Entry # 208
Big Bear Cabin
Brief overview of the project
This is a three-temperature hydronic system providing 1) snow melt, 2) indoor heating and 3) domestic hot water within a cabin located in Big Bear, California. Big Bear is located 100 miles west of Los Angeles. The average annual snowfall is nearly 70 inches.
Caleffi components use in this project:
1. NAS200 Series ThermoCon Storage Tank
2. DISCAL 551 Series Air Separator
3. DIRTMAG 5463 Series Magnetic Dirt Separator
4. Z-one Series Zone Valves
5. 573 Series AutoFill Combo
6. 132 Series Quicksetter Balancing Valve
7. 5021 Series Automatic Air Vent
We used a HTP EFT-399 boiler to drive a SSU-119 indirect water heater and provide heat to the snow melt and heating zones. Because the system is so highly zoned, a Caleffi 25 gallon Thermocon tank was used to prevent any boiler short cycling and improve system efficiency. The boiler’s temperature sensor input is taken from the dry well we placed within one of the unused buffer tank ports.
A Tekmar TN2 control works with a motorized 3-way mixing valve to modulate the proper temperature to the infloor radiant and snow melt zones. The Tekmar control will allow the user to set the house in away mode in which the system will disable producing domestic hot water and set all thermostats back to an away temperature setting.
The snowmelt sub-system is isolated from the infloor radiant via a flat plate heat exchanger. The snowmelt is a 2-zone design utilizing two distribution manifolds. We employed equal loop lengths and since each manifold is one zone, we fully opened the valves on the manifolds and balanced total flow using Caleffi Quicksetters.
Installation is now complete and start-up was accomplilshed during the first weekend in December. It was a total success! The temperature of the floor increased 8F in the first 45 minutes and by the end of the day the three-level cabin was warm and comfortable with and outside temperature of 38F. The project has 10 indoor zones, two snow melt zones and one domestic hot water storage tank.