Page 1 of 2 12 LastLast
Results 1 to 13 of 16
  1. #1
    Join Date
    Apr 2008
    Location
    Northwest Arkansas via Chicago Area via Straight Up from There on Lake Superior
    Posts
    1,411

    Confused 2 Stage HP Cooling Capacity & Power Usage

    Have a 4-ton York 8T Affinity 2 stage HP. After lowering the stage 2 blower speed to around 417 CFM/ton and thanks to a HW VP IAQ tstat and VS furnace it is spending a lot of time in stage 1 cooling. The VS furnace blower is also running in stage 1 cooling at less than 300 CFM.

    Can anybody tell me as a percentage of the stage 2 HP numbers:

    1) the cooling capacity of the stage 1 HP and

    2) the power used in stage 1 HP?

  2. #2
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,763
    72% capacity
    69% power
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  3. #3
    Join Date
    Feb 2009
    Location
    north of 49
    Posts
    233
    I can see the 72% capacity. How is the 69% on power arrived at?

  4. #4
    Join Date
    Sep 2002
    Location
    I don't know
    Posts
    2,909
    .......................deleted.................... ..................
    General public's attitude towards our energy predicament: "I reject the reality of finite resource depletion and substitute it with my own; energy is infinite, we just need an alternative storage medium to run the cars on. The economy can grow indefinitely - we just need to "green" everything! Technology is energy! Peak what?"

  5. #5
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,763
    Quote Originally Posted by trout lake View Post
    I can see the 72% capacity. How is the 69% on power arrived at?
    Second stage KW is 3.3
    First stage KW is 2.3
    2.3/3.3=.6969
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  6. #6
    Join Date
    Feb 2009
    Location
    north of 49
    Posts
    233
    thanks

  7. #7
    Join Date
    Apr 2008
    Location
    Northwest Arkansas via Chicago Area via Straight Up from There on Lake Superior
    Posts
    1,411
    Quote Originally Posted by beenthere View Post
    72% capacity
    69% power
    BT, thank you!

    Looks like I am running at less than 3 tons most of the time on a house that had a 4 ton split AC/furnace. Pretty good for a house with about 3700 sqft.

    But to be honest, wifie won't let me run it below 79 degrees and it does run a lot trying for 50% RH, so I set it at 55%. I realize that a lower temp setting would help with the RH, but ..... Peace is important too.

    Also set the Fan On to 40% of blower capacity to get circulation but no hurricanes. I turn on Circulating from time-to-time just to even out temps across house due to sun load or closed door (cats!) bedroom humidity at night.

    Thanks again, BT.

  8. #8
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,763
    Is the IAQ actually wired up to slow the blower on a dehumidify call.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  9. #9
    Join Date
    Apr 2008
    Location
    Northwest Arkansas via Chicago Area via Straight Up from There on Lake Superior
    Posts
    1,411
    Quote Originally Posted by beenthere View Post
    Is the IAQ actually wired up to slow the blower on a dehumidify call.
    BT, as I have often said, I am an HVAC non-wannabe, as you can probably figure out from some of my ignorant questions, but I have been through the HW VP IAQ manual numerous times trying to figure out how to fake it out. If you are asking if I have Option 369 set to Dehumidify with Air Conditioning, the answer is yes. I also have Option 383 set to allow a 3 degree Over-Cooling Limit although it seems to never go down more than 2 from the set point. The AC does run mostly in stage 1 and the temp is at set point almost always.

    By the way we have a YTH9421C1002 which has a remote equipment interface module at the furnace and only 3 wires (it's the the old tstat wiring) to the actual tstat. Is there some other settings you are asking about like in the EIM, VS York furnace or HP? If so, please explain.

    PS: The contractor says he has installed many IAQ's but not this high end tstat.

  10. #10
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,763
    Their is only 1 IAQ stat fromHoneywell. He may be refering to the Vision Pro stats.

    I was wondering if your contractor actually set the jumper in the furnace to allow the IAQ stat to slow the blower.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  11. #11
    Join Date
    Apr 2008
    Location
    Northwest Arkansas via Chicago Area via Straight Up from There on Lake Superior
    Posts
    1,411
    Quote Originally Posted by beenthere View Post
    Their is only 1 IAQ stat fromHoneywell. He may be refering to the Vision Pro stats.
    Believe that is what he said and I misspoke.

    Quote Originally Posted by beenthere View Post
    I was wondering if your contractor actually set the jumper in the furnace to allow the IAQ stat to slow the blower.
    I would really like to achieve 50% RH without continuous running except for 95 degree days of course.

    The "YTH9421C1002 which has a remote equipment interface module at the furnace and only 3 wires" that are then wired at the furnace (I think from looking at the furnace control board diagram) to something like 10 terminals (LO COMP, HI COMP, ... C). He has set the 2110 CFM capacity blower to Hi Cool 1670 CFM and Lo Cool 1085 CFM. The blower is running almost totally in low with the compressor at stage 1. Run times are much longer without the old short cycling problem.

    I notice that one of the 10 terminals on the furnace control board is DHUM. Is the wiring of that terminal something that you are referring to?

    Also set the furnace Continuous Fan Speed Jumper jumper to 40% of blower capacity. Circ setting for the fan on the tstat which I experiment with does seem to lower humidity some.

    I strongly suspect that our temp setting of 79 degrees is part of the problem (but that's what Mom wants). A lower setting would probably take out more humidity, correct?

    The contractor suggested caulking the tstat wiring hole in the wall behind the tstat in case there is some leaking from the attic or other locations that affects the tstat readings. Saw this mentioned in another post. Is that a candidate for correction?

  12. #12
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,763
    The Dhum must be wired for the IAQ to control the blower.
    If its not. Then it can't dehumidify as well as it should.

    Its easier to maintain 50% RH at 79, then it is at 76.

    Your system probably still isn't wired or set up right.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  13. #13
    Join Date
    Apr 2008
    Location
    Northwest Arkansas via Chicago Area via Straight Up from There on Lake Superior
    Posts
    1,411
    Quote Originally Posted by beenthere View Post
    The Dhum must be wired for the IAQ to control the blower.
    If its not. Then it can't dehumidify as well as it should.

    Its easier to maintain 50% RH at 79, then it is at 76.

    Your system probably still isn't wired or set up right.
    Right again, BT! The DHUM is not wired at the furnace. He used 8-wire cable from the EIM to the furnace and didn't wire that one.

    He is supposed to talk to Honeywell on Monday about getting some larger temp difference between the IAQ temp setting and AC on/off. I am emailing him to suggest that he also discuss the DHUM wiring.

    As I have said several times in other posts, the HW IAQ documentation lacks a lot on theory of operation that would enable one to figure out all of the interactions of this complex tstat. I would have been beat up pretty bad for that kind of documentation in my past life. I will renew my suggestion here that there are several topics that if placed where HO's could find would greatly relieve many of the questions we (and our contractors) have. One topic is the IAQ and its settings another is Ryan Hughes' start on explaining the AHRI directory search capability.

    Ryan forwarded a suggestion to make permanent his thread on AHRI, but nothing came from it. Could you look into getting his post into a more permanent and findable status? The thread is titled "For New Systems: How To Search for Performance Data". Maybe a review and additions by other knowledgeable pros could make this a big winner for confused and uninformed HO's/contractors.

    Thanks again!

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event