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Thread: Outdoor coil icing up...
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02-08-2008, 02:59 AM #1
Outdoor coil icing up...
Ok the customer has a ducted unit in the house and they complain of the outdoor unit icing up when they have the unit on heating and the temperature outside is below 5 degree celcius..........i have seen photos of the iced up coil and it seems it's only some sections of the coil icing up mainly the top half.
I have checked charge and also relocted the thermistor to a better location due to it being placed very low on the coil and quite close to the compressor which may be affectng it's reading.........
I couldn't get the unit to icing up at all when i was there but the ambient temp was 20 degree celcius, even tried blocking the coil but still no ice.
I did witness the unit go into a defrost once while i had it running for 45min, when it goes into defrost i hear the Reversing valve go and the outdoor fans slow right down for 1 minute.
Oh and it's doens't have its own defrost board.............the defrost is built in to the units outdoor pcb, i can't adjust any defrost setting as the unit doesn't allow it. The only thing i can change is the thermistor.
Anyone got any suggestions??????
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02-08-2008, 08:48 AM #2
Re: Outdoor coil icing up...
quote "the outdoor fans slow right down for 1 minute." The outdoor fans should stop and stay
off until if comes out of defrost.
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02-08-2008, 11:40 PM #3
Re: Outdoor coil icing up...
And the make and model of the unit is ?
Brian - Newton Abbot, Devon, UK
Retired March 2015
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03-08-2008, 10:16 AM #4
Re: Outdoor coil icing up...
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03-08-2008, 04:37 PM #5
Re: Outdoor coil icing up...
OK, the icing up is normal, but the lack of defrosting is the problem.
As above, what brand/model unit is it, what were the temps and pressures?
I had to track down a problem pana, the issue went for over two winters with others looking at it (The issue was dropped after winter ended). No one could find the fault because of course no techs went there when it was cold between 9pm and 8am So it's a hard issue to solve without heaps of info.
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05-08-2008, 08:09 AM #6
Re: Outdoor coil icing up...
The unit gets turned on heating 27degrees at 5:30am (outside air temp 4degree celcius) and by 7am it's iced up to the point where it will not blow warm air inside...............the unit is made in china and has a copeland scroll and is correctly charged with R407C using scales to charge.
The defrost is built into the outdoor units pcb and i have already tried replacing and moving the condensor coil thermistor.
I though only some units completly shut down the outdoor fan on defrost??? i have seen a few that actually slow right down during a defrost.
Any ideas guys?
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05-08-2008, 03:49 PM #7
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Do you have any other unit of that make/model in that area to compare functioning in same conditions. Could be small outdoor heat exchanger.
What is humidity in that area at testing time?
Also try to add more refrigerant (10% of total charge) to see if there is any difference in indoor unit discharge temperature.
I did witness the unit go into a defrost once while i had it running for 45min, when it goes into defrost i hear the Reversing valve go and the outdoor fans slow right down for 1 minute.
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06-08-2008, 07:22 AM #8
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06-08-2008, 12:36 PM #9
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Last edited by nike123; 06-08-2008 at 12:48 PM.
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07-08-2008, 05:34 AM #10
Re: Outdoor coil icing up...
the unit didn't ice up when i was there but when i blocked off the coil for 15min or so i caused the unit to go into defrost, there was no frost on the coil though.
The outdoor fan is working fine......... all pipes from the distributor are at equal temps....
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07-08-2008, 06:54 AM #11
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07-08-2008, 08:17 AM #12
Re: Outdoor coil icing up...
We can assume the suction pressure has been running lower than what we are used to?
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07-08-2008, 08:32 AM #13
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08-08-2008, 01:32 PM #14
Re: Outdoor coil icing up...
The coil is actually quite large and the fans are also pretty powerfull.
I did notice that the coil seems to be doubled up and that the fins are extremely close together it's pretty much impossible to see through the coil due to it being doubled up.........and thats a brand new unit with no dirt on it yet.
Could i possibly improve the airflow over the coil by using a fincomb to widen the fins ????
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08-08-2008, 01:39 PM #15
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10-08-2008, 07:09 AM #16
Re: Outdoor coil icing up...
well i won't be going back out to the job untill i hear from the manufacturer..........but i checked all the neccassary measurements.............when i was there.
Gas is all good..........
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08-09-2008, 04:45 AM #17
Re: Outdoor coil icing up...
It is normal the outside coil iced up. So, many customer are beginning to select GSHP to replace air source HP.
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28-10-2008, 06:08 PM #18
Re: Outdoor coil icing up...
Does the outdoor unit sit under the drip line of the roof. Could be moisture dripping from the roof causing top half of the unit to freeze. You will need a gutter to deflect the moisture from drpping on top of the system.
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28-10-2008, 07:12 PM #19
Re: Outdoor coil icing up...
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