Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Chilled water reset controls... (ME)

[Deleted User]
[Deleted User] Posts: 0
in THE MAIN WALL
Wallies, I am experiencing a situation during partial load considerations that is causing a GSHP W to W heat pump used for chilling to lock out on FP, which is freeze protection. I think I can rectify the situation with an outdoor reset control to change the temperature of the chilled water based on the OSA.

Anyone have any experience in this area?

TIA

ME

Comments

  • don_185
    don_185 Member Posts: 312
    What about

    What about a pressure actuated regulating valve?

    That should help you keep from freezing the water coil.

    Acts like a low ambient control on a condenser that set outside.

  • hot_rod
    hot_rod Member Posts: 23,173
    Did you see that Honeywell

    control on that nifty heat pump demo at the Able Distributing booth at REX?

    Contact Pitor at Able 773 889- 5555 he can fill you in on the control and it's functions. It sounds like exactly what you need.

    Or contact Thom Wiggle at Honeywell he's the brains behind that control.
    thom.wigle@honeywell.com

    hr
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • MPF
    MPF Member Posts: 50
    Maybe this?

    http://cgproducts.johnsoncontrols.com/met_pdf/125188.pdf

    Apparently this will offset to a different setpoint but I'm pretty sure they make a rset control as well that may work more the way you want it to. Give them a yell
  • Unknown
    Unknown
    hbx?

    Have you checked out HBX? they have geo specific reset controls, which I believe are for heating & chilled applications. ECO-1000
    geo application

    Tekmar has some cooling reset controls in the pipeline... which means in 2 years ;)
  • Matt_67
    Matt_67 Member Posts: 299


    Honeywell makes a T775R series of controllers that is a fairly inexpensive way to do outdoor reset. I'm curious though - it seems that when I see freeze protection on a chiller it is usually the result of a flow problem. What kind of load do you have?
  • klaus
    klaus Member Posts: 183
    Adequate flow?

    Are you sure you have adequate flow through the GSHP Mark? I've sometimes found that to be the problem in these situations. Seems like the most critical element with these units is adequate sized piping and buffer tank. You've got to be able to unload these units as they're operating for proper performance.

    How low is your set point and where in the system is the sensor?
  • RJ_4
    RJ_4 Member Posts: 484
    reset

    Johnson controls has a A350/S350 series you can use to reset chill water.

    There was an error rendering this rich post.

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,329


    I agree that make sure that the water flow is correct. They usually have "peats plugs" on those to check PD wich is somewhat critical. 2-2.5 gpm/ton on chilled water and 3 gpm/ ton on condenser water should be close to what the mfg. wants.. Is your condenser water temp correct? Two low could cause lo refrig pressure/freeze ups atc's like low load.

    The problem with resetting the water temp is you cant dehumidify with warmer chilled water. Normal 10 deg. td 54 return and 44 supply will get you to about 52% rh. Do you have glycol in the system that could be affecting heat transfer? What are your chilled water and condenser water temps and TD's? 10 deg. TD is normal on both. Condenser water from a tower should be about 80-85 on and90-95 off.
    Ed
This discussion has been closed.

Categories