Need suggestions

I am looking for ideas on how to heat and humidify a greenhouse. Any suggestions would be greatly appreciated.

Thankyou!

Here are a couple of heating links that might be helpful: http://www.engr.uga.edu/service/extension/publications/extengrhndbk/Greenhouses%20and%20Plant%20Growing%20Facilities/heating%20requirements.pdf
http://www.ext.vt.edu/pubs/greenhouse/430-101/430-101.html#L2

More specific answers about heating could be given if we had a little more information. First, what do you want to grow? How will you use the greenhouse? Second, what kind of greenhouse do you have? Third, what is your climate? (We can guess on the climate based on the fact that you live in Texas.)

People do all kinds of things for heat in the greenhouse, from propane to corn stoves to kerosene to electric to nat gas to nothing at all (solar/thermal techniques).

Humidity is somewhat easier to manage with either a mist system or fogger. There are a number of variations on these themes and you can spend a lot or a little of $.

Welcome to DG and the Greenhouse forum.

SB

you sound like a professor SB!!!

Yardqueen-Stressbaby is the best-he will give you the most considered reply of us all.

My greenhouse is heated with a Torpedo kerosene heater with an inline thermostat. Here is a photo of the inside.

Karin ~~~~~~~~~~~~~~~

I don't have my greenhouse yet, but it will be used to winter over plants that i have been bringing into the house into a "plant room" that really doesn't have enough light. They survive, but do not thrive. I also will start seedlings for annual flowers in my greenhouse. I think I have attached a picture of what my greenhouse will probably be like. I have never done an attached picture so I don't really know what will show up. LOL Also, I live in Northeast Texas so the winter here aare a little colder than some parts of Texas. I think I am in 7a.


This message was edited Jul 1, 2006 9:33 AM

I can tell you what worked for me in Arizona. I didn't realize I was building the worlds biggest oven when I decided to build my GH! So, we installed an evap with a water source (float and water line) then we installed upducts (works with the evap and drawing out excess heat) I added misters and two circulating fans with those and when it wasn't exactly cool enough I put up cheap retractable blinds INSIDE the house. I finished it up with a thermostat that controls the fans and cooler. I'm sure I didn't do any of this right and i'm sure it cost way too much but i'm having the most fun now. Temps inside stay right around 92 during the hottest parts of the day 2-5.

OK, late fall, winter and spring use...let's play with these numbers a little bit...

Eyeballing that GH, let's say it's 4mm twinwall polycarb, 8' x 10' and a surface area of 292 square feet. Zone 7a minimum temp is 0*F. Using the standard heat calculator formula (Q=deltaT*A/R) and assuming a minumum temp of 55*F, you would need 11242 BTU of heat on the coldest nights of the year. You could use this figure to size your heater. Min temp of 60*F requires 12264 BTU.

Working backwards, and knowing that a typical 1500W electric heater puts out 5120 BTU, with two of these heaters you could keep this GH at or above 50*F on the coldest night of the year. Three of these heaters could theoretically keep you at 75*F.

Small electric heaters are available anywhere, cheap. You can also get single electric or gas heaters in this BTU range, you just have to shop around.

Here is a link to a heating calculator: http://www.littlegreenhouse.com/heat-calc.shtml

Remember that this calculation is for the extremes of temperature and will not reflect energy consumption and cost over the course of the winter. If you are interested in knowing costs (that is, average BTU/day, BTU/month, $/month) we can work that out, too. We would need to know your average winter temps.

Peppercrazyaz posted while I was typing and brought up the point I was also about to put in my post...you will still need to ventilate and cool this GH, even though only using it in the cooler months. A sunny day up to 50 or 60 and you'll be way, way warmer than that in this sized GH.

Hope this helps!

SB

Thanks to Stressbaby for also pointing out that I didn't read her first post correctly! ha I haven't tried to "HEAT" mine yet so just ignore the whole cooling thingie.

I'll be needing Stressbaby's advice this winter tho!

Here's the problem I have with electric space heaters. Several times my heater has gone out late in the day, and I needed some heat in there, so I put elec space heaters-which I think are rather costly to use, and the breakers kept breaking. I have a pretty good electrical panel in the 100' grhouse-I run a big fan all thru the day, but it couldn't run 2 heaters. If thats the way you are going to go-then I would look at the app usage you need and make sure you have it in there. Stressbaby-you have your calculator out?? :)

You betcha.

TL, you could have 200 amp service to the GH, but if the heaters are not plugged into properly sized circuits, you'll still trip the breakers.

1500W electric heater draws around 12.5 amps. You get one, and only one, on a 15 amp circuit, with room for little to nothing else. Even with this draw, you might occasionally trip a 15 amp breaker. Safer to go with a 20 amp circuit; this way you have a little wiggle room for a fan, radio, maybe a pump, whatever. You don't want to overload that circuit, because if breaker trips, it will do so in the middle of the night...not good.

I have three separate 20amp circuits for the outlets in my GH. And I have lots of outlets. Some people say too many. But I can plug in 3 separate electric heaters just about anywhere in my GH (if I want to) and still have capacity on each circuit for the HAF fans, lights, whatever.

Equil was kind of making fun of me the other day when I told her to let us know when she was ready to talk electrical... this is what I meant...locations and types of heaters/fans etc determine sizes of circuits, numbers and locations of outlets, gauge of wire... and so forth.

SB