Heat Pump
Frequently Asked Questions


  1. How long will the Comfort Control Board used in the JEZ Series store the codes if no new faults are experienced?
  1. Why have accumulators been removed from the higher efficiency equipment?


  2. Why do I have to remove refrigerant from the heat pump to make it operate in heat mode?

  3. What will cause the compressor to trip the high pressure switch to open or the compressor to cycle on internal pressure relief to open when in the heat pump mode or on JEZ model cause a protection fault?

  4. Are there any after market start assist kits approved by Rheem?
  1. How long will the Comfort Control Board used in the JEZ Series store the codes if no new faults are experienced?

    • The faults are stored indefinitely until they are overwritten or erased by the technician.

  1. Why have accumulators been removed from the higher efficiency equipment?

    • Accumulators have been installed in many products for years. They are designed to prevent liquid refrigerant from returning to the compressor. In addition, they must be able to return the oil carried by the refrigerant to the compressor.
    • In years past with fixed metering devices, the superheat was not controlled. An overcharged system or one that lacks airflow will feed liquid back to the compressor and damage the valves in reciprocating compressors.
    • In higher efficiency equipment the superheat is controlled by Thermostatic Expansion Valves. There should be no liquid leaving the evaporator. This should eliminate the need for an accumulator.
    • For additional information, please visit
  1. Why do I have to remove refrigerant from the heat pump to make it operate in heat mode?

    • There are several possible reasons for this condition.
    • The first possibility is mismatched equipment. If the coil is not a factory approved match the internal volume of the coil may not be large enough to hold the refrigerant required for system and therefore trip the high pressure switch. If this condition occurs the only solution is to install a factory approved matching coil. Until this condition is corrected there is no need to call for technical assistance.
    • Poor air flow! Low air flow in the cooling mode will almost always result in overcharging the system. The overcharge will be absorbed into sub-cooling in the cooling mode bit will cause the head pressure to rise in heating complicated by a lack of heat rejection.
    • Moisture! Even if you think you pulled a deep vacuum, moisture may be waxing and partially blocking the outdoor metering device or obstruction a parallel circuit and disappearing when the system shuts off. Perform a triple evacuation and charge with virgin refrigerant.
    • Restricted parallel circuit in the indoor coil.
    • Uneven airflow patterns through the indoor coil.
  1. What will cause the compressor to trip the high pressure switch to open or the compressor to cycle on internal pressure relief to open when in the heat pump mode or on JEZ model cause a protection fault?

    • One place to start is to observe the Suction and Discharge gauges, when connected to the service valves. If a considerable difference, hence the large vapor line, is higher than the small liquid line, a restriction is occurring either in the line set or the indoor coil.
    • Second, an in-operative TXV may be the culprit especially if a by-flow liquid line drier is not installed allowing dirt, contamination or trash restricting the valve ports. Trash, dirt and/or contamination can clog the capillary tubes internal of the coil as well.
    • Low air flow, -2 " water column return air and + 3" water column supply air is ideal, dirty filters blocked register and grills should also be inspected for un-obstructed air flow. Small ducts, return and supply plus, even though apparently clean, return air filters have a been known to have extremely high air restrictions.
    • An over charge of refrigerant or with a combination of air and non-condensable can be the cause, the charging charts along with proper super-heat and sub- cooling should be identified.
  1. Are there any after market start assist kits approved by Rheem?

    • Yes! Rheem has approved the use of the 1P100-ST soft start distributed by Superior Technology & Supplies Corp. of Waipahu, Hawaii for use on single phase air conditioning or heat pump units from 1.5 thru 5 ton. The use of this device will not violate the equipment warranty. Click here for a copy of the approval letter.

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