The plumber continues to make progress in the basement. This picture shows some radiant tubes under the main floor. As I've mentioned before, each radiant heat loop can be up to 250' long, which necessitates many seperate loops in the main floor. Rather than running all the loops' tubes back to the boiler room, the plumber runs a single large-diameter copper pipe (a "remote manifold") down the center of the house and connects each loop right where it's installed. Here you can see the manifold with the yellow-handled valves attached to it, as well as the ends of several tube loops (as well as electrical wires and waste plumbing - our floors have a LOT of stuff crammed in them!)