Safe heat for greenhouse?

[Lucinda Brown]

Can anyone out there help me to decide on the best way to heat my new greenhouse? My hubby says propane heaters,but I'm not sure how safe these are for orchids. Whether to vent them or not,or forget them! Electric ones seem maybe safer to me but perhaps pricier to run. Is a propane heater safe and if so,vented or not vented? Electric a better choice? Help! I need to purchase one soon,as we are almost done building it and nights are already dropping into 40's occasionally. Can anyone help me with this one. It's my first greenhouse,although I've worked in many. We are trying to avoid natural gas because it is so costly here. Any help appreciated. Thanks,ahead of time!

[Cynthia, Prescott, AZ]

Wow, my propane is much more expensive than the local natural gas, but the natural gas line will probably never get this high up the mountain/hill. Wish it would.

Always, always use a vented heater. Propane is OK. My back up heater is a propane heater, a Southern Burner, which uses no electricity, only batteries for the thermostat. The calculation for cost came out about equivalent or better for electricity when we allowed for a good percentage of the heat going up the vent pipe.

If you use an electric heater, be prepared to have a 220V or two 110V feed lines, as you can only run one 1500 watt heater on a single 110V circuit breaker. In my 8' X 12' GH, I have to use a second 1500 watt heater to keep the temp up to 61F when our outside temp goes down to 13F. Cynthia

[Lucinda Brown]

Thanks Cynthia, My Hubby was worried about the electrical cost, I was worried about the propane running out in the middle of the night. I think after hearing from you, I'll go with vented propane heat and have a backup electrical heater so I can sleep in peace . THANK YOU,THANK,THANK YOU!

[Cynthia, Prescott, AZ]

If you really want to sleep well, get a Thermalarm.
http://www.aaagreenhouse.com/alarmmonitoringsystems.htm
I hooked one up with a few miscelaneous things from Radio Shack, instead of buying the kit. I test it every fall and mid winter. I also have an Oregon Scientific wireless temp & humidity system that reads out in the house, but the built in alarm is totally untrustworthy. Every time it gets really cold, the alarmed channel goes into never/never land. I can get it to work again if I want to see what the temp and humidity is, but this does me no good if I am sound asleep and something goes wrong in the GH while the system is not working. But it is great to just look up from my computer to see the info. I caught an open door (humidity too low), and the fact that I left one of my heaters unplugged (temp just a couple of degrees lower than expected). Cynthia