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Heating the greenhosue...

adnedarn

I'm growing CPs in the Desert of Tucson, Az
Admin
Hello- I have a greenhouse that is said to need approx 12,000 BTU for heating. I only have 110v in the g/h and no natural gas. I see that natural gas heaters can also come as propane... But is this really a okay way to go? I don't want to be chainging tanks daily or anything. The problem with running 220v or natural gas- is permits and such... I guess if they are definatly the "best" way to go I can look into it... But I'd rather look into using propane if anyone has anything to say
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Thanks!
Andrew
 
Considering heating and BTU's Propane /gal contains approx 93,000 BTU's Kerosene contains 240,000BTU's /gal , Oil about 150,000 /gal, etc etc. I wouldn't do electricity unless u get it for cheap. For conversions from NG to LP, its completely safe, buy a 100 pounder (53 gallon) propane tank for your fuel, you may have to refillit 1 time every 2 weeks depending on what you lowest winter temperatures are. (What are they?) So, on propane you'd use approx. .13 of a gallon for 1 hour of heating..id say thats pretty darn good.
 
We barely ever reach freezing... So I'd say setting 30f for my low is safe. Is there a problem with over sizing a heater? (Like oversizing ac is a problem....) 53 gallons every 2 weeks... that sounds expensive.
 
Why is oversizing an AC a problem? My brother in law said an AC guy told him use a half ton larger unit on the outside than the inside unit and it cools better. To me it would use less because your pumping more cold for less space so it would have to run less. I figure the same for heating. The more you have the faster it can heat the less it has to run. Propane is safe to use. It just needs to be properly installed. I use electric personaly, and I want to go to 220V but need to run it. I will get my brother in law to do it. 220 is more efficient than 110.
 
One of the benifits of running AC is dehumidifying... If the AC unit is too big... The air doesn't pass over the coils as much as it "should" so the air ends up staying humid... thus not feeling as cool as it could inside your house. That's the main reason. Thanks for calling Whirlpool/Kitchinaid. I hope you have a wonderfull day! (Yah, I worked tech support for them one time for a few years and that's what they said... LOL)

As far as electricity goes... I'm just using an extention cord for my 110v already.. So getting 220 out there would be quite a feat...
 
Not really. Its expencive for the lines, but not that dificult to set up. Also Since your running an extention cord how many heaters and what size wire are you using? I have 2 1000 watt milkhouse heaters and running a 12 gauge extention cord. I have it hard wired into boxes on either end because the plugs got hot so now I have boxes with standard plugs to relieve the heat. I was running a 3 way splitter and one of those ends just toatly melted and was singed. I;m glad it didn't start a fire. But with the normal electrical box that now has 4 plugs everything is cosher for the time being. I will be hard wiring my GH in after the rebuild. I am hoping to run 220 out there because I want to power my shed too. Wire is just pricey. Then you need to have an extra box off your main box for it too, but I already have that from my hot tub. There is already 220 run to it and I just came off it with a 110 breaker for the GH at the moment.

Propane is said to put off more heat than electric, but I think its more expencive to run. I get by with 2 1000 wat milkhouse heaters and it keeps my GH around 55 to 60 depending how cold it is outside. The key is to have a fan circulating the heat around the GH. I might have to add another heater this winter because of the expansion, but I might set the GH up to have a cold zone for thigns that like to get chilly. I duno yet the GH is not built. Hopefully will get started this week. Dang it sucks having to rely on help!!!
 
Right now I don't have any heaters... This is a new g/h since this spring. I think my extention cord is a 10 gauge.. it's a monster. In my smaller g/h i had a 1500watt oil filled radiator style.. and I dont' think it did very good in there.. so I really don't think it'll even dent the new house.. That's why i'm looking for somethign better.
 
Dang a 10 gauge!!! I didn't know they made those. Any who. Hard wire it into a socket. Black to back and white to white because plugs notoriously get hot! Then on the end in the GH get yourself a dual socket box and hard wire the other end into the 4 plugs and mount it someplace in the GH. Get yourself one of those fancy new covers that keep the plugs covered while things are plugged in. Then go to walmart or lowes and get the 1000 watt milkhouse heaters. They have a high and low setting. You are going to need to get thermestats for them too though because the ones that are built into the heaters STINK. Your 10 guage wire will be able to handle current drawn from both heaters. How big is your GH? Mine has a base of 12x12 and the peak is 9 foot tall and the two I have heated it well enough to keep my orchids alive. If you only plan on keeping it above 30 then you need to bring in your orchids because those Catts will not survive that cold of temps.

Your absolutely correct about the oil filled heaters. They stink! I tried that first and took it back. Thats when I got the milkhouse heaters from lowes. They cost me only around 17 dollars each and have lasted 2 years so far. Again I built my own thermastat to use with them because the ones that come built in are unreliable!!
 
Did some quick calculations at 12,000 btu/hr.

Will take 3,500watts from an electric heater.  (assuming 3,143btu per Kwatt hour)
Take your kwatt/hr rate and multiply by 3.5 to figure how much it would cost to run electric.  So for example if your electric rate is 15cents/kwhour it would cost 52.5cents/hr to heat

For fuels/gallon
Price/gallon divided by btu/gallon multiply by btu/hour needed = cost/hour

Compare to propane at 91,000btu/gallon and $2.25 gallon = 30cents/hr burning 12,000 btu.. the only problem is you will have to burn 15,000 roughly if your heater is 80% efficient which brings the cost to 37cents/hour

Compare to kerosene (which is about 130,000 btu/gallon)
or to #6 fuel oil which is 150,000 btu/gallon
Again figure you need to burn about 15,000 btu to get 12,000 btu out.
Take the cost/gallon divide by btu/gallon then multiply by 15,000
so if kerosene is 2.50gallon it would cost $29cents/hour

I don't know the prices on fuels currently but you can find that out locally and plug in the numbers.  Your electric costs and fuel rates can vary considerably locally anyway.

Now for my 2copper:
Electric is probably the simplest but cost the most!

Propane is fairly simple to install and clean and easy to maintain.  Can get a bit pricey though if you need to have a vented heater installed as it will take a plumber to do the venting.  The propane company can install a tank outside and run the pipe to the heater once installed.

kerosene/fuel oil most economical but need a fuel tank and can be messy and the equipment is more dependent on regular maintance.  Also will need to have the heater vented. The heaters generally are more expensive than gas/propane heaters because they are more compex.  So while it is cheaper to run the cash outlay initially is higher.

Note I did not compare natural gas since you don't have it.. for those that do however, natural gas usually comes in very favorably on the cost analysis. The benefits of simple to install equipment and clean easy to use.. but again have to be vented and running the gas line is more complex/work.

tony
 
  • #10
Well, not around here.  Natural gass is more expencive when you figure in all the line usage fees and all that that we have in GA.  I was paying a bill of around 60 bucks a month JUST FOR MY HOT WATER HEATER and gas grill that I has on nat gas.  You don;t want to use Kerosine with plants because of the fumes even though its vented it is not normaly recomended from what I read about GH and I have been told to stay away from it for orchids so I would assume the same goes for CPs.  So that leave propane or electric in my situation.  Of course everyone is different as they are in different parts of the country.  You can also store heat in your GH yby using water barrels to collect solar heat during the day and disurse it at night.  It reduces need slightly.  When I get a larger GH I am talking about a large GH then I will consider propane, but for right now electric is what I am going with.  Possibly a 220 heater in the future.  Good luck Andrew.  I hope you figure something out.
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  • #11
Back when I was a kid and my mother had a GH, we used a propane(I guess) space heater and an automatic vent-opener thingy.
 
  • #12
Kerosene is fine, just be sure it is vented, I've been using it for about 4 years now.
 
  • #13
Nepg- can you give an example of that type of heater?
Oh and Orchid guy... there is a warning one one site to use vented with orchids... That goes for natgas and propane too. The quote was:
the direct wall vent draws outside air to the sealed combustion chamber and vents exhaust gases directly outside. This feature is highly recommended if you grow orchids.
 
  • #14
Thats what I have, a direct vent, sealed combustion heater. Its like this one, peak capacity is 43,000 BTUH, but it is variable heat, so it will adjust itself (93% gross efficiency, 88% net)

Right here
Mine is the first one, Monitor 441 Heaters
 
  • #15
Sorry for jumping in here, but was wondering what people use for a backup heater when the power goes out?
 
  • #16
Well, if your using propane, the heater will run withouth electricity. I on the other hand have a couple of small propane tanks that I connect to a fish fryer and put on a pot of water to boil inside the GH. I have to open up to vent it sometimes to clear the fumes, but in am emergency it works in a pinch. If I am not home when the power goes out I am screwed. When I get established as a nurse and get the big GHes I want I plan on having a whole house emergency generator as backup with a large propane tank sitting for it too. This is if I decide to stick with electric. I may have decided to go with propane when I get the large GHes.

<---thinking nursery space for the large GHes. LOL
 
  • #17
I have a small space propane heater on extended loan! Anyways, I'm usually home, except now for being in college but the plants are taken care of. Anywho, in winter, I have a remote alarm and this alerts me of the temperature inside the greenhouse. if it goes off, power goes out, I go over and start this little baby up, it'll run a long while on a little tank of LP. It also has a hydro-thermic sensory bulb so it can kick on and off as needed, its not vented, but remember its an emergency heater! I also have a 2nd gas heater I just recently aquired, a LP direct vent wall furnace, given to me, just needed to be cleaned and have a thermostat hooked up to it. That WILL run without electricity, but the fan will nto function, still gives off heater however, and thats what counts.
 
  • #18
[b said:
Quote[/b] (JB_OrchidGuy @ Sep. 18 2006,8:29)]Well, not around here.  Natural gass is more expencive when you figure in all the line usage fees and all that that we have in GA.  I was paying a bill of around 60 bucks a month JUST FOR MY HOT WATER HEATER and gas grill that I has on nat gas.  
I am really quite suprised at that. The total bill including all other fees besides the cost of the gas was $60, or just the cost for the gas?? Are line usage fees based on the amount of gas used or just a fee for the account?

I don't have natural gas so am not familiar with the fees. I think that when people are comparing gas vs electric etc they are comparing just the cost for the fuel as they already have an account for electric/gas and adding a greenhouse heater doesn't change any flat account fees for the extra fuel usage.
 
  • #19
Thanks all for your imput. I think I'm going to stick with propane. Here are the 2 I'm most stuck between... 10,500 BTU for $547.01 delivered and 17,500 BTU for $656.39 delivered. I think the first could keep up. And the second is a overkill... Supplementing on the few very cold nights with a electric heater is definatly doable... Will I be wasting more money than nessasary running the larger BTU unit? Or will it really use the same amount of gas, just run less? It seems if you calculate the cost per BTU on those 2 units... The larger one is the "more bang for the buck" the first unit costs approx $.052 per BTU and the second $.037 per BTU... (Per BTU the unit puts out.. Not the cost of gas per any time frame to use...) Does this make any sense?!!! lol.. So what's your views from here?

I'm also waiting to hear if my wife can get these in from her work (lowes) since I'm in AZ they don't carry anything like this LOL But their website shows some non vented ones that she thinks she can order. They are easily 1/4-1/5 the cost of the vented ones I'm looking at. But still want the above info so I know where to go with the BTU rating. One more question... If I have a choice... Do I want to go with open flame, or infared? (flame heats air which heats items in room, infared heats items in room as they heat the air... as I read it.)
THANKS!
Andrew
 
  • #20
Tony the 60 bucks was the entire bill. I wasn't using that much gas. Granted I did alot of grilling, but a propane tank lasts me for well over a month so I wouldn't think running the Natural gas grill would use that much more. The bill had a line usage fee, and a 25 dollar customer service fee and this fee and that fee. It just got that crazy when they deregulated the gas indistry in GA and started to let other companies come in and do gas service.

Andrew if I were you and the 110 dollar cost difference wasn;t a big issue I would go with the larger unit. Just because I think it will be more efficient in heating and if you ever did expand you would already have the heater. I think its just like a 110 heater vs a 220 heater. The 220 heater uses less power and heats faster than a 110 heater does. I know its compairing apples to oranges, but I like to have a little more than needed for the Just in case facter. Plus not to mention I think it may cost you less to run because I think it would run less to get the required heat faster. I would also use open flame units instead of the infrared unit. You want the air to be warmed and not the plants. Thats why you want to make sure you still have fans going to spread the warmth around the GH. Another thing you could do to reduce shock to the plants if a catastrofic failure happens is run your plants on the dryer side during the winter if they can stand it. According to a grower at Ratcliff orchids. If temps get cold a dry plant is a happy plant, but a wet plant is a cold plant. Ratcliffe orchids grows mainly Paphs. And paphs like to stay damp, but during the winter he runs them on the dryer side and normaly paphs don;t like to go down below 50 to 55, but with them being on the dry side they can take down into the 40s without rotting or dying because a dry plant is not a cold plant aqqording to this grower. Just my thoughts on the subject.
 
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