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Existing monoflow to reverse return

I have a 1.5 story cape home on 1 zone with an unfinished basement that I plan on finishing, so I'd like to add some emitters to my first floor  and the new basement. The house has 4 recessed convectors and the rest is fin tube. I am planning on adding a 2' section of fin tube at the front entry and a toe kick heater in kitchen. The basement I plan on adding roughly 15' of fin tube. 
- My system works well as is but 2nd floor gets hot. Thermostat is on first floor. 
 I like the idea of reverse return and having thermostatic valves on 2nd floor.  Any issues with having emitters below the main on reverse return? Do I need monoflow tees to force the water down? 
Will toe kick heater need monoflow?


  • Jamie Hall
    Jamie Hall Member Posts: 16,618
    The existing system is a monoflow system? And you want to convert it to a reverse return system? No particular reason why you can't do that, but you will need to do some rather significant repiping at least in the basement level, and possibly higher levels depending on just how the monoflow system's single circulating line is piped.

    Basically, all the radiation takeoffs will need to have the monoflow Ts removed, if they are on the feed lines. All the returns will have to be separated from what will become a supply main and attached to a new return main (again, no monoflow Ts remain). Additional new radiation -- such as the toe kick -- can be piped in the usual way fed from the supply main and returning to the return main.

    But honestly, if the existing system is working well, I'd leave it alone and just pipe new radiation as reverse return. That doesn't solve the overheating problem on the second floor, though...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EBEBRATT-Ed Member Posts: 9,727
    leave the monoflow as is and use trvs on the second floor. Add your new radiation and kick heater using new monoflow tees.

    Pipe the basement any way you wan't. It will be a small zone so you could use direct return or reverse return
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 2,910
    edited September 18
    I like the idea of reverse return and having thermostatic valves on 2nd floor.
    I like it, too! Get rid of the Corvair for the Cadillac. Monoflow system problems are a constant topic here on HeatingHelp.
    Any issues with having emitters below the main on reverse return? Do I need monoflow tees to force the water down?
    No problem; Monoflow tees not required.
    Often wrong, never in doubt.
    EBEBRATT-Ed Member Posts: 9,727
    What @Alan (California Radiant) Forbes said it fine if you can afford the Cadillac. You basically going to repipe everything
  • pauliewalnutz
    pauliewalnutz Member Posts: 4
    So I should have said that initially, I plan on repiping since the main that runs in the basement perimeter is pretty low and a fair distance off the wall, probably about 6'-2" off the floor and 18" of exterior wall. So I want to run pex through the floor joists to raise that pipe above the new ceiling. The supply and return from each convector and fin tube are 1/2 " and easily accessible. 
    My thoughts on the reverse return was that I might be able to keep everything on one zone still not worry about adding any circulators and getting a new relay and not have to pull wires from the 2nd floor.
    EBEBRATT-Ed Member Posts: 9,727

    Here's the thing. If you are going through all this trouble to re do the system don't take a chance on it not working.

    I wouldn't use TRVs on the second floor they are ok to try and fix a problem job but why not fix it once and for all. Pipe the second floor as it's own zone. If you don't you will regret it and it's not much more work. I am sure the second floor monoflo drops originate from the basement so you can pick them up their.

    Unless your house is huge I wouldn't bother with reverse return especially on the second floor

    It's not that hard to get a stat wire to the second floor. Put a zone valve for the first floor and one for the second floor use the existing relay and your all done you only need one pump.

    Make sure to buy zone valves with end switches. Use the Taco zone valves some of the others have a high pressure drop.

    Measure up your baseboards , kick space heaters etc and we can help you size the pipe etc.
  • pauliewalnutz
    pauliewalnutz Member Posts: 4
    Sounds like a good idea with the zone valves. If I run the first floor and basement on one zone that's a monoflow and my 2nd floor a series loop, will I have balaNcing issues when both zones call for heat?
     The existing 2nd floor has 3 rooms all with fin tube piped in series and at the end of the series the pipe is fed from mono flow tee in basement. At some point changes were made upstairs and the supply and return for each individual fin tube to the main was deleted and  tied together in series.
  • pauliewalnutz
    pauliewalnutz Member Posts: 4

    EBEBRATT-Ed Member Posts: 9,727
    Any zone that heats differently needs to be it's own zone. The basement will heat much differently than the 2d floor and they both will heat different than the first floor.