2020 RETA Breeze Jan-Feb

SERVICE

The Shade Tree Mechanic volume XLIV

Huntin Season! As winter approaches hunting season is closing in. The boys are scheduling vacation and I’m stocking up on charcoal. The boys always manage to spare a few deer steaks for the old man. Unfortunately, Huntin Season always starts early at the plant. As the weather gets colder, we start to get thermal expansion valve problems. Our insulation is getting old and we have issues develop. Usually the first cold We found the TXV was closed. So, after rebuilding the valve we decided the issue was the bulb. We found the bulb was covered with ice, water that had froze when the weather turned cold. During warmweather the water was about the same temperature as the suction line. So, the evaporator worked. When it was really warm the valve went wide open. Apparently, the thermostat was cycling the solenoid to keep the room from getting too cold. But when the weather turned cold, the TXV closed and we couldn’t match temperature. We replaced the insulation, problem solved. Two days later we found the second bad valve. This time the valve was stuck. A quick rebuild and we were back on line. We noticed the room temperature was getting warm. This could have happened anytime but changing snap means, the first TXV failure. Our first issue came up, early last Thursday. Liquid shut off in cooler #12. The Solenoid was on, but no liquid flow.

So, by making the modifications I could see if the TXV was not operating properly. A minor control charge gave us a good trouble shooting tool. One word of caution, I originally set it up with an Adapt-a-horn. That drove me nuts. I changed it in favor of a counter it was much quieter. Now I don’t go crazy every time the counter cleared but I did put it on our “check when we have time” list. Less emergencies, more time under the Shade Tree. The shade tree grows outside of the little town of Broughton, Ohio. Where everyone is always welcome, the beer is always cold, and something is always needin fixin.

weather seems to bring them to light. The third failure was a little less obvious. Temperature in cooler #7 was erratic, but the puzzling thing was that the colder it got outside the less cooling we would get. When it was warmwe had plenty of cooling, but as soon as it was cold outside the valve pinched off. We found the TXV bulb had fallen out of the insulation. So, the valve was operating based on outside temperature, instead of suction temperature. Thank goodness, none of the other TXV’s had problems. So, we’re ready for season with only a few holdups. But I’m always lookin to make next year easier. So, I got to thinking. How can I tell if my TXV’s are hunting? I talked to the control boys and decided to trend my solenoid valves. This is how it works. The solenoid valve should be on anytime the room is on. The only time the solenoid would close was temperature). Normally, the solenoid would be on and the liquid flow would be regulated by the TXV. So, the control boys’ setup an alarm. If the room got cold enough to shutoff the solenoid the counter would advance. Once in awhile is ok, but if it’s going off every hour or so, it’s a problem. if the roomwas too cold (our thermostat will shutoff the solenoid on low

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