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[Aroid-l] Heaters, vented & otherwise

  • Subject: [Aroid-l] Heaters, vented & otherwise
  • From: "Weaver, Bill" bill.weaver@hp.com
  • Date: Tue, 21 Nov 2006 18:11:47 -0600
  • Content-class: urn:content-classes:message
  • Thread-index: AccNx7ppNQXBA1+QRYWEnRlRdyJASQAATxug
  • Thread-topic: Heaters, vented & otherwise

The major problem with unvented heaters is the buildup of ethylene gas
is present in some natural gas supplies. Ethylene is the gas released by
ripening fruit like apples that accelerates flower maturity/death. I
been using an unvented heater in one orchid greenhouse for about ten
and I haven't had any problems.
I should note that a properly installed "unvented" heater is generally
not really unvented. At the very least an air vent is required to
combustion air otherwise the flame would eventually go out. (Soon after
setting off your carbon monoxide detector) Plus, some sort of "outlet"
vent is generally called for as well. This causes some of the heated air

to exhaust out the outlet vent and draw combustion air in the other
Cuts back a bit on the effiency, but prevents ethylene buildup.

(BTW unvented heaters are no longer legal in California)

Bill Weaver

-----Original Message-----
From: aroid-l-bounces@gizmoworks.com
[mailto:aroid-l-bounces@gizmoworks.com] On Behalf Of Steve Marak
Sent: Tuesday, November 21, 2006 15:47
To: Discussion of aroids
Subject: [Aroid-l] Heaters, vented & otherwise (was "Anthurium")

The topic of combusting greenhouse heaters without external venting came
up at
an orchid society meeting a couple of years ago and the older, more
growers unanimously issued dire warnings. Most said that their orchids
die, but dropped flowers and leaves and generally ailed until they
vented their
heaters externally or switched to another heat source.

I've always assumed this was due to carbon monoxide from incomplete
since that's always a concern when burning things indoors, and since
read/heard many times that carbon monoxide damages plants at very low
concentrations. I have no idea what the chemical mechanism would be and
some reason find it counterintuitive, but it seems to be so - dying
plants is
often listed as one of the things to watch for when a carbon monoxide
is suspected. 

But I've seen a lot of these self-venting greenhouse heaters advertised,
I've used a portable kerosene heater to heat my sunroom, one winter
until we
could get the failing house system replaced. I was meticulous about
to get the most complete combustion I could, used the heater the bare
and kept two carbon monoxide detectors nearby, and didn't see any

If there are people with experience here, I'd love to hear from them - I
need a 
non-electric backup heat source for a new structure.


On Mon, 20 Nov 2006, D. Christopher Rogers wrote:

> Hi Tom,
> The heater I purchased supposedly does not need a vent, but is "self
> and was sold as a greenhouse heater. You have given pause to worry
now! But
> then, my greenhouse is fairy small (17 feet x nine feet with an eight
> peak), and I have a strong exhaust fan, a good circulating fan, and
> sliding glass windows that I use for vents, one of which is
immediately above
> the heater.

(stuff deleted)

> -----Original Message-----
> From: aroid-l-bounces@gizmoworks.com
> [mailto:aroid-l-bounces@gizmoworks.com]On Behalf Of Tom Croat
> Sent: Friday, November 17, 2006 2:34 PM
> To: Discussion of aroids
> Subject: [Spam] RE: [Aroid-l] Anthurium
> Dear Chris:
>             Will this propane burner be exhausted in your greenhouse.
> have to be concerned with the combustibles because as I recall we
> leaves to fall off plants by using a burner within the greenhouse.
> Tom

(more stuff deleted)

-- Steve Marak
-- samarak@gizmoworks.com
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