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  1. #1
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    Scroll with start capacitor..would appreciate input

    Just got a call on an estate that has a dehumidification system with a variety of problems. The original recip compressor has been changed to a scroll with an add on start capacitor & I've seen advice on both sides of the fence as to the necessity of this. I have not been able to get any clear definition from the compressor manufacturer either. I don't believe that an add on start capacitor does this unit any good & might ever wear out the compressor prematurely.

    What say you guys & gals?Name:  20180314_174646.jpg
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    "The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
    - Alexis de Toqueville, 1835

  2. #2
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    Copeland states that while start assist in generally not required for any single phase scroll to start, the addition of a start capacitor or PTC relay can help minimize voltage dips which can cause annoying dimming of lighting.

    I had this issue with my 4-ton heat pump in my home back in Florida, so per this bulletin I added a simple PTC start relay. For a start cap and potentilal relay, I would use the OEM Copeland parts as listed in Table 7, simply because they are approved for use with these compressors, whereas the Kickstart types are not.

    Copeland's Application Engineering Bulletin AE-1312 explains how and when to use start assist with ZR single phase scrolls on p.5:

    http://www.hvacrinfo.com/cope_ae_bulletins/TAE1312.PDF

    Here are a couple of screenshots:

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  4. #3
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    Nov 2014
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    Philadelphia area
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    Scrolls start unloaded so you really shouldnt need it unless the system for some reason or another does not equalize when it turns off. It will not harm the system at all though.

  5. #4
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    That compressor is 21 years old. I wonder how many of those years were with that start assist ?

  6. #5
    Join Date
    Mar 2013
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    I'd be more worried about the cracking/weathering compressor leads.
    Experience - knowing when to get the hell out of the way and plug your ears. "Don't be a sissy. Turn it on!"

    Glennac - Failed my biology test today: They asked, "What is commonly found in cells?" Apparently "BL*** people" wasn't the correct answer.
    Poodle Head Mikey - "the world is well populated with the unknowing and the uncaring and the stupid."

  7. #6
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    Reducing starting torque is never a bad thing

    Sent from my SAMSUNG-SM-G930A using Tapatalk

  8. #7
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    Thread Starter
    Quote Originally Posted by icemeister View Post
    Copeland states that while start assist in generally not required for any single phase scroll to start, the addition of a start capacitor or PTC relay can help minimize voltage dips which can cause annoying dimming of lighting.

    I had this issue with my 4-ton heat pump in my home back in Florida, so per this bulletin I added a simple PTC start relay. For a start cap and potentilal relay, I would use the OEM Copeland parts as listed in Table 7, simply because they are approved for use with these compressors, whereas the Kickstart types are not.

    Copeland's Application Engineering Bulletin AE-1312 explains how and when to use start assist with ZR single phase scrolls on p.5:

    http://www.hvacrinfo.com/cope_ae_bulletins/TAE1312.PDF

    Here are a couple of screenshots:

    Name:  Copeland-AE4-1312-R2-Single-Phase-Starting.png
Views: 140
Size:  82.2 KBName:  ZR17-68-PFV-Approved-Start-Components.png
Views: 141
Size:  66.6 KB
    Thanks a ton. I should mention that we, in the Pacific NW, do not have low voltage problems here at all. When I had my business in the Washington/ VA/ Maryland area we had low voltage most all summer. This system has a strong, constant 239 volts night/day/summer/winter. So what I take is that some here say it's OK & some tend to think it's not necessary. That is what I have been running across. One weird thing about this unit is that it does have a solenoid valve installed that I have yet to figure out it's operation just due to the short time period I have been working on this system. This system has a unique piping arraignment & seems to be one of a kind based on my experiences with these systems. Here's a picture of the solenoid valve too. I'm not too sure it can be called a liquid line solenoid valve in true purpose due to the control & piping arraignment. As I get more into the system testing will tell me the true operation of this unit.
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    "The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
    - Alexis de Toqueville, 1835

  9. #8
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    I added the start assist PTC relay to my compressor not because it had low voltage or a starting problem, but it was causing annoying dip in any lights which were on a dimmer control...and I had most of my lighting on dimmers. Any dip in line voltage would be greatly amplified through the dimmer...sometimes even to the point of shutting off the light if it were dimmed way down low.

    The start assist took care of the problem and I ran it for maybe ten years after that with no problems. Also, it was probably one of the few units I can recall working on that never lost a run cap, now that I think of it.

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  11. #9
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    Thread Starter
    Quote Originally Posted by icemeister View Post
    I added the start assist PTC relay to my compressor not because it had low voltage or a starting problem, but it was causing annoying dip in any lights which were on a dimmer control...and I had most of my lighting on dimmers. Any dip in line voltage would be greatly amplified through the dimmer...sometimes even to the point of shutting off the light if it were dimmed way down low.

    The start assist took care of the problem and I ran it for maybe ten years after that with no problems. Also, it was probably one of the few units I can recall working on that never lost a run cap, now that I think of it.
    Thanks for the clarification. This home does not have that problem & it's loaded with a ton of energy users. The machine room in the home alone has 5 or 6 200 amp panels.
    "The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
    - Alexis de Toqueville, 1835

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