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  1. #1
    Join Date
    Jun 2011
    Posts
    21

    zoning an existing hydronic system

    I'm considering making some modifications to my hot water heating system with cast iron radiators, to have some zone control. There are only 2 people living in the house, and there's no reason to heat more than the bedroom overnight. I only need 2 zones: the bedroom, and everything else.

    I think it could be done using a thermo electric radiator valve (see link below) strategically placed in the basement to choke the flow to the risers and radiators in rooms I don't want to heat. I'd like to find a programmable thermostat with remote sensor capability that can also control these valves.

    It would have a "heat whole house" mode where the valve is open and the boiler is controlled to keep the living room thermostat satisfied. It would also have a "heat bedroom only" mode where the valve is closed, blocking flow to everywhere except the risers to the second floor bedroom, and the boiler is controlled to keep the bedroom thermostat satisfied.

    I'm just curious of the opinion of anyone who has seen this sort of modified system. Is there anything to worry about with regards to closing the valve on the majority of the house? The valve would block flow to 6 of my 7 radiators while allowing flow only to the other 1. Is this type of control common in residential applications? Am I going to have a hard time finding a thermostat that will do this?

    Thanks in advance for your input.

    thermo electric radiator valve:
    Sites that direct sell, or post prices are not allowed to be linked to
    Last edited by beenthere; 10-03-2011 at 06:14 PM. Reason: removed link

  2. #2
    Join Date
    May 2004
    Location
    Frederick, MD
    Posts
    1,058

    The valve

    you showed is just what is says. A RADIATOR valve, designed to go each individual radiator. You should probably consult a pro and have them look at your entire piping system. Cutting flow to some radiators could put your whole system out of balance or stop flow completely.
    GO NAVY, BEAT ARMY!

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  3. #3
    Join Date
    Jun 2011
    Posts
    21

    contacting a pro

    As an HVAC designer myself, I like to have a good idea what I want done before having a contractor out to tell me I need more than I really do. You're right, I linked to the wrong valve, that was the one I was looking at when I was thinking about putting them at every radiator.

  4. #4
    Join Date
    Jun 2011
    Posts
    21

    i meant to link to this valve

    Sites that direct sell, or post prices are not allowed to be linked to
    Or something similar to this, I should say. I haven't dug into the details of valve selection just yet. At those point I'm just trying to figure out if its a good idea or not.

    Thanks for catching that
    Last edited by beenthere; 10-03-2011 at 06:44 PM. Reason: removed link

  5. #5
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,770
    See note in your post.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  6. #6
    Join Date
    Jun 2011
    Posts
    21

    oops

    Okay, I didn't really want to get into the details of the valve anyway. What I really want to talk about is flow problems that might occur, and controls.

  7. #7
    Join Date
    Feb 2008
    Location
    Massachusetts
    Posts
    702
    Most cast iron hotwater radiators are piped in a parallel loop, you could isolate each room with thermostatic valves at each radiator, not always easy removing the old shutoffs to pipe these in.
    Trying to use zone valves at the boiler to isolate the parallel loop will shut off whatever radiators are fed off that riser, but you might have flow issues, and get airbound on your top floor radiators.

  8. #8
    Join Date
    Sep 2002
    Location
    Northeast Ohio
    Posts
    4,855
    It's hard to say without actually seeing the piping layout. It may be possible or then again........................There is a lot to consider and the actual savings realized might be disappointing. Re-piping at the boiler and having the 1 or two isolated radiators plumbed back to a new manifold might work but it will take a wet head on site to tell you if the magic will work.
    A good HVAC tech knows how, an educated HVAC tech knows why!

    DEM


  9. #9
    Join Date
    Mar 2010
    Location
    NJ
    Posts
    327
    I would greatly advise against completely shutting down any large portion of radiators for a long period of time. The money you think you'll be saving on "setback" will quickly go away when you need to heat up all those cold pipes and radiators again. Plus, your conditioned room will now have a greater heat loss due to the rest of the house being a colder temperature, so the radiators in that room will now be undersized. You'll wind up with higher fuel bills, and less comfort. The solution may be in Thermostatic Valves, as mentioned before. You'll have to manually adjust them every time you want the temperature to change, though.

    There really is no cheap, or easy solution.

  10. #10
    Join Date
    May 2004
    Location
    Frederick, MD
    Posts
    1,058

    Heaven help

    Quote Originally Posted by mlstark View Post
    Most cast iron hotwater radiators are piped in a parallel loop, you could isolate each room with thermostatic valves at each radiator, not always easy removing the old shutoffs to pipe these in.
    Trying to use zone valves at the boiler to isolate the parallel loop will shut off whatever radiators are fed off that riser, but you might have flow issues, and get airbound on your top floor radiators.
    him if it's diverter tee!
    GO NAVY, BEAT ARMY!

    A DECADE OF DOMINANCE! +3

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