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Heat Exchanger from Refrigeration Rack

Here is what I have: Flatplate C5AG Heat Exchanger, R404A Side A (refrigeration side) & 50% Prop. Glycol on Side B (heating side). Pressure Drop of 9 ft/head.

Modine HSB258 Unit Heater (2 piped in parallel -1 in a 57F room & 1 in a 36F room) on the glycol side Pressure Drop of 5.7 ft/head.

400' of 1" type M copper pipe. (which should have been larger)

Grundfos UP26-116F pump (which is to small)

I am not get the heat out of the HSB as I need. Currently the glycol temp. out of the flatplate is between 95-105F. The glycol temp back to the flatplate is 81-85F 

I am thinking that I will need to bring the GPM up. Am I right?


  • Tom Blackwell_2
    Tom Blackwell_2 Member Posts: 126
    Additional questions

    The delta-t on the circuit seems about right. Are you saying that the unit heaters do not give off enough heat to condition the space, or is the refrigeration circuit operating at too high head pressure? 
  • Todd Refrig
    Todd Refrig Member Posts: 2
    Additional Information

    Not enough heat to the space. I have enough heat from the compressors on the rack.
  • Tom Blackwell_2
    Tom Blackwell_2 Member Posts: 126

    If the head pressure is ok, then you are extracting as much heat as there is available. Additional water flow would not extract any more heat.
  • Techman
    Techman Member Posts: 2,144
    refrig rack

    What head pressure are you running the systems at?
  • Wayne_16
    Wayne_16 Member Posts: 130
    What is the entering water temperature of the coil?

    What temperatures have you measured from the coil, entering water temp & leaving water temp.  Glycol temp leaving the heat exchanger seems about right.  What kind of control valves are in the hydronic side for the water to air coils?


    Minnesota Wayne
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