Cast Iron Radiators on a hot water series loop

Darren_5

I have a 3 family brownstone, each floor will have it's own boiler and is approximately 900 sq.ft. including the hallways outside the apartment. As typical with railroad flats there was a steam fed radiator in the front room and the back room but nothing in the middle rooms or kithchen/bath.
I am coverting to hot water and would like to add cast iron radiators in the middle room, kitchens, & baths. is there a poosiblity that the last radiators on the line will not get hot enough if I run a series loop as oppposed to mono - flo tee's. I don't want to use baseboards. Also is it necessary to heat the halls since there are buildings on both sides? my contractor says it's not necessary. Thanks in advance.

ernie_3

hmmm...

I wouldn't series loop CI rads. You run the risk of 'run through' w'out fully heating the rad or room. Best to go w' monoflo tees. I would also heat the halls. You can always throttle them back, whereas if there not there....you're S.O.L if we get a bitter winter like the last one (in NE anyway). IMHO. If you're concerned w' the last one heating, make it its own zone. That will even out the heat.

Mike Kraft_2

No to Series on CI

The mass of the rads from the start of the loop will suck the heat dry!!Your return will be very cool.You will defintely want to pipe primary secondary if the boiler is cast iron.If you don't your going to experience some serious flue gas condensation and maybe a cracked heat exchanger.

With this type of conversion I would suggest using radiant manifolds for distribution.You can use pex or better yet PAP.This will give you even distribution throughout.Mono flow is good but you will need to do some math figuring the temperature drop through the loop.If you add TRV's(thremostatic radiator valves)with a constant flow and reset you will ahve a commanding system.

cheese

Darren_5

Ok, I think were getting some where, but I'm still not clear. I am talking 5 radiators per floor, the plumbing supply house say series loop with the proper size boiler should be ok. Or run the mono flo's in the basement and feed up to each radiator. This seems like a lot of pipe in a 3 family house.
The contractor says if he is doing mono flo tees he would also run the feed to each rad up from the basement.
My quesion is if I go with the mono flo's why can't I run a feed up to each floor with a loop back to the return and run the tee's to the rad's on their floor instead of up from the basement? Would this be more efficient? Who should I listen to the supply/plumber guy, contractor ( who want to rip out the cast iron rads and install basboard, or my confused self? Heelllppp!!
BTW I'm in NYC and it was freezing last winter

dconnors

Rads

I would run a loop to each floor with a circ on each loop. Pressure drop through monoflos is quite high. This will enable you to use a smaller circ on each loop. Also give you more control on distribution. This should eliminate your concerns about flue gas condensation. Adiverter valve can be used to control how much flow is sent through each radiator.

Mike Kraft_2

Not to be an alarmist

but..........job I'm redoing after another installer ran 5 cast iron rads on 3/4" series loop.Notice the chimney.

cheese

Mike Kraft_2

pics are bad

But the real thing was worse.Long story with these pics but bottom line is the boiler was and is new.It is a Net90Kand it was getting a work out.The chimney is relined and the system is being redone.

good luck
cheese