Homes get built in many ways. Some people meticulously plan and draw every aspect of the home, often with the help of an architect or designer. The house plans can be many pages and layers of drawings. They may include not only the physical structure, but the window, door, trim and insulation schedules as well as all mechanical systems and landscaping. Other people start with an over sized piece of graph paper and make a single line drawing that may not even be to scale. Decisions will then be made on an 'as needed' basis. Either approach, and any in between, will eventually involve decisions that will affect the geothermal system. Two of the most important considerations are the heat loss requirements and the duct work layout. Heat loss A geothermal system is best when a detailed and accurate heat loss/cool gain is calculated. The designer needs to know all sorts of things about the home to be accurate. Firstly, the heated space needs to be defined. It may seem very basic, … [Read more...]
Geothermal Heat Pumps and the Back-up System
Geothermal heat pumps are nearly always installed with some provision for back-up heat, supplemental heat or emergency heat. Often, this is electric resistance. This is done because it has the cheapest installed cost for any back-up heat system. Unfortunately, it is the most expensive to operate. There is often confusion about the operation of the back-up system. To start, I'd like to distinguish some terms. Back-up heat is often associated with older air source heat pumps that suffer significant reductions in capacity when the outside air temperature dropped into the 20 degree area. The air source heat pump either isn't worth much under those conditions, or it would actually shut off. The controls would then enable the back-up, and the whole heat load would then be on the back-up. Expensive! This is one of the causes of the lingering negative perceptions of heat pumps in general. For this reason, I'd like to discard the term 'back-up'. Supplemental heat is closer to the … [Read more...]