Kentucky How many gallons per minute should flow in stage 1 cooling?

Discussion in 'Maintenance and Troubleshooting' started by JeffM, Apr 26, 2016.

  1. JeffM

    JeffM New Member

    I have a newly installed Climatemaster 4-ton Tranquility 30 unit (replaced Waterfurnace unit). The diagnostic data always indicates "N/A" when the unit is in stage 1 cooling. Is this normal? A manual check via p/t ports indicates a pressure drop of 3-4 psi.

    Here's a picture of the diagnostic screen. Does anything look out of the ordinary?

    In Stage 2 cooling I usually have a flow rate of 11 or so gpm. The unit does have a variable speed water pump so I wonder if it reduces water flow so dramatically that it doesn't register a gpm reading?

    If anybody knows if this is normal, or if I need to get my installer to address an issue, I would appreciate any advice. Thank you.

  2. JeffM

    JeffM New Member

    By the way, closed loop system.
  3. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    N/A means no data in this case so for whatever reason, it is not reading. If it's otherwise ok, forget about it.
  4. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    looking good. Don't worry, they use cheap ways to measure flow, which are not always reliable.
  5. JeffM

    JeffM New Member

    Thanks, Joe and docjenser. It seems to work ok so I'll take your advice and let it go. Frustrating, though, to see that "N/A" every time I check the system.

    I appreciate your help.
  6. stew1340

    stew1340 New Member

    I have 25 year old Marvair 3.5 ton pump and dump system. Unit has been using 5 gpm all this time never had a problem til a month ago it got a slow leak, i need a new unit cause old has leak r22 so in looking at all the new units they all want 10 to 12 gpm. I added new centf pump to well and got it up to 8 gpm. I need 4 ton now cause i added room to house is the GPM going to cause me problem. Will appreciate any help and will look at any units you think will work. Had to add two more lines for room and i am adding a 20x20 return for room also my unit is vertical.
  7. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    New units do not need 10-12 gpm. With EWT in an open system in the upper 50s, or maybe touching 60F, you need only 1.5-2 gpm/ton.
  8. stew1340

    stew1340 New Member

    TY docjenser
  9. ==================================================
    I am retired hvac and blog in a separate area of the website. We all want complete instrumentation and rarely have it. NA (at a glance) simply means not available. I've seen it for twenty years when my facility doesn't want to spend an extra dime.
    to get an honest flow reading, or purchase instrumentation or something else. It means spending money on electronic flow instrumention which needs to be recalibrated say every 15 months. It can be done, but it costs extra money. I had electronic flow meters monitoring chemicals added to my commercial water towers automatically. They work. They fail. You find them for $400.00 on the internet and replace them. Or you let the water testing company replace them for a $700.00 bill, each.

    The standard "orthodox" way of verifying measured water flow is to manually plug a low value ( 0 - 10 psi ) water pressure gauge into both inlet and outlet "Pete's ports" and read pressure drop against the flow charts included with the heat pump. You set your flows from that. That is probably NOT done by 40% of installers. BUT, even if you get a good reading, is that a lifetime adjustment ? I doubt it. Seasons change.

    What I now share may be controversial. I am personally more interested in inlet and outlet water temperatures. I have accurate electronic instrumentation that gives me a live indication of those temperatures. My manufacturer has told me that I should not have a leaving water temperature below 45 degrees in winter. (We are assuming charge is correct, when it isn't your unit will lock out in winter) I also bought a plexiglass mechanical flow meter (see my blog) (I used similar ones at work to monitor chemical feed into cooling water towers) that indicates in real time WHAT my water flow IS. Because I use an on/off well pump system, I can watch the piston go up and the piston go down, HUGE help for adjustments ! I use "generally accepted hvac rules" and their "range" for delta t and check them 2 - 4 times a year, spring and fall, especially winter. How much heat has the heat exchange coil picked up in the summer ? How much heat has been absorbed as it enterred the heat exchange coil in winter ? If I believe that the delta 'T" is too high, in the summer, I increase water flow. EDIT May 19 2018 : (Can't believe I what posted earlier) If I saw a delta "T" of 6 degrees in the winter, I would CORRECTION: INCREASE water flow slightly past October, AND WATCH TEMPERATURE OUTLET READINGS. Increased water flow in winter = more available heat present in the water,

    Works for me.
    Last edited: May 19, 2018
  10. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Generally your approach is not a problem, but it requires a full functioning refrigerant circuit. If there is an issue with the refrigerant circuit, your temperature method might mask an underlying problem, which you are not alerted to.
  11. Thanks Docjenser,

    My 100% commercial/professional friends recommend to me, (because of the industry problem with refrigerant leaks) , as a starting point, to recover and if possible measure refrigerant that is recovered. And in any case, (especially with microleaks) to start over with an exact weighed in, charge: using either a professional appliance glass charge container or modern electronic weight scale. At that point we are at least, not guessing. That gives us a baseline for suction and head pressures, superheat, subcooling that we can reference back to. As you alluded, once we have leaks, everything you think you know pretty much goes out the window.

    And by the way, according to my expert hvac teacher friend at a local technical college, and what I read on the net, adding R-410a is totally permissable. There is documentation that the qualities including "fractionalization" and "glide" for R-410a DO NOT CHANGE MUCH even after adding 5 - 15 times, (I think R410a is a zeo-trope not a-zeotrope) although you should be adding in liquid phase, not an issue as long as we are metering it in in small measured amounts.
    Last edited: May 19, 2018

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