circulator pump sizing

[ssupercoolss]

my new boiler is in production as we speak. (so i am told) i will be hooking up in series with my oil boiler, with some piping that will allow me to take the wood boiler out of the loop for when i run the oil burner on weekends when i am not home. i figure i will need a circulator for the wood boiler. should it be the same size as the one on the oil boiler? maybe a bit larger to accomodate for some friction loses (little extra pipe, probably a few 90 degree elbows too)?

 

[Bob Rohr]

Piped in series will cause flow through both boilers all the time. so when the oil fired boiler is running you will lose some, maybe a lot of heat up the wood boiler flue. this is typically the least desireable way to pipe them together. however if you DHW is generated from a tankless coil in the oil, then you will need to flow through the oil boiler.

Ideally DHW would be generated via an indirect tank or hx that either boiler could feed.

If the boilers truley are in series you probably only need the one circ. as long as it moves the gpm and over comes the head the system presents.

Parallel piping, if possible would be a better way to go, as flow only goes through the boiler when it runs.

hr