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Goodman Heat Pump trips High Pressure Lockout when defrost cycles are required

Goodman Heat Pump trips High Pressure Lockout when defrost cycles are required

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  #1  
Old 12-30-11, 05:14 PM
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Goodman Heat Pump trips High Pressure Lockout when defrost cycles are required

I have a new Goodman Model DSZC180361 heat pump which charge checked correct during summer. Ran fine all summer long. Also ran fine until ambient dropped below 10 degrees F. That is when the system will trip and lock out due to High Pressure Lock Out function. Basically any time the High Pressure Switch trips three times consecutive cycles, circuit board will lock out. I have to reset power to resume heat pump operation. We currently are experiencing warmer weather (about 30 deg night to 50 degrees F day.) Has not missed a lick or trip out since weather is warmer. Appears to be an issue when defrost demand is increased during extreme cold. System uses R-410 and high pressure lock out is supposed to not trip until 610PSI. Is the high pressure lock-out switch faulty? I cannot say I know what the pressure is during defrost change-over, but seems to be when fault occurs.
 
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  #2  
Old 12-30-11, 06:00 PM
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Unit should have a year warranty call the company back. My first guess would be low on freon
 
  #3  
Old 12-30-11, 07:23 PM
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not alot of warm to squeeze out of 10 degrees, should had been on aux. well before.
 
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Old 12-31-11, 03:40 AM
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If refrigerant was low, so would the high pressure side be lower. Installer checked sub-cooling and superheat and both correct. System is equipped with TXV, not a met-jet, if that is a factor.

I am trying to acquire support from the original installer but has been over a month in response. Must be the Holidays?
As stated the charge checked correct
 
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Old 12-31-11, 03:57 AM
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System is all electric, not gas. HP is paired with an AEPF426016CA air handler with coil. Piston is replaced with a 3 ton CA 48K ZAA 0151R00011 TXV.
Heat pump was originally configured by installer to lockout when outdoor ambient was 40 degrees. HP spec"s suggest ability to -10F. Per chart should easily be able to handle outdoor ambient @ 10 deg F. Have since changed the HP to switch to aux ht at 20 deg F due to lock-out problem. Trying that for now.. . .
 
  #6  
Old 12-31-11, 06:31 AM
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just old school.me would rather go to pure heat from toaster strips at 36*.i'am sure the maker's considered wear and tear in their operational spec's and math.in their older units if there was even a little bump in the road had to put hard starts and timers on.maybe they have change major components. could be week h.p. safety.good luck with it and have a happy New Year.
 
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Old 12-31-11, 11:45 AM
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Oh did not see u said high pressure. Anyway it should have a year warranty have it looked at by them.

Today's heatpumps still make very good heat well into the teens. At 36 degress your using lots of energy to run electric heat. Units are designed to run. Let them eat!
 
  #8  
Old 12-31-11, 12:51 PM
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whats the watt total of the outside unit?are the o.d. fans variable and insulated?whats the t.d. between lines at 10* and at that temp. would not the strip heaters be blasting anyway? i don't know but respect your opinion still sticking to mine till you convince me otherwise.have a happy.
 
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Old 12-31-11, 07:50 PM
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The strip heaters bridge the gap between heat loss and heatpump output.

Provided that the cop is above 1 including defrost cycles, it's always more efficient to run a heatpump than to shut it down and completely rely on strip heat.

Once mechanical wear is considered though, I wouldn't run a heatpump below 10-15F - not worth it for insignificant energy savings.

Actual performance in cold weather varies between models - I doubt that the older units do a good job below 40F. (smaller outdoor coil)

whats the t.d. between lines at 10* and at that temp.
Not relevant actually.

Most of the heat is given off as the refrigerant condenses into a liquid in the indoor coil. (latent heat)

The refrigerant enters the coil greatly superheated, quickly drops to saturation (specific heat of r22/410a gas is low) and condenses. It exits the coil only slightly subcooled. Probably at least 80% of the coil's surface area is used to extract latent heat from the refrigerant.
 

Last edited by user 10; 12-31-11 at 08:06 PM.
  #10  
Old 12-31-11, 08:04 PM
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If the original installer refuses to come back, contact another goodman dealer - warranty should still be valid.

The charge should be checked in heating mode.
 
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Old 12-31-11, 09:54 PM
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ok Muggle you schooled me,never to late to learn.always thought the liq. line was a indication of ambient and some how could get a ideal of the work being done between the two.best wishes this coming new year and listen to Muggle.
 
  #12  
Old 01-01-12, 12:38 AM
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Clarification:

As the ambient temp increases, the high side pressure/temperature goes up, but capacity of a given system is proportional to the boiling point (determined by pressure) of the refrigerant. Higher coil temp = greater heat transfer.

Coil size, airflow, indoor temp also influence operating temps and pressures; ie a 10 seer heatpump with a smaller indoor coil will run a higher head pressure/saturation temperature in heating mode than a 13 seer unit (larger indoor coil), operating conditions and capacity being equal.
 
  #13  
Old 01-01-12, 12:41 AM
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Performance data for your heatpump - http://www.goodmanmfg.com/Portals/0/.../SS-DSZC18.pdf
 
  #14  
Old 01-01-12, 10:38 AM
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You need to get a pro out to check the charge and the metering device operation.
 
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Old 01-01-12, 07:44 PM
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The installer is a seasoned certified technician with about 8 years experience. Just has not been able to determine reason. I have about 30 yrs experience with R-22 systems. My problem is I do not have equipment for supporting R-410. I am going to respond to Muggle and guyold regarding Temp. Rise. Maybe installer is missing something with electric furnace configuration? Otherwise may be still be faulty HPLO as it is not supposed to open till reaches 620psi.
 
  #16  
Old 01-02-12, 09:18 AM
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I guess the first thing to do is VERIFY the high pressure switch is opening.

We will NOT give out refrigerant pressure information on this forum. Please see http://www.doityourself.com/forum/he...heat-pump.html
 
  #17  
Old 01-02-12, 03:54 PM
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Dear Muggle, Thank you very much for the updated information. The HP was shipped with Performance data version 1/10. The link provided supersedes as version 11/11. I note the latest version differs in two key areas. Superheat is now specified to be 7-9deg.F versus 5-7degF. Also the Subcooling is specified for both High and Low Stage. In other words original version stated 8-10degF for both? The newer version still identifies High Stage @ 8-10degF but also advises the Low Stage to be 5-7degF.

During startup the technician as trained indicated this unit is to be charged in low speed cooling for best accuracy. Based on the Goodman R-410 Sub-cooling Calculator or slide-ruler regarding Liquid-Line temperature, it would appear the unit may be overcharged. Basically a difference of 5degF. Do you agree the unit is possibly overcharge as well?

When the technician does arrive, I will review this information as well.

I also must note, I find where it is not unusual to acquire a delta T higher than the product specifications. According to the chart on page 20, it would appear the unit is surpassing the Heating Data. Maybe you see a concern but I can attest I have double checked the CFM to be correct with a calibrated hot wire and Dwyer to be between 781-797CFM on low speed with following delta T readings.

OA Supply Return Delta T
30 104 71 33
28 104 72 32
15 93 71 22
9 91 71 20
5 89 70 19

The air handler is configured with dip switches 7 (off) & 8 (on) to reduce CFM by 15%. This works great to support dehumidification but not sure if causing a problem in heating mode? Do not find any information in Goodmans installation manual which differentiates? I have it configured as such as humidity in our area is a key concern for creature comfort. (Plenty of irrigation in the agricultural area.)

Thanks again for your tip to investigate. Problem is probably need to wait till cooling season to really determine an accurate charge.
 
  #18  
Old 01-04-12, 06:24 AM
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have 2 heat pumps goodman 2.5 ,12 yrs old ,3.5 , 2 yrs old seer 16 The old unit works well at 25 degrees the newer one wont hold temp of 70 when out side is 25 degrees Had new one serviced twice by a/c service. Had to put 2 lbs. in after nine months use. Is this excessive leakage?Is it the reason unit wont hold temp? During cyle cold air is pumped into house would suspect that defrost would put defrost air out side rather than through system?
 
  #19  
Old 01-04-12, 09:57 AM
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During defrost your aux hear should run.
 
  #20  
Old 01-05-12, 04:47 AM
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I would question adding 2Lbs of refrigerant after 9 months. Keep in mind a HP is considered a sealed system. If the technician did not indicate repair of a leak, I would suggest having checked and confirm proper charge. Charge is critical to a HP's performance. Your HP should have come with the specifications to provide performance data. Follow the charts and compare your temperature rise. Should be close. You didn't provide the model number but if you search on net by model number, you probably will locate required data. (Just in case you do not have manual.) I am questioning your statement for 3.5 suggesting a 3 1/2 ton. Basically Goodman does not provide half sizes in HP's. Maybe determined by your indoor coil match?

I agree with hvactechfw. When defrost cycle is initiated, the aux. strip heat should be "ON". Keep in mind a HP is basically an Air Conditioner in reverse. (via a reversing valve within the HP) So when the HP is defrosting it is actually cooling mode but the heat strip is to be "ON" to prevent the cold air indoors.
 
  #21  
Old 01-30-14, 04:33 AM
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Problem Solved! at least to date

I appreciate the responses i've received from this site, and wanted to post the solution. After confirming accuracy of the refrigerant charge in summer of 2013, I knew there had to be another reason for the Goodman system mentioned in this string to why it intermittently kept tripping the high pressure switch. Appeared very random.
In watching carefully each day and trending the operation, I stumbled onto the termination time was typically 3 minutes when ambient was about 34 to 25. Then if temperature was around 22 or lower, the termination lockout would occur. This appeared to be a result of the termination sensor being affected by colder ambient conditions. Knowing other manufactures equipment I've serviced had this sensor insulated. Then noted the Goodman unit I had purchased was not.
I used a short soft rubber hose about 2.5" long and slit the length of the tube. Then clipped the hose over the sensor. In addition I added some thumbgum over the tube to assure it stayed in place and better insulate. It has been 3 weeks now and dipped down to 5degF and back up to 40degF and has stayed operating without needing reset.
So far has been operating like it should. If lockout occurs again will post my findings.
Thanks to all that have posted to this issue.
 
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