Maryland Short Cycling???

Discussion in 'Maintenance and Troubleshooting' started by goochman, Jan 15, 2016.

  1. goochman

    goochman New Member

    I have 2 Waterfurnace Envision Series NSZ030 geo units on a closed loop system. One of the systems has been trowing a "Water Flow" error (atleast thats the light that comes on) every so often. When I open the front panel the yellow light is blinking 3 times which indicates a "Short Cycle" problem. Here is where things get kinda tricky:

    This happened 3 times in the first year of ownership. The installer ran into a few issues with water pressure (the well pipes expand) and such. After the first year this has not happened again until now (5 years later).

    The issue came up just before my yearly maintenance check so the tech was here to see the problem. At first he thought the coils or condenser were bad but went through alot of checks and at one point switched over to AC mode and then back (we did the 5 min wait time between unit switching). The condenser appeared to work ok so his next thought was the freon (or whatever its called today :) ) - thinking that might be low he connected his tank but only a few ounces were required. After his complete check the unit was working great once again.

    Fast forward 1 month and the light came on (I know when this happens since my upstairs gets cold since something is not working to generate heat). There is a plug inside the unit which can reset the lights and during my first year of problems was told to try this to see if things get rest. Well I did this and the light would come back on. The compressor is definitely running as its making a sound. Whats not happening is the copper coil is not getting warm (the refrigerant is not getting charged?) - Im also not sure if the water is flowing since the EWT and LWT were the same temperature. The other unit is connected to the same well piping so when that kicked in I can read a difference in water temp.

    So Im sitting here scratching my head - the green light turned off so the system was not functioning well at any level...........................

    After sleeping on this I remembered that we turned the AC on during the maint check so this morning I used the termostat to shut the unit down - waited 5 mins - switched to AC and turned the temp down. If of course felt cold :), but in checking the Geo Unit the EWT and LWT were showing a difference and the copper coil pipe was really cold. After letting it run 10 mins I turned it off via the thermostat, waited 5 mins and switched back to heat. Wala, the heat is running like normal..........the Water Flow light is still on but Ive read that the system needs to havee x amount of successful cycles before turning that off................

    So any thoughts on why I would get a short cycle error on Heat mode that is corrected by switching to AC mode and back????
  2. heatoldhome

    heatoldhome Geo Student Forum Leader

    I'm no expert but it sounds like the loop exchanger is freezing up.

    What's your EWT and LWT?

    Antifreeze in the loop?
  3. goochman

    goochman New Member

    The lowest temp Ive seen the water is 47 degrees on my thermometer. I have one of those rubber gaskets that you can poke the temp gauge into to read it.

    There def was antifreeze put in originally - but as the pipes have expanded a bit and water added to increase the pressure I dont think antifreeze was included.
  4. heatoldhome

    heatoldhome Geo Student Forum Leader

    Do you have a accurate pressure gauge you can use on the same loop ports to see the pressure difference between the in and out.

    Your Gshp should have a data chart in the specs that show how many gpm flow you have based on the pressure difference you record.

    Not enough flow can cause it to freeze up in the coil. Also Ice forming in the loop exchanger can restrict flow.

    If you can check that we could see if this is actually the problem or something else.

    Might want to check before and during the problem.

    Also when you see 47 deg water is that the water in EWT or water out to the loop LWT? If you can check the LWT during the problem.
  5. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    I agree, it all points towards your fluid freezing up in the heat exchanger, not enough antifreeze for the temperature your loop is at.

    Air in the loop in pressurized systems (versus no pressurized) can lock certain circuits, than flow goes only through a part of the loop field, and the EWT is colder since you don't have the whole lop field anymore.
    Ice does not form in the loop, it is always the heat exchanger inside the unit. The fact that you have normal flow after putting it into A/C mode is evidence for that.

    Check you antifreeze levels.
  6. goochman

    goochman New Member

    Good info everyone, thanks. The pressure when measured last month was close to 50 psi which is what is was 18 months earlier on last check. This is the first time the pressure hasnt dropped over time..

    How do I check the antifreeze levels?
  7. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    It is not the pressures.

    Are you on glycol or methanol/ethanol as an antifreeze.

    Glycol measurements with a spectrometer, alcohols you check the density.
  8. goochman

    goochman New Member

    I believe they put glycol in - but this is where I prob should have my installer come back out :) - They used a red liquid that looked like wine mixed in a metal jug.
  9. geoxne

    geoxne Active Member Forum Leader


    Check to make sure freeze detection dip switch is in the correct position first. Only set to Closed Loop 15F if proper antifreeze levels are verified. Then check causes in order of likelihood listed above.

    The Comfort Alert "Short Cycling" alert is a red herring. It was caused by the HP trying to restart unsuccessfully. See below.

  10. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    The fact that your symptoms were cured temporarily by putting the unit in A/C mode, which melts any ice within the heat exchanger within 30 seconds, tells you that the coil was frozen. Even if the dip switch was in the wrong position, the freeze protection might turn your unit off temporarily, but it would not freeze your coil.

    What you describe sounds like glycol. Sometimes the supply houses sell you glycol mixtures which only contain 60% glycol, the rest are rust inhibitors etc. Your installer might think he put the right amount of glycol in the loop, but if he was not aware that the product only contained 60% instead of 100%, his calculations might be off. Common problem.
  11. Stickman

    Stickman Active Member Forum Leader

  12. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    If waterside checks out have refrigerant charge level rechecked. Loss of charge reduces evaporation temperature which system interprets as a water flow issue.
  13. goochman

    goochman New Member

  14. Stickman

    Stickman Active Member Forum Leader

    Very simple - calibrate it with distilled water (there's an adjusting screw, although mine didn't need adjusting). Then place a few drops of your loop fluid on the tool's glass and look through the lens to see the glycol concentration percentage on a scale.
  15. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Now that you know?
  16. goochman

    goochman New Member

    Just got the unit today - preparing for a snowstorm so this has hit the back burner - will get to it over the weekend and report my results.
  17. goochman

    goochman New Member

    Ok performed my test today and Im pretty sure the levels are off. From the reading I got it showed 10% Glycol mix with a freezing point of 25 degrees F - That does not seem right but I am not expert.
  18. Stickman

    Stickman Active Member Forum Leader

    I'm no expert either, but 10% seems awfully low. I am at 23% in NY. See the attached pages from my unit's manual. Although our equipment differs, I would imagine the antifreeze principles remain the same.

    Attached Files:

  19. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Yep, you don't have enough PG in the loop. It should be 25%. Explains all your symptoms.
  20. goochman

    goochman New Member

    So an update on my situation. Shortly after my last post the system went down again. This time it was a capacitor which was covered under my warranty. I spoke to the tech about the low glycol and they told me to contact their well driller about the situation.

    I spoke to the well driller who agreed that if the 10% was correct it was low. They thought it should be 15-20% and they could add more to the loop for approx $900.............The loop is 6 years old - is this normal for a loop to lose this much mix in a short time and is this stuff really that expensive to add? I have 2x2.5 ton units so safe to assume I have a 5 ton loop to fill.

    For $900 Im also wondering if I could do this myself for much cheaper - adding glycol doesnt appear to be rocket science from what I saw during the install.

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