Best Options & Considerations for a 120v Electric Heater?

[Rivka]

Although i will give my specs in a sec, i think this is a useful general discussion for any folks looking to heat and that don't have access to Natural Gas or a 220/240v power source.

So personally I'm heating a 4x10 lean to greenhouse that has the 10ft side "leaned" over a wall with the sliding glass door to a heated room on my house and actually has another 4ft wall against another side of the house, the house is brick. Mine has a surface area of 168sqft and a volume of around 240 cubic feet with 4mm twin wall poly. I am also looking into secondary wall insulation. I'm in a 7a zone, so it can get down into the teens, I have intermediate orchids for the most part so will aim to keep thing over 60 at night if I can. I do plan for a back up propane heater for power outages that are an annual thing around here and my collection is small enough that i can drag everything inside if we have a truly cataclysmic winter. I will have a humidifier, it gets wicked dry here in winter.

My math on the calculation sites has me needing between 8k and 11k BTU depending on who I ask and one place translates that to 2 Kw electric

sites i found useful to figure those sizes and amounts out were:
Greenhouse Surface Area Calculators
and
Greenhouse Heater BTU Calculator
They had the best info to figure out all the details, but their overall numbers were lower than other simpler sites I calculated at.

General questions:

1. How do the various types of heaters (IR, Ceramic, Forced Air) compare when it comes to efficient heating, affects on energy bills in models with similar heating capacity?
   
2. I know in many cases you get what you pay for, but I also know that things marketed to already costly hobbies tend to have a "passion tax" markup on them. What are folks' feeling about some of the more costly heaters over the 70$ models that are everywhere? What are you getting for this sometime huge price difference? This is assuming that we are all talking about heaters that are sold as outside and/or greenhouse heaters in some way, not cheep-o desk heaters. a good example of these two types are here: Charley's Best 120-volt Heater vs 120v Portable Heater both these are very similar on Amps, Watts and translated BTU's
   
3. Heat that is possibly more or less healthy for plants and/ or people? do any of these heater put out gasses as a result of their tech that bothers orchids?
   
4. Is there a standard for translating BTU requirements for a given space to Watts? or does this vary with the type of heater tech used?

   Here you go: 1 watt equals 3.4 BTU/hr Watts to BTU conversion calculator Thanks David!

5. Brands folks have consistently liked or had problems with?
   
6. other consideration that i need to think about with heaters that i haven't mentioned?

[DavidCampen]

My math on the calculation sites has me needing between 8k and 11k BTU depending on who I ask and one place translates that to 2 Kw electric

The translation is between watts and BTU/hr (BTU per hour). 1 watt equals 3.4 BTU/hr.
Watts to BTU conversion calculator

So a 1000 watt heater puts out 3,400 BTU/hr.

I like the oil filled electric heaters that look like a steam radiator since these have some thermal mass that helps reduce temperature variations. Of course, if you have an electric heater placed in the greenhouse in a location where it can be touched then you will want it to be on a GFCI protected outlet.

The type of electric heaters that I use:
Delonghi - Oil Filled Radiators

Last winter I used these heaters with their integral thermostat but this is not all that accurate so this year I will be using an external thermostat:
J&D Single Stage Thermostat - Heating Controls | Greenhouse Megastore
I do my own electrical wiring but I imagine that you would want one that comes prewired.

[Rivka]

thank you that is a very helpful site! i also soo that my iphone has a app on it that does BTU's as well, never thought to look if it had that type of measurements. I will add the link to the first post for other to notice more.

and yeah i have a external GFCI protected outlet to use and was going to look into a cover that closed when power cords were plugged in since the cover that is on it now only closes when nothing is plugged in.

i have a oil filled heater asa supplemental heater in my basement family room and do like it for how quiet and stable heat it is, hadn't thought of one like that, will look into them, do you have a favorite outdoor version? i guess since i will always have some sort of fan moving air any what, the heater itself does not need a fan to move the heat around?

[DavidCampen]

I have circulation fans that provide significant air movement so I don't see any need for the heater to have a fan. I use just a basic Delonghi oil filled electric heater. Mine have timers but I don't use that.

and yeah i have a external GFCI protected outlet to use and was going to look into a cover that closed when power cords were plugged in since the cover that is on it now only closes when nothing is plugged in.

They call those "in use covers" and I have them on all the outlets in the orchid room.

[Rivka]

is your heater rated for outside use? do you feel like that is something that is important to have, i thought it may be because of moisture levels. i plan in being neat with my watering, always had since they are usually indoors, and of course a proper outlet is a must as we have already said.

thanks for the search term on the covers.

what do folks think of these floor mat heaters? Amazon.com: Indus-Tool FWB 16-by-36-Inch Foot-Warmer Mat: Home & Kitchen they would actually fit completely inside and cover each of my shelves, costly, but wow root heat! woohoo, specially nice with my S/H. in genral what do folks thing of them vs seedling mats like:Amazon.com: Growers Supply Company GSHM 9-by-19-1/2-Inch Small Seedling Heat Mat: Patio, Lawn & Garden is there one reason to really go for one over the other, seems like the floor one puts out more heat, could it actually put out too much?
are the seedling mats ok to rally have in standing water?
(Ray can you beat these prices is i need maybe 4 of the large ones?)

[DavidCampen]

AFAIK the Delonghi oil-filled electric heaters are not intended for outdoor use and doing so would be entirely at your own risk. That said, I find that they work fine in my orchid room. As always, they should be connect to power only via a GFCI outlet.

[DavidCampen]

For supplemental and emergency heat I use an older model of this Coleman catalytic heater.
Coleman - BlackCat Perfectemp Catalytic Heater

Last year I used the one-pound propane bottles but that gets expensive. This year I have run a propane line into the orchid room that I will feed from a 20 lb propane tank that is outside and I will attach the Coleman heater to this. This is a completely unapproved use of these heaters.