I have a Longwood Wood/Oil Furnace. I just bought a brand new Beckett AFG oil burner w/ the clean cut fuel pump. I thought the unit would come w/ the primary control, but it didn't, so now I gotta buy one. I've been digging online and looking at different ones. I read that the clean-cut fuel pumps have to have the pre-purge feature. I've been looking at the Honeywell Primary Control Units: R7184A 1026 ($113), R7184B 1024 ($127), R7184U 1004 ($159), and the R7184P 1094 ($139). Here is an address to a comparison on the honeywell site: http://customer.honeywell.com/Honey...s/Catalog/SearchResults.aspx?multiselect=true Also can someone help me understand the difference between interrupted and intermittent? I'm nearly positive I want an interrupted unit, but I'd like to better understand the differences just out of curiosity. I've gotten the burner set up and adjusted. Literally, all I need is the primary control, hook it up, tighten a few bolts and I should be ready to purge the air. I asked this question in a different forum and a guy replied suggesting that the units I mentioned above all basically do the same thing, but are worlds apart in what they're used for; I don't understand that. If they all do the same thing, why are they used for different things? Can someone explain?