7" Oil Vent Damper

I have been looking for this device for several years. Luckily, someone on an HVAC forum pointed me to PEX Supply and the Oil Vent Dampers. I had already done several things to improve efficiency, including upgrading my 40+ year old burner to a modern flame retention burner, installing a smaller nozzle, using a pressure shutoff valve on the nozzle, installing a heat manager, insulating all the heating pipes and insulating walls and roof much better during a renovation. I finally bought and installed two OVDs this fall. One for my domestic hot water heater, the other for my furnace, both of which are oil-fired. The difference was immediately felt in several areas: Our convectors upstairs used to liberate all their heat in about 30 minutes as the boiler would throw out much of its heat up the chimney within the hour after shutdown. With the OVD, the radiator stay warm up to 3 hours now. The house continues to heat up past the thermostat set temperature and will stay warm all night long now, for up to 12 hours without refiring the furnace. The basement, which used to be chilly, is now warm. I never realized how much heat we were losing through the barometric dampers before. With the OVDs installed, the basement stays warm and the heat exchanger/fan I have installed on the furnace flue can really heat the cellar now, long after the furnace shuts off. I expect that we will save a significant amount of oil this winter as a result of this marvelous damper technology. Installation was easy. My only minor issue was that the length of cable and the angle of the connector for the blocked safety vent switch could have been longer and adjustable to make a straight run instead of a bend in the BX cable. But no problem, really. The assembly itself is really well built, quality materials and works quickly and transparently. 3 seconds, it opens then the furnace fires up. After shutdown, about 3 minutes pass, and it closes, which takes 3-4 seconds. It's nearly silent, too. I can't imagine why this isn't installed on EVERY oil furnace, given the price of heating oil today. This is a must-have item for every oil heat system.

thanks to the 4th review (cosmicthermos) I needed info on the ovd-6 stuck open. my unit would sometimes close after 3 min and other times after 30 min and other times after 1 hr. so I replaced the 220uf cap as suggested by cosmicthermos and it is working great now. It is a pain to do because you need to remove the ac motor to remove the defective surface mounted capacitor. I mounted the new 220uf @ 35v on the back side on the pc card to make it easier to replace incase it needs to be replaced again.