Heaters, vented & otherwise

From: "Weaver, Bill" bill.weaver at hp.com> on 2006.11.22 at 00:11:47(14820) The major problem with unvented heaters is the buildup of ethylene gas that is present in some natural gas supplies. Ethylene is the gas released by ripening fruit like apples that accelerates flower maturity/death. I have been using an unvented heater in one orchid greenhouse for about ten years 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 provide combustion air otherwise the flame would eventually go out. (Soon after setting off your carbon monoxide detector) Plus, some sort of "outlet" type 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 vent. Cuts back a bit on the effiency, but prevents ethylene buildup. (BTW unvented heaters are no longer legal in California) Bill Weaver +More -----Original Message----- [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 experienced growers unanimously issued dire warnings. Most said that their orchids didn't 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 combustion, since that's always a concern when burning things indoors, and since I've read/heard many times that carbon monoxide damages plants at very low concentrations. I have no idea what the chemical mechanism would be and for 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 problem is suspected. But I've seen a lot of these self-venting greenhouse heaters advertised, and 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 everything to get the most complete combustion I could, used the heater the bare minimum, and kept two carbon monoxide detectors nearby, and didn't see any problems. 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. Steve On Mon, 20 Nov 2006, D. Christopher Rogers wrote: > Hi Tom, > > The heater I purchased supposedly does not need a vent, but is "self venting" > 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 foot > peak), and I have a strong exhaust fan, a good circulating fan, and three > 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. You > have to be concerned with the combustibles because as I recall we caused > leaves to fall off plants by using a burner within the greenhouse. > > Tom (more stuff deleted) -- Steve Marak -- samarak@gizmoworks.com _______________________________________________ Aroid-l mailing list Aroid-l@gizmoworks.com http://www.gizmoworks.com/mailman/listinfo/aroid-l _______________________________________________ Aroid-l mailing list Aroid-l@gizmoworks.com http://www.gizmoworks.com/mailman/listinfo/aroid-l

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