Radiant Rescue – Inadequate and Uneven Floor Heating – West Tisbury


We were asked to “rescue” a radiant floor heating system in a large Vineyard home – the heating with the radiant floor had always been inadequate for the coldest days of winter, there was not enough tubing installed in the floor, it was poorly zoned, and it was built around a fixed water temperature.  The fixed water temperature meant that the radiant system worked well for only one outside temperature – if it was warmer outside then the house would overheat.  If it was colder outside then the house would be chilly.


Finally, a floor renovation project created the opportunity to remove the old radiant system and start over with more radiant tubing in the floor, automatic temperature mixing, and an internet portal to view and adjust all zones.  After the old concrete and tubing were removed, we installed Warmboard brand radiant panels (aluminum skin bonded to a plywood substrate).



We then installed 6,000 feet of 1/2″ hePEX radiant tubing in the Warmboard radiant panel grooves.  The tubing snapped in place and only needed to be held down in the corners with the help of some nail plates.





Because the basement level below was finished, we had to open up the subfloor at various points across the first floor level to create access points through which to snake our PEX tubing.  (the floor was painted black to increase its radiant heat transfer because in this application there was an air gap between floor layers.)




Finding ways to snake the radiant tubing between the 1st floor and the basement finished ceiling was challenging but we managed to get all 6,000 feet successfully routed to three different mechanical rooms in the basement level.





IMGMar 11 2016 17-30-58radiant tubingbundle past stairs

Where we couldn’t get access across in the void above the basement ceiling, we carefully went across the 1st floor level with the radiant tubing – aware of balancing our flows so that we did not create hot spots.




We also installed air sensors in the 1st floor rooms to measure the local air temperature – some rooms were already wired for these sensors so we epoxied our new sensors to the backing plate.






We also installed floor sensors in the Warmboard radiant panel and in the finish floor layer above it.  This gave us a good sense of how effective our heat transfer was between layers.






For the rooms that did not have wires already run in the walls, we had to find an innovative, robust, yet inexpensive solution.  We installed BAPI wireless transmitting sensors in the rooms with no wires and were able to transmit the temperature information from the room to the basement mechanical spaces.  Each receiver had a LED indicator to tell us that transmission between the sensor and the basement receivers was successful.





Because the homeowner wanted a clean installation, all 22 radiant zone thermostats were located adjacent to their particular radiant manifold in the three mechanical spaces.  The thermostats looked at room air temperature and floor temperature to determine when to open and close the correct zone valve.






The radiant tubing from each room came down into the mechanical spaces to a dedicated manifold for that room.  These eight manifolds are controlled by the eight thermostats in the picture above.






These are some of the manifolds in the middle mechanical room.  Note the thermometers to assist in balancing and confirmation of correct radiant heat transfer.






We installed new piping from the boiler room to each of the remote mechanical rooms and installed separate closely spaced tees and air separators on each radiant manifold group.  This eliminated air purging issues and made the system quiet and low maintenance.






To automate the radiant floor water temperature, we installed motorized mixing valves for each manifold group.  This ensured that the radiant floor system would get the correct water temperature no matter what the outside temperature was.






We used the variable speed ECM style circulator pump to make sure that we were only pumping the correct amount of hot water to each radiant zone.  This saved money and helped to prevent over and under-heating of the rooms.






Lastly, we installed the internet gateway to permit monitoring of all 22 radiant thermostats and adjustment of setpoints for each room.   Now the entire radiant system was under supervision and control via the internet to the homeowner’s iPad or iPhone.





Our goal is to be Martha’s Vineyard’s premier plumbing and HVAC shop – we appreciate the opportunity to show you some of our work.