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  1. #1
    Join Date
    Feb 2007
    Posts
    18

    Heat Pump questions (outside fan stopped)

    Had a new Amana 16 seer heat pump installed this summer and it worked great, but, now that it is getting cooler I don't know if it is working properly.

    When it got colder the heat pump kicked on and it was about 5 times louder than it ever was cooling, and this morning I just happened to be outside and it made some loud clunking sounds and then some gurgling sounds and the fan on top stopped spinning.

    So I put my head over it and it looked like steam or something was coming out (couldn't tell from where and it was a good bit) since it was still making a humming sound but only about half as loud I was guessing some kind of defrost, but after about 10 minutes I just turned it off because I could feel a good bit of heat coming out of it.

    Does that sound normal or should I call the Installing Co. back? I just had them out yesterday for the loudness and excess vibration during heat, but it was too warm outside or something and he said he just bled off some refrigerant.

    Thanks
    KC in KC

  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,884
    DEFROST!

    Normal

  3. #3
    Join Date
    Jan 2005
    Location
    Emerald Coast
    Posts
    933

    Well

    If your outdoor temperature is in the mid 30s or cooler it's probably a defrost cycle.


    Fan stops, steam rising, making quite a racket... defrosting. Is the house warm?


    Do not attempt vast projects with
    half vast experience and ideas.
    ...

  4. #4
    Join Date
    Feb 2007
    Posts
    18
    Thanks, when the steam came out I got a little spooked. (it is about 36 degrees) Yes the house is warm, it actually kicks some pretty good heat.

    Any opinion why it is so much louder on heat than cool? Its not a little louder it actually vibrates my kitchen window.

    Weird, it is a little quieter after the defrost cycle, this thing is sure different than an a/c.

    Thanks again
    KC in KC

  5. #5
    Join Date
    Mar 2007
    Location
    Myrtle Beach, SC
    Posts
    2,919
    DEFROST SYSTEM:
    A heat pump is a lot like a regular air conditioner, except that it reverses every heating season to blow cold air outside and warm air inside. Because the outdoor coil is getting colder than the air outside in the winter, the outdoor coil can freeze in the winter. This is because the outdoor coil condenses water on it in the winter. Only instead of liquid water running off the coil into a drain line, the moisture freezes onto the coil. The heat pump still operates efficiently with a light coating of frost on it. However, eventually the frost becomes a heavy layer of ice and the efficiency is reduced. This is why heat pumps have a defrost system that regular air conditioners do not have. Heat pumps have either a timer or differential thermostat to initialize the defrost cycle. When defrost starts, your heat pump will do some very strange things. This is especially true if you are used to a different type of heating system, such as gas or oil forced air.
    The first thing you will notice when the system goes into defrost is a “Woosh” noise, like the air being let out of a tire. Then the outdoor fan will stop. After a short while a vapor cloud will start to rise from the outdoor unit. We have occasionally had customers call the fire department at this time. But this is normal operation for a heat pump. If the vapor cloud is white, then it is just water vapor (steam) coming from the hot outdoor coil. Only if the cloud is black is it smoke. (Then you can panic!) The compressor noise will usually get louder during the defrost cycle than during normal operation.
    What is happening during the defrost cycle is that the reversing valve has switched back to cooling mode so that the outdoor coil will get hot. The outdoor fan has shut off so that the outdoor coil gets hot faster because no air is blowing across it. Then the auxiliary strip heat comes on so it does not blast you with cold air coming out of the supply registers. You will also see water running off the outdoor coil. This is not a leak, just normal operation.
    The defrost cycle normally lasts up to ten minutes. Then the heat pump resumes normal operation. The outdoor fan will come back on. The white vapor cloud above the unit may get really huge. The reversing valve will switch back to heating mode with another “Woosh” and the auxiliary strip heat will go off after a short delay.

    Too bad your installing contractor did not explain this to you. we have a 4-page instruction book we hand out to explain these things. It also has our phone number on it. :-)
    Remember, Air Conditioning begins with AIR.

  6. #6
    Join Date
    Feb 2007
    Posts
    18
    Thanks Kevin,

    I feel like I should send you a check

    That explained alot, that is why I really like this forum.

    KC

  7. #7
    Join Date
    Mar 2007
    Location
    Myrtle Beach, SC
    Posts
    2,919
    KC

    That is taken directly from our heat pump instruction sheets. I don't understand why more contractors don't have such things to help their customers out. It is part of being a service contractor.
    Remember, Air Conditioning begins with AIR.

  8. #8
    Join Date
    Jun 2007
    Location
    Metro St. Louis
    Posts
    181
    Quote Originally Posted by kccustom View Post
    Thanks, when the steam came out I got a little spooked. (it is about 36 degrees) Yes the house is warm, it actually kicks some pretty good heat.

    Any opinion why it is so much louder on heat than cool? Its not a little louder it actually vibrates my kitchen window.

    Weird, it is a little quieter after the defrost cycle, this thing is sure different than an a/c.

    Thanks again
    KC in KC
    Hope all is well over in Chiefs land. Normally, I am able to make it to one game each year, but not this year.

    I've had my Amana ASZ16 for about a month. Ran it on cool for a couple of days - very quiet.

    Do you have a variable speed blower? If so, you will notice that the indoor blower kicks up to high speed during defrost. Then, it should drop back down to low speed blower after defrost is done.

    As for the higher noise - this is due to the lineset vibrating. I started a thread a couple of weeks ago about this very subject. There are a couple of different ideas on why this happens - all of which are feasible:
    1) The compressor is "closer" to the indoor unit in heat mode. In cooling mode, the refrigerant flows from the indoor unit thru the reversing valve to the compressor and then thru the outdoor coil and then thru both TXVs to the indoor coil. In heating mode, the entire flow is reversed. Therefore, the compressor's vibration is not dampened by the outdoor coil before it comes inside.
    2) Low airflow. The TXV (inside the outdoor unit) has to reduce the refrigerant flow to ensure that the liquid fully vaporizes before reaching the compressor. This implies that it is the TXV itself that is causing the vibration as it opens and closes. I don't know exactly how the TXV meters the refrigerant - whether it opens and closes (which would cause vibration), or modulates.
    3) TXV bypass vibrating due to low refrigerant flow. Kinda like #2, but places the resposibility for this vibration to the indoor TXV (which is bypassed in heating mode). If the flow is too low, then the check valve which allows the bypass might be vibrating.
    4) Overcharged. This could also explain either of the above, as it would seem to force the system to reduce refrigerant flow.
    5) Other (according to service manual under "compressor is noisy") - broken internal parts, broken valves, loose holddown bolts, TXV bulb loose. I would think that most of these would present themselves in cool mode as well as heat mode. Except maybe the TXV bulb loose. But that might be more of a noise and not a vibration.

    #2/#3 seem quite likely to me. The Amana ASZ16 compressor will run in HIGH speed (with low fan) when first stage of heating is requested. When second stage of heating is requested, it will bump up both blowers speeds. Therefore, by definition, you are at a "low air flow" condition causing the expansion valve to meter down the flow.

    #4 also seems quite logical. The vibration wouldn't necessarily manifest itself during cooling, as the compressor would run at the appropriate speeds relative to the indoor fan speed.

    I'm taking a "wait and see" approach on mine. The installers will be coming out in a few weeks to hook up my humidifier (they're waiting on me getting my hot water tank moved first). When they come, I'll have them check the charge. Unfortunately, my understanding is that you cannot check superheat/subcool during the heating season - you have to just use the pressure charts.

    The other reason I'm waiting is to see if #2/#3 are the causes. If so, as the outdoor temps get lower, you would expect the vibration to reduce. Assuming my charge is correct, I can live with some vibration during the "shoulder" months when the compressor's ability is highest and the indoor needs are the lowest.

    As for you - you might want to just have them come out and check out your system. They should be able to do something to better isolate the vibration from your structure and from the ductwork. They can also check the system's charge. Just make sure that they look at the appropriate charts based on outdoor temp.

    If your contractor is able to significantly reduce the noise, please let me know. Here's some links to documents about the ASZ16 and MBE/MBR blower:
    ASZ16: http://securenet.goodmanmfg.com/pdf/...T6214003R4.PDF
    MBE/MBR blower: http://securenet.goodmanmfg.com/pdf/...T6223002R3.PDF
    Service Manual: http://securenet.goodmanmfg.com/pdf/...S6200006R2.PDF

    What we really need here is RoBoTeq's input, but he's been less active on this board lately.

  9. #9
    Join Date
    Jun 2007
    Location
    The Twilight Zone
    Posts
    2,964
    Good info from Waterloo and Kevin O'Neill.

  10. #10
    Join Date
    Feb 2007
    Posts
    18
    Wife is the big Chiefs fan around here, I like the Saints


    Any way I am not crazy!

    Tech just left and lucky for me he said he was recently on a similar call and said he believes it is a problem with the "A" coil not having a way to compensate for the extra vibration caused by heating mode so they are going to call Amana and see if they can get a better mounting kit to keep it from vibrating so much. (I am sure it may be a little bit more complicated but that was good enough for me)

    Better late than never he also took the time to explain how the dang thing works.


    Thanks everybody!

    KC in KC

  11. #11
    Join Date
    Jun 2007
    Location
    Metro St. Louis
    Posts
    181
    Quote Originally Posted by kccustom View Post
    Tech just left and lucky for me he said he was recently on a similar call and said he believes it is a problem with the "A" coil not having a way to compensate for the extra vibration caused by heating mode so they are going to call Amana and see if they can get a better mounting kit to keep it from vibrating so much. (I am sure it may be a little bit more complicated but that was good enough for me)
    KC - Any news from your contractor? Was he able to reduce the vibration?

  12. #12
    Join Date
    Apr 2005
    Location
    Kingston Ontario Canada
    Posts
    1,210
    Yes, great info Kevin O'neill and Waterloo!!!! Kevin would you be able to tell me, if a heat pump has a timed defrost to initilize the start of a defrost cycle, what signals the end of the defrost cycle? Is it a preset time or another condition that ends the defrost. I'm just wondering. Lately, my heat pump seems to defrost quicker then other times.

    thorton
    ____________________
    Common sense isn't that common

  13. #13
    Join Date
    Feb 2007
    Posts
    18
    Quote Originally Posted by Waterloo View Post
    KC - Any news from your contractor? Was he able to reduce the vibration?
    No news yet, I will probably have to call them back. I will give them another week before I start bugging them again.

    Funny thing though, it is a little quieter after it went into its first defrost mode.

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