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[MTJAG]

I have a CB5036 that is plenty to heat my house.  Just built a greenhouse and am thinking of running a line to it...about 50' away.  Just wanted to see if anybody out there has done this for a greenhouse application and if so, what are the problems, if any, with having done that.  What do you connect the pipe to on the other end, or do you just use exposed pipe on the inside of the greenhouse?

[Ridgekid]

Suspended space heater thermostatically controlled is the first thing that popped in my head.

[willieG]

green houses can take many more btu to heat than your home. they are usually not insulated as well as a home and therefore lose btu's faster and they need them replenished at a faster rate. depending on what yoru green house is made of can (or insulated with) will have a huge effect on your btu consumption.  try the link below for some help in determining your needs

http://www.littlegreenhouse.com/heat-calc.shtml

[MTJAG]

Hey, thanks for the link...according to that calculator, I will need approximately 172 gallons of propane to heat!  However, the entire structure is not polycarbonate.  I just posted some pictures of the greenhouse: http://outdoorwoodfurnaceinfo.com/forum/MGalleryItem.php?id=140

The construction is 2x4 insulated walls, 2x6 insulated ceiling, double wall polycarbonate, black water filled barrels on the back wall facing south to gain and retain solar radiation, rock floor.  I don't think it would take 172 gallons of propane to heat as it is substantially more efficient than a full glass greenhouse.  However, it will take more than the 10 barrels I have on the back wall to heat when there are days like today with all snow and no sun and an overnight temp in single digits.

I think I saw the Central Boiler makes a simple radiator appliance for barns and such and was thinking this might be a solution.

[willieG]

i have seen a complete kit sold by one of the bigger manufacturers that consited of a metal box with everything in it..the blower the rad and the thermostat and any valve needed you just hooked  up the feed and return line and plugged the unit into 110 volt power,

it may have been CB i am not sure now

[MTJAG]

One of my limitations is power since I am off grid (solar/batteries).  I am currently at my limit during the winter at night with power consumption and energy storage.  So, anything I do for heat in the greenhouse has to be minimal.  For instance, my circulator pump on my OWB is a Grundfos Alpha which uses less than 20 watts of power to circulate at 3 GPM.  I would use the same type of pump for the greenhouse, but I don't think I could stand much more than that with my current battery bank. 

[Ridgekid]

Yeah I knew about the off grid situation. I was thinking about a fan similar to the one you have on the roof. But then again, there wouldn't be any sun available when you needed the heat. (at night)  Didn't think that one out. 

[MTJAG]

Solar is not "fire and forget"...everything has a cost of energy and you ignore it at your peril.  My first dumb mistake was to not get enough energy storage (battery bank).  It's going to cost me now in a shorter life for my current batteries.     However, I am learning how to make the most of what I've got.  BTW, I liked your energy graph you posted here.  It qualifies the effort you have taken to reduce your energy footprint.  I don't consider myself a "green freak", but I do know that all of us are going to have to think through how we use the energy that is available to us. 

On to the greenhouse.  Last night I ran a two burner propane heater for a couple of hours before bedtime.  This morning at 5:30am , the temperature in the greenhouse was 38 degrees and the outside temperature was 7 degrees.  I cranked up the propane burner for an hour and the temperature came up to 70 degrees before shutting it down again.  Once the sun came up, it was no problem.

[willieG]

you could use baseboard heaters (no electricity needed) but you would  have to figure out how many feet of baseboard you would need to get your btu output to what you want. there are charts (and likley people) that can tell you the btu output per foot of basebaord (depending on the style) per the delivery temp.

[RSI]

I have a lot or aluminum fin tubes that were removed from a green house. If you are interested, let me know. They are 1-1/4" pipe so will flow real well with a smaller pump.

[MTJAG]

you could use baseboard heaters (no electricity needed) but you would  have to figure out how many feet of baseboard you would need to get your btu output to what you want. there are charts (and likley people) that can tell you the btu output per foot of basebaord (depending on the style) per the delivery temp.

Yes, the baseboard heaters sound like what I need...now to determine how many feet...

RSI-those aluminum fin tubes you have would probably work well, just trying to understand how I would control the temperature with that configuration.  Just like the baseboard heater, I could run the inside perimeter of the greenhouse with this at ground level.