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  1. #14
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    To the OP:

    What you have described would be called "normal operation."

    Heat pumps are not designed to be quiet. They are designed to meet their task while remaining reasonably priced and efficient.

    If the unit is directly adjacent to an occupied space, and you wish to reduce the level of normal sounds you are hearing, there is acoustical grade drywall you can add to the inside of the wall closest to the unit, and you can ask your tech to make certain the lineset is not in direct contact with the structure at the point of entry.

    A reminder to all posters in this thread:

    ONLY pro members with an * can offer advice in the AOP forums. Regular members responding to an OP often are found giving some form of advice in their posts, and the point of the forum is for the HO to "ask our pros," not "ask anyone."

    Regular members who are qualified should apply for pro membership and ask for their * so they can take part in the forum while remaining within the guidelines.

    All the needed info is in the links at the end of this post.

    Thanks.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  2. #15
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    Quote Originally Posted by offsite View Post
    Tom, Another newbie here. I was amazed at the effort you went to to try to gather all the issues into one thread for those of us who will encounter them in the future... good job!

    Out of this comes the impression that Heat Pumps generically are noisier than A/C compressor units.

    This raises a red flag for me.

    I live in So Cal (San Diego) in a wood frame condominium complex where all the A/C compressor housings are on the roof (ie directly above the ceiling of the top units).

    Recently we had to install some more aggressive isolation blocks under the corners of each housing to attempt to decouple vibration from the structure. Prior to that some residents were bothered by the noise in their units. After, the noise was still there but it was more tolerable.

    I currently am getting bids on either a Trane or Rheem Heat Pump to replace the existing Trane A/C - Gas Furnace system.

    So, two questions arise for the experts here:

    1) Does the 'defrost' cycle only occur in cold climates? (our min temps in winter are in the 50s and occasionally the low 40s)

    2) Would the normal noise/vibration level of even the quietest Heat Pump roof unit be expected to be higher than that of a quiet A/C compressor?

    I'm basically trying to head off 10 years of misery dealing with complaints from my neighbors if Heat Pumps are really not a good idea in this situation.

    Thanks for having this discussion!

    -rb-
    To answer your first question defrost will take place in all climates under the right conditions.

    A heat pump is no noisier than the comparable AC unit.

  3. #16
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    Since this thread was resurrected I put together a bit of a summary of the conclusion I came to as a homeowner and added it to the thread.

    Then I re-read TimeBuilder's post and realized that HVAC-TALK had updated its posting requirements for this forum and that it was inappropriate to post as it fell into the category of advice. So I felt I had to edit this message and remove my conclusions.

    Sorry fellow homeowners....

  4. #17
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    Thank you, Tom.

    If you like, you can forward your conclusions to one of the Mods or AOP Committee members for a review, and if one of us believes it will be both accurate and enlightening, then, who knows, one of us might decide to post it. Most of us have an email in our Profile.

    We'd like to offer professional opinions to the homeowner, rather than non-professional, anecdotal ideas about what a system should or should not be doing, as we see many, many more systems than any one non-pro could see in a lifetime.

    You can feel free to answer your own original post, telling if something was done that ameliorated the sounds to your satisfaction, and what your local pro told you was the needed repair, if any. That is well within the rules.

    Thanks again.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  5. #18
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    snip-snip ---- Message outdated and removed.

  6. #19
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    Click on the user name.

    Click on "view public profile"

    On the profile page, click on the "about me" tab, if not already displayed.

    Most of us have an email there. I do, too.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  7. #20
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    Okay, Tom sent me his comments. I don't know of many people who are troubled by the defrost cycle. Most homes have the bedrooms on the second floor, and so most heat pumps are not really "close" to the bedroom. Here is what Tome wanted to share:

    Thanks everyone for all the input and attempts to explain something complex to a layperson like me.

    Based on everything posted here, Timebuilder's response is the (unfortunate) answer that all of us with noisy Heat Pumps will have to accept. They must occasionally go through a defrost cycle. And while some brands and add-on features may diminish the frequency or loudness, it will nearly always be at least perceptible. Specifically, if you have an existing heat pump, there is typically little that can be done to change how loud or frequently it will go through the cycle.

    Perhaps most importantly, unless you have a high-end heat pump system and / or get a strong assurance from your contractor that its defrost cycle is unusually quiet, never place a heat pump compressor outside a bedroom window or other area where it's likely to be heard inside. Most people who have never had a heat pump only think of the fan noise they hear when it is operating as an air conditioner and know nothing of the defrost cycle. Your contractor may not be thinking of this as he suggests a location for the compressor, and to some extent, shame on the contractor for not thinking of your comfort in advance.

    But in any case, don't expect miracles once a system has been installed.

    As for me, I'm paying to have both compressors moved to the far side of the house (the original units were placed by the bedroom windows by the previous owner and the new units I upgraded to were installed in the same place as the old ones). Paying to move them is money I hadn't expected to have to pay, but I've already contracted to do so before the weather turns colder. I really need to be able to sleep for periods longer than 90 minutes at a time.

    Tom Campbell
    My question would be to ask if this was a straight AC system originally, which was replaced with a heat pump, giving rise to the noise issue. If this change to a heat pump system happens before you move in to a home, it might be something to ask your real estate agent about before you make an offer on a property. You can save some significant money with a heat pump, especially if you go with a dual-fuel unit that avoids strip heat in some localities where electricity is more expensive. That alone would help me sleep better.

    So, if you have a choice of where to place the condensing unit, you might consider the variety of usually innocuous noises a heat pump can make as it changes from heating to defrost and back again.


    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  8. #21
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    Quote Originally Posted by timebuilder View Post
    Okay, Tom sent me his comments. I don't know of many people who are troubled by the defrost cycle. Most homes have the bedrooms on the second floor, and so most heat pumps are not really "close" to the bedroom.
    I started this thread last winter because I noticed that I wasn't the only person asking the same set of desperate-for-a-solution questions. No-one comes here asking these questions over the summer, but as we roll into November, December, and January, I'm sure it will be like last winter were every 8th post was asking for help with defrost cycle noise. And if it's like last winter, the pros here will graciously answer questions for the first month or two, and then their patience will run out, having gotten tired of answering the same questions asked different ways.

    I was hoping that I could help other homeowners out, and save the pros here the grief of repeatedly answering the same questions, by creating a thread where definitive answers, or at least as definitive as is possible with a squiggly topic like this one, would be available. I tried to include as many keywords in my first post as I could think of so that responsible visitors who use search would find the thread. And those that did start heat-pump noise threads could just be reprimanded for not using search and then pointed to this thread.

    Unfortunately, most of the responses from the guys here are still very technical - I THINK I understand most of their responses, but only because I've invested 30+ hours reading here and in some textbooks to understand heat pump technology better. I was hoping to uncover a wizard who could explain the options to a typical homeowner so they would have realistic expectations about what their local HVAC contractor could or could not do to address their issue.

    And so, my final post above, which Timebuilder has posted on behalf. Thank you.

    Still, I think you guys would be doing SO MANY homeowners a service, and saving yourselves tons of trouble with redundant posts, by creating a set of simple English FAQs on topics like this. When homeowners stumble in and ask stupid questions - point them to the FAQ, and tell them to come back with a fresh thread only if the FAQ doesn't answer their question.

  9. #22
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    The noise associated with a heatpump defrost is the rapid change and equalization of the refrigerant system. An R22 system operating normally in the heating mode is operating with a150 psig or more difference between the high and low pressure side of the system. When the system goes into defrost, this pressure quickly equalizes and then reverses. This is the cause of the "wooshing". This noise also happens at the end of defrost, but usually not as bad. This is because the pressure difference is not as high because coil temps are usually lower.

    Some of the ICP units on the market are attempting to combat this by adding a"quiet shift". They stop the compressor, pause for 30 seconds, then shift the reversing valve and restarts the compressor. This gives the refrigerant system time to equalize prior to shifting.

    The best solution for this noise is to not put the condenser by a bedroom window.

    If you are replacing an AC with a dual fuel heatpump, defrost is not a problem as the system should turn off the heat pump and engage the furnace if defrost in needed.
    "Customer Service" is not a department, it's an attitude!
    ???

  10. #23
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    I may or may not be correct however, the noises you refer to, if I am thinking of the sounds you are referring too, sounds a lot to me like liquid refrigerant making it's way past a solenoid/valve. I do not know if you have a solenoid but I would look there. The jackhammer sound would lead me to look for pipes that are hitting on something. It would find the solenoid(or item where liquid refrigerant is squeezing by) and near it is were your jackhammer will be. Find what it is hitting on and place something between that and the pipe.

    It maybe that your reversing valve is having trouble opening. This would be the same as turning off your water hose, as the valve is close to shut off you hear a moaning noise of the water squeaking by. As this happens it causes the pipe to rattle and hit something.

    I hope that is helpful but it is only a guess.

    Goodluck!
    If you're too "open" minded, your brains will fall out.
    Artificial intelligence is no match for natural stupidity.

  11. #24
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    Thanks for the follow up guys - but I really am no longer looking for a solution to my specific problem. The real spirit of this thread was to generically help others in the same boat as me. The very best thing I could ask of all of you would be to help build a checklist for the average homeowner to run through before contacting their HVAC installer, and then a list of questions and observations to feed to their installer so the installer can do a good job of servicing them.

    The first thing might be to establish if there is any kind of industry standard for noise levels - dB at 5 feet, perhaps even by frequency? This could conclusively close the door on what is "normal" and not worth pursuing, or what might be due to something that needs adjustment or correction.

    From there, some sort of checklist such as:
    1. Did the system make the same noises last year (if over a year old). If not, then something has clearly changed, and your HVAC service person can probably fix it. Don't go any further with this list until you've had them out to service it.
    2. Does the compressor fan stop and the the noises happen immediately afterward, or is there a 15-30 second pause? If the noises start immediately, some systems have a pause setting that gives the systems time to switch gears between modes. Check with your HVAC service person if yours has this feature and if it can be activated.
    3. Is your system relatively new, or do you know if it uses a "Scroll" compressor? It may simply be part of the design. Different makes and models have differing levels of sound protection, but the basic design will always produce different noises during transfer into defrost mode (see measurable noise levels above).
    4. Do you know if your system is R22 or R410 based? (i.e. maybe that makes a difference???)
    5. Are there more steps a homeowner can check into or collect info to help their HVAC service person diagnose the situation?



    Perhaps more importantly, and this isn't just for this thread, how does a homeowner know when to question their HVAC service person's "That's just the way these things are" response? Heck, just within the last 4 posts here we've seen some pros suggest that it's worth the effort to specifically test a few components. If my service person, who I think is good but I have no way of really knowing, says "That's just the way these things are," is he just being lazy? Should I just accept it? If Timebuilder were my installer, would I be out of line if I asked him to look at the things that Xceltech suggests? Is going to a different service company for a second point of view ever the right thing to do?

  12. #25
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    I believe I understand what you are attempting to start, more importantly I applaud your effort, and thank you for your hard work.

    Well here is the thing. There are so many different brand names, system builds, parts, and levels of quality that creating an overall check list that could encompass the wide extent of noises that should or could be would actually be unproductive to the point of being destructive.

    A good example of what I am saying can be seen in the basic Preventative Maintenance checklists used by governmental agencies for government buildings. I have never done first time PM's on a government building that had a proper PM system. They even had items on their required check point lists that could be harmful to their equipment.

    I have two great examples.

    Most government PM's have a requirement to lube all bearings monthly. This is harmful to the bearings. Bearings (sealed bearings such as pillow blocks), should never be grease more then two squirts in a one year period. The amount of grease that should be inside of a bearing should only encompass 1/3 of the space. More grease then that will actually cause a force the bearings have to push against, think of this as walking on a beach and walking in water. It may also cause the bearings to be forced against one another or even prevent the bearing from rolling correctly cause a flat spot to be rubbed on one side. We call this over greasing, "Washing the Bearings." The other problem is most bearings come now with a thin layer of plastic that seals the grease in and prevents dust or dirt from entering the bearing. Many technicians are instructed, incorrectly, to grease a bearing tell the old grease comes out so that you can push the dirt and dust out of the bearing. This in turn breaks the thin plastic seal and allows dust and dirt that previously couldn't enter the ability to do so. It is also bad to get grease all over the windings of your motor and other equipment. Because an all inclusive PM was created, usually by someone who is not an equipment repairing technician/engineer, the person doing the work greases the bearings every month and causes damage.

    Another often seen PM mistake is telling technicians to always check the pressures of a unit. Although this is generally good advice, some units, such as pneumatic air dryer, use such a small amount of refrigerant that by hooking up hoses to test the pressure you actually remove ALL of the refrigerant. These units usually use less then 8oz of refrigerant and are called, "Critically Charge Units." Ice machine repairmen will be able to verify that information. These units tend to come with no services ports to hook gauges to, however technicians will install ports to do the PM work, and end up hurting the system.

    The best solution to what you are trying to achieve is to:
    1.) Check the BBB for information regarding companies you are thinking of calling.

    2.) Listen to word of mouth from friends and family.

    3.) Look for groups in your area that review complaints or give service awards to local contractors.

    4.) Before hiring a company call and speak with a manager. If the manager doesn't instill you with confidence that he will fix any problems his technicians cause/don't fix then hire someone else.

    5.) Remember that there is such a wide variety of equipment and designs that will change dramatically by the region and weather differences that even a morally strong and well educated technician with 15+ years of experience will be caught off guard from time to time. No technician can fix everything, the amount of knowledge needed is just to much. Hence places like HVAC-Talk.

    6.) Remember that one bad technician does not a company make. Talk to a supervisor give them a chance to resolve the issue. It maybe much cheaper in the long run for you and it maybe that you got the 1 out of 10 technicians who is a bad apple. Remember that most companies have a 15/70/15 employee ratio. That is 15% who go above and beyond, 70% who are average workers, and 15% who are barely employed and don't care. That means out of 10 employees only 1 to 2 of them are bad employees. You may end up losing a great company on a knee jerk reaction.

    Finally, the best PM system is one created by you, your technician, and your units manufacturing suggested maintenance plan. All Pm's should be designed around the needs of the equipment and not by an all inclusive check list.

    Thanks Tom and good luck!
    If you're too "open" minded, your brains will fall out.
    Artificial intelligence is no match for natural stupidity.

  13. #26
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    Quote Originally Posted by Tom Campbell View Post
    If Timebuilder were my installer, would I be out of line if I asked him to look at the things that Xceltech suggests? Is going to a different service company for a second point of view ever the right thing to do?
    Out of line? Not really.

    BUT, if I WAS your installer, I would have already heard the thing, and no one online would have heard it. The guys here are coming up with alternative ideas that may not be in play for your particular system. Without having heard the sounds, these suggestions are at the "well meaning guess" point, and we can't base the suggestions made here on the reality you are experiencing.

    To me, all of the sounds you talked about are typical of many systems I have heard. I'd be hard pressed to imagine they all had a common failure.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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