# Heat pump ice up



## pbservano (Nov 11, 2008)

signpainter said:


> Hi,
> We just got a heat pump this fall so we are new to this. We have the York Affinity 3 ton unit and a variable speed air handler. There are 4 (5kw) heat strips in the air handler. I used to have an oil furnace but this has replaced this. I also have a woodburner which I plan on using but have put off to see how this heat pump is working. A few weeks ago the outside unit froze up...it was a cold snap and the temp had been in the teens. The guy told me this was normal but I had him come out..he checked the refrigerant (added a little) and set a jumper on the board. But the temp went back up (into the 30's) and things seemd fine. The unit does run almost continuosly and I see the AUX lite on from time to time. I notice that the ice forms in bands around the heat pump but the defrost cycle seems to melt them off (until now). Now this morning the temp is about 17 and there is ice all over the unit. The weather side looks the worse but it did snow. I have the thermostat set at a continuos 68 and it is only 64 in here. The AUX lite is on but only two of the four strips are being used (checked with amp meter).
> So my question is.....could I possibly have a heat pump that is too small for my house? I have a 175 year old house in Ohio and it is pretty well insulated with thermopane windows. It is about 2200 square feet. It does sit on a hill and gets wind. I need to add another one or two cold air returns (I do not have enough volume) and am planning on adding bigger heat run to the kitchen (farthest from the unit). The Manual J called for about a 3.5 ton but York does not have that size. I don't think my guy know all the ins and outs about York either. I am concerned about the ice build up on the unit....my neighbors don't have this.
> Any advice would be appreciated... I could post pictures if you want.
> Linda


Your defrost sensor is faulty. This sensor is attached to your outdoor coil copper piping. It has two wires normally colored pink or red. Check for continuity using a multimeter. If this sensor remains open at surface temp of less than approx. 20F it is faulty. These wires goes to your defrost control board to initiate automatic defrost during cold ambient temp. 35F or lower. 

Now, if the defrost sensor is not faulty the defrost control board has a 30, 60, and 90 minutes option for defrost cycle. I'm suspecting maybe it was set to 90 minutes instead of 30 minutes defrost cycle. Try switching the defrost cycle to 30.


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## beenthere (Oct 11, 2008)

Sorry, but the York Affinity defrost system doesn't work that way.

It has an on demand defrost system. It uses a NTC thermocouple to determine outdoor temp, another one to determine liquid line temp, and then decides if the coil is frosted enough to need to go into defrost.
There is no timer to set.

Your contractor could have use the 4 ton 2 stage for your house, if your house called for 3.5 tons, and probably should have.
Because now you have an undersized heat pump.
The 4 ton, can be set to move the same air volume as a 3.5 ton.


What thermostat did he install.


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## signpainter (Dec 7, 2008)

I have a Robertshaw 9700i programmable thermostat. I had it on a program similar to the one I had with my oil furnace. I would like to bring the temp down (way down) at night but after the first freeze up., I set it at a constant 68 to see how much the AUX come on. It is only 64 in here though.
Any other advice?
Linda


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## beenthere (Oct 11, 2008)

Can you post the entire model number.

Because you said the contractor said teh Affinity doesn't come in a 3.5 ton.
I'm guessing you have a 8T series.
If you can post its mod number, as in is it a YZE, YZB, or YZH outdoor unit.

The Robershaw 9700, is not compatible with the YZE, or YZH model heat pumps.


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## signpainter (Dec 7, 2008)

It is a York Affinity 5t series Model number YZE03611C and the Robertshaw thermostat is 9720i not the one I said before. I posted a picture of the freeze up in MY PHOTO right below my screen name.
Thanks
Linda


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## beenthere (Oct 11, 2008)

You have a multistage system.
And a 2 stage thermostat.

I'm not overly familar with Robertshaw thermostats.
But, the 9725i2 would have been a better thermostat for it.

Its probably your thermostat causing the most trouble of not maintaining temp.

The frost is a bit heavey.

Low air flow at the indoor unit can cause some of that.
Low indoor air flow, causes the outdoor coil temp not to drop like it should as the outdoor temp drops, and the unit won't always go into defrost as soon as it should.


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## signpainter (Dec 7, 2008)

Just an update...our guy came today and manually (with water)defrosted the outside unit. He changed another jumper which is supposed to make a warmer defrost. He did check the refrigerant level (was fine). After he left the heat pump ran for an hour and the AUX lite was on. The temp did not come above 60. We checked and there are no AUX heat strips running. Poor guy has been here in the coldest of weather...wind chill 7 degrees. He said he will check about the thermostat but that is the one the supply house sold with the unit. I am at my wits end...it is going to be a long winter. 
Another question. Could these problems be because this unit is too small or it this just related to something else. If my unit is too small...should I get a bigger one or can I improve the heating of this unit with some insulation added, having proper air flow ducts, and possibly insulating the duct work. The basement is an unconditioned space....kinda like an old dungeon. I am worried.....will be out splitting wood tomorrow I guess.
Thanks for any advice
Linda


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## beenthere (Oct 11, 2008)

He should check to see if the OD unit is flashing any fault codes.

He should also, measure the readings of the outdoor sensors.

If the OD temp sensor has an open or shorted circuit, it will NOT go into defrost. And should flash a code.

Next, would be a check that the defrost program jumper is on the right pins.
I he moved that to another program. It won't defrost correctly, or at all. As not all boards installed in new units have the program loaded in all the settings for other sizes.(Yours should be set to #3)

Another thing that can cause it, is if the defrost board isn't receiving a constant 24 volts.
It MUST have constant power, even when it isn't runniig, in order for the timer to know how long the compressor has run, since the last defrost.

Another thing for him to check, is that the compresor is in second stage. If the pilot valve on the compressor isn't working, then when its attemps to defrost in first stage, it won't defrost right either. 

If he has Hot Heat Pump enabled. Might want to disable it, and see if it defrost better.

Ask him what temp he has the balance point set for.
Should be set about 5° higher then when it really need to come on.

If its wired correctly, and that stat was compatible with your system. And the BP is set correctly, then you should have atleast 1 set of aux heat on, if you have your stat set to 64 and its only 60 in the house.

Call him and ask to set up to have a factory rep come out and check the system also.
The rep will schedule a day to come out.
And will check the system with him.

Adding insulation will help both in heating and cooling. And if the load calc said you need 3.5 tons. Your going to have to lower your cooling needs in order for that unit to cool your house right.

You might want to seal any receps and switches that are on outside walls. And replace or repair any door seals that are worn or leaking air in or out.
Plus caulk around your windows to stop any drafts from them.

This may be his first 2 stage unit. And he may not have had any training on them.


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## thecatman (Mar 8, 2011)

i need a wiring diagram for a york heat pump model no.E1RAO3OSO6D, not going into defrost mode i noticed the hi volt red wire and a low vol red wire looked at one time they were connected but came loose from each other dont no if this has anything to do with it or not.thanks


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