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Inspecting HVAC Systems Topics include heating, venting, and air conditioning inspections.

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  #1  
Old 1/31/07, 3:16 PM
Harry McBride's Avatar
Harry McBride Harry McBride is offline
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Default Frozen Heat Pump

The outside coil of this heat pump was frozen over. Does this mean that the defrost function of this system is faulty? Any help would be appreciated. Thanks!

Last edited by hmcbride; 6/30/07 at 7:31 AM..
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  #2  
Old 1/31/07, 4:30 PM
brepanshek brepanshek is offline
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Default Re: Frozen Heat Pump

Could be condensor fan motor not working, low on refrigerate, reversing valve stuck, and so on. There are so many factors to consider, yes it appears it could be in the defrost sequence, yet on some models there are time, temp, and pressure applications that may induce defrost. If you were doing an inspection, I've am learning that when i see a problem I simply defer it to the qualified contractors. I am certified in HVAC and yet I am learning that on a HI my job is to report the situations not trouble shoot them. I'm learning that when I say "it the defrost board" it could be misleading and hurts your credablity when a HVAC tech comes to service and finds that it could be something minor or major.
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Old 1/31/07, 5:09 PM
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Harry McBride Harry McBride is offline
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Default Re: Frozen Heat Pump

I appreciate it Brian. I always refer the client to a qualified contractor. Just wanted to get a idea of what would have caused this. First time in 6 years of seeing a heat pump frozen. I am sure you have seen your share of frozen evaporator coils and condensing fan units, just like I have. Thanks alot for the info.
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Old 1/31/07, 5:41 PM
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David A. Andersen David A. Andersen is offline
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Default Re: Frozen Heat Pump

It has been cold in Fla the past few days.
The outdoor coil operates about 30 degrees below the outdoor temp, so if there is moisture in the air, it will freeze the coil.

First is to go about your inspection business and come back to the HVAC coil about 45 min later. The ice may be gone by then and all is normal.



First, it may be just an adjustment on the defrost board. The board can be changed for the time between checks of the defrost thermostat. In Fla, these boards may not be set correctly or at least not for the extreme weather. The most common problem is with the defrost thermostat (which is a cheap piece of control in most cases). To test the defrost t-stat when the coil is frozen, simply jump the test pins on the defrost (it is labeled "test"). This accelerates the time clock and will bring around a defrost cycle in a matter of seconds. If this does not happen, it is likely the t-stat.

Next is to test the board. You must remove and jump the defrost t-stat wires, then do the test above again. If it doesnt defrost, the board is bad.


Quote:
Could be condensor fan motor not working, low on refrigerate, reversing valve stuck, and so on.
These issues cause a different pattern of icing on the coil and are not the issue.
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Old 2/1/07, 7:38 AM
brepanshek brepanshek is offline
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Default Re: Frozen Heat Pump

How can you tell what the ice pattern is David, I can't seem to open the picture can you see what he's talking about? If so then your probably right. The thing that gets me is if this is a new installation then the timing could be off like you stated but if this is an older unit then it could be an never had a problem before till no then I'd have to agree on your tstat and board tests. Harry, I guess I wasn't as imformative as David, This is way the message board and those willing to help are so valuable. This is why I don't like to give advice on what it maybe the problem with something until I accually see it.
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  #6  
Old 2/1/07, 8:09 AM
Bruce M. Graham Bruce M. Graham is online now
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Default Re: Frozen Heat Pump

I always loved when a service call would come in and they would say "can you come over right now I think my Heat pump is on fire". Happened every spring.



http://www.nachi.org/forum/image.php?type=sigpic&userid=6376&dateline=1330979  258
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1st Inspection Services
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352 871 8989
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Old 2/1/07, 6:04 PM
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David A. Andersen David A. Andersen is offline
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Default Re: Frozen Heat Pump

Brian, I did manage to get his photograph open and it is a snowy like Frost out to the protective wire around the condenser coil.

Seeing it was frosting consistently from top to bottom and all the way around and that Florida recently had some messed up weather, I venture to say that there is and adjustment problem or that simple little sensor finally gave out.

I'm sitting in my office right now looking at the next-door heat pump that has been frozen for three days now. It does clear up every now and again.

Tennessee is one of the worst places I've seen for heat pump frosting. It can be 10░ in the morning and 60░ in the afternoon. In the afternoon all the moisture evaporates into the air and at night, whammo!

I used to make a substantial amount of money when I was working HVAC by just driving around in neighborhoods that had Janatrol HVAC systems, just looking at the frost patterns and dropping off a courtesy note in the mailbox. Advising them of the forthcoming $300 electric bill if they don't get their HVAC system fixed.

Very seldom was at the defrost controllers, rather leaking coils that caused White stripes and big snowballs to occur. Our high moisture levels of the outdoor air during the winter provides perfect conditions to assess the operational conditions of the units from across the subdivision!

Bruce, it never ceased to amaze me how many people lived so long with their heat pumps and never saw the steam from the defrost cycle occur!
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Old 2/1/07, 7:28 PM
brepanshek brepanshek is offline
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Default Re: Frozen Heat Pump

Very seldom was at the defrost controllers, rather leaking coils that caused White stripes and big snowballs to occur.

what did you mean leaking coils?
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  #9  
Old 2/2/07, 1:09 AM
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Harry McBride Harry McBride is offline
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Default Re: Frozen Heat Pump

Thanks, David! Of course I am not going to suggest what the repair should be. I definitely appreciate the education. Just going to recommend someone like Bruce who happens to be a home inspector right here in my area. Right, Bruce.
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  #10  
Old 2/2/07, 8:07 AM
Bruce M. Graham Bruce M. Graham is online now
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Default Re: Frozen Heat Pump

Harry, will that be cash or check?



http://www.nachi.org/forum/image.php?type=sigpic&userid=6376&dateline=1330979  258
Professional Inspection Services, LLC dba
1st Inspection Services
Bruce M. Graham III
Gainesville, FL 32608
352 871 8989
Florida Licensed Home Inspector #HI10
Certified Level II Infrared Thermographer
Radon Measurment Technician # R2279
NACHI05091592
ICC 5268478
www.1stinspectionsfl.com
www.bungalowstomansions.com
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  #11  
Old 2/2/07, 10:18 PM
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Harry McBride Harry McBride is offline
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Default Re: Frozen Heat Pump

Just put it on the card, my friend.
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