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3 zone boiler control

SOunds like a real mess..... First of all you should understand that radiant floors require much lower supply water temperatures to operate than other cast iron or baseboard radiation. So.. you have to mix the supply water temperture to the radiant floors below the minimum return temperatures of the Weil Mclain Gold series (130 Deg F ). There are different methods of mixing. It is very important that primary/secondary piping method is employed in the piping method. You should also have an outdor reset control to limit the temperatures to the system, that way you get longer heat cycles out of your boiler(s). Short cycling is no good. If you are doing multiple boilers, which is not a good idea for your it's very expensive to install, you should have a staging control to operate the boilers. Having one boiler for the radiant, seperated from the rest is very inefficient.

All control strategies depend upon how the system is piped and the type of devices are installed (pumps or zone valves).

I'd recommend A whole new Tekmar Control system....Throw all your other stuff in the garbage.

PLease visit to downloadable literature.. then go to all of the essays. That's a good place to start. Then get into the new tN4 system data brochures.

I'm not a salesman, but an installer. This is by far the best control system around.... Their controls are designed specifically for hydronic applications, and they've done lotta research to design their controls. All of the systems that we've put in are trouble free and work great.

Good Luck


  • Joshua Berne
    Joshua Berne Member Posts: 6
    3 zone boiler control

    We're (hopefully) nearing the end of a disastrous heating replacement. Our contractor put in 2 boilers, one for radiant on the second and third floor, one for radiators on the first floor and baseboards in the basement.

    We finally (after repiping everything) have the radiators piped correctly on the first floor for 2 zones. We have 3 thermostats controlling 3 circulator pumps for those 3 zones, through a TACO switching relay box.

    We currently have an SR-502 relay box, which obviously doesn't work for all 3 zones. (I foolishly thought that it supported 3 because the board in the relay has connections for all 3, but the 502 only has 2 transformers on it - one of the pumps is getting no power.) I can get a 503 and switch it out, and then we'd be able to control all 3 zones properly, but that won't solve our other problem.

    The boiler isn't controlled at all by the thermostats - it's on all the time, and brings its water to 180 degrees. This is fine for the radiant system, where the water is stopped to all zones by zone valves. For the radiators, there are no zone valves, just the circulator pumps on the returns. We had no pumps going for a day the first day we ran the system, and the heat went up by 10 degrees by the end of the day. (The heating installer obviously told me this was 'magic', and to read the instructions for my thermostats since that must be the problem.)

    I _think_ the solution is to switch the boiler as well when any of the thermostats are on. (So it won't produce any hot water if there is no demand for heat.) The problem is i have no idea what to buy for a relay box that can do that (control the pumps for each zone as well as switch the boiler on and off if any of the zones is on.) Can anyone suggest where to go to learn/what to buy for this? I'm totally lacking any confidence that the people who put this system in are ever going to get it right.

    (The boilers are Weil-McLain gold series, the radiators are all runtal, the thermostats are aprilaire communicating thermostats.)

  • Weezbo
    Weezbo Member Posts: 6,232
    you have vagarities that have quality materials...

    the only minor technicality is that the qualities combined are not producing a synergy of a Quality system.

    not seeing the piping layout completely within my crystal ball, i may have a few things a bit hazy....

    i happen to like zone valves..i see a taco ZVC 404 EXP, some zone valves, that communicates in your future and maybe a rib relay,...its domestic Hot water priority will take care of one of the Vagarities...or an AQ 2000 with some check valves on the three circs....

    the radiant system unless it has a boiler control and a system control and something was done to insulate for heat transmitting from floor to floor ,....( the reason a room gets overshoot sometimes has nothing to do with how well it is piped or wired) , it has everything to do with the basic laws of physics, it is a persistent problem and will not go away. insulation being a biggie in fluidly adapting to ones environment...magic boxes of any manufacturer can only do so much :) you would be better served to have someone, humor me on this one, stop by and cop a visual. try find a professional on the top of the page...

    or post a few JPEGS on the Wall it would help you get some second and third opinions...
  • Joshua Berne
    Joshua Berne Member Posts: 6

    We had intended to also get tankless hot water heaters for domestic hot water, but as we realized how clueless our installers were we chose to not go that route at all this year, and are staying with our old simple tank for now, so domestic hot water isn't an issue here.

    the radiant floors have a layer of bubble wrap underneath, and so far (it hasn't gotten really cold yet) we've been happy with them. It's the configuration for the first floor radiators that right now is totally screwed up.

    I'll try to get some jpegs uploaded.. but let me try to explain a bit better.. (i'm going to skip various valves and expansion tanks, just describing the layout)

    The output of the boiler splits into 3 loops. one goes through the basement baseboards and comes back. One goes through a loop to 3 radiators on one side of the first floor , one to 4 on the other side of the first floor. all 3 of these loops come back to circulator pumps, which then combine and feed back into the boiler.

    The 3 thermostats then connect to the three zone connections on the taco switching relay, The outputs from that relay then go to the 3 pumps.

    From what i know of it i think i'd prefer zone valves as well for these, but replumbing anything right now is not that much of an option. I have much more confidence in my own ability to alter the electrical layout. I also fully intend to find a professional to come in and re-evaluate everything that's been done, but we can't really follow up on that much until after winter passes again. (Sadly, we tried going with an all-in-one gc who proved to be good at nothing much at all in the end, instead of finding quality subcontractors for every step of the process ourselves.)

    So considering we have 3 zones to control, can't really put in zone valves at this point, and no domestic hot water to consider, what would you suggest for wiring up the boiler?

    I believe we need something that will let us continue to control the pumps, but also cycle the boiler itself when any of the thermostats are calling for heat. Is there any good place to learn about the options for relay controls like this?

    (At this point the elecrician that did the wiring is supposed to come in tomorrow to look at it again, so there's hope that he might make things right, but i really want ot be educated beforehand, and i want to be ready to do it myself if this doesn't pan out tomorrow. He informed me today that he quit working for the gc ages ago, and has only been coming here as a courtesy to me - the gc hasn't been paying him. We're in the new york city area and it's getting pretty cold, so i want to minimize the delay before we can start using the system as much as possible.)

  • Joshua Berne
    Joshua Berne Member Posts: 6

    I'd love to get a real control system in place, but we need heat right now, not after i've either learned enough to do that or found someone i can trust enough to do it for me. After we manage to get through this winter i'll be revisiting again our approach to finding contractors. (Our first round with this house we found our own plumber, electrician, etc... that proved to take a huge amount of time and energy to juggle. This time we went with a full-service gc, who proved to be a liar and incompetent, and took even more time and energy on our part to keep in line. There is no easy way to do this.)

    Right now i'm looking for a solution that works easily and with the plumbing we already have in place.
  • bobbyg_2
    bobbyg_2 Member Posts: 139

    If you look at the wiring diagram for the SR-502 or the SR-503 you will see a X1 and a X2 connection.

    The "room thermostat/ sometimes it's called R and W" connection for the boiler should land there on the X1 and X2 connections. When any zone thermostat "calls for heat" the isolated end switch (X1 and X2) will close, allowing the boiler to come on.

    I really don't think you have any business messing with it, if you can't read or understand the wiring diagram provided on the SR-502 (If you don't have the paper copy, the wiring diagram will be on the inside cover-I think).

    We are trying to tell you that even when you get the wiring corrected you are going to have major issues that have to be addressed or you could cause permanent damage to your system.

    You've been warned and helped, I hope.
  • Mitch_4
    Mitch_4 Member Posts: 955
    Try this

    I like the ARGO. Real simple, in your case use the ARM 4P, runs 4 zones (your 3 + futur indirect) Has end switch to control the boiler. and is expandable with the AZ-1 expansion module.

    If you need a good, basic, simple to install...this is the ticket
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