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Replaced Quietside tankless with a new Triangle Tube Instinct Combi 199 - no heat floor

Beeps Member Posts: 2
edited April 2021 in Radiant Heating
Hi heatinghelp members,

We replaced a Quietside tankless boiler that finally gave up the ghost. When it worked, it worked fine heating the radiant floor system of our house as well as providing hot water at the tap.

It was replaced with a new Triangle Tube Instinct Combi 199 unit. I also bought the optional Triangle Tube "Timesaver" manifold as spec'd in the manual. The plumber also added a Grundfos UP15-42F 115V SuperBrute 9H Recirculator Pump, Caleffi microbubble resorber, and a Honeywell 4.4 gal expansion tank. The top of the Instinct has an included Caleffi air vent. Hot water works well for the tap but I don't know why I can't get heat to work at the radiant floor. Hot water doesn't seem to flow down into the pipe that leads into the floor.

Please see images:

Of the two insulated pipes, the right side is the COLD.

Thank you very much!


  • Jamie Hall
    Jamie Hall Member Posts: 22,924
    At some risk of asking a really dumb question... is the pump that circulates water through the floor loops running?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Beeps
    Beeps Member Posts: 2
    Yes it's running and pointing towards the right direction. Made sure of that! These pumps are near silent so I have to put my hand on it to know it's working. 
  • Paul Pollets
    Paul Pollets Member Posts: 3,656
    edited April 2021
    The pump needs to be rotated 90 degrees to the horizontal. The pump shaft should be horizontal, not vertical. The 4 screws holding the pump to the housing will allow the control to face upwards when rotated. Since union iso flanges were not used, you'll need unions at the flanges