I RECENTLY FINISHED up on a project for Habitat for Humanity of Metro Denver. I’ve been trying to donate a hydronic radiant floor heating system to this organization through the auspices of the local chapter of the Radiant Panel Association for more than three years now but for one reason or another never seemed to be able to convince them to do it.
Then the National Renewable Energy Laboratories got involved. This home, when completed, is slated to have one of the highest energy ratings of any home built in Colorado this year. NREL was an active donor of labor and funds.
Early in the discussions, NREL said the home needed to be “unique” from its perspective. I offered a radiant floor system.
“No, thanks,” NREL said, “everyone’s doing radiant floors already.”
I offered radiant ceilings and NREL replied, “Nah, everyone’s done radiant ceilings.”
“You’re not leaving me a whole lot of options,” I said.
“We know!” NREL said.
And thus the first Metro Denver all radiant-wall, solar-assisted, handicap-accessible Habitat for Humanity home was born.
The home is a reasonably sized, three-bedroom, one-bath, single-family home with non-electric thermostatically controlled valves controlling individual built-in-place radiant wall heating panels. The heat source is a fully condensing, fully modulating Munchkin M-80 boiler. In addition to the space heat, the boiler provides backup DHW to an active solar thermal domestic hot water pre-heat system. The home also has an active non-storage type photovoltaic system. It is one of three almost identical homes that were built side-by-side in the neighborhood.
That last statement probably doesn’t mean much to the common man, until he finds out that the other two homes have conventional forced-air heating systems installed in them. What this represents is the possibility of doing a three-home, side-by-side comparison of energy usage differentials between a forced-air home and a hydronic radiant-heated home.
Time will have to pass before we get some relevant exposure data, and as it becomes available I will make it public. Stay tuned.
The actual design and installation came off without any hitches. Getting the system approved by the local code officials was one of the most difficult challenges we faced on this project. We used a well-known manufacturer’s PEX tubing and heat transmission plates and used their specifications for a radiant ceiling, turned on its side, for a radiant wall.
Simple enough, I thought, until it came time for the plan review. The plan review folks wanted letters from the manufacturers of the tube, the heat transmission plates and all attached components stating that this application was approved for a wall installation. We were able to comply with their needs and construction began.
We started by developing a large router template that could be attached to the rough stud framing and would allow perfect duplication of the grooves we were putting into the face of the studs to receive the aluminum heat transmission plates.
Once complete, I tested it on a sample stud wall I built specifically for that reason. It worked perfectly.
Next, we took the template to the jobsite and began the job of routing our target wall to receive the radiant panels. I had my 16-year-old summer assistant running the router, and he had all six panels completely routed out and the aluminum heat transmission plates installed in one day. This home has a total of six radiant panels, each of them being about 6-ft. long.
The next phase of the project was installing the tubing into the plates and installing nail guards to avoid the possibility of people running screws into the tubing where the tubes crossed the studs. Bear in mind that these homes are built, for the most part, by volunteer labor. The thought of a jolly volunteer with a screw gun in his hand and a wall full of plastic tubing has a tendency to send a chill up and down the old spine. Hence, the need for nail guards.
The tubing and the nail plates were installed by a group of volunteers representing the Rocky Mountain Chapter of the Radiant Panel Association, and the association was responsible for getting the materials and labor donated to complete the installation.
A thermostatic non-electric valve manufactured by a German company called Oventrop controls each room’s temperature. The good folks from Uponor Wirsbo donated the tubing and plates.
Many of the necessary ancillary materials were provided by one of our local wholesale plumbing outlets, Dahl Plumbing Supply, with the difference being donated by the local chapter of the RPA.
Tune in next month when we look further into the workings of this system. Until then, Happy Volunteer Hydronicing!
Mark Eatherton is a Denver-based hydronics contractor. He can be reached via e-mail at [email protected] or by phone at 303/778-7772.