GaryFerg wrote:The way you describe of hooking up with the tee would be parallel? I presently use the oil fired for hot water using its coil. If I get a keystoker I will use its coil directly. Not sure how I will hook that up yet. Think I am in series s? now, one boiler runs into the other via circulator.
Maybe I can say this better
Assuming you have two parallel lines going from inside to outside, one of the lines as the primary loop going out to the outside furnace and one coming back...
Just before they go out, insert a tee in each line. Assuming 1.25" pipe, your tees would be 1.25x1.25x1.25
Insert these directly across from and facing each other. Insert a section of 1.25" pipe connecting the tees with a valve in the middle.
Now, if your lines are running from left to right, with the inside being left and outside being right...
Just to the right of the tees (even connected to the tees is ok) are a valve in each line.
Picture the vertical lines and such akigned. The forum appears to strip leading spaces when posted
Inside || Outside
+ is tee, / is valve, || is vertical run of pipe (don't knock the high tech diagram, it's android and I just smashed two fingers, maybe broke a knuckle
The idea is close the middle valve in the connecting pipe and leave the other two open for normal series operation. Close the top and bottom valves of the primary loop and open the middle cross-connect valve to allow the oil boiler inside to run and be isolated from the outside.
Aparallel installation as we discussed earlier would be pretty tough unless you changed the inside oil boiler to be parallel. IMHO, the outdoor coal furnace will likely be the one more likely to be taken offline, no matter how reliable and well installed. Personally, with the situation you are describing, a series install, where both boilers are in the primary loop, is what I would do.
Hope this helps. I am going to put the bag of frozen mixed vegetables back on my fingers now