Greenhouse Unit Heaters Redefined
The revolutionary tubular heat exchanger inside the Lennox LF-24 series of greenhouse heaters ensures you years of performance and high efficiency. Combustion is precise because of special "in-shot" burners and fan assisted exhaust. Equipped with a TrueLeaf Combustion Air Separator, it's bullet-proof.

Reconsidering

Greenhouse Construction Considerations
The 3/4" Paradigm


Why are inches inches? Miles miles?

I think it all has to do with an arbitrary edict issued by a pharaoh, long, long ago, about the length of his knuckles or some such. Is that really how “standards” get started? The same conclusions could be drawn about much of the way we approach greenhouse engineering these days. Though not quite as exotic as measuring ancient pharaoh’s body parts, we in the horticultural engineering community have conspired to create such nonsensical “rules of thumb” on our own. Case in point— here is why we have settled on 3/4" tubes (or the metric equivalent) on 12" centers for greenhouse floor heating.

So much of what we do in our daily lives is the result of “myth and legend”, we plod away not questioning the “whys” behind the things we do. A little reality check and rudimentary analysis from time to time are healthy, don’t you agree? Some might say, “heck if it ain’t broke, don’t fix it.” You know what? That’s what Henry Ford said about the Model T. He made more than 14 million of them, and found great success in doing so, but in the end, his refusal to change his car allowed his competitors to catch up.

Converse to what you might think, here are the facts: Fact 1: In a 1 acre greenhouse 1/2" tubing, placed on 9" centers, can transfer 12.3% more energy.
Fact 2: In a 1 acre greenhouse 1/2" tubing, placed on 9" centers, will have 41% less water volume. Cost: 1/2" tubing, placed on 9" centers, should cost only 3.1% more.

Startling Facts about Greenhouse Floor Heating Revealed!

Well, in the scheme of things, this may not really qualify as “startling”. I mean we are dealing with a pretty mundane subject here. Or are we? Do you realize that fuel efficiency and heating system response can have a huge effect on your bottom line? Making good decisions about the way you outfit and equip your greenhouse now will have far-reaching effects on the profitability of your operation for it’s entire economic life.

A wise man once said, “The devil is in the details”. That statement gives a very concise and eloquent view of the importance really “small” things have in the process of specifying the environment systems for your greenhouse.

Ok, enough lofty stuff. Here’s the bottom line: 1/2" floor heat tubing may work better for you than 3/4"!

The limitations come about in the form of maximum length. For best efficiency, 1/2” tubing is limited to floor areas of 250’ long or less, but that’s a healthy 500’ round trip or “loop length” and should be fine for most projects.

One Grower’s Experience:

A grower with probably more experience with heated floors than practically anyone is Bill Swanekamp of Kube-Pak, a large plug and finished crop producer in Allentown, NJ. Besides being excellent growers, this is one of the best run businesses around. Just ask anyone familiar with Kube-Pak and they will remark about how this operation is a model of efficiency on many fronts. Bill did his first 1/2" tubing on 9" centers floor about 8 years ago and hasn’t looked back since. It’s become the standard at this operation.

Bill reports that the heating response at the floor level is quicker and that the actual tempertures measured across the surface are more even. It works. It costs pretty much the same, and it can make your facility more efficient. Pretty hard to find fault with that.

Next time you plan a floor heat installation, give 1/2" tubing on 9" centers a thought. Even though it’s a little “non-standard”, it could be a good investment for you!