We have been in business since the early 90s manufacturing outdoor furnaces, air handlers and unit heaters, distributing plumbing and heating supplies and offering custom metal fabrication. Greentech Manufacturing produces an industry leading outdoor furnace known as Crown Royal Stoves. Manufactured with quality workmanship and skilled labor, confident in our product, we stand behind our stoves with a 20 Year Limited Warranty. A warranty that cannot be matched, even by a Lifetime Limited Warranty.