Green Envelope
Radiant Heating System
 First step: cover the plywood subfloor with 3/4 XPS insulation. |
 Next we weave a grid for the tubes by cutting 3/4 plywood with a jigsaw and tablesaw. |
 We use spacers to enforce enough separation between the plywood for the tubes. |
 Large areas of the room which don't need heat get solid 3/4 plywood. |
 Other areas which need a lot of heat get tubes everywhere. |
 With the spacers in place, the plywood tracking is screwed to the subfloor using screws long enough to go through the XPS. |
 Once the screws are in, the spacers come out. |
 Next the grooves are lined with strips of 3/4 XPS. This means the tubing will be surrounded by insulation on 3 sides. |
 In this room the outside walls get all the heat. This means there is less tubing needed and the room will heat more evenly. |
 Finally, heavy metal spreader plates are squeezed into the XPS grooves to spread the heat up. |
 The tubes must run perpendicular to the oak flooring that will be nailed into the plywood, so in order to favor the perimeter of the rooms you need a lot of turns, resulting in this serpentine pattern. |
 In this room we pring the return back in front of the closet so the homeowners will have warm feet if they stand in front of their closet choosing what to wear. |
 This is how we unrolled nearly 10,000 feet of 1/2 inch pex tubing. |
 The Uponor hepex is glued to the snap plates with plenty of Uponor's 100% silicone adhesive which they sell for their radiant track system. |
 The tubing snaps in with a bit of persuasion. |
 The bathrooms and the entries get mud jobs. Here the mud job in the mud room shows how we put most of the heat near the perimeter. |
 Nylon zip ties hold the tubes in place. |
 All the run outs to the rooms were insulated with the foam insulation so that we don't drop our heat before we get it to its intended location. |
 In the basement we decided to experiment with radiant walls instead of a radiant slab. First we put 1 1/2" of XPS on the entire wall. |
 Then we coated the walls with a layer of thin plaster and attached the tubing. |
 We decided to only do the bottom half of the walls and sheet rock above the plaster so the owners could hang pictures. |
 We had to channel into the XPS for the turns. |
 We supplied it from above. Metal plates went over any tubes above the chair rail (not shown). |
 Then the tubes were covered in plaster. |
 A wall hung modulating condensing boiler from Viessmann heats water which goes through the yellow-handled supply valves (near top right) and returns through the red-handled flow control valves. |
 The state of the art hydronic system includes a low-loss header (top left), a single 70 W circulator, and a differential pressure bypass valve (grey handle in center). |
 A tekmar zone manager, the blue box, controls 6 zones. |
 The y-pattern flow control valves allow the loops within a zone to be precisely balanced and allows fine tuning to the occupants preference. |