clarification please.

[rick rottet]

I am of the understanding that your GH was poly film covered. Due to some statements in your Book of Propagation and a recent thread about poly carbonate glazing, I have several questions. Keep in mind that I live in East Central Illinois.

1) Did you have any temparature control issues in your GH? In the GH itself or the water. (Pennsylvania is very similar to Illinois with regards to extremes of climate)

a) If so, do you think an in floor/slab radiant heating system would be an adequate alternative or better as a supplement to a standard forced air furnace? (Would be set up with a household water heater and recirculating pump)

2) What was the BTU of your furnace?

I have been looking at a 20x36 with a 100,000 BTU which the company assures me, knowing what my requirements are, will be adequate with a double layer poly film GH. Do you agree?

Looking for the voice of experience.

[Anthony Calfo]

My greenhouse indeed was simply double-ply poly. The reason primarily was because the grade selected allowed more light admission (including/especially) UV in contrast to most glazing options which reduce or block UV and admit less than 92% light.

It has poor insulating value and short life (1-3 years) but is so inexpensive and allows so much unfiltered light in (the very thing that reduce its lifespan) that it is worth changing the GH covering every few years for the benefits IMO.

The only excpetion would be if you are certain this GH will be a very long-term endeavor (10+ years)... then you may be able to rationalize the expense of tubular Lexan. Very good quality and light admission with some grades, tremendous longevity.

As to the hanging furnace... it easily kept the GH warm in the most sever winters. Bearing in mind that my hometown gets lake effect heavy snowfalls (measured in feet at times!) and bona fide blizzards.


Admittedly it was expensive to heat in some severe months (over $300 per 1000 sq. ft) but easily absorbed as an expensive from productive pools of farmed corals.

I don't recall the BTU of my hanging furnace... would have to dig/check. But I assure you that you can trust your GH supplier. They deal with orchid growers that have the same demands as we coral farmers. If your supplier knows your region (temps/humidity) and you say that you want to maintain an ambient temperature of X degress F (82-86 likely for water temps slightly cooler), then you'll get an appropriately sized heater.

Keep in mind too that massive air flow cannot be underestimated in this or any GH for such production. Do not skimp on recirc fans!!!

Please post photos of your progress as you go along, my friend

Share the knowledge/inspiration as you take it.

Anthony