York Affinity (YZB) HeatPump defrost control

[dsomerv]

The York installation manual states that the full auxiliary resistance heat is activated shortly before a defrost until shortly after so as to compensate for the cooling during the defrost cycle.

I find that I get very cool air (60 degrees) during the defrost cycle. In tracking the reason I find that only one (W1OUT) of the two (W1OUT, W2OUT) resistance heat signals is being asserted at the defrost control board with the consequence that I am only getting 5kw of resistance heat rather than the expected 20kw.

To test that the wiring from the defrost control to the air handler is correct, I switch to emergency heat and observe that the full set of resistance heaters are correctly activated, showing that: the defrost control board is capable of asserting both control signals (W1OUT and W2OUT) and that the wiring to the airhandler is indeed correct.

I've observed this condition for two years now - and as luck would have it the control board has been replaced three times (thanks to York's inadequate protection from snow infiltration design) , otherwise that's what I'd suspect.

I've recently installed a house power monitoring system so can observe KW consumption minute by minute - so it's not imagined that the full resistance heat is not coming on...

The York documentation has many errors and omissions, so I wonder if there is some secret that one needs to know to get the defrost cycle functioning correctly.

My unit is 3.5 ton, with matched handler, 4 years old.

Is this a known issue or something I've overlooked ??

thanks, Dan S .

[beenthere]

Au-en-boy.

This is the Ask Our Pro's forum. In order to post advice here, you must have verified qualifications and have been approved by the AOP Committee.

You can find the rules for posting and qualifications here.

[dsomerv]

beenthere:

I'm new here and not quite familiar with the local etiquette.
But I wonder why you deleted the comment on my question from au-en-boy since he is listed as a pro.
It appears that his is the only guidance I'm likely to get, so am disappointed to not be able to see his counsel.
thanks.

[beenthere]

He is not a pro * member, and is not allowed to post answers to questions in the AOP forums.

[beenthere]

On that heat pump. it should only be energizing W1 during defrost. Its an easy fix for the installer to do.

[dsomerv]

beenthere:

here's what the York Installation Manual (page 16) states:

"
Auxiliary Heat Defrost Operation – Air Handler Mode
The control will energize W1 Out and W2 Out 45 seconds prior to and
during defrost operation. If a call for heating (Y1) is still present after the
defrost cycle has terminated, the control will continue to energize W1
Out and W2 Out for 180 seconds after the defrost cycle has been terminated.
The control will begin normal heat pump heating mode operation
upon termination of the defrost cycle.
"

In my handler (York SVY...), W1OUT alone turns on 5 kw, W2OUT alone turns on 10 kw , both W1OUT and W2OUT turns on 20kw (which is indeed what I need during defrost, especially when the ambient falls below freezing).

Unfortunately, I had to give up on the original installer because of incompetence and bad workmanship, and have been unable to find any qualified professional willing to even return 'phone calls.

thanks, Dan S.

[beenthere]

5+10 equals 15. So you probably only have 15 KW of strip heat.

Don't matter what the manual says, it still only energizes W1.

[beenthere]

Electech.

This is the Ask Our Pro's forum. In order to post advice here, you must have verified qualifications and have been approved by the AOP Committee.

You can find the rules for posting and qualifications here.

[dsomerv]

BeenThere:

There are three relays controlling 20kw of resistance heaters in the AirHandler :
HT1 controls a 5kw heater
; HT2 controls a 5kw heater
; HT3 controls a 10kw heater bank

The handler control board logic works this way:
- when only W1 is asserted, only HT1 comes on for 5kw
- when only W2 is asserted, HT1 and HT2 come on for 10kw
- when W1 and W2 are both asserted, then HT1 and HT2 and HT3 come on for 5+5+10 = 20kw


Considering that 10kw is not enough to compensate for the cooling during defrost the W1out + W2out description in the York manual makes a lot of sense; but you seem convinced that the York manual lies - so I wonder if this is actually a defrost control board bug or just more bad documentation.

thanks.

[beenthere]

Bad documentation.

Post full model number of your outdoor unit.

There is still an easy way for your installer to resolve it.

[dsomerv]

beenthere:

model number is: (Z) YZB04211A , installed December 2007

also, the original defrost control board was the non-communicating version, which has apparently been superseded by the communicating version - which I now have (I do not use the communicating features).

[beenthere]

It only energizes W1 during defrost.

From manual.

Defrost Operation:
The defrost mode is equivalent to the cooling mode except that the outdoor
fan motor is de-energized. The control shall do the following to initiate
a defrost cycle.
• De-energize the outdoor fan
• Energize the crankcase heater
• Energize the reversing valve
• Energize the auxiliary heat outputs based on the system configuration
• Energize Y2Out terminal if not already energized
• Begin the maximum defrost cycle length timer

On dual fuel systems, it will energize both W1 and W2 on a defrost call.

[dsomerv]

beenthere:

yes, I see that in my manual on page 12 ...

I take the line:
"• Energize the auxiliary heat outputs based on the system configuration"
literally , that is outputs (plural) = more than one.
Also the phrase under defrost operation termination at the bottom of page 12:
"• De-energize the auxiliary heat outputs" uses outputs plural.

And I believed the information on page 16 as reproduced in my reply post yesterday at 5:27 says that W1OUT and W2OUT are asserted before, during and after the defrost .
This makes sense because, considering the cooling during the defrost cycle, without a goodly BTU boost, very cold air comes out of the registers.
This is not only uncomfortable, but undoes a good bit of the preceding heating by heatpump that has gone on - in short, a big step backwards. .

I do agree that your interpretation of only W1OUT is the observed behavior.

The reason I posted was that I think that this behavior is a bug, and was wondering if someone, such as yourself, who might have access to the cloistered York UPG engineering might have any information - such as a TechnicalServiceBulletin or other advisory dealing with complaints about cold air during defrost .

So it looks like I'll have to resort to a workaround to force more resistance heat on, since 5kw is obviously inadequate; the easiest will be to just exchange w1out, w2out which will get me to 10kw without messing up the other Auxiliary / Emergency heat functions too much.

I really do appreciate your efforts and interest in setting me straight. I wish I could follow your other advice to let a professional do the job; I've been working on finding someone competent and willing for 3 years now, but so far no luck.

thanks,
Dan S.