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Radiant floor heating won't turn on

I recently moved into a house which has an addition heated with radiant floor heating. The problem is I can't seem to get it to operate. When I move the thermostat, I hear a click in the control box but nothing happens. I am doing something wrong or is it a defective part?


  • GordyGordy Member Posts: 7,122
    What is the heat source?

     That heats the water for the radiant floor in question. What type of heat does the rest of the house have?

  • DavidMichaelDavidMichael Member Posts: 6
    The heat source

    The heat source for the radiant flooring is a gas fired A.O. SMITH hot water heater. The rest of the house is forced hot air.
  • GordyGordy Member Posts: 7,122

     When you turn the thermostat to the desired setting does the pump turn on? Some pumps are very quiet.

     Is the water heater on?

     What type of radiant floor? Slab, gypcrete, staple up, ect.

    If you can verify the pump is running, and the water heater is running. Then check to see if there is any exposed supply piping to feel if it is warm. Do the same with return piping to the water heater.

     Thats a start.

  • Jean-David BeyerJean-David Beyer Member Posts: 2,534
    What is the heated floor?

    My house downstairs is built on a concrete slab that has copper tube in it for heating. The thermal mass of that is enormous. If I make a change in the temperature setting on the thermostat, I may notice a temperature increase in a few hours, but it takes about 6 hours to be sure and I normally do not check for 24 hours. So if yours is the same, the only way to tell if the system is responding to the thermostat is to look at the supply and return temperatures from the boiler. On mine, that is easy because the controller reports which thermostats are calling for heat, which circulators are running, the firing rate, and the supply and return temperatures -- all on the front panel. The circulator for that zone is a Taco 007-IFC, and I cannot hear it from inside the house (boiler is in attached garage).

    If you do not have temperature gauges for supply and return, you can feel the pipes. I use outdoor reset, so I can just touch the piping to see if it is running or not (although unless the circulator were seized up). If you are running more than 120F water, you might want to be careful about touching the pipes. Touching the circulator is less helpful because it runs a little hotter than the water, and would probably be hot even if it were seized up.
  • DavidMichaelDavidMichael Member Posts: 6
    Pump does not come on

    Although the thermostat causes the control box to click when turned up, the pump simply does not start. The slab is concrete and the water heater is on. The supply and return lines are stone cold.
  • GordyGordy Member Posts: 7,122
    edited February 2011
    More questions

      Some pics of the waterheater/control area would be helpful if possible.

    Have you used the system before, or is this the first time since purchasing the home?

    Sounds like the pump is possibly locked up. What type of pump is it brand/size?

  • DavidMichaelDavidMichael Member Posts: 6
    Here's a Picture

    Here is a picture of the tank and pump. The tank for the radiant floor is on the left.
  • Mark EathertonMark Eatherton Member Posts: 5,592
    edited February 2011
    That pump....

    if it has locked up bearings, it will let you know. It has a thermal overload protection circuit. It also has spring couplers that can and do fail, and if it does, the motor will spin, but the pumps impeller won't.

    A visual inspection between the pump motor and the bearing assembly will confirm or deny the presence of a coupler.

    An electrical tester will confirm or deny electrical availability. If it has 120 volts getting to it, and the motor is not spinning, you need a new pump.

    Is that heater dedicated to the heating use, or is it doing both DHW and heating with the same water?

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • GordyGordy Member Posts: 7,122
    More pics

     Up higher, and different angle.
  • GordanGordan Member Posts: 891
    Can you post a few more pictures?

    Is there an expansion tank anywhere? What's the rating on the pressure relief valve on the water heater? Are there signs of flooding in the basement? There's residue on the bottom of the relief valve discharge tube which would normally require prolonged wetting.

    It's difficult to tell from the single picture where that circulator is supposed to be circulating, but at first glance it looks like it's not really placed to circulate water through both the tank and the system.
  • GordyGordy Member Posts: 7,122
    edited February 2011
    Scratching head

     Until I see more pics also.  Kinda looks like crude mixing right now.  Trying to see the supply piping. unless hidden from the angle of the pic. Or other water heater has a role in the system. I think I see a soft copper line in the back ground by the gas piping to the left, but where it goes?  Is the valve above the circulator with out the handle open?
  • GordanGordan Member Posts: 891
    edited February 2011

    Or is that some kind of vertically mounted flow check valve?
  • DavidMichaelDavidMichael Member Posts: 6
    More Pics tonight

    I will post more pictures this evening. Thanks so much for taking a look.
  • NRT_RobNRT_Rob Member Posts: 1,009
    Just to eliminate the obvious

    check the wiring to see if there is an on/off switch for that pump, and make sure it's not "off".
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
  • DavidMichaelDavidMichael Member Posts: 6
    More Pics

    Here are some pics of the system. It is fairly simple the supply and return lines come out of the slab and back to the pump and heater. I do not see a check valve or on/off switch on the pump. As I say, when the thermostat is turned up, there is a click in the box, but nothing else happens.
  • GordanGordan Member Posts: 891
    edited February 2011
    Yeah, it sure is simple.

    No backflow prevention. No expansion tank. No provision for air purging or elimination in evidence - edit: I see that baseboard elbow on the return side, but that's inadequate, especially if that's not the high point of the system. What's the rating on that pressure relief valve? It should say it right on the tag.

    Did you have the home inspected prior to buying it? Were any of the problems with this "heating system" noted on the report? You may be better off not getting it to work.
  • GordyGordy Member Posts: 7,122

     But missing some key components. As Gordan pointed out.

    Some things that really need to be done.

    Back flow preventer. The water in that system is stagnant. If the domestic side goes low pressure you do not want the radiant system to bleed water in to your domestic side. You do have a shut off valve before the water feeder. Is it off now?

    expansion tank. That system is closed the only thing allowing for expansion of the heated water is the pressure relief valve which if it pops you lose water, and the walls of the water heater. If the PRV sticks it could actually expand the tank closing off the flue pipe...or worse blow up.

    Make sure the pressure relief valve for the water heater is a 30psi model not 150psi. Radiant systems operate in the 12-15psi range in most homes. You have no pressure temperature gauge so you really have no way of knowing.

    Addition of a pressure temperature gauge, and some strap on temp gauges on supply/return piping. What is the water heater thermostat set at?

    As Mark said that pump has a spring coupler between the motor, and the pump housing.  If it were broke you would know because the motor would spin, and there would be a bunch of noise from springs slapping around.

     To check if impeller is free for kicks take a small screw driver, and CAREFULLY try to spin the coupler on the impeller side just check for movement, and don't touch the springs.

    If its free then as Mark said verify power to the motor with a tester. If no power. Verify there is not a breaker at your panel popped. 

    You really need to do the things listed as a minimum before you run this system.  When a water heater blows up its quite an event as in through the roof.

  • MireaumaMireauma Member Posts: 1
    max PSI allowed on heated water flooring system?

    when i ty to turn up the heat on my system, at the tank control to obtain a line temp of 120 the PSI jumps up from 15psi to as high as 75 is that trouble...restricted flow?

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