Radiant heat isn't able to keep master bedroom over garage warm.

Discussion in 'HVAC Heating & Cooling' started by JPendergrast, Dec 21, 2019.

  1. JPendergrast

    JPendergrast New Member

    Joined:
    Dec 21, 2019
    Location:
    Albany, NY
    I live in Upstate NY to give you an idea of the winter temps I am dealing with. My system is about 16 years old and recently I have noticed the master bedroom temperature hovering around 60 degrees when the thermostat is set to 72 or above. The temperature at the manifold going to that zone seems to be at target, however there is a drop off at the manifold in the access panel in my closet. I have changed out the pump, and flushed the pex with water from the basement out of the manifold in the closet( it seems as if the pressure is ok). I'm concerned there is blockage somewhere in the circuit. I have hard water and have had issues with mineral build up in the past. How do I tell if this is the case? Also, after I bought the house I drained the garage heat tubing thinking my kids would leave the garage doors open during the winter and I didn't want to heat the outside. That being said, I don't remember the room being to cold in the past. I can post pics of the system if that helps. Any help would be appreciated. Thanks
     
  2. WorthFlorida

    WorthFlorida The wife is still training me.

    Joined:
    Oct 28, 2009
    Occupation:
    Retired
    Location:
    Orlando, Florida
    I assume it was OK last winter? What do you mean by "drop off"? Is the master bedroom on the first or second floor? Is the first floor wood or concrete? Is it radiant heat in the floor or baseboard? You are sure the garage and master are separate from each other? Each has its own circulator and loop? It might be possible that you have an air dam. Hydronic heating is a closed system and hard water should not cause any built up since it doesn't evaporate and leave behind minerals. Where the PEX enters the room does it feel hot and on the return side does it feel cold or warm? At your manifold is there a mixing valve to lower the water temp from the return side so the temperature of the hot water is lowered? This is to prevent too high of the temperature circulating under the floor. Any thermometers to read the temperature of the water?


    mixing valves inside yellow circle
    manifold.jpg
     
  3. Sponsor

    Sponsor Paid Advertisement

     
  4. JPendergrast

    JPendergrast New Member

    Joined:
    Dec 21, 2019
    Location:
    Albany, NY
    Thank you for the reply. It actually wasn't okay last winter, I had planned to look at it over the summer, but life got away from me and I got put on the back burner. The winter before that it was okay. When I mentioned drop off the temperature leaving the impella is greater than that of the temperature at the manifold in my closet. Last year I cut a hole in the wall thinking that it was losing temperature going up through the wall in my garage because it's cold in there and re-insulated the copper tubing. Unfortunately, this didn't do anything. I also switched out the pump for that specific circuit. Went from a takeout 007 to the 008 thinking that it might need a little bit more power to get it from the basement to the second floor. I'm 100% positive that the garage and bedroom are on different circuits. And answers you to your question about the tubing entering the room is definitely warmer than the tubing exiting the room. I was able to take a couple pictures last night of my system..
     

    Attached Files:

  5. WorthFlorida

    WorthFlorida The wife is still training me.

    Joined:
    Oct 28, 2009
    Occupation:
    Retired
    Location:
    Orlando, Florida
    Do check the mixing valve for the master bedroom zone. You might want to close it to get hotter water to circulate for that zone. With a infrared thermometer, at the pipe entering the bedroom get a reading on it and then check it leaving the circulator manifold. That will tell you if you are losing heat between the floors but I doubt it since you did insulate it.
     
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
    Sep 2, 2004
    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    DId it ever work right? If so, was that when you had the garage loop running? If that is so, you may not have enough capability to overcome the lower temperatures because the garage is not warmer, sucking heat from the master.

    Is there insulation in the garage ceiling? If so, how much? Without insulation, the radiant heat will go down as well as up. Heat always goes from a warmer surface to a cooler one.

    Do you have any heat distribution plates on the pipes running in the master bedroom?

    Is that piping pex or copper in the floor? If in the floor, is it embedded in something like gypcrete?

    Is it staple up or embedded?

    What temperature do you send into the loop?

    What temperature does it return at?

    How long is that loop?

    You may be able to raise the temperature of that loop. The zone valve may not be fully opening.

    Does that zone valve have a manual open lever? If so, manually open it and see whether that helps. If it does, you may need to replace the head or the whole valve, depending on the type. It may not be opening fully. The larger pump is probably overkill and over time, might lead to premature erosion in the piping. It might also create some water flow noises.

    If you want the garage to be warmed, that would entail replacing the water with a glycol antifreeze mix. TO avoid doing the whole house, you may consider adding a heat exchanger to keep that zone separate, and thus, only put antifreeze in that one versus the whole. If the system wasn't designed well enough to keep up with the heat demand as is, adding glycol will decrease the heat transfer capability of the system by about 10% if I remember my numbers correctly. Pure water transfers heat better than the glycol mix.
     
  7. JPendergrast

    JPendergrast New Member

    Joined:
    Dec 21, 2019
    Location:
    Albany, NY
    It did work right for the first ten years we lived in the house. The copper transitions to pex up on the second floor where it is stapled to the subfloor. There is heat shield between the insulation and tubing. The temperature going into the loop varies with the outside temperature there is a taco pc 702 controlling the electronic switching relay. I have adjusted the control and control valves trying to boost the heat but haven't had much luck. I'll upload the specs that came with the system, I don't completely understand all the terminology.

    Also, I have looked into adding antifreeze to the system, just not sure how to get in and mix with the existing water. Appreciate your time and input.
     
  8. JPendergrast

    JPendergrast New Member

    Joined:
    Dec 21, 2019
    Location:
    Albany, NY
    15770414424906143972054403105308.jpg 15770414424906143972054403105308.jpg
     

    Attached Files:

  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
    Sep 2, 2004
    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    Are you getting the design delta T on that loop? It doesn't take much air in the system to stop the flow. It could be as simple as air lock.

    If you didn't want antifreeze in the whole system, you'd need to add a heat exchanger. Then, you'd only need the antifreeze for that one loop. It would require its own pump.

    If the return water is really cold and much lower than the inlet, it's likely that it's not actually flowing. If you have, or can borrow, an infrared camera, it would be fairly obvious seeing the heating tubes, and how far the heat went. Even with no flow, there might be a little bit of convection in the loop up to the air lock. You can use an infrared thermometer, but it's not as easy to tell.
     
  10. Dana

    Dana In the trades

    Joined:
    Jan 14, 2009
    Location:
    01609
    Adding antifreeze REDUCES the heat transfer efficiency of the water, which is likely to aggravate whatever condition is holding it back from keeping up with the load.

    If there aren't check valves on all zone pumps you could end up with reduced flow under some conditions due to back pressure/backflow issues.

    A $200 FLIR IR camera using your cell phone or tablet computer as the display can be a useful debugging tool for finding blockages or low flowing loops. Just be aware that bare copper or other bare metals have very low IR emissivity, and are going to read substantially colder than they really are, but painted pipe and PEX have the right emissivity range to deliver pretty reasonable temperature readings.
     
Similar Threads: Radiant heat
Forum Title Date
HVAC Heating & Cooling Radiant Heat PEX recomendations Aug 25, 2020
HVAC Heating & Cooling Radiant Heat Mechanics Feb 23, 2020
HVAC Heating & Cooling Radiant Heat System Design Aug 29, 2019
HVAC Heating & Cooling Bathroom remodel - electric radiant floor heating? Feb 4, 2019
HVAC Heating & Cooling Radiant Heating Not keeping up Jan 22, 2019

Share This Page