Splitting up old gravity system

joe amadio

I have a customer with an old gravity system. The system has a split 2'' supply main and a spit 2" return main. The whole house is currently 1 zone. The customer is interested in a new boiler, raising the mains in the basement so they can create usable space and splitting the 1st and 2nd floors into 2 zones. What will be the best way of accomplishing this? I was thinking a new 1 1/4" copper monoflo loop for each floor. All current radiators are either Sunrads or 4 tube free standing cast iron. All radiators are piped off the 2" mains with either 3/4" or 1". I should be able to disconnect all radiators in the basement ceiling and adapt to either copper or pex. Do I have to pipe to each radiator with the current branch sizing 3/4'or 1". Can I pipe to radiator supply and return line with 1/2" pex off my new main? What do you think?

Paul S_3

what

about a homerun system, with 1/2" pex to manifolds , if your heatloss and GPM allows you too. you can either zone the first and second floor, or you can zone every room with TRV'S    Paul S

kcopp

the monoflow....

set up is the worst thing to do.

read this... http://www.heatinghelp.com/article-categories/332/Gravity-Hot-Water-Heating

Then ask a few more questions. Gravity heating has a number of things that don't make sense compared to todays systems. It is easy to put to big a circ pump on the system.

icesailor

Pumping High: Old Dead Twisters.

But with ODR and properly sized small pumps, there is nothing better. With the long runs at low/proper temperatures, the whole system/zone balances out.

Gravity systems I have seen are usually split into areas and not to floors. The old dead wrench slingers and Threader's of large diameter pipes used to split so that one side fed the North and the other circuit fed the South side. Wind infiltration had a tendency to "push" the heat from the North side and stack it up on the South side.

Bigger radiators on the second floor that the first because there is no heat loss in a first floor ceiling that has a heated space above it. But the attic above the second color wasn't heated so you had a larger heat loss area. They KNEW.

If you want a warm house, put the thermostat in a North facing room, NW second and NE  last. For a cold house, put it in a East or SE facing room so the morning Sun can warm the room and keep the thermostat satisfied. And the rest of the house cold.

Dan wants us to learn from the old dead Steam Heads. The old dead wet heads have tales to tell too.