I’m new to the site, and am just starting to sift through the plethora of remarkable information that you all are passing among each other. I’m brand-new to the deeper intracacies of HVAC, although I am an avid do-it-yourselfer and have had one, and now two, WVO cars for the last three years, with all the tinkering that they entail. With WVO stars-in-my-eyes, I picked up a newer used Bock oil hot water tank a couple of months ago, and am slogging through the process of getting it up and running, and to eventually experiment with various WVO or biodiesel blends. Fluing it in to the current wood furnace/oil furnace chimney went fairly satisfactory, but now I’m hung up on connecting to the existing oil lines running from the underground tank to our oil furnace.

I was just about to cut into both the incoming and return lines at any convenient spot, and then slip in a flare T to each to run a branch line to the Suntec pump of the new burner, when I realized that there are more issues here that have to be to be considered… issues like depth of tank vs. height of each pump/burner, location of T, loss of vacuum, priority of one appliance over the other, etc. Although we hardly use the oil furnace, having an ample supply of cordwood still on hand, I certainly don’t want to compromise the option of that back-up for this (or any other) cold upcoming winter…

So, I’m a bit stuck. I need to find resources to sort out these issues, and the couple of Audel manuals at our local library are not cutting it. I’m also expecting to set up an auxiliary tank, say a 35-gal drum, or smaller, to put into the same room as the water heater(on a pedestal for gravity feed?), and use that exclusively for the water heater, independent of the furnace lines. But I would want to T into the existing lines anyway, with a valve to be able to choose between the main oil tank outside or this auxiliary vegie oil tank, depending on how it was working, etc.

So, can anyone offer some advice, or direct me to a printed or on-line resource, both on the issues concerning where and how to safely T off a branch from the existing oil lines, so as not to compromise the current furnace set-up, and on the viability of setting up a small auxialiary tank near the water heater for it’s own use, in addition to the main tank…

You’ve got to isolate the burners from each other. I would suggest using a 2-way valve instead of just a tee. Or, you could use Tee’s and use a shut off valves on each of the tank feeds/or each of the feeds to the burners. Of course this would apply to both the feed and the return. You would definitely need to put either a 2-way or two shut off valves on your hot water setup, otherwise you run the risk of veggie oil flowing back the HHO tank.

You should never valve off the return side of an oil line, check valves are ok but if the line is either left closed by mistake or vibrates closed it will blow your oil pump causing oil leakage. Firematic valves on the supply sides with in 3ft of the burner and check valves on the return side if the tank is higher than the burner. Barry, what size oil lines do you have? Where is your oil tank? Do you have a single or two pipe set up?

Thanks for your reply, and especially for your reminder not to potentially close off that return line. My intention is to first hook up the lines for the water heater into the existing lines from the underground tank to the furnace, in order to get the water heater up and running initially on the petrodiesel that we still have in the tank, then when that is successfully going, to add two-way valves to a separate tank, inside, for the vegie oil/biodiesel. But I’m a bit hung up already on the first step of T-ing in the water heater lines onto those existing lines from the tank to the furnace (in order to simply get the water heater up and running, initially, on the petrodiesel that’s in our underground tank).

There are two 3/8 copper lines (intake and return) running from the tank to the furnace burner. That burner is lower than the top of the underground tank, but not as low as its bottom. Audel indicates that depth of the tank vis-a-vis position of the T to each of the pumps is significant for vacuum, but I’m not sure how to figure this in. Also, will T-ing both a incoming and a return line to a second appliance affect the draw to either. I’ve got everything here ready to install, but am just hesitant to make that first cut until I’m sure that I’m not going to screw up the dynamics of the furnace pump/burner.