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Installing radiant panels after radiant floor was installed

Mo9013
Mo9013 Member Posts: 6
At the moment I installed radiant floor heat in three rooms of my house during the summer as I renovated. Each room is zoned separately ( thermostat in each room) and a mixing valve to drop the 180deg to 100deg for the radiant floor. I have 3/4 hardwood floors. The rest of the house is still baseboard heat. the system works great, but the runtime is around the hour range to heat each room and the overheat is anywhere from 5 to 8 degrees. I set it at 65 and it will go to 70 to 73. I was thinking of adding radiant panels as a fast heat source to cut the run time down and run them at 140 - 150 to cut down the run time but still warm the floors and keep a steady slow heat. I'm not positive on what the BTUs of the panels should be. I was thinking 2/3 of the total BTU for the room. There also could be a better way of doing it. I would appreciate any ideas or help.

Comments

  • Ironman
    Ironman Member Posts: 7,088
    edited October 2018
    Without knowing more about your system, my initial response would be that you need a mixing device that works off of outdoor reset that would vary the water temp to the floor according to the actual load.

    What kind of thermostats and mixing device do you now have? What make/model of boiler? Did you install heat transfer plates?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    Rich_49
  • Zman
    Zman Member Posts: 7,435
    Run time is good. In the perfect system it would never stop running. The overshoots you are experiencing are likely caused by the water temps to the floor being too hot. They also occur when you use setbacks and are trying to warm the room up too quickly. Setbacks and radiant heat are not a great combo, you can actually use more energy because of the overshoot, "set it and forget it"
    You might consider using a mixing valve with outdoor reset like the taco I-series.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    Rich_49
  • DZoro
    DZoro Member Posts: 1,048
    Floor sensing thermostat, along with all of the above suggestions. Maintain constant temperature no set backs.
  • Mo9013
    Mo9013 Member Posts: 6
    I have Buderus GB142 with AM10, delta t calculators, and mixing valves without outdoor reset . If that run time is good then I'm not worried about the over shot. I figured it was because the water temp was to high but I was afraid to lower it causing the boiler to run longer. I guess I'm not use to Buderus gas boilers. I'm used to a boiler cycling and not staying on through the hole heat cycle. It feels like I'm using more gas then I should. I guess if I'm worried about gas usage I should experiment with the boiler BTU out put to find the proper load for the house. Eventually the hole house will be floor heat except for the basement. I already have 6'8" ceiling and I have no plans on making them lower.
  • Ironman
    Ironman Member Posts: 7,088
    If you have the AM10 reset curve properly set, then you should only see 180* SWT on the coldest night of the year. I believe the factory default targets 180* at 14* ODT.

    That being said, if you adjust the mixing valve(s) down more, they should to some degree mirror the boiler's reset curve.

    I'd also recommend that you use Tekmar 519 thermostats which are designed specifically for radiant floors.

    Taco iSeries valves have ODR, but you may have to set the delta T circulator to a fixed speed if you install that.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    Tinman
  • Mo9013
    Mo9013 Member Posts: 6
    Thank for all the tips. I did look into the Tekmar 519 and will test it out on the next remodeled room. Wish I knew about them before I did the bathroom with warmboard and tile. I Wanted to go back and do a heat loss again and this time do it with the am10 control in mind plus also do a heat gain for ac. The calculator I used before I can't find online and all the ones I find now are dumb down. Does anyone recommend a good calculator?

    Also, I remember someone posting on here that they were going to use the am10 to heat one zone and a high load to heat the other. I have been looking for that post to see how he did it because It would work in my situation. I can use the high load on my high temp side and the am10 to control my low temp side. it would help with the short cycles when only the low temp side is running. I also have been getting a P-code. I watched the system and I noticed the short cycles. after about 4 it would throw that code. I checked my btu output and it was 80 so I lowered it to 50 which is closer to my total heat loss and stopped getting the code. So I think that the high and low trick will fix a lot of problems.