circulator replacement

keyote

have what i think is probably an old gravity two pipe w cast rads that was long ago converted to pumped with series 100 that pumps so bad i have a tinfoil oiler rigged past several years to keep bearing to dull roar. im taking this system out of service one floor at a time but need it to limp along another year or two, i just added in an expansion tank upstream of pump to replace the 40?gallon non expansion type tank downstream of pump and wondered if i could just replace this circ as well before heat season. although i have taken one of three floors off its loop it still branches 30 feet in either direction across cellar ceiling with 2" s/r pipes and i figure theres about 170' of branches heading to the floor above and above that which are mostly 1" ish some are 1" pex i used to shift things around others legacy 1" steel and some 3/4" steel and copper of various vintages.Im wondering if theres a chanve a 007 or something will work guess i have a lot of flow and little head theres about a dozen cast rads still on it between the two floors half of them pretty big boys.

BTW i left the expansion tank at 12 psi figure 2 floors thats cool but its only 4.4 gals really didnt do the math is it ok or must i leave that old tank valve open

keyote

pretty sure they work hat, found the curve on that band g the 007 prolly wont have enough flow huh? the 010 is as expensive as the band g

keyote

thanks hat i already have that problem thought it was air but the farthest highest rad can sometimes take days to start flowing and stop again mid season. just didn't want to invest in a more expensive pump for a temp situation.

BTW got the KHN all piped up and only control left to do on the system is the DHW temp sensor same as boon put it in. so should begin commissioning any day hopefully dhw at least tomorrow.