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results of AC buck tranny

Started by default August 9, 2020
I wired a 24VAC transformer to my Air Conditioner to lower the
incoming line voltage to 220 from ~250 VAC.

The old AC was pulling 2100+ watts worst-case and went to 1700, with
the added transformer. 

Other observations:
It uses ~1500 in the mornings when the differential between inside and
out is close (all readings with the compressor running).  

During the day when the power was up at 1700, I turned the circulation
fan up to "high," and the power dropped to 1550.

That may be more efficient all-around, but I'll have to watch it for a
bit longer to see.  My gut says it is more efficient to just keep the
fan on "high,"  but it would be child's play to rewire the circulation
fan so it runs fast when the compressor switches on.  That way the
filters will stay cleaner longer and also contribute to higher
efficiency, while still circulating the air enough to monitor the air
temperature.

The AC is an old window unit that was broken when I got it - I found
the control board inside with water damage, so gutted the logic out
leaving the power supply and relays, then bought a Chinese "universal"
AC control board to provide the thermostat, fan control, remote, and
compressor delay.
On Sunday, August 9, 2020 at 6:03:30 PM UTC-4, default wrote:
> I wired a 24VAC transformer to my Air Conditioner to lower the > incoming line voltage to 220 from ~250 VAC. > > The old AC was pulling 2100+ watts worst-case and went to 1700, with > the added transformer. > > Other observations: > It uses ~1500 in the mornings when the differential between inside and > out is close (all readings with the compressor running). > > During the day when the power was up at 1700, I turned the circulation > fan up to "high," and the power dropped to 1550. > > That may be more efficient all-around, but I'll have to watch it for a > bit longer to see. My gut says it is more efficient to just keep the > fan on "high," but it would be child's play to rewire the circulation > fan so it runs fast when the compressor switches on. That way the > filters will stay cleaner longer and also contribute to higher > efficiency, while still circulating the air enough to monitor the air > temperature. > > The AC is an old window unit that was broken when I got it - I found > the control board inside with water damage, so gutted the logic out > leaving the power supply and relays, then bought a Chinese "universal" > AC control board to provide the thermostat, fan control, remote, and > compressor delay.
Turning off the fan lowers efficiency. It is needed to keep the air circulating around the room, and to warm the condenser back to room temperature rather than let outside heat leak in to do that job.
On Sun, 9 Aug 2020 18:28:35 -0700 (PDT), Michael Terrell
<terrell.michael.a@gmail.com> wrote:

>On Sunday, August 9, 2020 at 6:03:30 PM UTC-4, default wrote: >> I wired a 24VAC transformer to my Air Conditioner to lower the >> incoming line voltage to 220 from ~250 VAC. >> >> The old AC was pulling 2100+ watts worst-case and went to 1700, with >> the added transformer. >> >> Other observations: >> It uses ~1500 in the mornings when the differential between inside and >> out is close (all readings with the compressor running). >> >> During the day when the power was up at 1700, I turned the circulation >> fan up to "high," and the power dropped to 1550. >> >> That may be more efficient all-around, but I'll have to watch it for a >> bit longer to see. My gut says it is more efficient to just keep the >> fan on "high," but it would be child's play to rewire the circulation >> fan so it runs fast when the compressor switches on. That way the >> filters will stay cleaner longer and also contribute to higher >> efficiency, while still circulating the air enough to monitor the air >> temperature. >> >> The AC is an old window unit that was broken when I got it - I found >> the control board inside with water damage, so gutted the logic out >> leaving the power supply and relays, then bought a Chinese "universal" >> AC control board to provide the thermostat, fan control, remote, and >> compressor delay. > >Turning off the fan lowers efficiency. It is needed to keep the air circulating around the room, and to warm the condenser back to room temperature rather than let outside heat leak in to do that job.
I didn't say it didn't. What surprised me was that it uses significantly lower power by switching the circulation fan up to "high." The fan itself uses 20 watts more on high versus low, but the compressor uses 150+ watts less when the circulation fan is on high. I'm considering what it would take to add the option of preempting the fan to high whenever the compressor is running no matter what setting the fan is set to. The added noise the fan makes on high seems insignificant.
Michael Terrell <terrell.michael.a@gmail.com> wrote:
> On Sunday, August 9, 2020 at 6:03:30 PM UTC-4, default wrote: >> I wired a 24VAC transformer to my Air Conditioner to lower the >> incoming line voltage to 220 from ~250 VAC. >> >> The old AC was pulling 2100+ watts worst-case and went to 1700, with >> the added transformer. >> >> Other observations: >> It uses ~1500 in the mornings when the differential between inside and >> out is close (all readings with the compressor running). >> >> During the day when the power was up at 1700, I turned the circulation >> fan up to "high," and the power dropped to 1550. >> >> That may be more efficient all-around, but I'll have to watch it for a >> bit longer to see. My gut says it is more efficient to just keep the >> fan on "high," but it would be child's play to rewire the circulation >> fan so it runs fast when the compressor switches on. That way the >> filters will stay cleaner longer and also contribute to higher >> efficiency, while still circulating the air enough to monitor the air >> temperature. >> >> The AC is an old window unit that was broken when I got it - I found >> the control board inside with water damage, so gutted the logic out >> leaving the power supply and relays, then bought a Chinese "universal" >> AC control board to provide the thermostat, fan control, remote, and >> compressor delay. > > Turning off the fan lowers efficiency. It is needed to keep the air > circulating around the room, and to warm the condenser back to room > temperature rather than let outside heat leak in to do that job.
The condenser is in the outside on the AC unit and the fan cools it. My guess for the increased power draw with the fan in a low setting is the compressor working way harder due to increased pressures as the unit as it's not able to rejected heat properly. Are the coils clean? The surface of the fins can be be caked in dirt with the outside looking clean. If you can program all sorts of stuff on that univeral controller you'd still want the fan to be off shortly after the compressor stops, otherwise you're just blowing moisture from the evaporator coil back into your living space. That is if humidity is an issue where you live.
On Mon, 10 Aug 2020 08:30:52 +0000 (UTC), Cydrome Leader
<presence@MUNGEpanix.com> wrote:

>Michael Terrell <terrell.michael.a@gmail.com> wrote: >> On Sunday, August 9, 2020 at 6:03:30 PM UTC-4, default wrote: >>> I wired a 24VAC transformer to my Air Conditioner to lower the >>> incoming line voltage to 220 from ~250 VAC. >>> >>> The old AC was pulling 2100+ watts worst-case and went to 1700, with >>> the added transformer. >>> >>> Other observations: >>> It uses ~1500 in the mornings when the differential between inside and >>> out is close (all readings with the compressor running). >>> >>> During the day when the power was up at 1700, I turned the circulation >>> fan up to "high," and the power dropped to 1550. >>> >>> That may be more efficient all-around, but I'll have to watch it for a >>> bit longer to see. My gut says it is more efficient to just keep the >>> fan on "high," but it would be child's play to rewire the circulation >>> fan so it runs fast when the compressor switches on. That way the >>> filters will stay cleaner longer and also contribute to higher >>> efficiency, while still circulating the air enough to monitor the air >>> temperature. >>> >>> The AC is an old window unit that was broken when I got it - I found >>> the control board inside with water damage, so gutted the logic out >>> leaving the power supply and relays, then bought a Chinese "universal" >>> AC control board to provide the thermostat, fan control, remote, and >>> compressor delay. >> >> Turning off the fan lowers efficiency. It is needed to keep the air >> circulating around the room, and to warm the condenser back to room >> temperature rather than let outside heat leak in to do that job. > >The condenser is in the outside on the AC unit and the fan cools it. My >guess for the increased power draw with the fan in a low setting is the >compressor working way harder due to increased pressures as the unit as >it's not able to rejected heat properly. Are the coils clean? The surface >of the fins can be be caked in dirt with the outside looking clean. If you >can program all sorts of stuff on that univeral controller you'd still >want the fan to be off shortly after the compressor stops, otherwise >you're just blowing moisture from the evaporator coil back into your >living space. That is if humidity is an issue where you live.
Good point. The same fan that cools the condenser circulates the air, so shutting it off entirely will allow the air to stratify and the thermostat may not be showing the actual air temp in the room. Ideally, I should have two separate fans. That may be too much of a modification to make to this old AC. It would be a fun enough project, but the thing is big, very heavy, and hard to work with.
default <default@defaulter.net> wrote:
> On Mon, 10 Aug 2020 08:30:52 +0000 (UTC), Cydrome Leader > <presence@MUNGEpanix.com> wrote: > >>Michael Terrell <terrell.michael.a@gmail.com> wrote: >>> On Sunday, August 9, 2020 at 6:03:30 PM UTC-4, default wrote: >>>> I wired a 24VAC transformer to my Air Conditioner to lower the >>>> incoming line voltage to 220 from ~250 VAC. >>>> >>>> The old AC was pulling 2100+ watts worst-case and went to 1700, with >>>> the added transformer. >>>> >>>> Other observations: >>>> It uses ~1500 in the mornings when the differential between inside and >>>> out is close (all readings with the compressor running). >>>> >>>> During the day when the power was up at 1700, I turned the circulation >>>> fan up to "high," and the power dropped to 1550. >>>> >>>> That may be more efficient all-around, but I'll have to watch it for a >>>> bit longer to see. My gut says it is more efficient to just keep the >>>> fan on "high," but it would be child's play to rewire the circulation >>>> fan so it runs fast when the compressor switches on. That way the >>>> filters will stay cleaner longer and also contribute to higher >>>> efficiency, while still circulating the air enough to monitor the air >>>> temperature. >>>> >>>> The AC is an old window unit that was broken when I got it - I found >>>> the control board inside with water damage, so gutted the logic out >>>> leaving the power supply and relays, then bought a Chinese "universal" >>>> AC control board to provide the thermostat, fan control, remote, and >>>> compressor delay. >>> >>> Turning off the fan lowers efficiency. It is needed to keep the air >>> circulating around the room, and to warm the condenser back to room >>> temperature rather than let outside heat leak in to do that job. >> >>The condenser is in the outside on the AC unit and the fan cools it. My >>guess for the increased power draw with the fan in a low setting is the >>compressor working way harder due to increased pressures as the unit as >>it's not able to rejected heat properly. Are the coils clean? The surface >>of the fins can be be caked in dirt with the outside looking clean. If you >>can program all sorts of stuff on that univeral controller you'd still >>want the fan to be off shortly after the compressor stops, otherwise >>you're just blowing moisture from the evaporator coil back into your >>living space. That is if humidity is an issue where you live. > > Good point. The same fan that cools the condenser circulates the > air, so shutting it off entirely will allow the air to stratify and > the thermostat may not be showing the actual air temp in the room. > > Ideally, I should have two separate fans. That may be too much of a > modification to make to this old AC. It would be a fun enough > project, but the thing is big, very heavy, and hard to work with.
Can you setup some sort of High speed with compressor on and low speed with it off? I prefer old window units with real switches that don't need a remote. I should test the 25 year old one soon too. New window units have terrible fan bearings, clearly designed to die on you.
On Wed, 12 Aug 2020 00:12:05 +0000 (UTC), Cydrome Leader
<presence@MUNGEpanix.com> wrote:

>default <default@defaulter.net> wrote: >> On Mon, 10 Aug 2020 08:30:52 +0000 (UTC), Cydrome Leader >> <presence@MUNGEpanix.com> wrote: >> >>>Michael Terrell <terrell.michael.a@gmail.com> wrote: >>>> On Sunday, August 9, 2020 at 6:03:30 PM UTC-4, default wrote: >>>>> I wired a 24VAC transformer to my Air Conditioner to lower the >>>>> incoming line voltage to 220 from ~250 VAC. >>>>> >>>>> The old AC was pulling 2100+ watts worst-case and went to 1700, with >>>>> the added transformer. >>>>> >>>>> Other observations: >>>>> It uses ~1500 in the mornings when the differential between inside and >>>>> out is close (all readings with the compressor running). >>>>> >>>>> During the day when the power was up at 1700, I turned the circulation >>>>> fan up to "high," and the power dropped to 1550. >>>>> >>>>> That may be more efficient all-around, but I'll have to watch it for a >>>>> bit longer to see. My gut says it is more efficient to just keep the >>>>> fan on "high," but it would be child's play to rewire the circulation >>>>> fan so it runs fast when the compressor switches on. That way the >>>>> filters will stay cleaner longer and also contribute to higher >>>>> efficiency, while still circulating the air enough to monitor the air >>>>> temperature. >>>>> >>>>> The AC is an old window unit that was broken when I got it - I found >>>>> the control board inside with water damage, so gutted the logic out >>>>> leaving the power supply and relays, then bought a Chinese "universal" >>>>> AC control board to provide the thermostat, fan control, remote, and >>>>> compressor delay. >>>> >>>> Turning off the fan lowers efficiency. It is needed to keep the air >>>> circulating around the room, and to warm the condenser back to room >>>> temperature rather than let outside heat leak in to do that job. >>> >>>The condenser is in the outside on the AC unit and the fan cools it. My >>>guess for the increased power draw with the fan in a low setting is the >>>compressor working way harder due to increased pressures as the unit as >>>it's not able to rejected heat properly. Are the coils clean? The surface >>>of the fins can be be caked in dirt with the outside looking clean. If you >>>can program all sorts of stuff on that univeral controller you'd still >>>want the fan to be off shortly after the compressor stops, otherwise >>>you're just blowing moisture from the evaporator coil back into your >>>living space. That is if humidity is an issue where you live. >> >> Good point. The same fan that cools the condenser circulates the >> air, so shutting it off entirely will allow the air to stratify and >> the thermostat may not be showing the actual air temp in the room. >> >> Ideally, I should have two separate fans. That may be too much of a >> modification to make to this old AC. It would be a fun enough >> project, but the thing is big, very heavy, and hard to work with. > >Can you setup some sort of High speed with compressor on and low speed >with it off? I prefer old window units with real switches that don't need >a remote. I should test the 25 year old one soon too. New window units >have terrible fan bearings, clearly designed to die on you. >
I can, and that's what I'm planning on doing. I got a 3PDT relay and plan to wire that to the compressor and fan. If I get fancy I could also put in a slow cycle timer to goose the fan on and off periodically when the compressor isn't running. I got the remote, because if the old lady and I are getting hot and heavy, I don't want to climb out of bed to make adjustments.
default <default@defaulter.net> wrote:
> On Wed, 12 Aug 2020 00:12:05 +0000 (UTC), Cydrome Leader > <presence@MUNGEpanix.com> wrote: > >>default <default@defaulter.net> wrote: >>> On Mon, 10 Aug 2020 08:30:52 +0000 (UTC), Cydrome Leader >>> <presence@MUNGEpanix.com> wrote: >>> >>>>Michael Terrell <terrell.michael.a@gmail.com> wrote: >>>>> On Sunday, August 9, 2020 at 6:03:30 PM UTC-4, default wrote: >>>>>> I wired a 24VAC transformer to my Air Conditioner to lower the >>>>>> incoming line voltage to 220 from ~250 VAC. >>>>>> >>>>>> The old AC was pulling 2100+ watts worst-case and went to 1700, with >>>>>> the added transformer. >>>>>> >>>>>> Other observations: >>>>>> It uses ~1500 in the mornings when the differential between inside and >>>>>> out is close (all readings with the compressor running). >>>>>> >>>>>> During the day when the power was up at 1700, I turned the circulation >>>>>> fan up to "high," and the power dropped to 1550. >>>>>> >>>>>> That may be more efficient all-around, but I'll have to watch it for a >>>>>> bit longer to see. My gut says it is more efficient to just keep the >>>>>> fan on "high," but it would be child's play to rewire the circulation >>>>>> fan so it runs fast when the compressor switches on. That way the >>>>>> filters will stay cleaner longer and also contribute to higher >>>>>> efficiency, while still circulating the air enough to monitor the air >>>>>> temperature. >>>>>> >>>>>> The AC is an old window unit that was broken when I got it - I found >>>>>> the control board inside with water damage, so gutted the logic out >>>>>> leaving the power supply and relays, then bought a Chinese "universal" >>>>>> AC control board to provide the thermostat, fan control, remote, and >>>>>> compressor delay. >>>>> >>>>> Turning off the fan lowers efficiency. It is needed to keep the air >>>>> circulating around the room, and to warm the condenser back to room >>>>> temperature rather than let outside heat leak in to do that job. >>>> >>>>The condenser is in the outside on the AC unit and the fan cools it. My >>>>guess for the increased power draw with the fan in a low setting is the >>>>compressor working way harder due to increased pressures as the unit as >>>>it's not able to rejected heat properly. Are the coils clean? The surface >>>>of the fins can be be caked in dirt with the outside looking clean. If you >>>>can program all sorts of stuff on that univeral controller you'd still >>>>want the fan to be off shortly after the compressor stops, otherwise >>>>you're just blowing moisture from the evaporator coil back into your >>>>living space. That is if humidity is an issue where you live. >>> >>> Good point. The same fan that cools the condenser circulates the >>> air, so shutting it off entirely will allow the air to stratify and >>> the thermostat may not be showing the actual air temp in the room. >>> >>> Ideally, I should have two separate fans. That may be too much of a >>> modification to make to this old AC. It would be a fun enough >>> project, but the thing is big, very heavy, and hard to work with. >> >>Can you setup some sort of High speed with compressor on and low speed >>with it off? I prefer old window units with real switches that don't need >>a remote. I should test the 25 year old one soon too. New window units >>have terrible fan bearings, clearly designed to die on you. >> > I can, and that's what I'm planning on doing. I got a 3PDT relay > and plan to wire that to the compressor and fan. If I get fancy I > could also put in a slow cycle timer to goose the fan on and off > periodically when the compressor isn't running. > > I got the remote, because if the old lady and I are getting hot and > heavy, I don't want to climb out of bed to make adjustments.
This project sounds fun. You could even move the temp sensor way from the intake of the AC unit. What type of univeral controller thingy did you buy? It's mostly too humid there, but I've wanted to setup what's basically an economizer in a window to just shut off the AC (it's central now) and take in fresh air from outside at night when the temps drop. I can't really fuss with the windows too much so the other issue becomes sucking in rain or stuff like that.
On Mon, 17 Aug 2020 05:52:28 +0000 (UTC), Cydrome Leader
<presence@MUNGEpanix.com> wrote:

>default <default@defaulter.net> wrote: >> On Wed, 12 Aug 2020 00:12:05 +0000 (UTC), Cydrome Leader >> <presence@MUNGEpanix.com> wrote: >> >>>default <default@defaulter.net> wrote: >>>> On Mon, 10 Aug 2020 08:30:52 +0000 (UTC), Cydrome Leader >>>> <presence@MUNGEpanix.com> wrote: >>>> >>>>>Michael Terrell <terrell.michael.a@gmail.com> wrote: >>>>>> On Sunday, August 9, 2020 at 6:03:30 PM UTC-4, default wrote: >>>>>>> I wired a 24VAC transformer to my Air Conditioner to lower the >>>>>>> incoming line voltage to 220 from ~250 VAC. >>>>>>> >>>>>>> The old AC was pulling 2100+ watts worst-case and went to 1700, with >>>>>>> the added transformer. >>>>>>> >>>>>>> Other observations: >>>>>>> It uses ~1500 in the mornings when the differential between inside and >>>>>>> out is close (all readings with the compressor running). >>>>>>> >>>>>>> During the day when the power was up at 1700, I turned the circulation >>>>>>> fan up to "high," and the power dropped to 1550. >>>>>>> >>>>>>> That may be more efficient all-around, but I'll have to watch it for a >>>>>>> bit longer to see. My gut says it is more efficient to just keep the >>>>>>> fan on "high," but it would be child's play to rewire the circulation >>>>>>> fan so it runs fast when the compressor switches on. That way the >>>>>>> filters will stay cleaner longer and also contribute to higher >>>>>>> efficiency, while still circulating the air enough to monitor the air >>>>>>> temperature. >>>>>>> >>>>>>> The AC is an old window unit that was broken when I got it - I found >>>>>>> the control board inside with water damage, so gutted the logic out >>>>>>> leaving the power supply and relays, then bought a Chinese "universal" >>>>>>> AC control board to provide the thermostat, fan control, remote, and >>>>>>> compressor delay. >>>>>> >>>>>> Turning off the fan lowers efficiency. It is needed to keep the air >>>>>> circulating around the room, and to warm the condenser back to room >>>>>> temperature rather than let outside heat leak in to do that job. >>>>> >>>>>The condenser is in the outside on the AC unit and the fan cools it. My >>>>>guess for the increased power draw with the fan in a low setting is the >>>>>compressor working way harder due to increased pressures as the unit as >>>>>it's not able to rejected heat properly. Are the coils clean? The surface >>>>>of the fins can be be caked in dirt with the outside looking clean. If you >>>>>can program all sorts of stuff on that univeral controller you'd still >>>>>want the fan to be off shortly after the compressor stops, otherwise >>>>>you're just blowing moisture from the evaporator coil back into your >>>>>living space. That is if humidity is an issue where you live. >>>> >>>> Good point. The same fan that cools the condenser circulates the >>>> air, so shutting it off entirely will allow the air to stratify and >>>> the thermostat may not be showing the actual air temp in the room. >>>> >>>> Ideally, I should have two separate fans. That may be too much of a >>>> modification to make to this old AC. It would be a fun enough >>>> project, but the thing is big, very heavy, and hard to work with. >>> >>>Can you setup some sort of High speed with compressor on and low speed >>>with it off? I prefer old window units with real switches that don't need >>>a remote. I should test the 25 year old one soon too. New window units >>>have terrible fan bearings, clearly designed to die on you. >>> >> I can, and that's what I'm planning on doing. I got a 3PDT relay >> and plan to wire that to the compressor and fan. If I get fancy I >> could also put in a slow cycle timer to goose the fan on and off >> periodically when the compressor isn't running. >> >> I got the remote, because if the old lady and I are getting hot and >> heavy, I don't want to climb out of bed to make adjustments. > >This project sounds fun. You could even move the temp sensor way from the >intake of the AC unit. What type of univeral controller thingy did you >buy? It's mostly too humid there, but I've wanted to setup what's >basically an economizer in a window to just shut off the AC (it's central >now) and take in fresh air from outside at night when the temps drop. I >can't really fuss with the windows too much so the other issue becomes >sucking in rain or stuff like that.
https://tinyurl.com/y2qkmf9z Looks like the same one I used (some years ago) They say it is for mini-split AC's but it works fine for window units. (one unused relay - for the louver movement) I built some Bahamas Shutters for the bedroom windows. Painted white, they let the light in but keep the heat and rain out. I used wood and they do require yearly maintenance but have been working for ~12 years now. Took me a day to make the pair, and another to paint them. I didn't make a jig but carefully marked the wood and cut the six vertical pieces as a bundle on a table saw. Aluminum would have been a much better choice, or maybe epoxy coated wood to minimize the upkeep.