Convert a two pipe system to a one pipe system??

Steve Weeks

My house was built in the 1920's(??) and has a newer hot water boiler (w/ circulator) connected to an old cast iron two pipe system. Most of the rooms have old 26 inch high 5 column radiators, each with their own spply and return branching off of the main supply and return. We also have some a newer copper 2 pipe section (connected to old radiators) that just tees off of the main coming out of the boiler before the cast iron starts (those rooms are very hot). Many of the cast iron pipes in the basement are large and low hanging and we're going to finish the basement. There are also two large "dead-end" pipes (a supply and a return) that are no longer used but I assume are full of cold water. To get us the headroom we need and improve the efficiency, a friend suggested we convert the system to a one pipe copper system w/ monoflow tees. The supply and return to each radiator would remain unchanged since that would be hard to replace. I wanted to convert to copper but keep it a two pipe system because I am worried about temp. drop as the water runs through all of those big radiators (it's a 2,900 s.f. house). I don't want to spend alot of $ and end up with the same balance problems we already have. We also have some cast iron baseboard in the house. Any thoughts?? Thanks.

Charlie_10

Ballance

The problem of balance may be do to the mixed radiation you have in the home.
Repiping the system can be done. You will loose heat in the basement area, so consider this.
Radiators and copper fin tube require different operating temperaturers so a primary/secondary loop arangement will be nessessary to supply high temp to the fin tube and mixed temp to your standing radiators.
There are numerous control packages to work with this and provide the comfort level you require.
We see this mistake all too often in the Albany, NY area.

Steve Weeks

Would you go to a one pipe system or stick with a two pipe design? One web site I found suggests converting to a two pipe reverse return system instead of a one pipe system, but I don't know what that is.

Ed_22

Balance

There are a few different options you may want to consider. The first thing you want to install into your system is either a control that immediately turns the circ pump on with the burner or wire the circ to run continuously with a low limit control to shut it down after the boiler turns off. I have done work in countless older homes, mine being one, and found this is the most important issue as many older systems were designed prior to circulating pumps. If you choose to raise the mains throughout the basement, one monoflow per radiator is suffient but not always needed. This will save on the amount of overall water being heated as well as acheiving your temperature sooner, hence, more economy.

Ed_22

Balance

There are a few different options you may want to consider. The first thing you want to install into your system is either a control that immediately turns the circ pump on with the burner or wire the circ to run continuously with a low limit control to shut it down after the boiler turns off. This will ensure each radiator or baseboard section heats and cools at the same temperature. Radiators hold heat longer which has to be a consideration of mixing in the system. I have done work in countless older homes, mine being one, and found this is the most important issue as many older systems were designed prior to circulating pumps. If you choose to raise the mains throughout the basement, one monoflow per radiator is suffient but not always needed. This will save on the amount of overall water being heated as well as acheiving your temperature sooner, hence, more economy.