A2L sensor
has anyone had the pleasure of installing this yet? Wiring diagram is a lackluster.
we’ve had a couple dead ACs and updated them to R454B. popped in new TXVs although I understand the existing 410 TXV would work just fine
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The last one we did (this pic) was at a 6-year-old home, built by a “premium” home builder. The ac that died- was never registered. I gave the homeowner a price to change out the compressor, and to replace the entire outdoor unit. They chose the latter. We go to change the TXV and to our surprise, the original TXV bulb was zip tied to the U bends on the coil. The original installers never touched the bulb to fasten it in its proper position.
This home had two 2 ton ac systems. Zillow has it at 3668. The first floor- I’m guessing 50% larger than the second floor. Beth floors had the exact same system. After confirming with ADP that I could drop the AC down to 1.5 tons (the model said 2436), that’s exactly what I did. It ran like a top, 11.4 WB split
yes I dropped the cfm down
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given my experience with electronic refrigerant detectors there isn't enough refrigerant in a residential system to ever set one of those off.
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what is the "cc" output?
you have to put 1/4" qc connectors on all your field wiring or get screw terminals that push on to 1/4" qc connectors?
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Probably flooded and slugged the compressor with the bulb not in the right spot. Cooled really good for a short time.
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all of the black wires are factory installed- just a buncha wire nut connections on the other side. Probably 18 or 20” of length.
CC is the “compressor”, it took me 30 or 40 minutes to unravel the mystery with my multimeter (kinda slow I know- my left brain was fighting my right brain)
apparently, if there’s an alarm, the outdoor unit gets disabled and the fan gets enabled0 -
I find it amazing that you can run LP and NG lies all over the house but install a few lbs. of a A2l refrigerant and you need to monitor it! A2L's do not burn without a flame to exinite them and go out when that flame is extinguished.
Unfortunately, the law is the law. These sensors are now required with the new refrigerants.
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And have kitchen stoves that have no safeties at all on them, you can have a burner go out and just keep feeding fuel……
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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I haven't used that specific brand, it's a little frustrating seeing that diagram…. The Allied Air brands had an external retrofit RDS controller but it just has full thermostat connections on each side of it (in from stat, out to furnace, 4 wire connections for communicating systems as an option) hardest part is setting the dip switch correctly for 1 sensor…. 410a TXV probably works OK but keep in mind there is refrigerant in that sensing bulb that matches the rated refrigerant of the TXV so it will react slightly differently than a TXV that matches the refrigerant in the system.
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Like my 1948 Chambers Stove. Still need to manually light the oven.
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Very off subject, but how does the thermostat work on an oven like that? Just high/low for the burner rather than on/off?
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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Modulates. The flame drops very low.
With 1" of asbestos in the wall the outside only gets warm even after several hours.
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are those asbestos? even back then most appliances used high temp fberglass.
for some reason ranges, cooktops, and ovens were allowed to have wild pilots long after other appliances had to be total shutoff.
then my grandma had a hamilton dryer from the 50's that for unknown reasons shut off the pilot whenever the power went out.
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Does it seem like guys are finally getting an understanding of TXVs or are there still a ton out there that don't know what to do with them?
It seemed like 10 years ago an awful lot didn't understand them and pretty much hated them and claimed they were unnecessary.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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I think most understand how to use them but don't understand what they are actually doing. They are also possibly the most incorrectly diagnosed failure, it's a meme on FB/reddit . picture of a smashed condenser "must be the TXV" etc
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the installer that installed my furnace and ac 25 years ago made some disparaging comment about them when the one he installed appeared to be clogged. he replaced it. i think what actually happened was that some combination of opening the service valves too fast and possibly transporting the condenser in some weird position caused a slug of oil to get propelled through the liquid line and stop at the txv. i think it would have been fine if he just let it sit over night.
he also charged it to the check chart on the condenser instead of measuring subcooling.
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I only get to do this once in a while and usually check the book to make sure I'm right, but I believe you're supposed to open the suction valve first so any oil that gets sucked out will just be pulled right back into the compressor.
But I also think you're right, if it had some time it'd work it's way back.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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Chris that sentiment might go back many many many years. I think all the hvac guys know the basics with TXV.
with that said, the chances of a fixed orifice going awry is pretty super low. I did a couple basic ACs in a couple of apartments I have a couple years ago and I decided to slap in a fixed orificeTX it’s supposed to be a little bit more efficient. The fixed orifice is supposed to be a little bit more reliable.
but we’ve installed many hundreds of coils with TX, extremely few TXV issues
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Txvs in my experience seldom go bad. I have had cap tube to the powerhead vibrate and break or rub through.
Other than that, unless the system gets contaminated there are usually no issues.
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the txv also makes it less likely that you will flood the compressor(though it doesn't eliminate it) and makes it more forgiving of variances in charge.
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One PITA time waster on an A2L system is, if power is interrupted for service, when you turn it back on there's a 5 minute fan only delay. You don't even have 24 vac at the terminals during this delay. So if the thermostat is 24 vac powered, its dead for 5 minutes. Then when 5 minutes is up and the thermostat powers up, IT goes into its own 5 minute compressor protection delay. Really grinds my gears. Yeah, I'm getting paid to wait. But that doesn't make it right.
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depends on the brand of RDS, you can bypass the delay with some units. The manufacturer I deal with only "requires" the delay during initial startup, as apparently the sensor and board are calibrating or something, not sure how its doing that its just what they said lol. right in the manual for ours it tells you how to end the test mode. I would think the universal setups would have that option as well for troubleshooting etc?
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