propane heater for greenhouse

RichR · Post by **RichR** » Fri Sep 09, 2011 2:30 am

Has anyone used a forced-air propane heater for their greenhouse? People use them in workshops and garages so it seems like they would be fine for plants. My greenhouse is not airtight so I think there wouldn't be a problem with oxygen depletion. (Don't plants use CO2 anyway?)

*Barracuda_52* · Post by ***Barracuda_52*** » Fri Sep 09, 2011 4:07 am

Im gona be using a ventless propane heater next winter. This winter since this is a new GH and we remodified it alittle to make sure it can with stand our snow loads we are just gona see how it does this winter if she passes with flying colors then next winter im gona use solar pool cover over the whole cacti GH and have a ventless propane heater going to keep it warm enough inside to leave my cacti and succulents out all yr round.. But for now on the cold nights we have been having, i use a small electric heater.. All my tropicals in the tropicals GH come in for the winter no heater in that GH.

Harriet · Post by **Harriet** » Fri Sep 09, 2011 12:05 pm

Just be careful. I know things change and are safer now, but years ago a friend was tending his (commercial) greenhouse during an unusually cold snap... went to sleep (or passed out???) and never woke up. I suppose Carbon Monoxide sniffers are out there now for just that kind of thing.

JeffWhiteDevil · Post by **JeffWhiteDevil** » Fri Sep 09, 2011 7:51 pm

I wouldn't use a ventless heater in a greenhouse.

Ventless heaters create great amounts of moisture in the air and this may become an issue the longer it runs in very cold weather. In the dry southwest it may not be so much of an issue. Vented heaters cost more but are better in the long run. Spend the money and go with a vented heater and avoid the whole mess.

iann · Post by **iann** » Fri Sep 09, 2011 8:23 pm

Ventless heaters have been standard issue in the UK for decades. However the issue about moisture is a valid one, as if we don't have enough humidity in the winter here. There are other potential problems, although oxygen depletion wouldn't be high on the list. More than one person has coated their collection in soot, and of course the fuel supply can run out.

Electricity has become preferred now. There is little or now cost benefit to fuel-based heating now (unless you can use mains supply natural gas), electric heaters have been widely and cheaply available, they are easy to drive from a thermostat, and you get the instant bonus of a fan.

Think about two heat sources even if you only use one of them most of the time. Ideally have the other one configured to kick in if it gets too cold, so it will automatically take over if the first one fails.

RichR · Post by **RichR** » Fri Sep 09, 2011 9:11 pm

As always,thanks to everyone who replied.I will most likely go with electric.

Regarding winter humidity, I take it that it is worse than summer humidity? My central Texas winters tend to have much lower humidity than summers do.

iann · Post by **iann** » Fri Sep 09, 2011 10:48 pm

Winter humidity is a bigger problem because the greenhouse will be ventilated less, solar heating will be lower, and nights will be colder. You will get condensation, it will be slow to clear, or just the lack of warmth and air movement will encourage fungi on the plants. Remember that even in winter a cactus is giving off moisture all the time and you need to remove it.

Of course if you heat enough in cold weather then the relative humidity goes way down, but it isn't usually practical to supply that much heat to a greenhouse except using the sun.

vlani · Post by **vlani** » Sat Sep 10, 2011 3:22 am

I have installed one last winter, connected to a house line. Saves a bunch on utility bill compare to electric, but there is a initial investment. The cheapest one is about $500-600, and for me it has already paid for itself.

The one I have is forced air with vent. It is called "Hot Dawg" 30000 btu

*Barracuda_52* · Post by ***Barracuda_52*** » Sat Sep 10, 2011 5:18 am

Im stickin with a propane heater, i cant afford the stinkin electric bill for heating the GH all winter especialy here in northern MI where winters can be LOOOOONG and brutal.. Propane will run me far cheaper than the electric..

Valley Succulents · Post by **Valley Succulents** » Sat Oct 15, 2011 3:35 pm

I use a Hawtdog and they work great. Ventless sounds a little suspect. I'm sure they work but CO.2 is an unfriendly gas meaning that it won't expel you from the area with strong smell. You will just pass out. It also takes the place of oxygen in your blood stream so even if you are found in a timely manner your body is full of CO.2. Not good. The Hawtdog is made by Modine very nice little heater.

Post by **daiv** » Tue Oct 18, 2011 5:54 pm

Here is the exact heater that I use:

http://www.mrheater.com/product.aspx?catid=41&id=116

I only use it in early spring/late fall and run it just at night to stave off frosts. My greenhouse is way too drafty to do any sustained heating. I wouldn't want to run it for more than a dozen nights at most because it can be expensive.

It works for me since frosts can be sporadic and separated by many good days and nights and so I can wait until the cold is more consistent before bringing the plants in for the winter.