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Heating a grow room

Discussion in 'Grow Room Design & Setup' started by Doctor Pot, Oct 9, 2008.

    Doctor Pot

    Doctor Pot Well-Known Member

    As you all are aware, it will soon become winter in the northern hemisphere, and my attic where I do all my growing is not heated. I'd like to heat it, but I'm debating how to do that.

    First of all, I need to insulate it, but that shouldn't be hard. The attic is drafty though, and will probably still be drafty even after it's insulated. The lights will of course add some heat, but there will need to be more heat after it's turned off.

    My choices thus far appear to be as follows:

    • Natural gas
    • Propane
    • Kerosene
    • Electric
    Natural gas would be my first choice, except I would need to run a line from the basement to the attic. Not impossible, but it would need to stretch 25-30 feet and be flexible enough to bend around pipes and through floorboards. The people at the hardware store told me that gas lines should be black steel. This is not flexible at all and would be almost impossible to run up to my attic. However, most of the gas line in my house appears to be copper, so I thought I'd be able to use that. Copper line is flexible, but supposedly it's hard to add the right ends to. I might need someone to do that for me, but I definitely don't want some plumber installing a gas line in my grow room! Maybe I could have a plumber do the ends, and then install the line myself. It's too bad they don't make flexible gas line. Unless they do and I just don't know about it.

    Propane would eliminate the need for running a gas line to the attic, but I'm not sure how long a tank would last. If it ran out on a cold night, my plants could all freeze. I'm not sure if it would be much more expensive than gas as well.

    I could borrow a kerosene heater from my dad, but I don't like the idea of using one in my attic. I know they're a fire hazard, or at least more so than my other options.

    Electric heat is expensive and I'd have to run a new line up to the attic if I was going to use it. It's safe, but doesn't have the output to keep a room warm if it's really cold. Plus I was kind of hoping to get some elevated CO2 levels from the combustion.

    Right now, I'm thinking I should just work on insulating my attic. When it starts getting really cold, I'll get one of those ventless heaters that can run on either propane or gas. Then I'll hook it up to the propane tank from my grill. If I find I'm refilling it twice a week, I'll look into natural gas. Anyone have experience with this sort of thing?

    BongJuice Well-Known Member

    Just get one of these and hook it up to a propane tank.
    You could probably get away with one tank lasting you
    about a week if you keep it on low.

    Doctor Pot

    Doctor Pot Well-Known Member

    Thanks for the tip! I was looking at a very similar heater at the hardware store today. It was 10,000 BTU and could hook up to either gas or propane. My first impression is that the grill tanks aren't very economical and may even be more expensive than electricity, so I'm looking into this. I'm thinking I may put a little electric heater up there too. Maybe I could rig it so it's only on when the lights are off, so it could make up for the heating effect of the lights.

    BongJuice Well-Known Member

    I don't what your paying per kilowatt/hour.
    Let's say your paying .08 cent's per.
    It's gonna get cold up there if there's no heat ducts up there.
    So you'll probably have to have it on all the time
    The average electrical heater uses 1500 watts.
    So now your at .12 cents per hour
    multiplied by 24 hours equals...$2.88/day
    Now multiply $2.88 into 30 days in a month....$86.40

    A filled propane tank usually goes for about $17/tank
    Multiply that by 4 weeks and you get.....$68
    Those propane heaters are way more efficient
    than an electrical heater.
    Doctor Pot

    Doctor Pot Well-Known Member

    I did the math using BTU. Electricity is 3140 BTU/kwh and costs $0.15/kwh. Propane is 93,000 BTU/gallon. One of those 20 lb tanks for barbecue grills holds 4.73 gallons, and costs $20 at the hardware store. Doing the math, and solving for dollars per million BTU yields:

    Propane: $45 / million BTU
    Electricity: $48 / million BTU

    Of course, this assumes 100% efficiency for both, and I'm pretty sure electricity is more efficient. My next step is to see if I can get a better deal on propane anywhere else. $4.22 a gallon seems really steep for propane.

    I looked at a new kerosene heater at Home Depot:

    DuraHeat Convection Kerosene Heater - DH2304 at The Home Depot

    The first review says "Light up save money and enjoy." Perhaps a sign? :mrgreen: The only thing is, it doesn't seem like there is any way to have this thing controlled by a thermostat, which is very important to me. Some of the reviews warn about getting too hot too. My attic isn't that big that it would need to be heated that much.

    AKDrifter Well-Known Member

    I am working an attic grow and my temps are dropping as well. I am using a grow tent and stealing fresh air from the laundry room below. My house is always between 74-79F, with my intake fan on a variable speed controll I can keep track of temps in the tent. it is only 40"x40"x6.5' so this is easy to heat.
    My 600W is cooled seperately and the exhaust from that runs through an insulated duct into my garage/workshop which is insulated. I rigged that today. I figure for the cost of a length of insulated duct ,what the hell maybe it will knock the chill out of my workshop this winter.

    hobo80 Well-Known Member

    I have experienced his before. What I did was keep the door to my attic open, the heat from my house would naturally rise and warm things up. Also, if you're exhausting the heat from your lamp, you could stop doing that and it would be warmer. When you're flowering, keep the lights on during the night, helps with the cold, unless you're worried about the heat signature...

    Therion Well-Known Member

    If you're heating are ceiling vents, get up in the attic and rig you up some of the duct work to blow-off just a bit in your growspot.

    You can get the 8-inch dryer hose and tap into your heating system and run it where you want it. The hoses come in like 10-foot length at lowes and are about $12 a box.

    BongJuice Well-Known Member

    Your gonna do what you feel is best, no matter what we say.
    Trust me dude.....Propane is the safest, cleanest, and most efficient way to heat your grow area in the attic. Other than hooking up heating ducts to the attic.
    Kerosene has gone up in price in the last few years. If I'm not mistaken, I'm sure Kerosene is close to $4/Gallon. A Kerosene heater will burn through a gallon in just a matter of hours. You'll be spending hundreds of dollars a month in Kerosene. Plus, Kerosene will smell like someone was running a truck engine in your attic, it may even harm your plants.

    An electrical heater is probably the #1 cause for fires in a house. Plus, this electrical heater is not gonna be supervised 24/7. Which makes it even more risky. I wouldn't be able to sleep at night if I had an electrical heater on all the time in the attic.

    Those blue flame gas heaters have a thermostat on them.
    Seriously dude....you should really consider this method.

    I'd hate to see a fellow grower die from breathing in burned kerosene, or a fire.
    Doctor Pot likes this.
    Doctor Pot

    Doctor Pot Well-Known Member

    Even if kerosene is $4 a gallon, at the price I'm seeing for propane, it's $4.22 a gallon. And propane has a lower volumetric heat of combustion. Don't worry though, I won't go with kerosene. It's virtually impossible to use kerosene heat with a thermostat. They also tend to have puny 1-gallon tanks that run out after at most 12 hours.

    Electric heaters aren't really a fire hazard unless your wiring is shitty. Unfortunately, the wiring in the attic is indeed quite shitty. However, there is another line that runs up there that was installed quite recently for the smoke detector system, and I could easily install a new outlet there.

    Propane seems one of the better solutions, but the instructions for the heaters state that they'll run for a day or two tops on a 20 pound propane tank. I also asked a guy who refills propane tanks and he said the cost for propane has skyrocketed over the summer. So $20 a tank is about as good as I'll get, and running to the gas station every other day to get a new tank seems like too much money and effort.

    However, I looked into it some more and copper tubing is approved for natural gas lines in at least the state I live in. It's only been approved since the eighties, which could explain why a few contractors I talked to had the vague notion that it's not something you should do. I guess before then, the additive they put in the gas so you could smell it would corrode copper, but now that's no longer the case. I talked to another contractor today who said there isn't a problem with copper. I've installed gas line before with no problem, so now I'm thinking this is something I could do.

    eric1313 Active Member

    you could always use the heat from your house to heat the attic no?
    Doctor Pot

    Doctor Pot Well-Known Member

    The attic is only connected to my bedroom, and my bedroom barely gets any heat as it is. I'm used to sleeping in a bedroom that water will freeze in overnight, so this doesn't bother me but I think the plants might have something to say about that. There aren't any ducts that run near that attic to channel heat from either.

    Where I live, it gets COLD in the winter. Insulation will help, but I do think I need a real heat source up there.

    vangraffe Active Member

    Try living in the UK - we pay 21pence (42 cents) per kwh

    I'm moving near you...soon


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