Adding radiator to 2 pipe hot water system

DiyEverything

Hello everyone. I'm back, in need of more help. I have gas fired hot water 2 pipe heating system. With cast t radiators. I want to add a small radiator in the second floor, to a closet that is going to become a bathroom, another one on the first floor cause I'm closing in my front porch and making my living room bigger. And one in my finished attic where my sister is living. The attic isn't terribly cold , but she does use a space heater. I have the extra BTUs on the boiler. If necessary I'll upload pictures. Thank you in advance for all the help.

Jamie Hall

Doing so may or may not be very simple. It depends on how the rest of your system is piped. Can you describe that?

DiyEverything

It's all one zone. Currently have 6 radiators on the first floor and 3 on the second floor. I'll take some pictures when I get home. From the boiler it has an 1 1/4 copper main and 3/4 branch lines that feed the radiators and anther main that has all the return lines. One circulator pump.

Jamie Hall

OK. So each radiator is fed individually from the feed main, and then returns to a return line? That makes it easy. Or at least easier... If I were doing it, I'd run a nice new feed to each of your new radiators -- 3/4 inch would be fine, but even half inch might work if the spaces are tight. Then a similar return back to the return line.

DiyEverything

Will I need to use regular tees or flow tees? Will I need to increase the temp the boiler operates at. I think the feed water is around 140 right now.

EBEBRATT-Ed

If you don't have monoflow tees on th e system now you don't need them. You said it was two pipe system

DiyEverything

Yes it's a 2 pipe. How do I know if it has them?.

Jamie Hall

Monoflow T's have an arrow on them. That said, if a particular radiator is fed from a T with a lateral to the radiator, then the pipe coming back from the other end of the radiator goes to a return line -- not the same line the feed came off of -- it's a parallel flow system, not a monoflow system. If it comes back to the same line it came off of, about the same distance as the length of the radiator, then it's a monoflow.

Alan Welch

You might want to consider making the second floor a separate zone, and use the tees that feed those radiators to feed the new downstairs heat.

DiyEverything

I would definitely like to make the second floor its own zone. But I would have to figure out how to wire the second thermostat and circulator pump or zone valves. It's definitely a parallel system.

DiyEverything

Sorry it took so long. Work is work. I looked and there are no arrows on the tees. How much work would it be to put the second floor on its own zone.

Alan Welch

In the first picture, the brass tees might be monoflo, look at them closely. As to what is involved, you might want to get prices from heating contractors. You will need a thermostat, relay, circulator, flow control valve, wiring, piping , isolation valves, will need to drainthe system to cut in to the supply and return piping, then refill and bleed the radiators after taking the second floor radiators off what will become the first floor zone. Probably not something that you want to do this time of year if you don't have to. That's in addition to the new radiators getting placed and piped into the basement.

DiyEverything

I'll definitely wait till after winter to do any work. BTW what is that green fitting? What does it do? It is very old, and I doubt it still does what it used to. I think I'm going to put the second floor on its own zone and a another bathroom on a zone for a total of 3. I'd prefer to use a relay with separate circulator pumps, I'm sure I can find vids how to do it on YouTube. When I add a tee on the feed to a new radiator does it need to be a minimum distance from another or does it not matter on a 2 pipe system? Also has anyone ever put small fans on the back of the radiators to circulate the air in the room?