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Two and a Half Zones?

Stovepipe Member Posts: 5
edited November 2018 in Domestic Hot Water
I would appreciate some informed thoughts on putting heat in an add-on room.

The original system was one zone with a flow control valve and a pump. That's four radiators on the first floor, three on the second. Each floor is roughly 1000 sq ft., radiators roughly 48" x 30" x 4" (bathroom smaller). A second zone was added to the basement (another thermostat, flow control valve, and pump). It's about 80 ft of 3/4" copper pipe; 20 of that is fin-tube. It works just fine.

When a first-floor room was added, the basement loop was split. Part of the loop went to fin-tube in the new first-floor room. The flow that doesn't go to the new room returns through the basement loop into the boiler. But the flow that is diverted to the new room returns through the original zone. Thinking about that just makes my head hurt.

When the pipe in the new room froze and burst, I just got rid of it altogether. But when I remarried, my cats were evicted from the new room, and it was turned into our new kitchen. My wife wants heat in the kitchen.

I have all the old fin-tube; I can just solder it back in. (I also picked up some cast-iron baseboard radiators that I understand give really nice heat.) I figure someone out there probably knows a bit more than I do, especially concerning the way the zones have been interconnected.

"A" is the original system: (1) thermostat, (1) 1-1/2" flow control valve, (7) radiators on two floors, (1) pump at the return inlet on the boiler.
"B" is the basement loop: (1) thermostat, (1) 3/4" flow control valve, ~20' 3/4" fin-tube baseboard radiator, and (1) manual valve added before the loop was split.
"C" is the fin-tube baseboard radiator that was added in the new first-floor room, later removed when it burst.
"FCV" Bell & Gossett "SA" Flow control valve.
"V" Manual 1/4-turn ball valve.
"P" Pump (Little Red Booster, I think)


  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
    How do you not get flow thru both zones when either circulator is running?
    HVACNUT Member Posts: 5,764
    The first thing that grabbed me was one zone, two floors.
    Is zone "A" a monoflo system?
    One perimeter loop around the basement with branches to each radiator?
    And "C" was cut out so now theres the original loop and the added basement loop.
    If the main is monoflo, it would be best to make the kitchen it's own zone.
    You'll need to do a heat loss on the room and see if you have the linear feet for fin tube.
    The easy way would be to install 2 zone valves north of the basement circulator. One zone for the kitchen, one for the basement.
    But I bet your new wife would love radiant floor on the kitchen.
  • Stovepipe
    Stovepipe Member Posts: 5
    edited November 2018
    1) Monoflow.
    I can only see the way the pipes are arranged for half of the radiators on the first floor. That is the sketch I'm attaching. So a 3/4" black pipe runs from the main 2" pipe to each radiator. Then another pipe runs from the radiator back to the main 2" return. I can't see how the second floor is set up. There was a radiator where the door to the new addition is placed. The return for that missing radiator is gone is where the third "loop" goes. And I'm about to read up on monoflow.
    2) Flow.
    When the Flo-Control valves are working, one thermostat does not cause flow in the other zone. It would seem that the basement thermostat would not put much heat in the kitchen side loop, but I remember that it did actually work. Maybe enough water was forced in so that the main pump wasn't necessary to get the kitchen flowing. But this is just guessing.
    3) A Possible Solution.
    So the kitchen side loop empties into the return from the radiator that was removed. Why didn't they use the supply from that radiator for the kitchen? It's on the same floor as the main thermostat anyway. Looks like I need to rip out some drywall.