A Failure To Communicate?

Most articles inThe Newsare worthwhile. Sometimes they rise to outstanding. Unfortunately, “A Heat Pump Failure Investigation” (May 19) is way off the mark. This is even more troubling since the writers are engineers. To me, noteworthy problems include:

  • Authors say a main part is an expansion valve. This is a Carrier heat pump. It has no expansion valve. It does use fixed orifices to regulate refrigerant flow.

  • It is misleading to say a heat pump has a condenser and an evaporator. It has a water source and an air source heat exchange. These are alternately either used for condensing or evaporation, depending on the mode of operation.

  • The “temperature-controlled refrigerant pressure relief valve” would be better described with the common trade term “fusible plug.”

  • Thermocouples consist of two dissimilar metals which, when heated at the hot junction, give off a small DC voltage.

    Thermocouples only click if you bang them together. Your authors need to learn about thermostats — in this case we could call them freezestats.

  • These failures could have been avoided by using a side-stream filter at the system water circulating pump, rather than filters lost above the ceiling. To not mention this much better way of maintaining the water is a significant failure of analysis.

  • Mention is made of leaves found in the filter. It would have been insightful to discuss the type of cooling tower used. An open sump circulated through the heat pumps would be a poor choice for a heat pump system.

    Gary Stults, Steamfitter, Wisconsin Dept. of Administration, State Facilities Bureau, Madison, Wis.

    Author's Response

    Thank you for the opportunity to reply.

  • Expansion valve — This is purely a confusion about terms. The fixed orifice to which he refers is the expansion valve. A review of any undergraduate text on thermodynamics (Thermodynamics by J. P. Holman, for example) should clear up the confusion.

  • Condenser and evaporator — All refrigeration systems have a condenser and an evaporator, and as the reader correctly stated, “These are alternately either used for condensing or evaporation, depending on the mode of [the heat pump’s] operation.”

  • Fusible plug — I wanted a more detailed description here, but fusible plug is fine too.

  • Thermocouple — The small DC voltage output of a thermocouple is used in conjunction with circuitry and a relay to provide switching. The audible click is from the relay switching when the setpoint temperature is reached.

  • Side-stream filter — Many repair methods could have been used, including the one that the reader suggested. The repair was very straightforward once the cause was identified. What was not straightforward in this case was the cause of the failure, which was what I featured in the article.

  • Type of cooling tower — Like my previous response, I did not think that this was really appropriate for an article on the failure analysis of the heat pump.

    I welcome feedback such as this, because it makes for better articles in the long run.

    Dirk H. Duffner, P.E., Managing Engineer, Exponent Failure Analysis Associates Inc., Menlo Park, Calif.

    Honesty And Respect

    [Editor’s note: This letter is in response to the guest column by Charlie Greer called “Solving Your Biggest Problem.”]

    Chase away half your customers? That has to be one of the most absurd statements I have ever read. Day after day I work on keeping our customers that we have and building relationships with new ones. Where are all the customers supposed to go that we chase away? Down the street to an unlicensed, poorly trained “garage” company. Let’s give consumers another reason to distrust our industry.

    For eight hours a day, I answer phones and dispatch calls to service techs. My basic job here is to listen to our customers’ needs (and tell me their needs they do). Our customers trust us to take care of them, not to chase them off. The company I work for has a rock-solid reputation and has been family owned and operated for over 54 years. We live, work, have children, and attend churches in this community. I am proud of where I work and of what I do, and cannot even imagine treating our customers in such a disrespectful manner.

    We are obviously not the only heating and cooling company in our county. Quite frequently I answer calls from irate consumers who feel they have been taken and are quite frankly disgusted with their present heating and cooling company because suddenly, without warning, service and replacement prices have skyrocketed to what they feel is unreasonable. As a homeowner myself, I know what “sticker shock” is when I am facing a much-needed repair. The least I can expect is that the company that comes to do the repair will treat me with honesty and respect. Isn’t that what this industry is trying to evolve its image into?

    Frankly, this “editorial” sounds like just another push to justify flat-rate pricing. Maybe there’s a reason it hasn’t caught on like many thought it would.

    Lisa Isaac, Administrative Assistant, Modern Heating Co., Beach Park, Ill.

    Publication date: 06/23/2003