Greenhouse heater

[tropicalb]

Guys...

This year, I built a small greenhouse in my backyard (11' wide X 20' long), and winter is upon us....I need to get some kind of heat in there, and have been looking at various options.

So far, I have found that the easiet way for me to do this would be to use one of the electric oil-filled radiator style heaters they have for sale at Wal-Mart (and I know that some brands of this style heater have been recalled..I'll steer away from those).

Anyone got any other suggestions? I would greatly appreciate your thoughts! I have to do this soon, as I'll lose a lot of plants if it drops below 40F in there.

[Bilbo]

Thats a fair sized space to heat.

I think electric must be better than oil especially if its fan operated and gives air movement.

As you know if oil is not well adjusted it can produce fumes.

Electric can be more easily controlled by thermostats and timers and you can use supplementary lighting as well.

If a greenhouse is close to the house then hot water (if gas central heating) through well insulated piping is another option.

OK elect is the more expensive I admit.

Regardez

Juan

[Bilbo]

Apologies (speed reading again!) I misread original question.

Sorry

Juan

[tropicalb]

Bilbo...

That was the other option for me...the front of the greenhouse is actually about 12 feet (and thru a wall) away from the water heater for my house, which is located in my garage...I'd have to get a plumber out here to sweat additional joints onto the heater intake and out-bound pipe ( i suck at using torches) to get the hot water out to the greenhouse. Cost-wise, I don't know if this is the best way or not to add heat to the greenhouse...

Thanks for your reply!

Any other suggestions folks?

[BS Man about Palms]

I've told a few folks about a simple solution I have thought of, but not fully implemted yet.   I am looking at using Halogen lights.  I have worked in front of and near enough to several over the years to know they put out a lot of heat.    I plan on using a "dusk to dawn" outdoor out let box I found at Lowes. (Primarilly for Christmas lights)  I then will hook a line volt t-stat in series that only turns them on if it hits 40-42 degrees or whatever......  Then again, I may let it get in the 30's... you bought the V. Splendida, not me !

My greenhouse is much smaller and probably this will work fine.  (I hope)

[Neofolis]

I would say it depends a lot on how much heat you want to create and how much that heat is likely to cost based on different fuel types.  I initially used electric convector heaters which worked perfectly well, were thermostatically controlled and very easy to get setup, but cost a fortune to run.  I then switched to a flueless gas heater which generates more heat for less money, but required me installing a gas pipe to the greenhouse.  The gas heater has other advantages for me in that it creates a small amount of humidity, whereas the electric heaters reduced humidity.  It is also controlled by a thermostat and doesn't suffer the problem of power cuts and there is never a break in the gas supply that I can recall.  On the down side, the heat doesn't circulate as well, but I have a fan to overcome this, although I will be getting another fan, as the existing one doesn't seem to do enough.  Also I needed to install a duct pipe from outside to ensure sufficient oxygen supply to the burner.

If you can extend your central heating system, this is likely to be the cheapest option in terms of running cost, but because the greenhouse will lose heat faster than the house does, radiators are not ideal as the provide a small influx of heat and rely on the heat being retained.  There are plinth heaters avialable which run on hot water from the central heating system, but are fan assisted and produce a little more usable heat, but you are then relying on a permanent supply of two separate power sources.

To sum up, I would say for ease of installation electric is the one to choose if you don't mind the running costs, but for a long term solution gas is cheaper to run, but make sure you have sufficient air circulation.

[tropicalb]

Bill...

I thought about the halogen lights too...they definitely put out enough heat to keep it over 50F in the greenhouse even on the chilliest of night here in SD County...but man...those suckers are gonna be EXPENSIVE to run...

and the versha isn't the only marginal plant I have in there...if i don't get heat soon, just like last year, my living room is gonna be a JUNGLE this winter!

Neofolis...

Thanks for all your input! My main concern is just keeping the temp up enough so that my marginal plants don't die...i have a few palms and a LOT of zamias that just won't tolerate temps below say about 45F....I may end up with just the radiator this year, and maybe make a permanent installation using heat from my water heater in the coming years...

[monkeyranch]

Here in the sierra foothills at 2000' el. I get 6 to 30 frosts a winter, night averages around 40' F, and a 27' F annual low.  Most cold weather follows clear days.  Thus I have found using a hot water heating system with a propane water heater and a solar collector loop to be efficient.  The heated water feeds to manifolds at the end of the greenhouse rows.  Radiant water tubing runs down the benches and back.  The containers lie on top.   The roots and the airspace are heated for better growth.  A company called TrueLeaf sells kits that are easy to assemble.  Their website isn't the clearest but it will show you the basic system parts.  They even have these water heating mats called Roll&Grow for benches or insulated ground.  I scored a free water heater from a guy upgrading to a flash unit.  More water mass(i.e. drums) helps store daytime sun for a good base temp.  Any solar energy supply store will have the solar water collector.  The radiant heat tubing is also available from heating/cooling suppliers, as well as some other parts.  You can get it all from Trueleaf or piece it together.  Anyhow with our cooler weather I still only go though about 20 gallons propane each winter.

[tropicalb]

THANKS for the info monkeyranch!

I'm definitely going to check into that option!

[BS Man about Palms]

(tropicalb @ Nov. 07 2006,09:01)

QUOTE

Bill...

and the versha isn't the only marginal plant I have in there...if i don't get heat soon, just like last year, my living room is gonna be a JUNGLE this winter!

Umm. Burt.........

while on the expedition for Dave, if you look in the background of post #19 of "Thank you all"....you'll note I need to be a little more concerned about heat in my greenhouse now too.    (silouette behind the red box)

Hey for $10.........

[tropicalb]

Bill...

can't make out what the plant it is....too dark..

also...i was in Home Depot checking out the cost of your halogen lite idea...around $50 gets you a dual lighting rig with 1200 watts of light / heat...i wonder how the plants would respond to the extra light during the night...

[BobbyinNY]

I have three separate greenhouses set up in my yard and I keep them at different temperatures. I use all electric heaters... This is the most expensive option but, by FAR the easiest. I have one HUGE greenhouse (I'll call the biosphere) 15x15x12ft high that I keep above 50f at all times - mostly for my tender tropicals (cocos, bananas, citrus, etc). For this one I ran a 220volt line for a DAYTON L5600 watt, 21,000btu electric heater that comes on when the temp drops below 50.. I have another Domehouse 6x9x8 that I use to overwinter my more hardy plants (P. roeb, Sagos, Saw Palmetto, etc) for that one I just use a simple 1500-watt space heater that comes on when the temp drops below 40f. , and the 3rd one I'll call the Palm-Scraper that I constructed to overwinter my Pytchosperma elegans. I have a small 1500watt space heater in there that comes on when the temps drop below 40.   All of these are on thermostats to control the temps. All of these are in mostly full-sun locations so that the daytime temps can get to around 70-75f when the sun is out. I also have 2 fans installed in each one of the houses on Timers that come on at 10am and go off at 4pm.  So far so good... Hope this helps...

[BS Man about Palms]

(tropicalb @ Nov. 13 2006,07:27)

QUOTE

Bill...

can't make out what the plant it is....too dark..

also...i was in Home Depot checking out the cost of your halogen lite idea...around $50 gets you a dual lighting rig with 1200 watts of light / heat...i wonder how the plants would respond to the extra light during the night...

Burt-----

I gave you that big clue....  

That is the silouette of a large 1 gal Vershafeltii Splendida.

I tried a quickie little experiment last night as it got a little cooler.

I had my remote thermostat in the greenhouse and I put my 500 watt halogen light in there at one end, roughly 4 feet from the t-stat. (OFF at first)  The light was at floor level, pointed straight level, the t-stat about 3 feet above I waited to make sure the temp was stable...at 58F, I then plugged in the light from out side, waited a half hour and checked, went to 59F.   So- It will work, part of me wants to see how well, part of me DOESN'T want to know!!!

As to the light itself, other experts would have an answer. But I think they are not part of the light spectrum the plants need, thus "grow lights".  I dunno  ???

[tropicalb]

Thanks for all the info Bobby!

I'm kinda worried about fire danger with the electric heaters...but it seems you have been doing it for years with no problems...

I may have to try a coupla different tests with different sorts of heaters...I'll let everyone know the results, in case anyone else is looking for a cheap way to add some heat.

Bill.....

I THOUGHT it may have been a Vershafeltii Splendida.. aren't they COOL? Ya gotta love that leaf!

Thanks for your halogen info...I think I'll try a test in my greenhouse and see what happens...lowest temp in there so far has been 48F...

[BS Man about Palms]

Yea- I hit 47point something this morning.  New T-stat measures in tenths and humidity too,  No humidifier and I've noticed it hoovers between 75-90 percent overnight.

[Dypsisdean]

Bill,

The halogen fixture you are using.............it does have a lens to keep any water away from the bulb, I hope?

[BS Man about Palms]

yep, and a little protector grill too!

[BobbyinNY]

Thanks for all the info Bobby!

I'm kinda worried about fire danger with the electric heaters...but it seems you have been doing it for years with no problems...

I may have to try a coupla different tests with different sorts of heaters...I'll let everyone know the results, in case anyone else is looking for a cheap way to add some heat.

Electric is definitely the LEAST danger to worry about  - GAS is wayyyyyy more dangerous then Electric can ever be. With Electric I just have the GFCI outlets installed so that if it detects a circuit problem it cuts off.

[Neofolis]

I agree that electric is safer than gas, although gas is not particularly unsafe.  My heater automatically cuts out the gas supply if either the pilot goes out or the heater is not upright and there is no easy way for anything to touch the flame to allow external combustion.  The supply pipe is slightly vulnerable as it is surface mounted, but it is possible to run it through ducting below ground.

[BobbyinNY]

I agree that electric is safer than gas, although gas is not particularly unsafe.  My heater automatically cuts out the gas supply if either the pilot goes out or the heater is not upright and there is no easy way for anything to touch the flame to allow external combustion.  The supply pipe is slightly vulnerable as it is surface mounted, but it is possible to run it through ducting below ground.

While I agree Corey that gas can be safe, it just gives me the jitters knowing that it's on and running while I'm sleeping. I've heard so many stories (actually one just happened yesterday 2 miles from my house) about contractors that are doing work on a house and they accidentally hit a gasline and the entire house is leveled to the ground..