floor joist every 16", then closely spaced 2x whatever I had, going 90 degrees to the joist. Then 5/8" plywood floor. Very strong. By the time I was done, I had somewhere around $2600 I think. (That was the trusses, dark green metal roof, etc.) No windows. One used 7'x9' overhead door (that I got for free). One 3' exterior man door(that I also got for free). I had enough siding left over from the house job to complete the front of it. Now all I have to do is the other three sides. It took me a little more than a year to collect all the stuff, but if you take your time and look around you can save yourself some serious cash.

My attempt at a solar greenhouse. It's a small shed originally built to house an EKO 40. Well insulated with 3" foam and two sliding glass doors. I have one array of evac tubes, plain water drainback. A basic 80 gallon well tank with bubble wrap. I did add a 100W light bulb that kicks on at 40F if the solar is not loaded.

The planter beds have radiant transfer plates with pex to warm them. We have had lettuce all winter, I'm actually looking for some over-heat window operators as it does get to warm on sunny days.

I think the key is to warm the planter beds and do a heat load to maintain 50f or whatever temperature you require. Of course the load is always dictated by the building insulation, glass, etc.

hr

inside the greenhouse

It's something I'm considering down the road. I plugged values into a heat loss calculator: http://www.builditsolar.com/References/Calculators/HeatLoss/HeatLoss.htm
so that I would have a general idea of the heat required. For a 12x16 greenhouse using R=1.43 for twin-wall polycarbonate for the walls and roof and R=5 for the floor, I came up with a design loss of about 34 KBtu/hr and an annual loss of about 75 MBtu. That doesn't account for any solar gain.

Edit: That's also assuming that the greenhouse is kept around 68 F. If you only plan on maintaining it at 55-60 F, it would certainly lessen the heat required.

I don't know how much it would take to heat a small one, but we heat the one in the picture. Of course it helps that there is a large radiator in it. ;-)

I have fiddled with a workshop greenhouse that my Profab 200 is in. Its not insulated yet, but i find it is consitantly ten degrees warmer in the building than outside. IM excited to get it insulated and more airtight and at a minimum i think i will be able to start plants in it in March. I suspect getting the space to be 20-30 degrees warmer than outside will be fairly easy once its insulated with no supplemental heat. Maybe sooner if i protect the plants inside the greenhouse with another "cold frame". the building is in my avatar. the long sloping roof has a green shaded fiberglass product in the roof. For the "glass" Im using a fiberglass glazing that matches my steel roof profile..and my plan is to add another laye of plexiglass on the inside to creat a crude insulated window.

I sharpen my saw in this space and the ten degree difference is huge...soon to be full on man cave.

some cool ideas on this thread!

barkeater

Folks on this list have seen this a number of times...sorry for the that...this drawing shows a floor plan...

oops, the other drawings were elevations...this is the plan.

it was all built with rough cut lumber WIndows were made by carpenter friend for very reasonable...they are a simplifed verson of a real window..but have plexiglass. I sketched it to look a bit like a real double hung but it aint. Carpenter buddy says its basically a cabinet door with plexiglass in it. I will add a piece of plexiglass to the interior to get that thermopane action.

cost was 13,000-15,000 including some labor help. rough cut lumber saved us thousands and it is behaving very well as it is drying out. Foundation is a pressure treated built up beam on top of crushed stone. no frost heave noticed yet..

We set up the main piping in the boiler building and this greenhouse in Tennessee last August. It will be getting root zone heating plus radiators along the wall. We also installed LP gas fired Modines for redundancy as the owner is going to grow tropical fruit trees in the building. Banana, mango, orange, lemon trees ....They will be direct planted so the soil needs to be kept at a minimum of 55* or according to him damage can be done to the trees. There will probably be a layer of tube at about 2' below grade and another at about 6". The radiators will actually do the bulk of the space heating.

Wish there was some way to "bottle" the heat that was in that building when we were doing the work. It was impossible to work in there at anything past noon each day. 108* to 112* at floor level. 10 feet up where we were hanging the gas line is was above 120* after noon.

Heaterman, thats a good ride in the morning from Michigan isn't it? But seriously, do you normally have travel jobs that far out?