Nevada Geothermal Utility System Standards
The Warren Estates and Manzanita Estates geothermal systems are individual closed-loop systems. Truckee Meadows Water Authority (TMWA) water is heated in a heat exchanger by geothermal water. The TMWA water is circulated throughout the system at a temperature between 140 and 180 degrees Fahrenheit. The pressure in this system is regulated to not exceed 100 pounds per square inch. The flow rate is near 400 gallons per minute (gpm) in the Manzanita Estates distribution system and near 300 gpm in the Warren Estates distribution system. The system only works properly if all water circulating through individual homes is returned unaltered and only heat has been extracted from the water.
All customers of the Nevada Geothermal Utility Company (NGUC) are required to meet the following minimum connection requirements prior to receiving service from the utility. These connection requirements will help to ensure that the customers’ facilities will provide an efficient and safe use of the geothermal heat provided by NGUC. Prior to receiving service from NGUC, all customers shall submit plans and specifications of the heating facilities located on the customers’ premises. Said plans and specifications must include the following:
Homes should utilize forced air heating systems rather than hot water baseboard systems. The reasons are as follows:
- Geothermal System Description
- Minimum Connection Requirements
- All water entering a home must be returned. It is not to be used as potable water, nor dumped into a sewer.
- All homes must have shut-off valves outside the utility box on both the supply side and return side. A floor drain must be installed in the heating-plumbing room.
- All home systems must be equipped with a circulating pump. The customers' systems should not rely on the existing differential pressure between the hot and cold side.
- All zone control valves, pressure relief valves, and other components of the system must be rated for 100 psi. The pressure relief valves should be set at 100 psi.
- All systems must be equipped with a drain valve, to be located in the utility box. A hose bib is adequate.
- No home system should be installed in such a manner that TMWA water is connected to our circulating water system.
- Pipe size, from the utility box to the home, should be no larger than 1 1/2 inches in diameter.
- Pipe insulation in offset from the house to utility box and all pipe within the dwelling should be insulated to R-11 or better. The insulation should be waterproof and non-collapsible or non-compressible.
- All systems should have operating instructions and/or control diagrams available to or for the homeowner.
- All systems must be equipped with an automatic pressure shut-off valve.
- Customer must maintain a reliable backup system of either natural gas or electric space and water heating.
- Design of Customer Facilities
- Forced air systems and air conditioning are compatible. Air conditioning and baseboard heat would be substantially more costly.
- Forced air systems operate better at lower temperatures than hot water baseboard heating systems.