Bob got a call from the dispatcher to go to an office building that has a 3-ton heat pump compressor that has been shutting off after startup. The fan would continue to run. The building maintenance man said that he had observed the shutting down of the compressor several times.
Bob has gone on a service call where the customer is complaining that her house is not getting up to temperature. The house was heated with a heat pump with three stages of auxiliary strip heat. Bob removed the panel to the strip heat and found one of the units was not pulling current.
This troubleshooting situation is a look ahead to the upcoming cooling season. Our customer has called to say that their heat pump “isn’t cooling at all,” and while the outdoor temperature is only in the mid 80’s, it’s quite uncomfortable in the house. You find that the underlying reason is that the compressor and outdoor fan motor aren’t operating.
Bob and Btu Buddy have gotten together for a review of their last service call, which involved a control system that Bob was not very familiar with - pneumatic controls. Bob asked, “Why would anyone want to use air as the power source to operate the controls for a building?”
Effective pump maintenance allows industrial plants and commercial facilities to keep pumps operating well, to detect problems in time to schedule repairs, and to avoid early pump failures. Regular maintenance also reveals deteriorations in efficiency and capacity, which can occur long before a pump fails.
The customer’s complaint on this call was an overall overheating of his building. The manager told Bob, “We arrived this morning and the entire building was hot and keeps getting hotter.” He led Bob to the basement where there was a boiler. Bob found that the system had pneumatic controls.
When the customer calls for service, he tells you that when things got very cold in the house, he disconnected the power supply to the unit, and then, after turning the 120-volt service switch back on, the operation seemed normal and the house got warm “for a day or so.” But the failure repeated.
Bob’s service call yesterday involved a leaking underground refrigerant piping system. Bob replaced the refrigerant lines, leak tested the lines, and left them yesterday afternoon under 150 psig of pressure. He has now returned to the job the next day to see if the pressure held and to check for moisture in the system.
For several years, refrigerant retrofitting has been a common procedure for a lot of the commercial kitchen and restaurant equipment I work on, so I’ll go over some of the things I’ve learned that might help you save some time and money on your own retrofit projects.