Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

GB142 - RC10 control?

This question is really for Mark Hunt because he has seen the pictures of our install.
We have a GB 142/24 with a phase III indirect and 5 zones. 1 in concrete slab, 3 in staple up radiant and 1 for baseboard. The installer has the boiler set to 190 deg to feed the 1 baseboard zone and has mixing valves with circ pumps on all the other radiant zones. We have been told that this will never allow the boiler to modulate, so we should have saved our money and bought a cast iron boiler. The installer thinks that hooking up the RC 10 in the upstairs baseboard room will fix this and now allow the boiler to modulate.
We now understand that this system has faults and that this control may or may not help with overshooting but nearing the end of our project and almost out of money we are looking to fix if possible.


  • John_82
    John_82 Member Posts: 63

    It's only an on/off boiler when you wire something to TT that will fire the Burner. If you have an Argo panel, just don't go back to TT and the circs will run independant from the Boiler. Try lowering the boiler water temp. Maybe you only need that 190 when it's zero outside. Bring it down from the AUT setting and it should modulate just fine. It has sensors in the supply & return & that's how it modulates. The RC10 only fine tunes the modulation, it isn't what makes the unit modulate. If you decide to use the RC10 remember not to wire anything back to TT on Boiler control. I hope this helps. With the amount of radiant on the job, this boiler should condense in spite of the high temp zone!! You won't be dissapointed in the product!
  • Brian (Tankless)
    Brian (Tankless) Member Posts: 340
    I don't know if the

    supply & return sensors are mounted in "wells" or are strap-on-the-pipe type.

    If they are standard two-wire themistors, which are clipped/clamped to the piping, they must be insulated to prevent ambient "interference" with the readings.

    I learned this the hard way. I helped install & commission a huge network of monitoring & control systems for refrigeration efficiency, in hundreds of supermarkets all over the U.S.

    The entire thing (hundreds of thousands of sensors) was Sat-linked "home". Something was wrong, it wasn't working as planned.

    You've guessed the problem, yes?

    We had to go back to 100's of Kroger Stores, and wrap at least 64 sensors on comp' suction & discharge lines. "They" knew as soon as we did the first store, that that was the problem.

    I drove from Lake Charles, LA. to Nashville, TN. just to wrap foam insulation around sensors. Good money while it lasted, and they are saving millions.

    I could have saved them millions more, but they wouldn't listen to a guy with no B.Sc. after his name, oh well.

    It's all in the little things.

    Good luck and Happy New Year.


  • Mark Hunt
    Mark Hunt Member Posts: 4,909
    RC10 control

    controls everything. If he wires the boiler that way, all of the other zones become slaves to the RC10 controlled zone. If the RC10 zone doesn't call, the boiler will not fire and your other zones will have to wait until the RC10 zone brings the boiler on.

    This will not solve the issue.

    Mark H

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
  • Dave_22
    Dave_22 Member Posts: 232

    Your GB will modulate based on supply and return temperature in the GB itself. It's too bad that it is set to 190 for the baseboard-that doesn't have a chance to condense. If your loads are matched well, I would try the RC-10 and you may possibly get some condensing and longer run times. It does require a good reference room that represents most of your house. If not keep your ears open for the upcoming outdoor reset function.
  • Brian
    Brian Member Posts: 285

    How long is your baseboard?Can it be made longer so you can run at a lower temp. to take advantage of the condensing features of the boiler.I always oversize my baseboards so I can run the radiant and basebord at the same temp.Baseboard is cheap,fuel isn't.

    Good Luck
  • Brian
    Brian Member Posts: 285

  • Joe@buderus_2
    Joe@buderus_2 Member Posts: 302
    Supply and Return Sensors

    The supply, return and safety sensor are installed in a "wet" location in the flow stream. They are not strapped on. The GB142 will modulate based on delta T. With an RC10 the other zones are "slaves" to the RC10 - system temperature. Suggest trying the RC10, but make provisions to return to on/off operation if not providing satisfactory results. What is the return temperature of the radiant? Thanks,
  • Mark Hunt
    Mark Hunt Member Posts: 4,909

    This person has multiple zones with drastically different requirements than the MASTER RC10 zone will have.

    The RC10 is NOT an option in this case.

    Mark H

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
  • Joe@buderus_2
    Joe@buderus_2 Member Posts: 302

    Thanks for the information and input.
  • dave_85
    dave_85 Member Posts: 2
    GB142 and RC10

    Guys, when using the RC10 on a reference zone with T-Stat controlled slave zones; this will only work properly if the reference zone is at least twice the load of any individual slave zone. When you have a mix of temps in one system; remember that the mixed return temp will be more critical to efficiency than modulation. Condensing boilers are always best applied to low return temp systems. Lets not oversell the equipment. This is a great product if applied correctly.
  • Mad Dog_2
    Mad Dog_2 Member Posts: 5,864
    C'Mon Central Vermont...........................................

    When are you going to get a knowledgable pro out to the house....???and once again, why are YOU asking these questions and NOT the installer? You nearly had a MAJOR catastrohpohe!!!!!!!!Are you that much of a gambler. Just concerned! Mad Dog

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
  • Darin Cook_2
    Darin Cook_2 Member Posts: 205
    Parade Rest -- Matt!!

    The issue is being worked. Mark has talked to the HO and the builder who was poisoned. Hopefully the builder will not be using this guy again. I know I would not be. The plumber did not call till three days after the poisoning incident to see what was going on. It sounds like a bit of a money pinch is on now for central vt. A real crying shame. But for all intents and purposes the system needs some real reworking ( piping and controls ). Its too bad we had wanted to do that job but due to logistics we could not. If I had done that install it would have been another customer we never heard from again.

This discussion has been closed.