heating ideas for outdoor greenhouses

I live in Seattle and we don't have severe winters, but I am looking for ideas from experienced growers for heating. As I don't have any more room in my panel for another 240V pair of breakers, I have only a 120V feed for my 16' X 8' greenhouse. I am considering using a Williams Direct vented heater using a separate 9 gallon propane tank as a heat source. I have seen that this would be OK for orchids as it draws in air from outside and vents to the outside directly. However when I reviewed the installation sheet, it states not to use in trailer homes, or recrational vehicles. Is this due to fumes, CO, proximity to heat?

I also would like to build a solar collector to supplement the heat. I have a lot of material left over from a convection hydronic heating system that had to be removed from a remodel project. The system used 3/4" copper with aluminum fins for the heater transfer boxes. Just a thought for fun.

Any ideas or suggestions? Thanks!

 

Is this something you need to relight the pilot often? I thin I heard the same complaint on the Williams Direct, although it doesn't look bulky. I don't have a very airtight space presently either. Did you purchase directly from the manufacturer?

 

It has a vent into the appliance and out. There is a greenhouse supply that sells them and recommends them for orchids. However when I contacted the seller, they never returned my call or email. Home Depot sells them for less and I wouldn't have to pay for shipping.

 

Thanks, I'll give them a call. I guess I am surprised that the unvented causes no problem. It's good to hear from experience.

 

Thanks for the feedback.

 

My greenhouse is also 16' X 8' . I just orded one and was impressed by the service so far. The sales guy actually knew the technical questions without looking them up. I don't believe I will have any difficulties with installation. Any idea how much gast you are using for that temp? I have a LP version.

 

I do the same thing, so no problem. Besides, time has given me experience with the unit. First, I would say determine your needs for heating. You can go to several sites that sell greenhouses, such as AFC Greenhouses, http://www.littlegreenhouse.com/heat-calc.shtml and calculate the heating needs of your growing area. This will take into consideration glazing and area volume. The Southern Burner will heat a fairly sizable area. Marni is in California and the temperature gradient between the outside temp and needed growing temp may not be that large or for any extended time. She said she doesn't have an area so well sealed. I put in an intake air supply next to the burner as advised, but there is still a small amount of gas odor to my nose. If you have a well sealed area or one that has air common to the house, you may need to have the vented unit. Also, given the cost of propane and tanks and fittings needed, it may be more cost effective to use electric heat. I didn't have enough breakers for another circuit, so a space heater eats up most of the power needs for my greenhouse and I opted for gas which needs no electrical. Fittings were a much bigger pain because I wanted an auto-changeover regulator and had to use extra fittings to get all the parts connected. I didn't want to worry about running out of gas from one tank at night or during cold weather. I have done some hydronic heating in my home interior, and that would be another option of heating.

All depends on your needs, size of your wallet, and skills if you are installing it yourself. I will give you more specifics if you wish.
Best wishes.

 

I have checked all connections - twice. No bubbles. Because of concerns over the appearance of the pilot flame and the burner flame, I checked the feed pressure with a gas manometer - perfect feed pressure. I called Southern Burner and was informed that the pressure regulator had been reset to a different flame height and that mine was burning properly. I have no indication of any physical findings that there is a leak. It is possible that the odor I perceive is from the byproducts of fuel burned. It is not the same odor as that of unburnt propane. Burning fuel will always produce some form of hydrocarbons and other vapors from doing so. When the unit is not lit, there is absolutely no odor even though all the gas connections are the same and the line to the burner is on and with propane gas in it. I did check and verify that I had the correct regulator for propane fuel. I have spent considerable time in looking at any possibilities and will assume that the unit is working properly. Any other ideas?

 

I think if I call him one more time, he will run away. No odor when there is gas connected and pressurized, but no pilot lit. Therefore, no leaks prior to the regulator. Once the pilot is on, there is an odor of "gas heat" is the best I can describe it. Thus, I did the check on the line pressure from the regulator to verify that was correct and verified that the height of the flame was proper. If after the gas is distributed after the gas regulator into the pilot, then I don't know. I can't really check it at the pilot burner itself. However, I will check it out again later this fall and bring it to their attention for analysis. Yes, it annoys me.