1/7/99 The hydronic heating system functions by circulating hot water through tubing imbedded in the floor. These pictures show the 1/2" plastic tubing laid out about one foot apart and stapled to the plywood floor. A 1 1/2" layer of concrete will be poured over it and will form the floor surface. A cement-rich mixture will provide extra strength: 6 sacks ready mix plus one sack cement plus 3.5 pounds Davis #160 red powdered pigment make up each mixer-load.

2/3/99 The floor area is divided into three foot squares by wood strips 1 1/2" high. The concrete is poured in two stages, leaving strips for the workers to stand (mostly kneel, actually) while working. Here the darker colored strips were poured 2 1/2 weeks ago. The raised strips were poured two days ago, and are covered with plastic fastened to a wood frame that keeps it from touching the surface. The plastic retains moisture, so the concrete cures very slowly (about 2 weeks) for maximum strength.

1/7/99 The system is built around a standard 40 gallon propane fired water heater. In this 500 square foot building, there are two loops of pipe in the floor, each about 250 feet long. This length provides an optimum temperature drop between the supply water and the water that returns (cooler) from the floor to the water heater.

1/7/99 The bronze log-shaped object in the center is a "manifold" that collects returned water from the two plastic pipe loops and routes it back to the water heater. It includes two valves that are used to bleed air from the system. The supply manifold, attached to the supply end of the floor loops, can be partially seen just below it.

1/7/99 The pipe supplying hot water from the water heater (top) is equipped with a pressure equalizing tank (gray) that contains an air bladder. The vertical bronze object above the tank traps microscopic air bubbles and vents them from the system. A small electric pump (green) circulates the water.

1/7/99 The round bronze object in the center is a pressure regulator on the water supply line. This is a low pressure system, limited to about 20 pounds pressure. The two pipes and valves at lower left are for future connection to an electric water heater in the basement. Electric power will be supplied during winter months, without charge, by the Dog Creek Hydroelectric Project to be located nearby.

1/7/99 Temperature control is accomplished by starting and stopping the flow of hot water through the floor. The small electric pump is connected to a standard thermostat inside the building. A combined temperature and pressure guage monitors the system. Here, at the initial trial run, it is showing 80 degrees and 20 pounds pressure in the supply line.