Due to the complexity of the refrigeration circuit only trained service technicians should attempt to adjust the refrigerant charge.

 

There are two paths to take when charging a Hydro-Temp forced air system.  Normally if you haven't replaced or tampered with the expansion valve you can go by the superheat method alone.  If the expansion valve needs adjusting (due to a replacement) then you must go on the subcool / superheat method.

 

Most systems will have a refrigerant weight stamped on the name plate.  This will get your system functioning but for optimal performance from you Hydro-Temp system you should always finish by taking a superheat reading and fine tune the charge from there.

 

Directions for charging via superheat method

To get optimal performance from your Hydro-Temp system, proper charging is essential.  Use the nameplate charge as a starting point.  You will almost always need to adjust the charge after the nameplate rating is added.

 

  For proper charging you need to have the entering air at the normal temperature.  We advise around 72 - 75 °F.  As a rule of thumb you will need to move 400 CFM’s per ton of air.  The ground water must flow at a rate of approx. 2.5 - 3 GPM’S per ton if closed loop or 1 GPM per ton if well water.

 

  Charge in the mode needed most at that time depending on house conditions.  You should always charge in the highest speed the system will run.  Dual compressor systems need to have both compressors running and variable speed systems should be in high speed.

 

DETERMINE AND SET THE SUPERHEAT.

A. Determine the temperature of the suction line 4 - 6 inches from the compressor. If a dual compressor system then 4 – 6 inches before the tee in the suction line going to each compressor.  (Be sure the temperature probe is under the insulation so as not to be effected by ambient temp.)

B. Determine the Saturation Temp of the low side in °F. (Normally the inner most number on low side gauge)

C. SUPERHEAT = A – B

 

The ideal compressor superheat is 10-12 °F.  (Never target a superheat below 10)

 

To adjust the superheat you will need to adjust the refrigerant charge.

 

  >To DECREASE the superheat add refrigerant.

  >To INCREASE the superheat remove refrigerant.

 

Directions for charging via subcool / superheat method