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Heat Pump problem

I have a customer who changed their air handler about 8 years ago. They got a nice variable speed model from Bryant. Last FaLL they wanted to upgrade the outside unit. Problem was the new heat pump was 410a refrigerant and the Air handler was R-22. I thought I was being smart and changed the expansion valve to a 410a x valve. The system worked great all heating system but this cooling system It began to have trouble. The new expansion valve started shutting down and causing low suction pressure. I changed it with a new one. In a weeks time it happened again. I am now changing out the air handler to make it a matching set but don't know why the X valves kept going bad. Any ideas?


  • JStar
    JStar Member Posts: 2,752

    Did you completely clean and flush out the coil and lineset?
  • Techman
    Techman Member Posts: 2,144

    Hi WW, how about the old r22 indoor coil was physically smaller than its newer nowaday r410a indoor coil.The older units ran and were designed around a different Delta T than todays higher SEER units . The r410a TXV still works off of temp[superheat] so w/ a smaller coil the new TXV would feed less freon,w/ lower suction pressurers,with possibly under sized return grill/ducts.
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