Propane Heating - Orchid Board

Bradfo69 · #1 07-31-2007, 09:39 AM

Doesn't appear as though many people visit this forum but I'll ask anyway. As you may have read, I'm a new greenhouse owner and working on setting it up. I'm making my considerations for heat. It's set up already with a 240v electric heater. I'm considering switching to propane.

It's a small 8 x 15 Sunglo and I'm guessing I need about 13,750 btu's. I'm finding most un-vented heaters are less expensive than vented but I know you need to be careful using un-vented with orchids. A manufacturer rep (who is familiar with greenhouses) claims the main issue is putting out excessive CO2 and water. The water vapor of course, causes condensation issues on the walls and the co2, while good for the plants, is excessive at night (when the heater is most frequently run) while the plants should be resting. I also understand the issue is ethylene gas but I've heard people used un-vented anyway. Same with kerosene, natural gas etc. What are peoples experiences? I'm thinking about something like a Comfort Glo blue flame heater.

littlefrog · #2 07-31-2007, 10:18 AM

I think there are a fair number of people visiting this forum, actually...

I heat with propane. I don't have the option for natural gas, and I'm not spending the money to heat 1500+ sq feet with electric. I haven't had any problems so far, except for spikes in propane prices last year.

The last thing you want to skimp on is heat. So, even though the vented heaters are more expensive, you shouldn't even consider the unvented option. I'm pretty sure the vented heaters are more efficient as well, so that will save you money. A difference of a hundred or even a few hundred dollars isn't worth the chance you will have a burner malfunction and kill yourself (carbon monoxide) or your orchids (ethylene).

The downside to vented heaters is that they require electric power to operate. You could get a backup unvented unit (some of which don't require electricity), or invest in a battery backup system that will run your heater for a few days in the case of emergency. I elected for the latter option.

kmcalpin · #3 10-08-2007, 04:24 PM

Ok so I am new this year to the greenhouse thing and moved into a house that has a greenhouse already in place, attached to the house. It has a propane heater. I am not sure if it's vented, do you have any idea how I can tell?? I think I have a clue in that since the heater has been on at nights for the past week, all of the flowers have died, a lot of the dendrobium leaves have turned yellowish green, and all of my my buds have died in spike. So. I don't think it's vented. Anyway.

I called the air people from our area, and they are backed up a week so can't send anyone out. Can I use an electrical space heater in the interim? Should I combine it with a cheap humdifier, like the kind you get at walmart? Do I have to buy a whole new vented propane heater or can someone just put a vent in the one I already have? This has been a horrible week for my orchids and me and I would appreciate any insight anyone has!!!

Thanks!
Kristin

littlefrog · #4 10-08-2007, 05:49 PM

Well, if it is vented there will be a chimney that goes to the outside and a fan that turns on when the burners are lit. If the unit is in the side of the greenhouse, it might vent outside. Look outside, if the unit comes through the wall and there is a vent on the outside, there is your answer.

I'd certainly have the unit serviced if it is behaving like you indicate. That just isn't safe, for you or your plants. You can use an electric heater if you need to, no reason not to. I wouldn't bother with a humidifier unless it feels really dry in there.

If it is an unvented unit to begin with, I'd replace it with a vented one. I don't think you can retrofit the vent, you will need a new heater. It is possible that yours is a vented unit and the ducts are plugged up, if you can find the ducts it is easy enough for you to check. Take the chimney apart and look through it with a flashlight. See if you can find a filter and change it if there is one.

But if you can't find an obvious reason that the furnace isn't working right, turn it off and don't turn it on again until it is serviced. Really, it isn't safe. People die from carbon monoxide poisoning every year, don't be a statistic.

OrchidTess · #5 10-08-2007, 06:58 PM

Brad, I have an 8x12 greenhouse and I heat with electric....Propane wasn't very much cheaper. (At least the last few years it wasn't) I am sure propane is a better option in larger greenhouses.
When it's really cold out I use the solar cover from my pool as an extra insulator.

Ross · #6 10-08-2007, 07:17 PM

Quote:

Originally Posted by OrchidTess

Brad, I have an 8x12 greenhouse and I heat with electric....Propane wasn't very much cheaper. (At least the last few years it wasn't) I am sure propane is a better option in larger greenhouses.
When it's really cold out I use the solar cover from my pool as an extra insulator.

Careful! There is a lot of difference between Maryland and Colorado for cost or BTUs. Also there may be a big difference between two locations on cost between electric and gas (propane or natural).

OrchidTess · #7 10-08-2007, 07:26 PM

Quote:

Originally Posted by rsfrid

Careful! There is a lot of difference between Maryland and Colorado for cost or BTUs. Also there may be a big difference between two locations on cost between electric and gas (propane or natural).

Yes, you're correct. But Brad, the originator of the post is from Delaware not far from me in Maryland. So I was sharing what worked for me.

stonedragonfarms · #8 10-08-2007, 10:29 PM

Hello
I also heat with propane; as Rob says, you should not skimp on heating capacity...I'd err on the side of having a furnace rated for more BTUs than you will most likely use, if for no other reason than you will not have to have it running at maximum output to heat the space. There are a few direct vented furnaces that do not require electricty to run (Southern Burner stoves come to mind, as do some of the newer model Orbis heaters), but most of them are insufficient for main sources of heat in larger greenhouses--I know that I would have had to install two Southern Burners for my set up. I'm not sure what everyone else is using, I have a Reznor that heats from overhead with forced air and am very happy with it, as an added bonus it takes up no floor space so I've not lost much in the way of growing space.
If you are considering furnaces, I would look at fuel efficiency and the way which the furnace is vented; mine has a horizontal power vent (which means less heat loss through the vent and better combustion in the long run), though there are myriad options out there. You may also want to consider whether or not you have to install a pig (propane tank)--if so, do you have sufficient room for its setback from the structure? A further point that I mulled over for a long time was whether the furnace I purchased would be able to be locally serviced should the need arise--I am more than willing to scout out a good deal on the internet, but should it fail and not be servicable in the area, I would have rather spent a bit more for something that can be (which is what I ended up doing...call a local stove supply house and see if they have any recommendations)
Just my two cents.
AP

Bradfo69 · #9 10-09-2007, 08:19 AM

Lot's of good information. Thanks all. A member of my society is a contractor, (with a greenhouse) and is certified to run natural gas. He is suggesting natural gas and came over to look at the greenhouse and is proposing an unvented 10,000 btu unit, with me digging a trench from the house to the greenhouse to run underground pipe. Thank goodness we've had an indian summer and I've been able to delay a decision. More people my way have suggested the natural gas option as well because propane delivery is not always assured on time and natural gas is "always on" - and doesn't necessarily require electricity.

Friggin plants.....

goodgollymissmolly · #10 10-09-2007, 08:30 AM

I would not even consider an unvented heater. The fuel type is immaterial. You are going to create an enormous amout of water vapor which will condense on the walls and drip everywhere. More importantly, the amount of carbon dioxide, carbon monoxide, and various hydrocarbon fragments are downright dangerous to you.

This is even worse in a confined greenhouse such as you describe. You'll walk into it one day and get carried out in a coffin. Please do not put in an unvented heater.

Jim