Project Report

Investigation of Multiple Callback Situations
with Residential GeoExchange Systems

Prepared for: Geothermal Heat Pump Consortium
Report Date: November 13, 1997
Prepared by: Proctor Engineering Group
Contributors: Tom Downey and John Proctor

Executive Summary

Proctor Engineering Group was selected to complete the investigation. This investigation involved surveys of industry contacts including Consortium staff, utility members of the Consortium, equipment manufacturers, installing and servicing contractors; surveys of affected customers; and a field investigation of problem systems. The information gathered in the surveys and from the field investigations was analyzed to determine the frequency of problems identified and correlate the findings to customer complaints. The surveys identified symptoms and causes associated with the respondent's complaints.

The symptoms identified from the survey included:

• High operating costs
• System shutdown
• Discomfort
• Noisy operation

As could be expected, not all parties agreed on the order of occurrence or the underlying causes. For example, manufacturers reported causes that were directly attributable to the quality of the installation. Installation contractors identified component failure and customer operation as being the causes of customer-reported problems and complaints.

This study provided valuable insights into the symptoms and causes of early customer complaints about residential Ground Source Heat Pumps.

The field investigation of problem sites confirmed the predominant symptoms expected from the survey. The field investigation showed significantly different problem causes than the survey.

Proctor Engineering Group concludes that:

• The predominant symptoms initiating multiple customer complaints are: discomfort, operating cost, and shutdown.
• The causes of discomfort and high operating costs are: improper duct installation, poor duct design, and undersized heat pumps. These three causes account for over 60% of the customer complaints in the field sample.
• Poor duct design leads to inadequate delivery to individual rooms and noise.
• Leaky ducts results in inadequate delivery to individual rooms, loss of capacity, excessive use of resistance heat, and high bills.
• Undersized heat pumps run on auxiliary heating too much of the time, which increases electric consumption.
• The causes of shutdown include:
• Poor installation (particularly on the air side).
• Component failure (in some incidents, the component failure was due to installation and service practices).
• Lack of system commissioning at installation.
• Lack of diagnostic expertise by those responding to callbacks.
• Ground loop design and installation were less of a problem than expected. It appears that since the ground loop is different from conventional air source heat pump/air conditioner technology, the contractors, manufacturers, and industry associations have worked to address ground loop design and installation. The "common" problems of system sizing, duct design, and duct installation have not been overcome by the switch to a geothermal heat source. The ground loop installation problems were limited to one job. The ground loop was always large enough for the installed unit, but the unit was often too small for the load of the house.
• The causes of customer complaints are identifiable and avoidable with more comprehensive technician training and certification. Training must go beyond the introduction of standards and policies. The training needs to include in-field ,hands-on instruction and testing. Technician certification should be based on inspected field performance for both installations and service calls. System sizing, duct design and installation must be included, as well as training specific to GHP systems.
• Contractors must improve their performance in being able to diagnose and correct problems causing the customer complaints. According to the customers interviewed, the average effort to address their complaints was 12 visits (median of 7.5 visits); and 11 of the 18 customers were not yet satisfied that the problem was solved.
• Manufacturers, distributors and contractors must work together to ensure the customer does not feel that they are “caught in the middle.” Customers reported feeling caught between manufacturers and distributors blaming each other for system performance problems. Proctor Engineering Group observed that:
• In many ways the customer problems associated with system shutdown are the results of "pushing the limits" to design a better product. Some manufacturers of GHP include controls that shut down the heat pump when a failure is identified. The controls often require manual reset for the compressor stage to run. In the case of air source equipment there are fewer controls and they reset automatically.
• The results of “pushing the limits” are mixed. The good news is that when something is not working correctly on a GHP the customer generally knows immediately. Problems are evident. The bad news is that the average technician does not know how to diagnose and repair these problems. Most technicians are parts changers, not diagnosticians. In order to ensure proper system operation, the performance of the technicians needs improvement.

Proctor Engineering Group recommends:

• No GHP should be installed without a documented heat loss calculation in line with ACCA Manual J.
• No GHP should be installed without a documented duct system design in line with ACCA Manual D.
• No GHP should be installed without commissioning of the actual performance of the equipment to ensure the capacity and efficiency are consistent with the manufacturers stated values.
• The standard sizing criteria for GHP should be reviewed and potentially revised to help eliminate excessive use of auxiliary heat in cold climates.
• Each manufacturer should have a professional diagnostic and repair "SWAT" team at its disposal to address problem systems wherever they occur. This could be an industry wide group.New training programs should be developed that deliver more comprehensive training on the whole system. The training now is geared specifically to address the ground loop side of the system, ignoring the areas that were identified as being the main causes of customer complaints with their GHP system.
• Service technicians should be certified based on observed performance in the field.

The project culminated in a checklist and decision tree to assist service contractors in determining deficiencies. It is fairly obvious from the experience gained in this project that the causes of customer complaints are easily discernible with the use of existing diagnostic protocols. The checklist is designed to aid the contractor by providing a listing of all of the tests or parameters needed to correctly assess the cause of the problem. It also provides a tool for making a clear presentation to the customer. It clarifies the areas of deficiency and the areas of correct operation. The checklist acts as a form for commissioning and as a diagnostic tool to determine the cause of the problems.

The decision tree guides diagnosis based on the particular customer complaint. It focuses the contractor’s efforts in the areas most correlated with the reported problem. The decision tree addresses the three main problems discovered during the investigation: high operating costs (during both heating and cooling season), discomforted noise. The decision tree leads the contractor through a progression of interview questions and/or tests that can be performed to help determine the cause of the complaint.

Bound copies of this entire paper are available for $35 each or free from GHP Consort.
For details about obtaining a copy see How To Order Project Reports