No apology needed at all. This scenario got my attention when I saw a few things, especially the climate and the SP's for the OAT's. This gives ME a good "comparison point" and you certainly exhibit quite a bit of vigilance, not to mention knowledge, by doing the right things according to Manf. Specs. Further glad to know you're within a good range at this stage of the game. It is difficult to get a good charge/read during colder temps. Ideally, I'm sure you're going to recheck again once warmer since you know what you're doing/up against/using your brain. I'd love to be retired vs disabled, but we're NEVER too "old" to learn!
I don't want to be too repetitive/redundant here either so I apologize in advance if I do.
Also, happened to notice the HP model # appears to be an Amana; could be some Goodman/Amana" joint effort of some sort but all I'm pulling are Amana specs. The "Communicating Stat" and "Comfort Net" portion kinda made me think a bit more on that, & whenever I use that model# you've provided, it's bringing up Amana instead of Goodman. Don't worry about it - just FYI for ya. Amana-Goodman, Goodman-Amana - they all seem to be commingled when searching; story of our lives LOL. That manual Tex
provided is the same one I found for the model#.
I'll try to not irritate much this time & keep it to the "bare bones"
:)
Tex
is one heck of a good knowledge base as well. I've read MANY of his posts since joining and I look up to him whether he realizes it or not
. His "outside the box" thinking makes ME think/explore when I otherwise would not have.
OK -
said by pende_tim:My defrost is a time/temperature sequence. If the sensor is below 28* and a heating call is active, the timer will start a count down. If the temperature goes above 28*, it is my understanding the timer will reset.
Since we're similar in all aspects except our Supplemental heat (you having 10k strips, me having natural gas), I looked up that timer just to get a better idea of what I'm dealing with before speaking about it. This OT18-60A (Outdoor Temp), which I found in the Amana accessories from your model's spec manual, I see where I misinterpreted. That timer only "tolls" during a call, and from what I was seeing in the post(s), I believe I merely misunderstood that it was "tolling" irrespective of what temperature the coil was at. Specs clearly define the operation as:
"...clamped to a feeder tube entering the outdoor coil. Defrost timing periods of 30, 60, or 90 minutes may be selected by connecting the circuit board jumper to 30, 60, or 90 respectively. Accumulation of time for the timing period selected starts when the sensor closes (approximately 34° F), and when the room thermostat calls for heat. At the end of the timing period, the units defrost cycle will be initiated provided the sensor remains closed. When the sensor opens (approximately 60° F), the defrost cycle is terminated and the timing period is reset. If the defrost cycle is not terminated due to the sensor temperature, a ten minute override interrupts the units defrost period." It has a fail-safe as well, so once the 10min mark is reached, the defrost cycle terminates & HP operation resumes & the entire process repeats itself.
Strip SP of 25, IMO, is a good SP for our climates & given the Stat/System is calculating the best use for you, even at the 20d you mentioned, not bad in the least!!!
This is a prime example of GOOD use of staging on an all-electric ("Traditional") HP system in a primarily COLDER climate.
Again, my apologies for the mis-read and believing that REGARDLESS of run-time, you're getting a defrost whether you want one or not! Lesson learned on MY part!
said by pende_tim:The key is to avoid radical manual changes in room temperature. If I have a scheduled temperature change, the 'stat anticipates the upcoming change and starts the heatpump early so it has time to make the adjustment.
Right on the money again; good use of the Stat's function to gradually bring up the temp upon a change in occupancy. Amazing what the recovery function will do - such as today, when we were in the teens, this gave me the first "true" ability to assess the Stat & System's ability to recover without under/overshooting while also ensuring the HP wasn't kicking in. Since you do not have the "Multi-Level Syndrome" as I call it, not feeling the variations is certainly a plus.
said by pende_tim:Now to get into a little theory: how much of an impact does this 3* make on Heating performance as far as efficiency and Delta T? How much of an impact will this make on Cooling performance?
Ughhh... Well - while we
want to be as optimum as possible, getting that 10d sub in these OAT's is gonna be a challenge. You're on 410A as well, that "kinda" changes things a bit but the concept remains the same. Of course, having the specs Tex found helps and using that, while using these "general rules of thumb" so to speak, about all we'd be doing is "Guesstimating" of which I DETEST
. I'll probably be crucified by my colleagues over this but I'll post it anyway for REFERENCE (there - hopefully this disclaimer saves me LOL).
Subcooling at 7d and ?? on superheat (from your post) would
generally indicate your under a bit, but I agree with the Tech who did not want to do that as over would cause problems as well. Once you're in good OAT's, then you'll be *truly* optimized, no guessing, no speculating.
Low subcooling & high superheat= Under;
Low superheat & high subcooling= Over;
Low subcooling & low superheat= (Not your problem here - you would be getting what you are if the case) is a backwards orifice, and yeah I've seen it before unfortunately, no orifice at all, or refrigerant is free-flowing due to an open (or missing) orifice.
Very high superheat & slightly high sub: Usually indicative of a blockage anywhere from the coil/dryers/orifice/TXV/list goes on. Also not the case in your situation
Could have blockage in coil, TXV strainer screen - settings, etc., orifice, filter dryers etc.
Hopefully, the tech took his readings properly to get your current charge proper. 410A's, depending on how much you've read/learned/etc., require multiple measurements of temperatures using a dry & wet bulb readings as well as 410A temp/pressure conversion chart for saturation temps (unless you're gauge set does this for you). The "simplified" version of getting the accurate reads is by following a
precise method - there is no way around it. FYI, this aspect can go on forever in a day, as sat temps change with the refrigerant being used, and I don't want to inundate
.
As reference for ya as it relates to 410A charging for your subcooling:
Measure OAT;
Measure the dry bulb temperature @ the return duct;
Measure wet bulb temperature the same way as the dry bulb @ return; the difference between the wet/dry bulb gives the "load" on the evap;
Measure the liquid-line temperature (has to be attached WELL & a few inches from the service valve) to determine sub-cooling;
Attach gauges & measure liquid and suction pressures. Now we use the conversion chart to change the high side pressure to the saturation temp;
Now we subtract the liquid-line temp from the sat temp giving us the subcooling.
Then we look at the Manf Spec sheet, find the applicable pressures for the OAT as well as the subcooling level needed based on those specs;
If the subcooling is too low, additional refrigerant is needed; if too high, too much refrigerant is in the system & will need to be recovered PROPERLY, not just vented.
Subcooling can have a "double-check" by also measuring the temp @ the TXV to see if there's any differences in the read as you shouldn't have a difference.
On the gauge set I have, it's an expensive one I got before my "demise" & inability to walk again, all this gets all the reads & sats through the age of digital technology. Some of the older gauges/temp sets would as well & if all else fails, we look at the old-faithful paper charts.
Superheat is performed in the same fashion, but obviously through different reads from the opposite side of the system (Suction side). Superhead temp checked at the end of the evap, at or as close to the TXV expansion bulb, that is in turn converted into saturation temp per the 410A chart, & comparing that read to the read of the ambient at the bulb & the load (WB/DB difference). We get our suction read, convert to saturation the same way, and compare to the ambient temp close to that suction line read.
Obviously, I didn't go totally in-depth as I'm just trying to give the overview.
Delta T: (TD), temp difference across the coil, if you do not know how to take these measurements::
Measure temp @ supply near the coil;
measure temp @ return near the AHU;
Difference between the two is your TD;
Should be around 15-20 degrees. This can also help confirm your subcooling/superheat are up to par. YOUR specs call for 7-9SH & 8-10SC, but - again - risking the overcharge did not outweigh the benefit of throwing in a bit more refrigerant to hit that 10d mark on your subcooling. I would say it's fairly negligible, for now, as long as you are still getting that TD range. If you are NOT, then I would worry about it. Come summertime, you'll be able to get the best charge under the most ideal conditions.
Again, not to get anyone irritated or the equivalent, this was all for FYI or Reference-type purposes only, not for "Have at it" purposes.