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I wonder if ChrisJ is stable yet ?

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Comments

  • Harvey Ramer
    Harvey Ramer Member Posts: 2,224
    With a properly functioning TXV, the superheat will not change unless it gets out of its range.
    You should see the same SH in low stage as high stage.
  • ChrisJ
    ChrisJ Member Posts: 13,558
    edited July 2017

    With a properly functioning TXV, the superheat will not change unless it gets out of its range.

    You should see the same SH in low stage as high stage.

    Interesting.
    I wonder why it was changing then?

    When i finished up, I had between 9-10 degrees in low and still around 12-13 in high.

    Unless I just wasn't waiting long enough between switching stages to know for sure. But I waited quite a long time for everything to stabilize.

    Low I know is right, because I checked it many times and waited a long time all of those times. High stage, I was just mainly looking to see what it did out of curiosity. I know the lowside pressure dropped, so maybe my temp probe just didn't catch up. I suppose it's possible.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,660
    12 deg sh with both stages is perfect. That's Sporlan's factory SH setting. Yes the distributor PD is supposed to be figured in could be as much as 45psi on R410A

    The reason you need superheat is to prevent liquid floodback to the compressor. If you ran a system with low superheat 2,3,4 deg the possibility exists that some liquid is getting back to the compressor. You need some margin of safety to prevent the compressor from pumping liquid which is NG. raising the superheat provides this.

    Not only do liquid slugs risk damage to the scroll but excessive liquid can mix with the oil (they have a high affinity to each other) this will cause foam in the crankcase (as the liquid boils off under lower pressure) and liquid mixed with the oil will not lubricate the bearings. used to call it washing out the bearings

    On larger semi Hermetics with oil pumps excessive liquid would cause the oil pressure switch to open and shut down the compressor
    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 13,558
    edited July 2017

    12 deg sh with both stages is perfect. That's Sporlan's factory SH setting. Yes the distributor PD is supposed to be figured in could be as much as 45psi on R410A

    The reason you need superheat is to prevent liquid floodback to the compressor. If you ran a system with low superheat 2,3,4 deg the possibility exists that some liquid is getting back to the compressor. You need some margin of safety to prevent the compressor from pumping liquid which is NG. raising the superheat provides this.

    Not only do liquid slugs risk damage to the scroll but excessive liquid can mix with the oil (they have a high affinity to each other) this will cause foam in the crankcase (as the liquid boils off under lower pressure) and liquid mixed with the oil will not lubricate the bearings. used to call it washing out the bearings

    On larger semi Hermetics with oil pumps excessive liquid would cause the oil pressure switch to open and shut down the compressor

    I'm about 1 1/2" turns more out than factory.
    I slowly opened it 1/4 turn at a time while adding refrigerant and checking both SH and SC. It took quite a while as I started at 20+ degrees of super heat due to low charge. One thing I've learned, charging and vacuuming are both terribly time consuming if done well.

    I basically followed Goodman's instructions. When I closed the system up my SH was, if anything, a tiny bit higher than they wanted, maybe 1 degree if that. They called for 6-9, mine is 9-10ish. Probably safe to call it 9.5.

    The system had been running for several hours after my final adjustments before I pulled the gauges off.

    I can only hope my 3/4" insulation helped make my SH more realistic down at the unit.

    @EBEBRATT-Ed Any ideas on why my SH would've been higher in high stage than low stage? Unless, like I said, maybe I just didn't wait long enough for the temp probe to stabilize.

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,660
    quite often field equipment doesn't hit the factory #s exactly. Lots of variables, condensing temp, indoor temp, indoor humidity, line length, line size etc.ec. I think your fine. A compressor has a certain range of operation and will usually last "forever" if operated in that range.

    Problem is compressors get forced out of their happy zone by dirty filters, plugged coils, low airflow, wrong charge etc etc.

    if the superheat is a little higher than they want I wouldn't worry at all. superheat needs to be high enough to prevent slugging, low enough to cool the compressor. Used to always run 15-20 superheat all the time with no problem. Don't know why the mfgs want lower superheat now must be an efficiency thing.. As long as the suction temp is always below 60 deg (and your well below that) your ok.

    When the suction lin etemp get up in the 60s compressors die a long slow death
    ChrisJHarvey Ramer
  • ChrisJ
    ChrisJ Member Posts: 13,558
    I do wish it had an accumulator.

    Hell, I still want a crank case heater but have had a very hard time finding one physically small enough. I have a 40W one here, but it's way too long.

    Off the top of my head, the compressor's diameter is 5.5" and it seemed like most hose clamp style heaters were larger than that.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • ChrisJ
    ChrisJ Member Posts: 13,558
    edited July 2017
    @EBEBRATT-Ed just went up and checked the sight glass in the attic. 69 outside and around 70 inside. Had some bubbles in the glass. I assume this is normal under these conditions especially with 410a? System was in low stage for 2 hours dropping the temp several degrees.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • ChrisJ
    ChrisJ Member Posts: 13,558
    19-20 deg drop across coil currently.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • ChrisJ
    ChrisJ Member Posts: 13,558
    edited July 2017
    After sleeping, I realized those bubbles are probably a good indication that my charge is good. No bubbles with 85F ambient temp, but bubbles at around 69. Sounds about perfect for a critically charged 410A system, no?


    What causes this, refrigerant backing up in the condenser?

    Would love to know if someone makes a low ambient fan controller that works on a 2 speed fan.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,660
    I know 410A acts a differently but if your only seeing a 3 deg SH swing between hi & lo can't see that being a problem.

    When I did a lot of R22 work I would charge to a full sight glass OR a 15-20 deg sub cooling whatever came first. On most jobs when we got to 15 deg the sight glass would still maybe have a few bubbles but the sight glass would usually go clear between 15-20SC.

    But, once in awhile you would get a job where the sight glass still bubbled at 15-20SC then I would stop charging because 15-20sc means liquid is starting to back up in the condenser. piping configuration, temperature, liquid line rise or drop, fittings or LL drier near the sight glass can all affect the sight glass
    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 13,558
    edited July 2017

    I know 410A acts a differently but if your only seeing a 3 deg SH swing between hi & lo can't see that being a problem.

    When I did a lot of R22 work I would charge to a full sight glass OR a 15-20 deg sub cooling whatever came first. On most jobs when we got to 15 deg the sight glass would still maybe have a few bubbles but the sight glass would usually go clear between 15-20SC.

    But, once in awhile you would get a job where the sight glass still bubbled at 15-20SC then I would stop charging because 15-20sc means liquid is starting to back up in the condenser. piping configuration, temperature, liquid line rise or drop, fittings or LL drier near the sight glass can all affect the sight glass

    Wow, 15-20F subcooling.

    With the bubbles in the sight glass I still had plenty of cooling going on. At the time, I was doing a 2 degree drop in the house and I purposely laid my duct work out so the 2nd floor gets more flow than the first, so during that the second floor ends up colder, faster. At my returns I had 68 degrees, and the diffusers were all running around 48 degrees. This was while it was 69F and humid as can be outside.

    I suppose that's a good sign that the TXV is working, consistent temperature drop at a wide variety of indoor and outdoor temps.


    Our area tends to be hot during the day, like yesterday I think was 88F, and then cools off fast at night, ending up in the 60s and muggy. What's amazing is how much heat the walls, ceilings and floors of the house hold. Even though it's cool out side, it takes a long time to drop the temp 2 degrees inside running in low stage.

    I've seen a similar effect in the winter when it's really cold at night, and warms rapidly in the morning. The walls and everything are still cold and the boiler's run times don't match what you would expect for the outdoor temperature.

    Do you think I'd see any benefit if I switch over to a PSC head pressure controller instead of the 2 stage fan, or not enough to matter?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,660
    Is your condenser fan two stage?? Does it change speed when the compressor does or does it respond to head pressure?

    I think I would only change it if the fan is cycling excessively or if the head pressure has a lot of swing which could drive the txv crazy.

    I would just keep an eye on it and see how it runs
    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 13,558

    Is your condenser fan two stage?? Does it change speed when the compressor does or does it respond to head pressure?

    I think I would only change it if the fan is cycling excessively or if the head pressure has a lot of swing which could drive the txv crazy.

    I would just keep an eye on it and see how it runs

    2 speed fan that changes with the stages, nothing else.

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,660
    depends I guess on the lowest outdoor ambient that you need to run cooling at.

    I would think that if you get down in the 60s regurally you may want to put head pressure control on. If the head gets to low the suction will also drop and you don't want to drop the coil temp (indoor) below 32 deg. Tha's about 57 psi suction on R-22, didn't look up 410A. txv controls superheat only has control of suction pressure indirectly
    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 13,558
    edited July 2017

    depends I guess on the lowest outdoor ambient that you need to run cooling at.

    I would think that if you get down in the 60s regurally you may want to put head pressure control on. If the head gets to low the suction will also drop and you don't want to drop the coil temp (indoor) below 32 deg. Tha's about 57 psi suction on R-22, didn't look up 410A. txv controls superheat only has control of suction pressure indirectly

    Yeah,
    This is why I put a freeze stat on the evaporator. It breaks Y1 to the outdoor unit only. I knew there was a chance I could have it ice up and didn't want to deal with those issues.

    Does this mean, the only real concern when running in lower ambients (40s, 50s etc) is icing up? So as long as I don't freeze, I'm golden?

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • ChrisJ
    ChrisJ Member Posts: 13,558
    edited July 2017
    This was when it was in the mid 70s out, I'm anxious to see how it does when it's in the high 80s. The long run time in low stage was just because I fired it up and walked away for a bit. I suspect it stabilized long before that.





    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • ChrisJ
    ChrisJ Member Posts: 13,558
    @EBEBRATT-Ed Did you see my question about regarding icing?

    Is freezing up generally the main concern during low ambient operation with systems?

    I have A freeze stat on the evaporator that shuts the outdoor unit off, and the Honeywell Prestige is configured to shut the system down if discharge temps hit 40 degrees. So I'm thinking in general, I should be safe even without a head pressure control?

    The system runs a few times throughout the might after temps drop, so I'm thinking the compressor should stay plenty warm.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Matt_67
    Matt_67 Member Posts: 231
    Icing is the main concern as long as we are talking 50 degree plus. The balanced port TXV helps with control in low ambient situations. We used a lot of the Johnson Controls P66 controls in the past but it seems like the new motors don't hold up as well as the older ones did. I probably wouldn't do anything but monitor it for a while unless you are going below 50 - especially with the controls you have in place.
    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 13,558
    Matt said:

    Icing is the main concern as long as we are talking 50 degree plus. The balanced port TXV helps with control in low ambient situations. We used a lot of the Johnson Controls P66 controls in the past but it seems like the new motors don't hold up as well as the older ones did. I probably wouldn't do anything but monitor it for a while unless you are going below 50 - especially with the controls you have in place.

    Thanks for responding.
    Yeah, pretty much high 50s low 60s is my main concern. Below 50? Highly doubtful, even for me.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • unclejohn
    unclejohn Member Posts: 1,778
    Carrier uses a 5 ton valve on most of there A./H units that range above 2.5 tons. Have you checked air flow as a possible problem. No I didn't read the entire post so sorry if it's been covered. I did have a lennox system that I installed last Dec. and got a call on this july. Custmer said it iced up. Went over and watched it and found the suction slowly dropped below 105# found that the Sheet metal that covers the top of the A coil had come off and was laying on the side near the drain pan. Put it back on and now ok.
    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 13,558
    edited August 2017
    unclejohn said:

    Carrier uses a 5 ton valve on most of there A./H units that range above 2.5 tons. Have you checked air flow as a possible problem. No I didn't read the entire post so sorry if it's been covered. I did have a lennox system that I installed last Dec. and got a call on this july. Custmer said it iced up. Went over and watched it and found the suction slowly dropped below 105# found that the Sheet metal that covers the top of the A coil had come off and was laying on the side near the drain pan. Put it back on and now ok.

    Thanks for taking the time to read the post and comment John.

    I have a friend that's a Carrier dealer and he told me most of their coils for 3 ton systems have a 3 ton TXV, except for a few that have a 4 ton and those tend to hunt at lower capacities.


    So now I don't know how to believe. :)

    Air flow is not an issue. Besides, even if it was, switching the valve to a 3 ton wouldn't have solved it. However, total static pressure across the air handler is 0.2" in low stage, 0.5" in high stage. This is measured at the input of the evaporator and output of the blower. Coil isn't restricted, everything is in place and clear. I'm running 400 CFM per ton and it's a variable speed blower.

    In high stage I'm seeing 18-20 degree delta T depending on conditions, 18 has been the lowest. In low stage, I've seen 20-22 degrees. This is being measured by a Honeywell Prestige with the duct sensors installed and it waits 10 minutes before logging. This is after I swapped in the 3 ton TXV which is very stable.

    The highest supply temp I've logged is 55 degrees and the lowest was 43 degrees. The TXV seems to control the system very well over a large range of indoor, and outdoor conditions.

    One thing seems to be for sure so far, there's been no shortage of liquid in the evaporator even with it in the high 50s outside. However, I haven't really had a high load on the system under those conditions yet.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • unclejohn
    unclejohn Member Posts: 1,778
    If going to a 3 ton valve fixed it thats good.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,660
    Basically yes low ambient can cause the evap to freeze .I was told that even though water freezes at 32 deg as long as the evap temp stays above about 25 deg it won't freeze because the air is moving. (this is basically a walk in box discussion) Are you hanging meat in there LOL.

    I would check the suction pressure when in a low ambient condition and keep the evap temp at 32 or higher. You have a freeze stat so you should be ok if the compressor hits that "occasionally"

    You don't want the compressor cycling on that freeze stat low limit all the time, that would mean your forcing the compressor outside it's comfort zone.

    If your constantly hitting the freeze stat in low abbient you could go to 450cfm/ton
    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 13,558

    Basically yes low ambient can cause the evap to freeze .I was told that even though water freezes at 32 deg as long as the evap temp stays above about 25 deg it won't freeze because the air is moving. (this is basically a walk in box discussion) Are you hanging meat in there LOL.

    I would check the suction pressure when in a low ambient condition and keep the evap temp at 32 or higher. You have a freeze stat so you should be ok if the compressor hits that "occasionally"

    You don't want the compressor cycling on that freeze stat low limit all the time, that would mean your forcing the compressor outside it's comfort zone.

    If your constantly hitting the freeze stat in low abbient you could go to 450cfm/ton

    You're not the first person to ask me that.......
    Or the 10th...... :p

    I've been keeping the first floor 72F at night, and the second floor 68F at night. That's basically how it balances out with all dampers open and I'm loving it, all the bedrooms are on the second floor. I wanted the second floor to stay cooler, and it does.

    During the day, 75F first floor, 71-72F second floor.


    So far, the only gotcha with this single zone system was on Saturday. We had 20 people over for a party on the first floor and it wasn't really that hot out. The system ended up in high stage (thermostat is on first floor by stairwell, which is my return for the first floor) and while it maintain temp no problem, which I had on 73 just to keep everyone happy, my second floor ended up 66F.

    Such is life. :)
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,660
    Can't design a system for an outlier!!! 20 ppl is a lot of btus probably 300/person or so depending on activity.

    Well actually you can, like doing a lab. Maintain constant 55 deg discharge air with the cooling and run the cooling full blast.with hot gas bypass. If the space gets too cold reheat the air with a steam or water reheat coil for each zone.

    Can't afford to run comfort cooling that way!!! but it will hold the temperature within 1 deg or so with good controls!!
    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 13,558

    Can't design a system for an outlier!!! 20 ppl is a lot of btus probably 300/person or so depending on activity.

    Well actually you can, like doing a lab. Maintain constant 55 deg discharge air with the cooling and run the cooling full blast.with hot gas bypass. If the space gets too cold reheat the air with a steam or water reheat coil for each zone.

    Can't afford to run comfort cooling that way!!! but it will hold the temperature within 1 deg or so with good controls!!

    So in other words..........
    Install TRVs on all of the radiators, and fire up the steam boiler to heat up the second floor........

    Hmmm....... :p
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment