pumping away/pumping to

[Deleted User]

when you have a circ pump pumping to the return, and 5 circs pumping away to 5 zones, what is the system called?

and since there are 5 circs/zones being pumped away, why would someone have installed a circ pump on the return?

hot_rod

could be a primary secondary piping

whereas one circ moves the flow through the boiler loop, and the others are zone circs. need a picture to know for sure.

hr

Brad White

If I gather correctly

what Hot Rod is saying, I agree that the boiler circulator may well be pumping into the boiler. This is usually to satisfy an internal pressure switch especially on a boiler with a high internal pressure drop. (Imagine restricting the suction side of a circulator, you could cavitate that in a hurry also.)

If it is an older boiler with the circulator on the return as was a bad habit for years, it may be that they just left it there and are otherwise pumping away as secondary circuits. As Hot Rod said, post a photo. I am just guessing otherwise.

[Deleted User]

yes, the 'to' circ

is what i guessed to be the loop for the boiler, and i do have pics, but the room is small and i'm shooting through a door so it's rather hard to see. and here's the puzzle for me, the 'to' circ is a b&g series 80, 90gph, 2.5x7 and maybe i don't understand, but i'm really puzzled as to why such a huge? pump if it's just for boiler circ. but maybe this will tell you something, i was told today that the total volume of the system is approx 1100gals

Brad White

How big a boiler?

More to the question, what is the firing rate and what kind of boiler? If cast iron, I would expect (or at least hope for) that boiler to have at least a gross output of 900 MBH more or less when matched with that 90 GPM circulator.

The volume of the system has less to do with it than the boiler output.

If the boiler had, say, a 200 MBH output, it would only pick up just under 4.5 degrees.. that boiler would condense and you would hear hiss and spittle in the combustion chamber. It would take a very long time to get that boiler from a cold start up to operating temperature, not to mention damage over time or sooner...

Start with the boiler gross output and size that for a 20 degree temperature rise would be what I would do.

[Deleted User]

thanks for the prompt response

i'll get the model number tomorrow

[Deleted User]

hey brad - How big a boiler?

it's a burnham 4FW-107-G0-40-GP, rated at 1120 MBH/896 MBH,
and the old boiler that was removed was a 4FW10740LB, and i can't find those numbers anywhere on the burnham site. the i/o manual says that circ through the boiler should be at least 1/2gpm/bhp, and no more than a 40deg fluctuation at any time

so, at approx 32hp@1/2gpm.............?